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Potentiometric maps for low to high flow conditions, Barton Springs segment of the Edwards Aquifer, Central Texas

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Potentiometric maps for low to high flow conditions, Barton Springs segment of the Edwards Aquifer, Central Texas
Alternate Title:
BSEACD Report of Investigations 2007-1201
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Barton Springs/Edwards Aquifer Conservation District
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ABSTRACT Potentiometric maps for the karstic Barton Springs segment of the Edwards Aquifer (Barton Springs aquifer) were constructed using data from high, below average, and low flow conditions. These synoptic potentiometric maps document varying hydrologic conditions and stresses and contain a dense set of data (n= 166 to 231) for this relatively small portion of the Edwards Aquifer (155 sq. mi.), allowing detailed examination of hydrogeologic features and phenomena. Results indicate steep gradients within the extremely dynamic aquifer system, with water-level changes from 20 to 100 feet over large portions of the area. Troughs and ridges in the potentiometric surfaces correspond to preferential flow paths (conduits) with contours significantly changing morphology from one aquifer condition to the next. Influence of discrete and diffuse recharge and discrete discharge (pumping) are evident on the potentiometric surfaces. Potentiometric surfaces for these different conditions provide some insight into the dynamic nature of the southern boundary of the aquifer, and the potential for flow from other sources such as the Trinity Aquifer and saline zone of the Edwards. These maps, and associated data sets, are important for calibrations of numerical models and evaluations of sustainable yield. Potentiometric maps are a significant tool for hydrogeologic characterization of the karst flow system in the aquifer, and when combined with dye tracing and other studies, better characterize the dynamic nature of this system. CONTENTS 5. Abstract 5. Introduction 6. Background 10. Potentiometric Maps 13. Methods 14. Results 38. Discussion 40. Conclusions 41. References 46. Appendix Appendix A: A-1: 1950s Drought of record A-2: July and August 1999 Average Flow A-3: June and July 2001 High Flow A-4: February 2002 High Flow A-5: November 2002 High Flow Potentiometric Map of Southern Groundwater Divide area A-6: October and November 2005 Below Average A-7: July and August 2006 Low Flow A-8: Trinity Potentiometric Data
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Description
ABSTRACT Potentiometric maps for the karstic Barton
Springs segment of the Edwards Aquifer (Barton Springs
aquifer) were constructed using data from high, below
average, and low flow conditions. These synoptic
potentiometric maps document varying hydrologic conditions
and stresses and contain a dense set of data (n= 166 to 231)
for this relatively small portion of the Edwards Aquifer (155
sq. mi.), allowing detailed examination of hydrogeologic
features and phenomena. Results indicate steep gradients
within the extremely dynamic aquifer system, with water-level
changes from 20 to 100 feet over large portions of the area.
Troughs and ridges in the potentiometric surfaces correspond
to preferential flow paths (conduits) with contours
significantly changing morphology from one aquifer condition
to the next. Influence of discrete and diffuse recharge and
discrete discharge (pumping) are evident on the
potentiometric surfaces. Potentiometric surfaces for these
different conditions provide some insight into the dynamic
nature of the southern boundary of the aquifer, and the
potential for flow from other sources such as the Trinity
Aquifer and saline zone of the Edwards. These maps, and
associated data sets, are important for calibrations of
numerical models and evaluations of sustainable yield.
Potentiometric maps are a significant tool for hydrogeologic
characterization of the karst flow system in the aquifer, and
when combined with dye tracing and other studies, better
characterize the dynamic nature of this system. CONTENTS 5.
Abstract 5. Introduction 6. Background 10. Potentiometric
Maps 13. Methods 14. Results 38. Discussion 40. Conclusions
41. References 46. Appendix Appendix A: A-1: 1950s Drought of
record A-2: July and August 1999 Average Flow A-3: June and
July 2001 High Flow A-4: February 2002 High Flow A-5:
November 2002 High Flow Potentiometric Map of Southern
Groundwater Divide area A-6: October and November 2005 Below
Average A-7: July and August 2006 Low Flow A-8: Trinity
Potentiometric Data



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POTENTIOMETRIC MAPS FOR LOW TO HIGH FLOW CONDITIONS, BARTON SPRINGS SEGMENT OF THE EDWARDS AQUIFER, CENTRAL TEXAS BSEACD Report of Investigations 2007-1201 Barton Springs/Edwards Aquifer Conservation District 1124 Regal Row Austin, Texas BSEACD Report of Investigations 2007-1201 i

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Disclaimer All of the information provided in this report is believed to be accurate and reliable; however, the Barton Springs/Edwards Aquifer Conservation District assumes no responsibility for any errors or for the use of the information provided. Cover. Wireframe potentiometric surface maps for high, below average, and low flow conditions in the Barton Springs segment of the Edwards Aquifer. BSEACD Report of Investigations 2007-1201 ii

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POTENTIOMETRIC MAPS FOR LOW TO HIGH FLOW CONDITIONS, BARTON SPRINGS SEGMENT OF THE EDWARDS AQUIFER, CENTRAL TEXAS Brian B. Hunt, P.G., Brian A. Smith, Ph.D., P.G., and Joe Beery Kirk Holland, P.G., General Manager Board of Directors Dr. Robert D. LarsenPresident Precinct 3 Jack GoodmanVice President Precinct 4 Craig SmithSecretary Precinct 5 Chuck Murphy Precinct 1 Gary Franklin Precinct 2 BSEACD Report of Investigations 2007-1201 December 2007 Barton Springs/Edwards Aquifer Conservation District 1124 Regal Row Austin, Texas BSEACD Report of Investigations 2007-1201 iii

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CONTENTS Abstract 5 Introduction 5 Background 6 Potentiometric Maps 10 Methods 13 Results 14 Discussion 38 Conclusions 40 References 41 Appendix 46 Appendix A: A-1: 1950s Drought of record A-2: July and August 1999 AverA-3: June and July 2001 High FloA-4: February 2002 High Flow A-5: November 2002 High Flow Groundwater Divide area A-6: October and November 2005A-7: July and August 2006 Low FA-8: Trinity Potentiometric Data age Flow w Potentiometric Map of Southern Below Average low BSEACD Report of Investigations 2007-1201 iv

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POTENTIOMETRIC MAPS FOR LOW TO HIGH FLOW CONDITIONS, BARTON SPRINGS SEGMENT OF THE EDWARDS AQUIFER, CENTRAL TEXAS Brian B. Hunt, P.G., Brian A. Smith, Ph.D., P.G., and Joe Beery ABSTRACT Potentiometric maps for the karstic Barton Springs segment of the Edwards Aquifer (Barton Springs aquifer) were constructed using data from high, below average, and low flow conditions. These synoptic potentiometric maps document varying hydrologic conditions and stresses and contain a dense set of data (n= 166 to 231) for this relatively small portion of the Edwards Aquifer (155 sq. mi.), allowing detailed examination of hydrogeologic features and phenomena. Results indicate steep gradients within the extremely dynamic aquifer system, with water-level changes from 20 to 100 feet over large portions of the area. Troughs and ridges in the potentiometric surfaces correspond to preferential flow paths (conduits) with contours significantly changing morphology from one aquifer condition to the next. Influence of discrete and diffuse recharge and discrete discharge (pumping) are evident on the potentiometric surfaces. Potentiometric surfaces for these different conditions provide some insight into the dynamic nature of the southern boundary of the aquifer, and the potential for flow from other sources such as the Trinity Aquifer and saline zone of the Edwards. These maps, and associated data sets, are important for calibrations of numerical models and evaluations of sustainable yield. Potentiometric maps are a significant tool for hydrogeologic characterization of the karst flow system in the aquifer, and when combined with dye tracing and other studies, better characterize the dynamic nature of this system. INTRODUCTION Groundwater levels and potentiometric surface maps provide critical information about the hydrologic relationships of recharge and discharge to storage within an aquifer, and the direction of groundwater flow. This report and accompanying compact disk contain a compilation of synoptic potentiometric maps from the study area. The purpose of this report is to provide a foundation of information and data for future hydrogeologic investigations and evaluations of water resources in the Barton Springs/Edwards Aquifer Conservation District (District). These maps and data will be useful for computer modeling, sustainable yield determinations, and resource protection. Location The study area is located along the Balcones Fault Zone of Central Texas within portions of Travis and Hays Counties (Figure 1). BSEACD Report of Investigations 2007-1201 5

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Figure 1. General location map of the District boundaries, rivers, creeks, roads, major cities/towns, springs, and other landmarks. BACKGROUND The Edwards Aquifer of Texas is a karst aquifer developed in faulted and fractured Cretaceous-age limestones and dolomites. Karst is terrain with distinctive hydrology arising from the combination of high rock solubility and well-developed solution channel porosity underground (Ford, 2004). Karst terrains and aquifers are characterized by sinking streams, sinkholes, caves, springs, and an integrated system of pipe-like conduits that rapidly transport groundwater from recharge features to springs (White, 1988; Todd and Mayes, 2004). The Edwards Aquifer system lies within the Miocene-age Balcones Fault Zone (BFZ) of Texas. Hydrologic divides separate the Edwards Aquifer into three segments. Ryder (1996) and Lindgren et al. (2004) provide detailed and regional information on the Edwards Aquifer. The smallest segment, the Barton Springs segment of the Edwards Aquifer, is the subject of this paper. Hereafter this segment is referred to as the Barton Springs aquifer. Detailed and regional information on the Trinity Aquifer is presented in Barker et al. (1994). Barton Springs aquifer The Barton Springs aquifer is 155 mi 2 in area, with about 80% of the area consisting of unconfined aquifer conditions, although the percentage fluctuates according to hydrologic BSEACD Report of Investigations 2007-1201 6

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conditions. The maximum thickness of the Barton Springs aquifer is about 450 feet. The primary discharge point is Barton Springs, located in Barton Creek about mi upstream of its confluence with the Colorado River (Figure 1). The Barton Springs aquifer is bounded to the north by the Colorado River and by the outcrop and saturated thickness of the Edwards Group to the west. The eastern boundary of the aquifer is the interface between fresh and brackish water (>1,000 mg/L total dissolved solids) and is a complex three dimensional boundary commonly known as the saline or bad-water zone. The saline zone of the Edwards Aquifer is also characterized by a decrease in the relative transmissivity (Flores, 1990). Hovorka et al. (1998) describe this boundary as hydrodynamically controlled rather than separated by a distinct hydrologic barrier, although local fault control was noted. The southern hydrologic divide between the Barton Springs aquifer and the San Antonio segment of the Edwards Aquifer is approximately located between Onion Creek and the Blanco River. This divide may fluctuate according to hydrologic conditions, as supported by potentiometric-surface elevations and recent tracer testing results (LBG-Guyton Associates, 1994; Hunt et al., 2005). Mapping of the Barton Springs aquifer has delineated geologic faults and several informal stratigraphic members of the Kainer and Person Formations of the Edwards Group (Rose, 1972), each having distinctive hydrogeologic characteristics (Small et al., 1996). Development of the aquifer was influenced significantly by fracturing and faulting associated with the Miocene-age BFZ and dissolution of limestone and dolomite units by infiltrating meteoric water (Sharp, 1990; Barker et al., 1994; Hovorka et al., 1995). Faults trend predominantly to the northeast and are downthrown to the southeast, with total offset of about 1,100 ft across the study area. As a result of faulting and erosion, the aquifer ranges from about 450 ft at its thickest along the east side, to 0 ft along the west side of the recharge zone (Slade et al., 1986). Dissolution along fractures, faults, and bedding plane partings and within certain lithologic units has created numerous sinkholes, sinking streams, conduits, caves, and springs. Recharge The majority (85%) of recharge to the aquifer is derived from streams originating on the contributing zone, located up gradient and primarily west of the recharge zone (Slade et al., 1986). Water flowing onto the recharge zone sinks into numerous caves, sinkholes, and fractures along its six major (ephemeral) losing streams. The remaining recharge (15%) occurs in the upland areas of the recharge zone (Slade et al., 1986). However, current studies indicate that upland recharge may constitute a larger fraction of recharge (Hauwert, 2006). Mean surface recharge should approximately equal mean discharge, or about 53 cfs; however, maximum recharge rates during flooding may approach 400 cfs (Slade et al., 1986). Studies have shown that recharge is highly variable in space and time and focused within discrete features (Smith et al., 2001). For example, Onion Creek is the largest contributor of recharge (34%) with maximum recharge rates up to 160 cfs (Slade et al., 1986). Antioch Cave is located within Onion Creek and is the largest-capacity recharge feature with an average recharge of 46 cfs and a maximum of 95 cfs during one 100-day study (Fieseler, 1998). BSEACD Report of Investigations 2007-1201 7

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Increased recharge due to urban leakage from leaking water and wastewater lines is another potential source of water (Jack Sharp, personal communication). Investigations are underway to attempt to calculate the potential amount of urban leakage contribution to the Edwards Aquifer. The amount of cross-formational flow (sub-surface recharge) occurring through adjacent aquifers is unknown, although it is thought to be relatively small on the basis of water-budget analysis for surface recharge and discharge (Slade et al., 1985). Under drought and low water-level conditions there could be an increased potential for cross-formational flow from the saline zone and the San Antonio segment of the Edwards Aquifer. Current investigations are underway by the District to estimate the potential for cross-formational flow to the aquifer from the Trinity and the saline-zone of the Edwards units. Massei et al. (2007) attribute up to 20% of the increasing conductance at Barton Springs during low flow (2000) conditions to flow from the saline zone. Based on geochemical data Hauwert et al. (2004) estimate that a flow path along the saline zone contributes about 10-20% of flow to Barton Springs. Groundwater Flow The Edwards Aquifer is inherently heterogeneous and anisotropic, which strongly influences ground water flow and storage (Slade et al., 1985; Maclay and Small, 1986; Hovorka et al., 1996 and 1998; Hunt et al., 2005). The Edwards Aquifer can be described as a triple porosity and permeability system consisting of matrix, fracture, and conduit porosity (Hovorka et al., 1995; Halihan et al., 2000; Lindgren et al., 2004) reflecting an interaction between rock properties, structural history, and hydrologic evolution (Lindgren et al., 2004). In the Barton Springs aquifer groundwater generally flows west to east across the recharge zone, converging with preferential groundwater flow paths sub parallel to major faulting, and then flowing north toward Barton Springs. For the Edwards Aquifer Halihan et al., (1999) describe permeability that varies with the direction and scale of measurement and values ranging over nine orders of magnitude. Accordingly, the system is often characterized as having a slow flow system (diffuse or matrix flow) and a fast flow system (fracture/conduit flow). Mean hydraulic conductivities are two orders of magnitude higher in the confined zone compared to the unconfined zone (Lindgren et al., 2004). Similarly, median specific capacity of wells in the Barton Springs aquifer is higher within the confined zone compared to the unconfined zone (Smith and Hunt, 2004). Matrix permeability is dwarfed by fracture and conduit permeability. Fractures may control flow on the well-scale, with conduits controlling flow on the regional scale (Halihan et al., 2000). Ultimately, it is likely that fractures (enlarged by solution) connect the matrix to the conduits. The probability of wells intersecting conduits is very low (Halihan et al., 2000), therefore most wells are influenced by matrix and fracture permeability, rather than conduit permeability, to varying degrees. This is consistent with a study by Hovorka et al (1998) that reported only 1 percent of flow is from the matrix. However, a trend of relatively high matrix permeability is observed on both sides of the freshwater/saline-water boundary. In contrast, the matrix permeability is relatively low for rocks in the outcrop (Hovorka et al., 1998). Groundwater dye-tracing and other studies demonstrate that a significant component of groundwater flow is discrete, occurring in a well integrated network of conduits, caves, BSEACD Report of Investigations 2007-1201 8

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and smaller dissolution features (Hauwert et al., 2002a; Hauwert et al., 2002b). Interpreted flow paths from tracer testing generally coincide with troughs in the potentiometric surface and are parallel to the N40E (dominant) and N45W (secondary) fault and fracture trends presented on geologic maps, indicating the structural influence on groundwater flow. Rates of groundwater flow along preferential flow paths, determined from dye tracing, can be as fast as 4 to 7 mi/day under high-flow conditions or about 1 mi/day under low-flow conditions (Hauwert et al., 2002a). Despite the rapid groundwater flow rates within conduits, Kresic (2007) states that, a disproportionately larger volume of any karst aquifer has relatively low groundwater velocities (laminar flow) through small fissures and rock matrix. Tracer tests have also helped define groundwater basins such as the Cold Springs, Sunset Valley, and Manchaca sub-basins of the Barton Springs aquifer. Traces from 2 features in Onion Creek have demonstrated divergent flow paths that appear to re-converge before discharging at Barton Springs. In one trace, dye injected into Cripple Crawfish Cave on Onion Creek displayed diverging flow paths to Barton and San Marcos Springs (Hunt et al., 2006). This has implications for the groundwater divide separating the Barton Springs and San Antonio segments of the Edwards Aquifer. Water-Levels and Storage Water levels in the Edwards Aquifer are very dynamic and heterogeneous. Water levels do not show long-term declines in storage, but generally recover from low to previous high conditions quickly (Smith et al., 2001), typical of many karst systems. Water levels and discharge at the springs respond very quickly to recharge events and then decline at variable rates, influenced by both conduit and matrix permeability and storage (Lindgren et al., 2004; Worthington, 2003). Although most wells show a combined influence of matrix and conduit/fracture flow, a continuum exists with a few wells demonstrating a conduit influence while a few others are influenced more by matrix flow (Hunt et al., 2006). Hovorka et al. (1998) report that the majority of water in storage is within the matrix porosity, and only 5-10% of the water is within conduits. Pumping The Barton Springs segment provides water for about 60,000 people and currently has about 7,800 acre-ft/yr (2.5 billion gallons; 11 cfs) of authorized pumping from 94 permit holders. However, in 2007 permitting of the Edwards was effectively capped to 6,100 acre-ft/yr (2.0 billion gallons; 8.5 cfs) under drought conditions (BSEACD, 2007). Groundwater use is characterized as 80% public-supply, 13% industrial (quarry operations), and 7% irrigation (golf courses). The District contains about 1,230 operational wells, with the majority (98%) producing water from the Edwards. Peak pumpage occurs during the summer months (July and August), with up to twice the volume used during that time as during winter months (Hunt et al., 2006). Trinity Aquifer The Trinity Aquifer is composed of Cretaceous-age limestones and sandstones that are divided into the Upper, Middle, and Lower Trinity Aquifers. In the BFZ the Edwards Aquifer both overlies and is adjacent to the Trinity Aquifer system. Groundwater quality of the Trinity Aquifer is generally poorer than the Edwards Aquifer containing higher total dissolved solids (TDS) and undesirable constituents such as sulfates. The boundary between fresh and slightly saline (1,000-3,000 mg/l) water is poorly defined for the Trinity Aquifer. BSEACD Report of Investigations 2007-1201 9

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Along the western part of the District, where the Edwards Aquifer is thin, water-supply wells commonly penetrate the lower Edwards units and are completed in the Upper and Middle Trinity aquifers. The Trinity Aquifer supplies water for public-supply and irrigation uses, which amounted to 44.3 million gallons of permitted water in 2005. Many Trinity wells have open-hole, or multiple zone, completion and produce water from the Upper and Middle Trinity Aquifers, with exact water-bearing units difficult to determine. Upper Trinity Aquifer The Upper Trinity Aquifer is comprised solely of the Upper Glen Rose Formation. The Upper Glen Rose Formation is composed of 350to 400-ft thick beds of alternating limestone, dolomite, marl, and shale; gypsum and anhydrite are common. This aquifer satisfies, almost exclusively, domestic and livestock needs with very small (less than 5 gpm) to small (5 to 20 gpm) yields of mineralized water (relative to the Edwards Aquifer) in the Central Texas Hill Country, and within the western portion of the District (DeCook, 1960; Ashworth, 1983; Muller and McCoy, 1987). Middle Trinity Aquifer The Middle Trinity Aquifer is composed of (from stratigraphically lowest to highest) the Cow Creek, Hensel, and the Lower Glen Rose Formations. The Cow Creek is a massive, sandy dolomitic limestone. The Hensel is composed of alternating gravel, sand, silt, and shale. The lower Glen Rose Formation is composed of massive fossiliferous limestone and dolomite that grade upward into thin beds of limestone, shale, and marl. The thickness of the Middle Trinity averages about 309 ft (Broun et al., 2007). The Middle Trinity Aquifer yields small to moderate quantities of fresh to moderately saline water (Brune and Duffin, 1983). The Middle Trinity Aquifer in the Hill Country varies from unconfined to confined conditions. The Lower Trinity The Lower Trinity Aquifer is separated from the overlying Middle Trinity Aquifer by the Hammett Shale (about 30-60 ft thick). The Lower Trinity Aquifer is composed of the Hosston and overlying Sligo Formations. The Hosston is composed of a conglomerate, sand, siltstone, and shale. The Sligo is composed of limestone and dolomite with local sandy units. The average thickness of the Lower Trinity Aquifer is about 190 ft, however the Lower Trinity Aquifer is rarely fully penetrated and so this may underestimate the thickness (Broun et al., 2007). This aquifer yields small to large amounts of fresh to moderately saline water in the Hill Country (Brune and Duffin, 1983). No wells are known to produce water from the lower Trinity in the District at the time of this report. POTENTIOMETRIC MAPS Groundwater flow systems are three-dimensional with lateral and vertical flow components. The lateral and vertical driving force of water in an aquifer at a particular point is hydraulic head, which is the sum of elevation and water pressure divided by the weight density of water (Winter et al., 1999). Hydraulic head is determined by subtracting the measured depth to water from the elevation of the land surface elevation at a well. Water generally flows BSEACD Report of Investigations 2007-1201 10

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from high head to low head values, characterizing the flow of an aquifer system (Kresic, 2007). Lateral flow can be described by determining the hydraulic head in a lateral distribution of wells and contouring lines of equal hydraulic head (or equipotential lines) resulting in a surface referred to as a water table or potentiometric map for unconfined and confined conditions, respectively (Domenico and Schwartz, 1990). This study presents contours of hydraulic head for both confined and unconfined conditions in a single surface, which is referred to as a potentiometric map throughout this report. Potentiometric maps must be attributed to a single aquifer, and this study recognizes, and presents maps for, the Edwards, Upper Trinity, Middle Trinity, and Lower Trinity Aquifer systems. Vertical flow can be characterized with piezometers (very short screened interval) completed at different depths. Strictly horizontal flow does not exist in aquifer systems (Kresic, 2007). However, at a regional scale it is assumed that significant vertical gradients are absent in the Edwards Aquifer, although this is not likely an accurate assumption at the local scale, especially at recharge or discharge areas. Most wells completed in the Edwards Aquifer are only partially-penetrating in the confined zone and have long screened, or often open hole, intervals. In the unconfined zone, many wells partially penetrate the underlying Upper Trinity Aquifer. Thus, vertical flow cannot be accurately determined within the Edwards Aquifer, although some estimations of vertical flow between the Edwards and Trinity aquifer systems could be made if vertical hydraulic conductivity is known. Potentiometric maps describe the direction of groundwater flow at a particular moment in time. Additional uses of potentiometric maps, under the right conditions, include calculating (Darcian) flow velocity, gradients, total volumetric flow, or gaining a relative sense of the spatial distribution of transmissivity and hydraulic conductivity. According to Darcys law, hydraulic gradients can reflect changes in hydraulic conductivity, changes in aquifer thickness, or cross-formational flow (Domenico and Schwartz, 1990; Kresic, 2007). Influences that impact the hydraulic head and potentiometric surfaces include recharge, discharge (springs and pumping wells), and barometric fluctuations (for confined settings). Observing these influences can lead to a greater understanding of an aquifer system. Potentiometric Maps in Fractured Karst Aquifers Potentiometric maps are commonly constructed for karst regions for understanding groundwater flow (see Previous Studies below). However, they should not be used to solely characterize groundwater flow direction or velocity in a karst aquifer. Potentiometric maps should be combined with hydrogeologic mapping and dye trace studies for a more complete understanding of flow within a karst system (Quinlan, 1989; Kresic, 2007). However, as Kresic (2007) points out, contour maps showing regional flow patterns in karst aquifers may be justified since groundwater flow generally is from recharge areas toward discharge areas and the regional hydraulic gradients will reflect this simple fact. Indeed Quinlan (1989) states that, it is logical, correct, and conventional to interpret the flow direction of ground water perpendicular to the potentiometric contours and downgradient. Sometimes, however, flow lines appear to be parallel to the contours rather than perpendicular to them, as BSEACD Report of Investigations 2007-1201 11

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has been demonstrated in the Edwards Aquifer of Texas (Maclay and Small, 1984; Waterreus and Hammond, 1989). Flow parallel to potentiometric contours has also been documented for the Barton Springs aquifer (Hunt et al., 2006). This type of flow likely reflects two phenomenons: 1) a lack of detailed data in some areas, and 2) refraction of flow due to heterogeneity. Because flow occurs within fractures, conduits, and the matrix, hydraulic heads may not provide a unique answer to determining flow directions. Hydraulic gradient (head loss/flow distance) is very sensitive to the diameter of fractures and conduits. Conduits have much lower gradients and heads than in the surrounding matrix, therefore flow is convergent to conduits (or divergent depending on aquifer conditions). Convergent flow within karst aquifers are a common attribute and has been well documented in the Edwards Aquifer by the dye tracing work of Hauwert et al. (2002). Depending on the hydrologic conditions, conduits can reverse local gradients and flow directions. This has also been observed in the Barton Springs aquifer (Hunt et al., 2006). During periods of rapid recharge the aquifer can behave similar to bank storage phenomenon in rising surface rivers (Palmer, 2004). Rapid flow through conduits can have an impact on hydraulic head measurements of wells completed in or near such a conduit. The hydraulic head may go up or down along the same conduit as the cross-sectional area increases or decreases, respectively (Kresic, 2007). Previous Studies Numerous potentiometric maps have been constructed for the study area (Table 1). Only maps with relatively dense data are included within Table 1. In addition to these maps, a recent publication by the Edwards Aquifer Authority (Hamilton et al., 2006) presents maps from the San Antonio segment of the Edwards Aquifer that extend into the Barton Springs segment, but with relatively sparse data. Table 1. Previously Published Potentiometric Maps Potentiometric Map Date # Wells Barton Springs Mo Avg Flow (cfs) Data Source Comments 1956 Drought of 1956 27 16 11 Slade et al., 1986 1956 August 24 11 DeCook, 1963 Map between Buda and San Marcos 1956 Drought of record* 56 11 Smith and Hunt, 2004 Composite drought of record map; used for sustainable yield evaluations 1978 Spring 41 55-113 Brune and Duffin, 1983 Travis County only 1978 August 71 22 Senger and Kreitler, 1984; Slade et al., 1986 1979 June 18 106 Slade et al., 1986 1979 & 1981 June 26 106, 81 Senger and Kreitler, 1984 Composite high flow map 1981 January 64 49 Slade et al., 1986; Baker et al., 1986 1993 July 17 95 Hauwert and Vickers, 1994; Hauwert et al., 2004 Detailed map of the Sunset Valley Area 1993 March 32 106 Hauwert and Vickers, 1994 1994 August & September 42 33-28 Guyton EAA Report 95-01 Study of southern groundwater divide BSEACD Report of Investigations 2007-1201 12

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Table 1. Previously Published Potentiometric Maps Potentiometric Map Date # Wells Barton Springs Mo Avg Flow (cfs) Data Source Comments 1994 January & Febuary 61 52-50 Guyton EAA Report 95-01 Study of southern groundwater divide 1994 March 31 48 Hauwert and Vickers, 1994 Water quality study 1996 August through November 67 22-31 Hauwert et al., 2004 Dye Trace Study 1996 May through November 65 21-31 BSEACD, 1997 Alternative Regional Water Supply Plan 1997 July through September 9 112-93 Hauwert et al., 2004 Dye Trace Study, Travis County only 1999 July & August* 99 65-55 Scanlon et al., 2001; Smith et al., 2001 Used to calibrate GAM 1999 March through June 95 90-69 Hauwert et al., 2004 Dye Trace study 2000 June & July 105 49-38 Hauwert et al., 2004 Dye Trace study 2001 June & July* 141 96-88 Smith et al., 2001 EPA-funded grant *Indicates figure within the report and data provided in appendix METHODS The maps presented in this report were constructed from a relatively high density of wells for the study area, greater than one well per square mile. Water-level measurements were collected with either manual measurements or with automated recorders. Manual measurements were most often made with a calibrated electric tape (eline) or, less commonly, a steel tape. Notes were made as to whether the depth-to-water measurements were varying over time, or other factors such as pumping were observed. Automated instruments include pressure transducers with data loggers. Manual measurements are generally accurate to within .1 feet. Data Compilation, Validation, and Quality Assurance A systematic quality-assurance review was conducted for this report and data. Data were entered from field sheets into the Districts well database. The database was then queried for specific time periods, well construction, and aquifer information. Locations and elevations of LSD data were cross-checked with published topographic maps. Anomalous data were carefully reviewed. Some data were omitted from the datasets if suspected of significant influence from pumping or other errors. Many wells within the Edwards Aquifer, generally the unconfined area, partially penetrate the Trinity Aquifer and have lower heads than surrounding Edwards Wells (BSEACD, 2004). Data was not used in the Edwards potentiometric maps from wells that significantly penetrate the Trinity Aquifer. For the construction of Trinity potentiometric maps careful examination of well construction is needed. Many wells reported as completed within the Trinity Aquifer are often hybrid completions of the Upper, Middle, and Lower Trinity aquifers. Trinity wells were carefully reviewed and omitted from the datasets if they were deemed to have hybrid completions. BSEACD Report of Investigations 2007-1201 13

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Contouring All water-level data were grided and then contoured using a linear interpolation algorithm by Golden Software SURFER. The computer-generated contours were then manually reinterpreted to account for hydrogeologic boundaries and experience of the authors. Data were gridded and contoured as a single system to include unconfined and confined settings. Datums and Coordinates Water-level measurements are made in reference to a measurement point (MP) at the well head. Commonly, the MP corresponds to the top of casing (TOC). The MP or TOC measurement is subtracted from the depth-to-water measurement to reflect a depth from the land surface datum (LSD). LSD is generally defined as the top of the concrete slab around the casing, or from ground level. All depth to water measurements are from the LSD (in feet). Elevations for LSDs are in feet above mean sea level obtained from USGS topographic maps (10-ft contours), City of Austin topographic maps (2-ft contours), or from surveys. Vertical datums from those maps are either North American Vertical Datum 1929 (NAVD29) or North American Vertical Datum 1988 (NAVD88). Horizontal coordinates are in latitude and longitude. Many of the horizontal coordinates were collected with a Global Positioning System (GPS), or by locating the well on a USGS topographic map, and by survey. Horizontal datums are in World Geodetic System 1984 (WGS84) or North American Datum 1983 (NAD83). RESULTS Tables 2 and 3 list previously unpublished potentiometric maps presented in this study. Figure 2 illustrates the hydrologic conditions of the aquifer based on discharge at Barton Springs during each of the synoptic periods discussed in this report. Potentiometric maps are presented in Figures 3 through 9. Comparisons between these potentiometric maps are included in Figures 10-through 13. Appendix A contains a tabulation of all the data. Table 2: List of Edwards potentiometric maps in the study. Figure Date # wells Barton Springs Discharge (cfs) Comments Figure 4 2002 February 172 105-103 (High) Figure 5 2002 November 93 91-98 (High) Southern divide focused study Figure 7 2005 October & November 231 50 to 43 (Below Average) Figure 9 2006 July & August 166 26 to 22 (Low) Table 3: List of Trinity potentiometric maps in this study. Figure Aquifer Date # wells Hydrologic conditions at Barton Springs Figure 15 Lower Trinity 2002 February 5 Below average Figure 16 Middle Trinity 2005 October & November 6 Below average Figure 18 Upper Trinity 2002 February 7 High flow General Flow Observations for the Barton Springs aquifer Potentiometric maps in this study indicate flow from the west to the east in the unconfined zone under steep gradients. Groundwater then moves northeast toward Barton Springs BSEACD Report of Investigations 2007-1201 14

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within a broad trough and with lower gradients as groundwater approaches confined conditions. The major source for water along the eastern and confined zones appears to be the southwestern area around Onion Creek and potentially from the saline zone. Edwards Aquifer High Flow Conditions Figures 3, 4, and 5 are potentiometric maps representing high flow conditions. Potentiometric troughs along preferential flow paths are pronounced as broad features that extend from San Marcos and Barton Springs. The troughs in the Barton Springs aquifer appear to occur along the west side of the confined boundary (Figures 3 and 4). However, a trough within the confined zone extends along the eastern side of the aquifer from San Marcos Springs north toward the City of Kyle (Figures 3 and 4). Significant mounding due to recharge along Onion Creek is evident in the potentiometric surface during high-flow conditions. For example, Figure 5 shows significant mounding around Antioch Cave. Depressions in the potentiometric surface are evident around pumping centers such as the City of Kyle (Figure 4). Edwards Aquifer Average Flow Conditions Figures 6 and 7 are potentiometric maps representing average and below average flow conditions. Compared to high-flow conditions, potentiometric troughs located in the northern portion of the study area become narrower, with steeper gradients, as recharge and flow decrease. In addition, these troughs in the potentiometric surface appear to develop in the confined portion of the aquifer. The trough extending northeast from San Marcos Springs becomes more pronounced compared to high-flow conditions, although these could be enhanced by pumping. Minor depressions in the potentiometric surface are also evident around pumping centers such as the City of Kyle (Figure 7). Edwards Aquifer Low Flow (Drought) Conditions Figures 8 and 9 are potentiometric maps representing low flow, or drought, conditions. Figure 8 is the drought of record map from Smith and Hunt (2004) and is a composite map (not truly synoptic) with less data when compared to Figure 9. In Figure 9 troughs in the potentiometric surface are very pronounced with steep gradients. Multiple troughs begin to develop as seen in the 500-ft contour. In addition, troughs develop along known preferential flow paths (conduits) documented by dye tracing, such as the one originating at Antioch Cave (Figure 9). Significant troughs in the potentiometric surface appear to develop in the confined portion of the northern study area. Edwards Aquifer Potentiometric Map Comparison Figure 10 is a comparison of the 600-ft contour from the potentiometric maps spanning low to high flow conditions. Significant fluctuation and change of shape in the potentiometric contours occurs from high to low flow conditions. The majority of flow within the boundaries of the Barton Springs aquifer appears to flow toward Barton Springs. However, potentiometric surfaces indicate a southern flow component toward San Marcos Springs at above average flow conditions (> 50 cfs at Barton Springs). Figure 11 illustrates the change of confined to unconfined conditions through each of the synoptic events. Significant changes in the boundary occur within the middle portion of the BSEACD Report of Investigations 2007-1201 15

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study area, particularly between Onion and Slaughter Creeks. Changes in this boundary are much more subdued along the southern groundwater divide and near the spring outlets. Figure 12 illustrates the change in head from low to high flow conditions. More than 100 ft of head fluctuation occurs from high to low flow conditions along potentiometric troughs in the middle portion of the aquifer. The trend in this area is also coincident with northeast-trending faulting (Figure 13), and in the boundary of confined/unconfined conditions. Minor changes in head occur near the springs and the vicinity of the southern groundwater divide. Major preferential flow paths, inferred from dye tracing (Figure 14), coincide with the western margin of the area of greatest head change. Significant amount of head change occurs along the saline-zone boundary and within the saline zone as well. Thus, the fresh-water zone appears to be in hydraulic communication with the saline-water zone. Trinity Potentiometric Maps and Edwards-Trinity Connection Figure 15 illustrates a synoptic event of the Lower Trinity Aquifer relative to the Edwards during high flow conditions. The flow potential is from the Edwards to the Lower Trinity in the western portion of the study area. On the basis of data from other time periods, this relationship appears to persist from low to high flow conditions. Figure 16 illustrates a synoptic event of the Middle Trinity Aquifer relative to the Edwards during average flow conditions. The flow potential is from the Edwards to the middle Trinity in the western portion of the study area. On the basis of data from other time periods, this relationship appears to persist from low to high flow conditions. Figure 17 is a hydrograph illustrating the Edwards and Middle Trinity water levels over time. A shallow Edwards well (~180 ft deep) was drilled adjacent to a Middle Trinity well (~1000 ft deep) in 2003, effectively creating a nested well pair. Data indicate the potential for flow is downward from the Edwards to the Middle Trinity Aquifer for the period of record in the unconfined portion of the Edwards Aquifer (Figure 17). Trinity water levels do not respond to some recharge events that affect Edwards levels. At other times the response to recharge in the Trinity is out of phase with the Edwards levels. Figure 18 illustrates a synoptic event of the Upper Trinity Aquifer relative to the Edwards. Potential for flow is generally downward from the Edwards to the Upper Trinity Aquifer under high flow conditions. This condition persists from high to low flow conditions. Water levels of the Edwards and Upper Trinity are very similar in elevation along the western fringe of the Edwards Aquifer (see 800 ft contour, Figure 18), suggesting good hydraulic communication in this area. Cross Sections Figures 19 through 21 are geologic cross sections with synoptic water-level data superimposed. Most cross sections show relatively consistent water-level changes from high to low flow conditions, with smaller changes along the western portion of the Edwards Aquifer. However, cross section C to C through the area with the greatest head change, reveals a trough formed under low flow conditions, and a mound formed under high-flow conditions. BSEACD Report of Investigations 2007-1201 16

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Heads from the Trinity Aquifer are also displayed, where available, on the cross section. These data support a flow potential from the Edwards toward the various Trinity aquifers in the western portion of the study area. Figure 2: Barton Springs hydrograph denoting dates of synoptic events and relative aquifer conditions. Note the axis break between 1957 and 1999. Solid lines denote 25 th and 75 th percentiles for the period of record. BSEACD Report of Investigations 2007-1201 17

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Figure 3: July 2001 potentiometric map under high flow conditions. This map was modified from Smith et al. (2001). BSEACD Report of Investigations 2007-1201 18

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Figure 4: February 2002 potentiometric map under high flow conditions. BSEACD Report of Investigations 2007-1201 19

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Figure 5: November 2002 potentiometric map of southern groundwater divide under high flow conditions. BSEACD Report of Investigations 2007-1201 20

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Figure 6: July and August 1999 potentiometric map under average flow conditions. BSEACD Report of Investigations 2007-1201 21

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Figure 7: October and November 2005 potentiometric map under below average conditions. BSEACD Report of Investigations 2007-1201 22

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Figure 8: 1950s potentiometric map under drought of record conditions. This map was modified from Smith and Hunt (2004). Onion Creek flow was not gauged during this time but is inferred to have been dry. BSEACD Report of Investigations 2007-1201 23

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Figure 9: July and August 2006 potentiometric map under low flow, or drought, conditions. BSEACD Report of Investigations 2007-1201 24

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Figure 10: Comparison of 600-ft potentiometric map contours spanning low to high flow conditions. BSEACD Report of Investigations 2007-1201 25

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Figure 11: Map illustrating the change of confined to unconfined conditions under varying aquifer conditions. BSEACD Report of Investigations 2007-1201 26

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Figure 12: Map illustrating the change in head from low flow to high flow aquifer conditions. BSEACD Report of Investigations 2007-1201 27

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Figure 13. Map of faults in the Edwards Aquifer. Note the Rose Diagram from Alexander (1990) indicating a strong NE structural grain. Source of faults from Small et al. (1996) and the G.A.T. (Geologic Atlas of Texas). BSEACD Report of Investigations 2007-1201 28

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Figure 14: Map illustrating the change in head from low flow to high flow aquifer conditions and dye trace results. Dye trace results summarized from Hauwert et al., 2002 and Hunt et al., 2006. BSEACD Report of Investigations 2007-1201 29

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Figure 15: Composite Edwards and Lower Trinity potentiometric map, February 2002. BSEACD Report of Investigations 2007-1201 30

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Figure 16: Composite Edwards and Middle Trinity potentiometric map. BSEACD Report of Investigations 2007-1201 31

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Figure 17: Edwards-Trinity hydrograph from the Wentzel (Borheim) Quarry, located in the Edwards Aquifer recharge zone in Hays County. The quarry lake is located very close to the Edwards well. Similar hydrologic responses between the well and quarry lake suggest that the lake represents the water table of the aquifer. The Middle Trinity well is located adjacent to the Edwards well. Data indicate the potential for flow is downward from the Edwards to the Middle Trinity Aquifer for the period of record in the unconfined portion of the Edwards Aquifer. Water levels in the Trinity well appear to be influenced by localized pumping. BSEACD Report of Investigations 2007-1201 32

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Figure 18: Composite Edwards and Upper Trinity potentiometric map. BSEACD Report of Investigations 2007-1201 33

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BSEACD Report of Investigations 2007-1201 34

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Figure 19. Cross sections A-A and B-B. BSEACD Report of Investigations 2007-1201 35

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BSEACD Report of Investigations 2007-1201 36 Figure 20. Cross section C-C along the middle of the Barton Springs aquifer. Note the pronounced trough and then mound that develop from low to high flow conditions, respectively.

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CD Report of Investigations 2007-1201 37 Figure 21. Cross section D-D near the southern groundwater divide of the Barton Springs aquifer. BSEA

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DISCUSSION Potentiometric maps presented in this report generally agree with previously published potentiometric maps and studies of groundwater flow in the aquifer. One of the biggest differences from previously published maps and this study is the relatively dense set of data in this study, allowing more detailed maps of the aquifer system and identification of unique hydrologic features. Potentiometric maps provide good insight into the boundaries of the aquifer system. The southern groundwater divide, located between Onion Creek and the Blanco River, when compared with dye tracing results (Hunt et al., 2006) indicate the divide may be hydrodynamic in nature, rather than a distinct hydrologic barrier. This is similar to the conclusions of LBG-Guyton Associates (1994). Gradients throughout the aquifer change from high to low flow conditions. Increased gradients, and therefore potential for flow, from the western portion of the aquifer and the saline zone are increased under low-flow conditions. Unique hydrologic features observed on the potentiometric contour maps include linear features, such as troughs and ridges, and localized features, such as mounds and depressions. Troughs in the potentiometric surface are often associated with preferential flow paths, or conduits (Hauwert et al., 2002). Ridges in the potentiometric surface also appear, at least during active recharge conditions, to define preferential flow paths in the confined zone (Hunt et al., 2006). Mounding in the potentiometric surface is most evident over the losing (recharging) streams, such as Onion Creek, which contribute the majority of recharge to the aquifer system (Figures 4 and 5). Depressions in the potentiometric surface can be the result of localto regional-scale pumping (Figure 3). However, many factors, such as the vertical and lateral distribution of hydraulic properties, can influence heads and therefore potentiometric contours. Vertical and lateral hydraulic properties of the Edwards and Trinity Aquifers are influenced by fractures, faults, conduits and hydrostratigraphic units. Anomalous potentiometric contours can be explained by those factors, each contributing to the heterogeneity and anisotropy of the aquifer. Ultimately, the maps limited in describing flow by the granularity, or lack of, data. Preceding hydrologic conditions, and not the season or year, are most critical to the contours on the potentiometric maps (Figures 4 and 5; Slade et al., 1986). This is due to the fact that the Edwards Aquifer is a very dynamic system and fully recovers from impacts of drought and pumping during times of moderate to high recharge. This is also apparent on the springflow hydrographs of Barton Springs (Figure 2). However, as the stress of pumping increases with increasing demand, those stresses should be increasingly observed on the potentiometric map. For example, dewatering in the area north of Onion Creek and south of Slaughter is apparent in this study as aquifer conditions vary from high to low. This was noted by Smith and Hunt (2004) to be an area of concern for groundwater availability during drought conditions and increasing pumping. BSEACD Report of Investigations 2007-1201 38

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The recent (August 2006) low flow potentiometric map, which was constructed at the lowest point after a year-long drought, is very similar to the potentiometric map representing the 1950s 7-year drought of record (DOR) (see Figures 8 and 9, 19 through 21). The similarity of water levels in Figures 8 and 9 suggests that current pumping under a moderate drought induces groundwater elevations similar to the DOR. However, there is an apparent discontinuity between these maps and their corresponding springflow. For example, despite reaching historic low water levels in August 2006, discharge at Barton Springs only dropped to 19 cfs (even with 8 cfs of pumping), which is not the equivalent 1950s DOR discharge of 10 cfs, which had less than 1 cfs of pumping at that time. This apparent discontinuity may be due to increased urban leakage in the urbanized portion of the study area that may be augmenting springflow during drought (Garcia-Fresca, 2004; Sharp et al., 2007). Further study is needed to understand this apparent phenomenon. This study has demonstrated that potentiometric maps should be combined with other studies to properly characterize flow in this aquifer. In particular, for a karst aquifer, tracer studies are critical to understanding groundwater flow. Tracer studies have identified radial and divergent flows that are not evident on the potentiometric maps. Additionally, sub-groundwater basins of the aquifer (e.g. Cold Springs, Sunset Valley, and Manchaca) identified by dye tracing are not apparent on potentiometric maps (Hauwert et al., 2002). Trinity Aquifer potentiometric maps (Figures 15 through 18) and cross sections (Figures 19 through 21) presented in this study contain very limited data. These figures may represent only local conditions or relationships. However, the maps consistently indicate a vertical potential for flow from the Edwards Aquifer toward the underlying Trinity Aquifer in the western portion of the Edwards Aquifer regardless of hydrologic conditions. In the eastern, confined portions of the Edwards Aquifer, flow potentials might be reversed from the Trinity to the Edwards. Geochemical studies indicate contribution of flow from the Trinity to the Edwards (Slade et al., 1986; Senger and Kreitler, 1984). More data are needed to better characterize the flow potential under varying spatial and temporal conditions. These maps will provide a foundation for a better understanding of groundwater flow within the Edwards and Trinity Aquifers. Since the maps presented in this study span the hydrologic cycle from low to high flow conditions, the data could be critical for the calibration of numerical groundwater models. In addition, the refinement of the aquifer boundaries has implications for the calculation of water budgets due to revisions to the boundaries or sub-surface potential for flow. BSEACD Report of Investigations 2007-1201 39

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CONCLUSIONS Water levels are very dynamic and in some areas fluctuate more than 100 ft between the high and low flow conditions in the Barton Springs aquifer. Influences of discrete recharge and discrete discharge (pumping) are evident on potentiometric surfaces. Troughs and ridges in the potentiometric surfaces correspond to preferential flow paths (conduits) with significant changes in contours from high to low flow conditions. Heads vary similarly within the fresh-water and saline-water zones indicating hydraulic communication between the zones. Potentiometric surfaces over these varying hydrologic conditions provide insight into the dynamic nature of the southern boundary of the aquifer. Vertical potential for flow in the western outcrop area of the Edwards is from the Edwards Aquifer to the Trinity Aquifer, on the basis of potentiometric maps and nested well pairs. Tracer studies have identified radial and divergent flows that are not evident on the potentiometric maps. Potentiometric maps are a significant tool for characterization of the flow system in the aquifer, and when combined with dye tracing and other studies, the complexity of this system can be better understood. ACKNOWLEDGEMENTS District staff, Joe Beery, Stefani Campbell, John Dupnik, Ron Fieseler, Brian Hunt, Mark Mathis, Beckie Morris, and Brian Smith collected data for maps in this report. City of Austin staff David Johns and Nico Hauwert also provided critical data. Edwards Aquifer Authority, Texas Water Development Board, U.S. Geological Survey, and the Hays Trinity Groundwater Conservation District also provided data. Kirk Holland, P.G., General Manager of the District, provided additional technical and editorial review of this report. BSEACD Report of Investigations 2007-1201 40

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REFERENCES Barker, R., Bush, P., and Baker, E. (1994). Geologic History and Hydrogeologic Setting of the Edwards-Trinity Aquifer System, West-Central Texas. U.S. Geological Survey, WRI 94-4039. Broun, A.S., D.A. Wierman, A.H. Backus, B.B. Hunt, 2007, Geological Analysis of the Trinity Group Aquifers in Western Hays County, Texas, with Focus on Implications to Groundwater Availability. in Reimers Ranch and Westcave Preserve: Landscapes, Water, and Lower Cretaceous Stratigraphy of the Pedernales Watershed, Western Travis County, Texas. Trip Coordinators B. Hunt, C. Woodruff, and E. Collins. Austin Geological Society Guidebook #28, 130 p. + appendix. Brune, Gunnar, 2002, Springs of Texas: College Station, Texas A&M University Press, 2d ed., 566 p. BSEACD, 2004, Status Report: Edwards and Trinity Aquifer Hydrogeologic Investigations, Wentzel Tract, Hays County, Texas. Report to the City of Austin Water Quality Protection Lands Scientific Review Committee, 16 p. BSEACD, 2007, Rules and Bylaws of the Barton Springs/Edwards Aquifer Conservation District, adopted April 12, 2007, 99 p. DeCook, K. J., 1960, Geology and Ground-Water Resources of Hays County, Texas: Texas Board of Water Engineers, Bulletin 6004, 170 p. Domenico, P.A., and F.W. Schwartz, 1990, Physical and Chemical Hydrogeology : New York, John Wiley & Sons, 824 p. Flores, R., 1990, Test Well Drilling Investigation to Delineate the Downdip Limits of Usable-Quality Groundwater in the Edwards Aquifer in the Austin Region, Texas. Texas Water Development Board Report 325, p. 70 Fieseler, R., 1998, Implementation of Best Management Practices to Reduce Nonpoint Source Loadings to Onion Creek Recharge Features, report to the Barton Springs Edwards Aquifer Conservation District, Austin, Texas, + appendices, December 16, 1998. Ford, D., 2004, Karst, in Encyclopedia of Caves and Karst Science J. Gunn editor, Fitzroy Dearborn, New York. p. 902 Garcia-Fresca, B., 2004, Urban Effects on Groundwater Systems, Geological Society of America Annual Meeting, Abstracts with Programs, Vol. 36, No. 5, P. 183. Halihan, T., J. Sharp, and R. Mace, 1999, Interpreting flow using permeability at multiple scales. Karst modeling : proceedings of the symposium held February 24 through 27, BSEACD Report of Investigations 2007-1201 41

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1999, Charlottesville, Virginia / edited by Arthur N. Palmer, Margaret V. Palmer, and Ira D. Sasowsky. Halihan, R. Mace, and T., J. Sharp, 2000, Flow in the San Antonio segment of the Edwards Aquifer: matrix, fractures, or conduits? In Wicks, C.M and Sasowsky, I.D. eds. Groundwater flow and contaminant transport in carbonate aquifers, Rotterdam, Netherlands, Balkema, P. 129-146. Hamilton, J.M., R. Esquilin, G.M. Schindel., 2006, Edwards Aquifer Authority Synoptic Water Level Program 1999-2004 Report, Edwards Aquifer Authority, San Antonio Texas, September 2006, 114 p. Hauwert, N., 2006, Characterization and Water Balance of Internal Drainage Basins. Abstract presented at Ph.D. Technical Session, University of Texas at Austin, Austin, Texas, 2/21/2006. Hauwert, N. M., Johns, D. A., Sansom, J. W., and Aley, T. J., 2002a, Groundwater Tracing of the Barton Springs Edwards Aquifer, Travis and Hays Counties, Texas: Gulf Coast Associations of Geological Societies Transactions, v. 52, p. 377 Hauwert, N. M., Johns, J. Sharp, 2002b, Evidence of Discrete Flow in the Barton Springs segement of the Edwards Aquifer, in Karst Waters Institute Special Publication #7. Hydrogeology and Biology of Post-Paleozoic Carbonate Aquifers. Edited by J. Martin, C. Wicks, and I. Sasowsky. Proceedings from the symposium: Karst Frontiers: Florida and Related Environments, March 6-10, 2002, Gainesville Florida. Hauwert, N. M., Johns, D. A., Sansom, J. W., Aley, T. J., 2004, Groundwater Tracing of the Barton Springs Edwards Aquifer, southern Travis and northern Hays Counties, Texas: Report by the Barton Springs/Edwards Aquifer Conservation District and the City of Austin Watershed Protection and Development Review Department, 100 p. and appendices. Hovorka, S., Mace, R., and Collins, E., 1995, Regional Distribution of Permeability in the Edwards Aquifer: Gulf Coast Association of Geological Societies Transactions, Vol. XLV, p. 259-265. Hovorka, S., Dutton, A., Ruppel, S., and Yeh, J., 1996, Edwards Aquifer Ground-Water Resources: Geologic Controls on Porosity Development in Platform Carbonates, South Texas: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 238, 75 p. Hovorka, S., Mace, R., and Collins, E., 1998, Permeability Structure of the Edwards Aquifer, South TexasImplications for Aquifer Management: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 250, 55 p. Hunt, B., Smith, B., Beery, B., Hauwert, N., Johns, J., 2005, Structural Influence on BSEACD Report of Investigations 2007-1201 42

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Groundwater Flow as Evidenced by Groundwater Dye Tracing in the Barton Springs Segment of the Edwards Aquifer, Central Texas: Implications for Modeling Conduits: 2005 Abstracts with Programs, Geological Society of America, South-Central Section, April 1-2, 2005, Trinity University, San Antonio, Texas. Hunt, B., B. Smith, S. Campbell, J. Beery, N. Hauwert, D. Johns, 2005, Dye Tracing of Recharge Features Under High-flow Conditions, Onion Creek, Barton Springs Segment of the Edwards Aquifer, Hays County, Texas: Austin Geological Society Bulletin, v. 1. Hunt, B., Smith, B., Beery, B., Johns, D., Hauwert, N., 2006, Summary of 2005 Groundwater Dye Tracing, Barton Springs Segment of the Edwards Aquifer, Hays and Travis Counties, Central Texas, Barton Springs/Edwards Aquifer Conservation District, BSEACD Report of Investigations, 2006-0530, p. 19. Kresic, N., 2007, Hydrogeology and Groundwater Modeling second edition. CRC Press, Boca Raton Florida, 807 p. LBG-Guyton Associates, 1979, Geohydrology of Comal, San Marcos, and Hueco Springs: Texas Department of Water Resources, Report 234, June, 85 p. LBG-Guyton Associates, 1994, Edwards Aquifer Ground-Water Divides Assessment San Antonio Region, Texas: Report 95-01 Prepared for the Edwards Underground Water District, 35 p. Lindgren, R., Dutton, A., Hovorka, S., Worthington, S., and Painter, S. (2004). Conceptualization and Simulation of the Edwards Aquifer, San Antonio region, Texas. U. S. Geological Survey Scientific Investigation Report 2004-5277. Lowery, R.L., 1959, A Study Of Droughts In Texas, Texas Board of Water Engineers: Bulletin 5914, p. 49. Mace, R., Chowdhury, A., Anaya, R., and Way, S., 2000, Groundwater Availability of the Trinity Aquifer, Hill Country Area, Texas: Numerical Simulations through 2050: Texas Water Development Board, 172 p. Maclay, R. W., and Small, T. A., 1986, Carbonate Geology and Hydrogeology of the Edwards Aquifer in the San Antonio Area, Texas: Texas Water Development Board, Report 296, 90 p. Mahler, B.J., Garner, B.D., Musgrove, M., Guilfoyle, A.L., and Roa, M.V., 2006, Recent (2003-05) water quality of Barton Springs, Austin, Texas, with emphasis on factors affecting variability: U.S. Geological Survey Scientific Investigations Report 2006-5299, 83 p., 5 appendixes. Massei, N., Mahler, B.J., Bakalowicz, M., Fournier, M., and Dupont, J.P., 2007, Quantitative Interpretation of Specific Conductance Frequency Distributions in Karst, in Groundwater, May-June 2007, Vol. 45, No. 3, pgs 288-293. BSEACD Report of Investigations 2007-1201 43

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Muller, D., and McCoy, W., 1987, Ground-Water Conditions of the Trinity Group Aquifer in Western Hays County: Texas Water Development Board, LP-205, 62 p. Palmer, A., 2004, Hydraulics of Caves, in Encyclopedia of Caves and Karst Science edited by J. Gunn, 902 p. Quinlan, J.F., 1989, Ground-water Monitoring in Karst Terranes: Recommended Protocols and Implicit Assumptions. US Environmental Protection Agency, Las Vegas, Nevada, EPA 660/x-89/050, 79pp. Rose, P. R., 1972, Edwards Group, Surface and Subsurface, Central Texas: The University of Texas at Austin, Bureau of Economic Geology Report of Investigations No. 74, 198 p. Ryder, P., 1996, Ground Water Atlas of the United States: Segment 4, Oklahoma and Texas. U.S. Geological Survey, Hydrologic Investigations Atlas 730-E, Reston, Virginia. Scanlon, B., Mace, R., Smith, B., Hovorka, S., Dutton, A., and Reedy, R., 2001, Groundwater Availability of the Barton Springs Segment of the Edwards Aquifer, TexasNumerical Simulations through 2050: The University of Texas at Austin, Bureau of Economic Geology, final report prepared for the Lower Colorado River Authority, under contract no. UTA99-0, 36 p. + figs., tables, attachment. Senger, R. K. and Kreitler, C. W., 1984, Hydrogeology of the Edwards Aquifer, Austin Area, Central Texas: The University of Texas at Austin, Bureau of Economic Geology Report of Investigations No. 141, 35 p. Sharp, J. M., Jr., 1990, Stratigraphic, geomorphic and structural controls of the Edwards Aquifer, Texas, U.S.A., in Simpson, E. S., and Sharp, J. M., Jr., eds., Selected Papers on Hydrogeology: Heise, Hannover, Germany, International Association of Hydrogeologists, v. 1, p. 67. Sharp, J. M., Jr., and Banner, J. L., 1997, The Edwards Aquifera resource in conflict: GSA Today, v. 7, no. 8, p. 1. Sharp, J. M., Wiles T.J. and L.E. Llado, 2007, Urbanization-induced increases in aquifer recharge and springflows, Geological Society of America Northeastern Section, Abstracts with Programs, Vol. 39, No. 1, p. 54. Slade, Raymond, Jr., Ruiz, Linda, and Slagle, Diana, 1985, Simulation of the Flow System of Barton Springs and Associated Edwards Aquifer in the Austin Area, Texas: U.S. Geological Survey, Water-Resources Investigations Report 85-4299, 49 p. BSEACD Report of Investigations 2007-1201 44

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Slade, Raymond, Jr., Dorsey, Michael, and Stewart, Sheree, 1986, Hydrology and Water Quality of the Edwards Aquifer Associated with Barton Springs in the Austin Area, Texas: U.S. Geological Survey Water-Resources Investigations, Report 86-4036, 117 p. Small, T. A., Hanson, J. A., and Hauwert, N. M., 1996, Geologic Framework and Hydrogeologic Characteristics of the Edwards Aquifer Outcrop (Barton Springs Segment), Northeastern Hays and Southwestern Travis Counties, Texas: U.S. Geological Survey Water-Resources Investigations, Report 96-4306, 15 p. Smith, B., B. Morris, B. Hunt, S. Helmcamp, D. Johns, N. Hauwert, 2001, Water Quality and Flow Loss Study of the Barton Springs Segment of the Edwards Aquifer: EPA-funded 319h grant report by the Barton Springs/Edwards Aquifer Conservation District and City of Austin, submitted to the Texas Commission on Environmental Quality (formerly TNRCC), August 2001. 85 p. + Figures, + Appendix Smith, B.A., and Hunt, B.B., 2004, Evaluation of Sustainable Yield of the Barton Springs Segment of the Edwards Aquifer, Hays and Travis Counties, Central Texas. BSEACD Austin, Texas. http://www.bseacd.org/research.html>(June 6, 2005). Todd, D.K., and L.W. Mays, 2005, Groundwater Hydrology third edition, John Wiley & Sons, Inc., 636 p. White, W., 1988, Geomorphology and Hydrology of Karst Terrains Oxford University Press, 464 p. White, W., and E. White, 2005, Ground water flux distribution between matrix, fractures, and conduits: constratins on modeling. Speleogenesis and Evolution of Karst Aquifers, Vol. 2, Issue 3, p.6. Winter, T.C., J.W. Harvey, O.L. Franke, and W. M. Alley, 1999, Groundwater and Surface Water: A Single Resource. U.S. Geological Survey Circular 1139, 79 p. Worthington, S., G. Schindel, E.C. Alexander, 2002, Techniques for investigating the extent of karstification in the Edwards Aquifer, Texas, in Karst Waters Institute Special Publication #7. Hydrogeology and Biology of Post-Paleozoic Carbonate Aquifers. Edited by J. Martin, C. Wicks, and I. Sasowsky. Proceedings from the symposium: Karst Frontiers: Florida and Related Environments, March 6-10, 2002, Gainesville Florida. Worthington, S., 2003, Conduits and turbulent flow in the Edwards aquifer: Worthington Groundwater, contract report to Edwards Aquifer Authority, San Antonio, Texas4, December 20, 2003, 42 p. BSEACD Report of Investigations 2007-1201 45

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Appendices: Potentiometric Data A-1: 1950s Drought of record A-1 1950s Drought of record composite data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-42-607 30.30139 -97.77194 580.00 1/1/1951 145.60 0.00 434.40 58-42-619 30.29722 -97.78972 490.00 0 490.00 Bee Springs 58-42-809 30.26583 -97.80972 720.00 2/16/1949 298.90 0.00 421.10 58-42-901 30.27583 -97.77917 530.00 3/7/1955 108.80 0.00 421.20 58-42-903 30.26330 -97.77124 458.15 3/15/1957 33.64 0.00 424.51 58-42-910 30.27695 -97.78972 570.00 2/1/1955 142.00 0.00 428.00 58-42-914 30.26368 -97.77082 433.90 0 433.90 Main Barton Springs 58-42-924 30.28667 -97.76972 600.00 8/1/1949 156.60 0.00 443.40 58-49-802 30.12825 -97.92657 937.91 1/26/1981 136.20 -0.85 800.86 58-49-904 30.13611 -97.88084 785.00 4/10/1980 191.00 0.00 594.00 Under drought of record, elevation must be lower than measured 58-42-916 30.27959 -97.78043 426.60 0 426.60 Cold Springs 58-50-101 30.22583 -97.86916 810.00 3/19/1952 139.26 0.00 670.74 58-50-104 30.23611 -97.84444 760.00 6/25/1940 232.13 0.00 527.87 58-50-105 30.23417 -97.85056 810.00 10/4/1939 228.80 0.00 581.20 58-50-201 30.21958 -97.79373 657.81 3/9/1956 225.52 0.00 432.29 58-50-205 30.23111 -97.80556 685.00 9/5/1939 254.12 0.00 430.88 58-50-208 30.21861 -97.82083 700.00 3/1/1955 242.00 0.00 458.00 58-50-218 30.24250 -97.79723 567.00 8/1/1978 126.00 0.00 441.00 58-50-301 30.21035 -97.78159 658.66 8/31/1956 199.20 0.00 459.46 58-50-406 30.19674 -97.84316 830.82 8/11/1978 298.26 0.00 532.56 58-50-411 30.18670 -97.85000 782.41 8/18/1978 227.46 0.00 554.95 58-50-416 30.17660 -97.86723 775.00 7/9/2001 201.40 0.00 573.60 Water Level adjusted for change in head (34 ft) from well 5850702. 58-50-502 30.18694 -97.81416 742.00 8/31/1956 255.28 0.00 486.72 58-50-511 30.17159 -97.82578 698.59 6/30/1956 220.00 0.00 478.59 58-50-701 30.13722 -97.84778 685.00 11/29/1949 169.55 0.00 515.45 58-50-702 30.14778 -97.87334 765.00 8/31/1956 138.91 0.00 626.09 58-50-704 30.13694 -97.85555 727.00 8/14/1978 202.33 -0.70 523.97 58-50-7DT 30.15528 -97.86182 755.00 7/9/2001 185.45 0.00 569.55 Water Level adjusted for change in head (34 ft) from well 5850702. 58-50-801 30.14281 -97.81076 663.82 8/29/1956 132.68 0.00 531.14 58-50-804 30.16159 -97.82873 704.40 2/10/1949 210.54 0.00 493.86 58-50-808 30.12556 -97.79972 708.00 6/27/1939 148.51 0.00 559.49 58-50-814 30.14056 -97.79694 630.00 3/21/1955 77.40 0.00 552.60 58-50-817 30.14000 -97.83222 700.00 1/1/1956 200.00 0.00 500.00 58-50-839 30.12972 -97.82166 625.00 8/14/1978 77.36 0.00 547.64 58-50-902 30.14139 -97.75777 680.00 11/1/1954 200.00 0.00 480.00 58-57-201 30.10278 -97.93694 925.00 12/28/1982 176.60 0.00 748.40 58-57-204 30.08361 -97.91805 800.00 12/5/1950 157.40 0.00 642.60 Water Level adjusted for change in head (-6 ft) from well 5850702. 58-57-301 30.09389 -97.89139 882.00 8/28/1956 287.20 0.00 594.80 58-57-3DB 30.11445 -97.91221 810.30 9/15/1999 143.79 0.00 666.51 Under drought of record, elevation must be lower than lowest measured 58-57-502 30.06635 -97.94447 890.00 5/24/1978 214.48 0.00 675.52 BSEACD Report of Investigations 2007-1201 46

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A-1 1950s Drought of record composite data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-57-5JM 30.04722 -97.95139 868.80 3/31/1952 158.73 0.00 710.07 58-57-902 30.00833 -97.89500 815.00 8/29/1956 247.63 0.00 567.37 58-57-903 30.03850 -97.88617 824.02 8/28/1956 263.88 0.00 560.14 58-57-905 30.02667 -97.90361 870.00 1/3/1951 289.30 0.00 580.70 Water Level adjusted for change in head (-21 ft) from well 5857903 58-57-9LN 30.02583 -97.87833 800.20 3/27/1952 222.10 0.00 578.10 Water Level adjusted for change in head (-21 ft) from well 5857903 58-58-101 30.08358 -97.84264 708.67 8/28/1956 146.64 0.00 562.03 58-58-104 30.10417 -97.84861 730.00 10/24/1950 162.90 0.00 567.10 Water Level adjusted for change in head (-18 ft) from well 5858101 58-58-301 30.09194 -97.78917 734.00 8/29/1956 179.61 0.00 554.39 58-58-4JH 30.06694 -97.85861 742.60 3/27/1952 166.62 0.00 575.98 Water Level adjusted for change in head (-5 ft) from well 5858101 58-58-4PR 30.04972 -97.86777 780.10 11/8/1950 189.77 0.00 590.33 Water Level adjusted for change in head (-24 ft) from well 5857903 58-58-502 30.05083 -97.80722 742.00 1/9/1951 181.60 0.00 560.40 Water Level adjusted for change in head (-6 ft) from well 5858301 58-58-7LN 30.02972 -97.85472 755.90 2/26/1952 184.03 0.00 571.87 Water Level adjusted for change in head (-20 ft) from well 5857903 67-01-3CC 29.97111 -97.89222 720.90 3/26/1952 146.40 0.00 574.50 67-01-3OG 29.98228 -97.89149 776.10 3/26/1952 201.80 0.00 574.30 67-01-3WL 29.98917 -97.89139 784.30 8/31/1954 210.30 0.00 574.00 67-01-6EN 29.93083 -97.90444 670.00 3/26/1952 99.09 0.00 570.91 67-01-801 29.89472 -97.93028 574.00 0 574.00 San Marcos Springs 67-01-807 29.90083 -97.91917 607.00 2/2/1940 36.11 0.00 570.89 67-01-809 29.91195 -97.92861 602.47 11/14/1950 27.87 0.00 574.60 67-02-101 29.98139 -97.86500 680.00 3/26/1952 111.70 0.00 568.30 A-2: July and August 1999 Average Flow A-2 July and August 1999 Average Flow Data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-42-619 30.29722 -97.78972 490.00 0.00 490.00 Bee Springs 58-42-819 30.26101 -97.81757 684.00 16-Aug-99 218.00 0.00 466.00 58-42-821 30.26306 -97.81389 740.00 20-Jul-99 244.00 0.00 496.00 58-42-8TW 30.26140 -97.79518 632.00 20-Jul-99 173.00 0.00 459.00 58-42-914 30.26368 -97.77082 433.90 0.00 433.90 Main Barton Springs 58-42-915 30.25121 -97.78089 653.00 14-Jul-99 207.00 -1.94 444.06 58-42-920 30.26356 -97.77422 446.32 0.00 446.32 Upper Barton Springs 58-42-921 30.26428 -97.77017 434.60 0.00 434.60 Eliza 58-42-922 30.26354 -97.76807 434.77 0.00 434.77 Old Mill Springs 58-49-916 30.27959 -97.78043 426.60 0.00 426.60 Cold Springs 58-49-919 30.13778 -97.89222 757.00 5-Aug-99 86.00 -1.89 669.11 58-49-9BC 30.16342 -97.90713 807.00 27-Aug-99 11.00 0.00 796.00 58-49-9SP 30.14721 -97.89689 767.00 13-Aug-99 56.00 -0.50 710.50 58-49-9WH 30.13528 -97.89584 765.00 4-Aug-99 78.00 0.00 687.00 58-50-123 30.23252 -97.86346 845.00 29-Jul-99 130.00 -1.80 713.20 58-50-1C1 30.23389 -97.86250 813.00 16-Aug-99 103.00 0.00 710.00 58-50-1GR 30.22333 -97.83528 731.00 16-Aug-99 178.00 -1.90 551.10 58-50-201 30.21958 -97.79373 658.00 20-Jul-99 190.00 0.00 468.00 58-50-207 30.21760 -97.82285 713.00 27-Aug-99 217.00 -0.75 495.25 58-50-211 30.24524 -97.82803 680.00 21-Jul-99 199.00 -0.70 480.30 58-50-212 30.22548 -97.80618 679.00 20-Jul-99 211.00 0.00 468.00 58-50-215 30.22764 -97.81035 681.00 20-Jul-99 211.00 0.00 470.00 58-50-216 30.23222 -97.79250 690.00 20-Jul-99 236.00 0.00 454.00 58-50-222 30.21722 -97.81879 695.00 4-Aug-99 203.00 0.00 492.00 58-50-2DS 30.23863 -97.81022 673.00 20-Jul-99 163.00 0.00 510.00 58-50-301 30.21035 -97.78159 659.00 26-Jul-99 159.00 0.00 500.00 58-50-414 30.18028 -97.83889 763.00 1-Jul-99 235.00 0.00 528.00 58-50-513 30.18263 -97.81969 752.00 19-Aug-99 257.00 0.00 495.00 58-50-517 30.17437 -97.81892 684.00 16-Aug-99 180.00 -2.10 501.90 58-50-5A 30.19084 -97.80651 747.00 19-Aug-99 254.00 -2.00 491.00 58-50-5BL 30.20341 -97.80330 703.00 19-Aug-99 225.00 0.00 478.00 58-50-5CC 30.17629 -97.79716 714.00 16-Aug-99 200.00 0.00 514.00 58-50-5ZB 30.20698 -97.83043 716.00 26-Aug-99 212.00 0.00 504.00 BSEACD Report of Investigations 2007-1201 47

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A-2 July and August 1999 Average Flow Data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-50-702 30.14778 -97.87334 765.00 7/9/1958 117.00 0.00 648.00 added this representative (above avg) wl data, BS flow at 84 cfs at time of measurement 58-50-718 30.13670 -97.84542 694.00 5-Aug-99 156.00 -0.90 537.10 58-50-731 30.15297 -97.85870 737.00 5-Aug-99 208.00 -1.36 527.64 58-50-739 30.13833 -97.84944 683.00 19-Jul-99 136.00 0.00 547.00 58-50-742 30.15485 -97.84156 761.00 26-Aug-99 238.00 -1.00 522.00 58-50-7DM 30.15316 -97.83937 729.00 24-Aug-99 212.00 -0.70 516.30 58-50-7RV 30.14485 -97.84625 680.00 24-Aug-99 157.00 -1.60 521.40 58-50-7SJ 30.14305 -97.84801 675.00 24-Aug-99 150.00 -2.00 523.00 58-50-7T 30.14028 -97.84583 650.00 16-Aug-99 130.00 -2.45 517.55 58-50-7TT 30.13917 -97.84139 655.00 19-Jul-99 112.00 0.00 543.00 58-50-7WM 30.14972 -97.84275 739.00 24-Aug-99 164.00 0.00 575.00 58-50-801 30.14281 -97.81076 664.00 19-Jul-99 110.00 -1.50 552.50 58-50-810 30.13361 -97.81028 629.00 19-Jul-99 58.00 0.00 571.00 58-50-827 30.13639 -97.81944 682.00 14-Jul-99 136.00 -1.35 544.65 58-50-838 30.13915 -97.82104 675.00 14-Jul-99 124.00 0.00 551.00 58-50-840 30.12972 -97.79833 710.00 24-Aug-99 126.00 0.00 584.00 58-50-842 30.15005 -97.83235 698.00 5-Aug-99 141.00 -1.50 555.50 58-50-846 30.13027 -97.82185 626.00 26-Jul-99 50.00 0.00 576.00 58-50-847 30.13015 -97.82169 620.00 29-Jul-99 51.00 -1.80 567.20 58-50-851 30.12582 -97.81564 622.00 29-Jul-99 42.00 0.00 580.00 58-50-855 30.14624 -97.81927 659.00 14-Jul-99 111.00 -2.85 545.15 58-50-8RR 30.14000 -97.82917 692.00 22-Aug-99 168.00 0.00 524.00 58-50-8SL 30.14625 -97.81918 658.00 14-Jul-99 106.00 -2.85 549.15 58-57-305 30.09917 -97.89222 811.00 21-Jul-99 197.00 -1.15 612.85 58-57-307 30.09986 -97.88229 791.00 21-Jul-99 200.00 -1.58 589.42 58-57-313 30.11333 -97.88333 805.00 21-Jul-99 202.00 -1.65 601.35 58-57-3AW 30.09572 -97.87863 774.00 10-Aug-99 203.00 -1.60 569.40 58-57-3MK 30.08750 -97.88750 810.00 21-Jul-99 189.00 -1.75 619.25 58-57-3RA 30.10000 -97.91167 823.00 21-Jul-99 133.00 -1.08 688.92 58-57-3TH 30.09167 -97.88750 820.00 21-Jul-99 193.00 0.00 627.00 58-57-4SB 30.04445 -97.95972 900.00 19-Jul-99 190.00 0.00 710.00 58-57-5BM 30.04556 -97.95805 910.00 19-Jul-99 164.00 -1.60 744.40 58-57-5CR 30.07240 -97.92031 797.00 21-Jul-99 120.00 -1.05 675.95 58-57-602 30.07421 -97.91580 798.00 21-Jul-99 127.00 -1.00 670.00 58-57-6BF 30.04611 -97.88333 820.00 19-Jul-99 208.00 -1.75 610.25 58-57-6DS 30.08139 -97.90945 790.00 21-Jul-99 134.00 -1.65 654.35 58-57-7JG 30.04089 -97.96284 940.00 22-Jul-99 180.00 0.00 760.00 58-57-8CL 30.02778 -97.92722 832.00 22-Jul-99 166.00 0.00 666.00 58-57-903 30.03850 -97.88617 824.00 19-Jul-99 212.00 0.00 612.00 58-57-9A 30.03000 -97.89222 833.00 26-Jul-99 223.00 -2.05 607.95 58-58-101 30.08358 -97.84264 709.00 19-Jul-99 107.00 0.00 602.00 58-58-102 30.10459 -97.85434 748.00 14-Jul-99 167.00 -1.30 579.70 58-58-107 30.10889 -97.86604 780.00 5-Aug-99 220.00 -1.60 558.40 58-58-114 30.11503 -97.86271 815.00 14-Jul-99 256.00 -2.20 556.80 58-58-118 30.11386 -97.86561 813.00 5-Aug-99 255.00 -1.50 556.50 58-58-119 30.11065 -97.86930 810.00 5-Aug-99 249.00 -1.25 559.75 58-58-120 30.11127 -97.86252 784.00 5-Aug-99 229.00 -1.86 553.14 58-58-121 30.10503 -97.86236 760.00 5-Aug-99 198.00 -1.47 560.53 58-58-122 30.09472 -97.84361 714.00 19-Jul-99 114.00 -1.00 599.00 58-58-1EG 30.10000 -97.87444 755.00 21-Jul-99 186.00 -0.85 568.15 58-58-1O1 30.11228 -97.85956 763.00 21-Jul-99 206.00 0.00 557.00 58-58-1O2 30.10972 -97.86188 770.00 21-Jul-99 209.00 0.00 561.00 58-58-1O3 30.10751 -97.85941 755.00 22-Jul-99 179.00 0.00 576.00 58-58-1PS 30.08919 -97.85257 748.00 21-Jul-99 150.00 -1.32 596.68 58-58-1RG 30.10000 -97.85778 745.00 21-Jul-99 164.00 -1.50 579.50 58-58-208 30.11639 -97.81976 666.00 5-Aug-99 105.00 -2.20 558.80 58-58-209 30.11934 -97.81612 647.00 5-Aug-99 91.00 -1.90 554.10 58-58-2PM 30.12187 -97.82211 661.00 31-Aug-99 112.00 -1.60 547.40 58-58-423 30.06781 -97.85912 745.00 15-Jul-99 131.00 -1.60 612.40 58-58-4L 30.07083 -97.87473 740.00 19-Jul-99 136.00 -1.50 602.50 58-58-508 30.07917 -97.83099 731.00 19-Jul-99 125.00 -1.70 604.30 58-58-7SH 30.00889 -97.86305 722.00 22-Jul-99 106.00 -1.95 614.05 67-01-303 29.99000 -97.87556 719.23 7/31/1999 172.39 0.00 546.84 67-01-304 29.984722 -97.876389 717.55 8/24/1999 167.88 0.00 549.67 67-01-311 29.98139 -97.89139 768.00 8/15/1999 204.65 0.00 563.35 67-01-801 29.89472 -97.93028 574.00 0.00 574.00 San Marcos Springs 67-01-809 29.91192 -97.92877 601.27 7/16/1999 25.17 0.00 576.10 BSEACD Report of Investigations 2007-1201 48

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A-3: June and July 2001 High Flow A-3 June and July 2001 High Flow data SWN DDLat DDLong Date Meas WL MPH WL Elev Comment 58-42-619 30.29722 -97.78972 0.00 490.00 Bee Springs 58-42-819 30.26101 -97.81757 7/23/01 217.55 0.00 466.03 58-42-825 30.26419 -97.81432 7/3/01 240.48 0.00 494.52 58-42-8G3 30.26040 -97.81711 7/3/01 202.39 -2.20 469.60 58-42-8TW 30.26140 -97.79518 7/12/01 169.00 0.00 462.66 58-42-903 30.26330 -97.77124 7/12/01 26.43 0.00 431.72 58-42-913 30.26667 -97.78222 7/12/01 102.26 0.00 444.34 58-42-914 30.26368 -97.77082 0.00 433.90 Main Barton Springs 58-42-915 30.25121 -97.78089 6/19/01 199.95 -1.94 451.11 58-42-920 30.26356 -97.77422 0.00 446.32 Upper Barton Springs 58-42-921 30.26428 -97.77017 0.00 434.60 Eliza 58-42-922 30.26354 -97.76807 0.00 434.77 Old Mill Springs 58-42-927 30.25000 -97.75333 7/5/01 7.44 0.00 497.56 LSD Elev 490.00 683.58 735.00 674.19 631.66 458.15 546.60 433.90 653.00 446.32 434.60 434.77 505.00 58-42-9CL 30.27778 -97.78472 610.00 7/11/01 170.00 0.00 440.00 58-42-9NC 30.27083 -97.77472 505.00 7/12/01 74.38 -1.00 429.62 58-42-9SG 30.27482 -97.78076 569.00 7/11/01 125.15 0.00 443.85 58-42-9WT 30.27417 -97.78889 620.00 7/11/01 175.73 0.00 444.27 58-49-916 30.27959 -97.78043 426.60 0.00 426.60 Cold Springs 58-49-9BG 30.13663 -97.89807 777.23 7/6/01 70.89 -2.00 704.34 58-49-9SP 30.14721 -97.89689 767.28 7/12/01 55.16 -0.50 711.62 58-50-122 30.23839 -97.83824 740.00 7/6/01 198.59 -0.25 541.16 58-50-123 30.23252 -97.86346 844.76 6/25/01 125.68 -1.80 717.28 58-50-1GR 30.22333 -97.83528 731.00 7/6/01 175.78 -1.90 553.32 58-50-1W2 30.22640 -97.84147 744.16 7/23/01 151.30 0.00 592.86 58-50-201 30.21958 -97.79373 657.81 7/9/01 153.26 0.00 504.55 58-50-211 30.24524 -97.82803 680.00 6/22/01 206.00 -0.70 473.30 58-50-212 30.22548 -97.80618 679.39 7/23/01 197.49 0.00 481.90 58-50-214 30.21136 -97.80354 705.55 7/3/01 212.94 0.00 492.61 58-50-215 30.22764 -97.81035 680.91 6/20/01 198.30 0.00 482.61 58-50-216 30.23222 -97.79250 690.00 6/25/01 212.36 0.00 477.64 58-50-217 30.24239 -97.80061 568.63 6/15/01 91.70 0.00 476.93 58-50-221 30.22545 -97.80619 679.10 7/3/01 193.04 0.00 486.06 58-50-222 30.21722 -97.81879 694.91 6/22/01 196.50 0.00 498.41 58-50-2DS 30.23863 -97.81022 672.58 7/3/01 177.31 0.00 495.27 58-50-2FF 30.21750 -97.82222 704.00 7/9/01 219.34 -1.00 483.66 58-50-2W1 30.22445 -97.81778 704.00 7/9/01 225.90 0.00 478.10 58-50-301 30.21035 -97.78159 658.66 7/23/01 137.12 0.00 521.54 58-50-3RS 30.24055 -97.78722 690.00 7/5/01 216.97 0.00 473.03 58-50-414 30.18028 -97.83889 762.66 7/6/01 215.24 0.00 547.42 58-50-416 30.17660 -97.86723 775.00 7/9/01 201.40 -0.20 573.40 58-50-417 30.19536 -97.84640 812.63 6/22/01 260.43 0.00 552.20 58-50-418 30.19833 -97.83746 846.72 7/9/01 311.41 -2.25 533.06 58-50-4DW 30.17250 -97.85583 752.00 7/9/01 210.40 -2.50 539.10 58-50-4MT 30.20278 -97.84778 780.00 7/9/01 195.72 -2.54 581.74 58-50-511 30.17159 -97.82578 698.59 6/20/01 140.40 -0.60 557.59 58-50-513 30.18263 -97.81969 751.53 7/6/01 207.38 0.00 544.15 58-50-517 30.17437 -97.81892 683.96 7/3/01 129.39 -2.10 552.47 58-50-520 30.20764 -97.80213 704.75 6/20/01 184.63 0.00 520.12 58-50-5A 30.19084 -97.80651 746.56 7/6/01 203.90 -2.00 540.66 58-50-5BB 30.17843 -97.80962 730.00 7/11/01 178.00 0.00 552.00 58-50-5BL 30.20341 -97.84212 692.00 7/11/01 176.00 0.00 516.00 58-50-5CC 30.17629 -97.79716 713.80 7/9/01 170.39 0.00 543.41 58-50-5JA 30.19350 -97.79524 711.11 7/11/01 184.95 0.00 526.16 58-50-5JV 30.17072 -97.81287 694.39 7/11/01 137.40 0.00 556.99 58-50-5M1 30.16565 -97.80952 665.00 7/9/01 97.02 -0.10 567.88 58-50-5PN 30.19222 -97.79778 687.00 7/11/01 149.30 -1.50 536.20 58-50-5ZB 30.20698 -97.83043 715.94 7/5/01 206.23 0.00 509.71 58-50-704 30.13694 -97.85555 727.00 6/26/01 135.60 -0.70 590.70 58-50-730 30.14000 -97.83833 683.00 7/6/01 98.55 0.00 584.45 58-50-731 30.15297 -97.85870 736.51 6/26/01 178.35 -1.36 556.80 58-50-742 30.15485 -97.84156 761.47 7/5/01 195.91 -1.00 564.56 58-50-7BW 30.13192 -97.83516 654.73 6/5/01 48.14 0.00 606.59 58-50-7CD 30.12972 -97.83833 645.00 7/6/01 52.90 0.00 592.10 58-50-7DF 30.14830 -97.84378 727.79 7/9/01 154.32 0.00 573.47 58-50-7DM 30.15316 -97.83937 728.52 7/5/01 161.04 -0.70 566.78 58-50-7DT 30.15528 -97.86182 755.00 7/9/01 185.45 -2.00 567.55 58-50-7LC 30.13611 -97.86806 745.00 7/9/01 152.60 0.00 592.40 58-50-7PC 30.13605 -97.85053 712.00 7/6/01 136.65 0.00 575.35 BSEACD Report of Investigations 2007-1201 49

PAGE 50

A-3 June and July 2001 High Flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-50-7PL 30.14581 -97.84589 717.22 7/9/01 131.76 0.00 585.46 58-50-7RG 30.14939 -97.87416 766.11 7/9/01 165.58 -2.39 598.14 58-50-7WC 30.14209 -97.85368 700.00 7/6/01 119.36 -1.96 578.68 58-50-7WC 30.14209 -97.85368 700.00 7/6/01 119.36 -1.96 578.68 58-50-801 30.14281 -97.81076 663.82 7/9/01 82.67 -1.50 579.65 58-50-820 30.12883 -97.82195 628.00 7/6/01 27.20 0.00 600.80 58-50-824 30.12692 -97.81834 636.18 7/6/01 36.06 0.00 600.12 58-50-825 30.13447 -97.81059 604.99 7/6/01 21.72 -0.60 582.67 58-50-840 30.12972 -97.79833 710.00 7/9/01 107.59 0.00 602.41 58-50-855 30.14624 -97.81927 658.84 6/27/01 87.50 -2.85 568.49 58-50-856 30.13489 -97.82649 660.00 7/6/01 80.51 0.00 579.49 58-50-860 30.15361 -97.82166 675.00 7/6/01 112.40 0.00 562.60 58-50-8D4 30.13783 -97.81794 652.00 7/6/01 74.86 0.00 577.14 58-50-8GJ2 30.15569 -97.82201 682.00 7/6/01 118.12 0.00 563.88 58-50-8IV 30.13542 -97.81973 638.07 6/5/01 57.08 0.00 580.99 58-50-8JH 30.13876 -97.80353 630.77 7/6/01 34.78 0.00 595.99 58-50-8JO 30.14750 -97.82639 677.00 7/6/01 104.88 0.00 572.12 58-50-8MG 30.13177 -97.82380 626.60 7/6/01 40.85 0.00 585.75 58-50-8PR 30.15142 -97.83259 690.12 7/9/01 118.43 0.00 571.69 58-57-302 30.09578 -97.87664 767.00 7/6/01 160.60 0.00 606.40 58-57-307 30.09986 -97.88229 790.51 6/21/01 162.71 -1.58 626.22 58-57-311 30.11246 -97.89114 857.70 6/21/01 243.00 0.00 614.70 58-57-3AM 30.08610 -97.91260 799.90 7/6/01 124.81 -2.00 673.09 58-57-3CC 30.11676 -97.88226 776.67 7/6/01 161.04 -2.00 613.63 58-57-3CG 30.08889 -97.91389 810.00 7/6/01 140.08 -1.60 668.32 58-57-3DB 30.11445 -97.91221 810.35 6/27/01 123.55 -1.60 685.20 58-57-3EC 30.11082 -97.88107 829.97 7/6/01 202.00 -1.10 626.87 58-57-3GC 30.09758 -97.88686 824.50 7/23/01 201.76 0.00 622.74 58-57-3NB 30.09937 -97.90118 833.03 7/6/01 167.45 -1.30 664.28 58-57-3RK 30.09167 -97.88667 805.00 7/6/01 169.43 0.00 635.57 58-57-3TM 30.12238 -97.87721 734.03 7/6/01 121.31 0.00 612.72 58-57-508 30.04346 -97.95557 879.93 7/6/01 175.35 -1.30 703.28 58-57-5CR 30.07240 -97.92031 796.53 7/10/01 108.47 -1.05 687.01 58-57-5DT 30.04967 -97.95486 875.00 7/6/01 172.82 0.00 702.18 58-57-5RR 30.04613 -97.95755 900.00 7/6/01 188.02 -1.60 710.38 58-57-5T4 30.05853 -97.92112 828.30 7/10/01 143.92 -1.95 682.43 58-57-602 30.07421 -97.91580 798.18 7/23/01 116.58 -1.00 680.60 58-57-6IC 30.04667 -97.90166 795.00 6/27/01 140.85 -2.32 651.83 58-57-6M3 30.07214 -97.91615 785.72 7/10/01 104.32 0.00 681.40 58-57-6R1 30.05508 -97.91069 805.12 7/10/01 138.24 -1.70 665.18 58-57-6RB 30.04667 -97.90166 795.00 6/27/01 139.37 -2.32 653.31 58-57-6RR 30.06606 -97.91080 840.15 7/10/01 159.39 -2.20 678.56 58-57-8DJ 30.02222 -97.92083 862.00 7/10/01 212.37 0.00 649.63 58-57-8RM 30.03547 -97.93542 842.00 7/6/01 180.71 -1.70 659.59 58-57-903 30.03850 -97.88617 824.02 7/9/01 185.95 0.00 638.07 58-57-913 30.03389 -97.89111 849.00 7/6/01 194.68 -1.10 653.22 58-57-9PC 30.02778 -97.87917 805.00 7/6/01 173.73 -1.40 629.87 58-58-101 30.08358 -97.84264 708.67 7/6/01 93.80 0.00 614.87 58-58-123 30.10943 -97.84173 700.89 7/23/01 105.20 -2.80 592.89 58-58-124 30.11908 -97.84083 714.97 7/6/01 122.55 -2.00 590.42 58-58-1DL 30.08587 -97.85644 759.75 7/6/01 131.37 0.00 628.38 58-58-1GB 30.10762 -97.87096 798.00 7/6/01 190.19 -1.60 606.21 58-58-1JE 30.08667 -97.85361 750.00 7/6/01 116.01 -1.60 632.39 58-58-1LB 30.10222 -97.85889 745.00 7/6/01 153.34 0.00 591.66 58-58-1MC 30.09111 -97.84028 700.00 7/6/01 78.38 -0.70 620.92 58-58-1PS 30.08919 -97.85257 747.53 7/6/01 123.60 -1.32 622.61 58-58-1PW 30.11315 -97.87292 773.00 7/6/01 158.94 0.00 614.06 58-58-211 30.08611 -97.82639 703.00 7/6/01 75.29 0.00 627.71 58-58-216 30.12277 -97.81532 685.33 6/22/01 98.75 -1.30 585.28 58-58-218 30.09472 -97.81555 688.00 7/9/01 74.47 -0.80 612.73 58-58-2KS 30.11056 -97.81889 670.00 7/6/01 64.60 0.00 605.40 58-58-406 30.06203 -97.85601 752.79 7/6/01 116.71 -0.85 635.23 58-58-410 30.06683 -97.83882 755.00 7/6/01 147.26 -1.90 605.84 58-58-418 30.07129 -97.85825 731.05 7/6/01 88.97 -0.40 641.68 58-58-423 30.06781 -97.85912 745.00 6/22/01 104.17 -1.60 639.23 58-58-424 30.07856 -97.87157 744.00 6/27/01 106.75 -2.00 635.25 58-58-4CT 30.06020 -97.86847 735.17 7/23/01 103.06 -0.30 631.81 58-58-4HO 30.07203 -97.84697 725.00 7/6/01 94.49 -1.25 629.26 58-58-4ML 30.07515 -97.85528 699.32 7/6/01 74.36 -1.80 623.16 58-58-4SG 30.08111 -97.84361 710.00 7/1/01 92.78 0.00 617.22 BSEACD Report of Investigations 2007-1201 50

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A-3 June and July 2001 High Flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-58-508 30.07917 -97.83099 731.45 6/25/01 101.94 -1.70 627.81 58-58-704 30.02750 -97.85389 746.00 7/6/01 162.46 -0.34 583.20 67-01-303 29.99000 -97.87556 719.23 7/1/01 163.84 0.00 555.39 67-01-304 29.98472 -97.87639 717.55 6/13/01 168.69 0.00 548.86 67-01-311 29.98143 -97.89140 768.00 7/23/01 209.05 0.00 558.95 67-01-801 29.89472 -97.93028 574.00 0.00 574.00 San Marcos Springs 67-01-809 29.91192 -97.92877 601.27 7/1/01 23.55 0.00 577.72 67-02-104 29.98278 -97.87139 680.00 8/5/01 112.10 0.00 567.90 67-02-104 29.98279 -97.87153 674.32 7/23/01 110.13 0.00 564.19 67-02-105 29.95830 -97.84212 646.70 7/23/01 67.61 0.00 579.09 67-02-106 29.97474 -97.85712 678.28 7/23/01 97.43 0.00 580.85 67-09-113 29.83874 -97.99074 704.73 7/23/01 123.26 0.00 581.47 67-09-401 29.82925 -97.96236 642.51 7/23/01 50.42 0.00 592.09 A-4: February 2002 High Flow A-4 February 2002 High Flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-42-619 30.29722 -97.78972 490.00 0 490.00 Bee Springs 58-42-819 30.26101 -97.81757 683.58 04-Feb-02 203.33 0.00 480.25 58-42-825 30.26419 -97.81432 735.00 04-Feb-02 236.78 0.00 498.22 58-42-8JO 30.26748 -97.82214 723.89 08-Feb-02 155.20 0.00 568.69 58-42-8TW 30.26140 -97.79518 631.66 01-Feb-02 164.81 0.00 466.85 58-42-903 30.26330 -97.77124 458.15 04-Feb-02 24.98 0.00 433.17 58-42-913 30.26667 -97.78222 546.60 06-Feb-02 100.15 0.00 446.45 58-42-914 30.26368 -97.77082 433.90 0 433.90 Main Barton Springs 58-42-915 30.25121 -97.78089 653.00 06-Feb-02 187.89 1.94 467.05 58-42-920 30.26356 -97.77422 446.32 0 446.32 Upper Barton Springs 58-42-921 30.26428 -97.77017 434.60 0 434.60 Eliza 58-42-922 30.26354 -97.76807 434.77 0 434.77 Old Mill Springs 58-42-927 30.25000 -97.75333 505.00 05-Feb-02 2.70 0.00 502.30 58-42-9CL 30.27778 -97.78472 610.00 04-Feb-02 160.87 0.00 449.13 58-42-9NC 30.27083 -97.77472 505.00 04-Feb-02 74.48 1.00 431.52 58-42-9SG 30.27482 -97.78076 569.00 04-Feb-02 122.51 0.00 446.49 58-42-9WT 30.27417 -97.78889 620.00 04-Feb-02 170.53 0.00 449.47 58-49-802 30.12825 -97.92657 937.91 11-Feb-02 126.70 0.85 812.06 58-49-916 30.27959 -97.78043 426.60 0 426.60 Cold Springs 58-49-926 30.12513 -97.90517 800.00 30-Jan-02 118.14 0.00 681.86 58-49-937 30.15801 -97.88745 777.56 07-Feb-02 90.80 1.30 688.06 58-49-9BG 30.13663 -97.89807 777.23 08-Feb-02 58.78 2.00 720.45 58-49-9DW 30.13556 -97.89389 750.00 08-Feb-02 103.67 1.60 647.93 58-49-9PA 30.14388 -97.89935 831.50 06-Feb-02 64.09 0.50 767.91 58-49-9PB 30.14714 -97.91476 841.00 06-Feb-02 14.40 1.00 827.60 58-49-9PC 30.13553 -97.90419 849.85 06-Feb-02 93.70 0.85 757.00 58-49-9SP 30.14721 -97.89689 767.28 04-Feb-02 53.36 0.50 714.42 58-50-122 30.23839 -97.83824 740.00 01-Feb-02 192.28 0.25 547.97 58-50-1C1 30.23389 -97.86250 813.26 06-Feb-02 94.60 0.00 718.66 58-50-1C4 30.23361 -97.86278 815.88 07-Feb-02 96.42 0.00 719.46 58-50-1GR 30.22333 -97.83528 731.00 07-Feb-02 168.54 1.90 564.36 58-50-1ML 30.21720 -97.84880 747.00 07-Feb-02 145.10 0.00 601.90 58-50-1W2 30.22640 -97.84147 744.16 04-Feb-02 150.27 1.45 595.34 58-50-201 30.21958 -97.79373 657.81 07-Feb-02 131.79 0.00 526.02 58-50-211 30.24524 -97.82803 680.00 01-Feb-02 182.12 0.00 497.88 58-50-212 30.22548 -97.80618 679.39 04-Feb-02 175.93 0.00 503.46 58-50-214 30.21136 -97.80354 705.55 01-Feb-02 189.55 0.00 516.00 58-50-215 30.22764 -97.81035 680.91 05-Feb-02 189.89 0.00 491.02 58-50-216 30.23222 -97.79250 690.00 04-Feb-02 198.15 0.00 491.85 58-50-217 30.24239 -97.80061 568.63 04-Feb-02 70.53 1.80 499.90 58-50-222 30.21722 -97.81879 694.91 07-Feb-02 188.00 0.00 506.91 58-50-2H1 30.23493 -97.81423 689.46 16-Jan-02 191.21 0.00 498.25 58-50-301 30.21035 -97.78159 658.66 04-Feb-02 135.06 0.00 523.60 58-50-411 30.18670 -97.85000 782.41 07-Feb-02 218.90 1.50 565.01 58-50-414 30.18028 -97.83889 762.66 07-Feb-02 206.75 0.00 555.91 58-50-416 30.17660 -97.86723 775.00 07-Feb-02 196.00 0.20 579.20 58-50-417 30.19536 -97.84640 812.63 04-Feb-02 250.20 0.00 562.43 58-50-418 30.19833 -97.83746 846.72 07-Feb-02 304.84 2.25 544.13 58-50-4DW 30.17250 -97.85583 752.00 07-Feb-02 183.60 2.50 570.90 58-50-4MT 30.20278 -97.84778 780.00 07-Feb-02 190.68 2.54 591.86 58-50-511 30.17159 -97.82578 698.59 06-Feb-02 131.70 0.00 566.89 58-50-513 30.18263 -97.81969 751.53 06-Feb-02 197.25 0.00 554.28 58-50-517 30.17437 -97.81892 683.96 06-Feb-02 114.85 0.00 569.11 58-50-520 30.20764 -97.80213 704.75 01-Feb-02 169.40 0.00 535.35 BSEACD Report of Investigations 2007-1201 51

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BSEACD Report of Investigations 2007-1201 52 A-4 February 2002 High Flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-50-5A 30.19084 -97.80651 746.56 06-Feb-02 185.17 2.00 563.39 58-50-5BL 30.20341 -97.80330 703.30 01-Feb-02 153.85 0.00 549.45 58-50-5CC 30.17629 -97.79716 713.80 06-Feb-02 155.12 0.00 558.68 58-50-5JV 30.17072 -97.81287 694.39 08-Feb-02 150.47 0.00 543.92 58-50-5M1 30.16565 -97.80952 665.00 06-Feb-02 77.84 0.10 587.26 58-50-5PN 30.19222 -97.79778 687.00 01-Feb-02 134.90 0.00 552.10 58-50-5ZB 30.20698 -97.83043 715.94 07-Feb-02 201.05 0.00 514.89 58-50-704 30.13694 -97.85555 727.00 06-Feb-02 131.18 0.00 595.82 58-50-707 30.14000 -97.83833 683.00 06-Feb-02 61.69 0.00 621.31 58-50-742 30.15485 -97.84156 761.47 30-Jan-02 180.04 1.00 582.43 58-50-7BW 30.13192 -97.83516 654.73 06-Feb-02 37.00 0.00 617.73 58-50-7CW 30.13361 -97.86667 740.00 06-Feb-02 133.66 0.00 606.34 58-50-7DF 30.14830 -97.84378 727.79 06-Feb-02 143.44 0.00 584.35 58-50-7DM 30.15316 -97.83937 728.52 30-Jan-02 141.86 0.70 587.36 58-50-7DT 30.15528 -97.86182 755.00 08-Feb-02 170.75 2.00 586.25 58-50-7PC 30.13605 -97.85053 712.00 06-Feb-02 126.12 0.00 585.88 58-50-7PL 30.14581 -97.84589 717.22 08-Feb-02 125.80 0.00 591.42 58-50-7RG 30.14939 -97.87416 766.11 08-Feb-02 146.75 2.39 621.75 58-50-7SJ 30.14305 -97.84801 675.00 06-Feb-02 89.51 2.00 587.49 58-50-7WC 30.14209 -97.85368 700.00 07-Feb-02 110.28 1.96 591.68 58-50-7WM 30.14972 -97.84275 738.91 23-Jan-02 144.61 0.00 594.30 58-50-7WM 30.14972 -97.84275 738.91 30-Jan-02 142.40 0.00 596.51 58-50-801 30.14281 -97.81076 663.82 04-Feb-02 42.83 1.50 622.49 58-50-820 30.12883 -97.82195 628.00 06-Feb-02 0.00 0.00 628.00 58-50-824 30.12692 -97.81834 636.18 06-Feb-02 12.36 0.00 623.82 58-50-829 30.15731 -97.82000 669.97 08-Feb-02 89.10 2.00 582.87 58-50-840 30.12972 -97.79833 710.00 06-Feb-02 92.14 0.00 617.86 58-50-856 30.13489 -97.82649 660.00 05-Feb-02 49.82 0.00 610.18 58-50-860 30.15361 -97.82166 675.00 06-Feb-02 84.50 0.00 590.50 58-50-8CW 30.14110 -97.82874 696.00 07-Feb-02 92.80 1.00 604.20 58-50-8D5 30.13382 -97.81322 618.96 06-Feb-02 17.45 0.00 601.51 58-50-8GJ 30.15560 -97.82142 682.00 06-Feb-02 105.00 2.00 579.00 58-50-8KF 30.14806 -97.82500 680.00 06-Feb-02 80.92 1.60 600.68 58-50-8MG 30.13177 -97.82380 626.60 04-Feb-02 8.00 0.00 618.60 58-50-8PR 30.15142 -97.83259 690.12 06-Feb-02 100.20 0.00 589.92 58-50-8ST 30.16503 -97.83125 705.00 07-Feb-02 130.77 0.00 574.23 58-57-2RR 30.08858 -97.91692 789.89 06-Feb-02 107.24 2.00 684.65 58-57-302 30.09578 -97.87664 767.00 05-Feb-02 141.50 0.00 625.50 58-57-313 30.11333 -97.88333 805.00 08-Feb-02 184.35 0.00 620.65 58-57-3AM 30.08610 -97.91260 799.90 06-Feb-02 113.62 0.00 686.28 58-57-3AW 30.09572 -97.87863 774.08 06-Feb-02 146.55 1.60 629.13 58-57-3BA 30.11889 -97.91055 810.00 06-Feb-02 98.64 0.00 711.36 58-57-3BF 30.10760 -97.90590 849.71 08-Feb-02 166.55 1.30 684.46 58-57-3BL 30.09111 -97.88139 780.00 01-Feb-02 153.85 0.00 626.15 58-57-3BN 30.11047 -97.87758 820.00 08-Feb-02 189.41 0.00 630.59 58-57-3CC 30.11676 -97.88226 776.67 06-Feb-02 154.27 0.00 622.40 58-57-3CR 30.12278 -97.88834 870.00 08-Feb-02 234.48 1.00 636.52 58-57-3DB 30.11445 -97.91221 810.35 06-Feb-02 98.04 1.60 713.91 58-57-3GC 30.09758 -97.88686 824.50 04-Feb-02 177.60 0.00 646.90 58-57-3GO 30.09664 -97.88301 790.00 06-Feb-02 156.61 2.00 635.39 58-57-3H 30.11278 -97.88667 806.00 11-Feb-02 182.60 2.00 625.40 58-57-3JO 30.09240 -97.87614 765.27 05-Feb-02 131.74 0.00 633.53 58-57-3NB 30.09937 -97.90118 833.03 06-Feb-02 152.14 2.00 682.89 58-57-3RC 30.12444 -97.90639 800.00 06-Feb-02 91.85 1.92 710.07 58-57-3RF 30.09618 -97.90588 850.00 06-Feb-02 163.92 2.00 688.08 58-57-3SD 30.09278 -97.91444 830.00 06-Feb-02 138.96 1.55 692.59 58-57-3TM 30.12238 -97.87721 734.03 06-Feb-02 124.01 0.00 610.02 58-57-4BD 30.04917 -97.97528 920.00 07-Feb-02 130.13 1.30 791.17 58-57-502 30.06635 -97.94447 890.00 06-Feb-02 172.90 0.50 717.60 58-57-503 30.06447 -97.92834 810.00 07-Feb-02 112.70 0.50 697.80 58-57-504 30.06210 -97.92007 821.00 27-Feb-02 130.30 0.00 690.70 58-57-508 30.04346 -97.95557 879.93 07-Feb-02 169.10 0.00 710.83 58-57-509 30.07240 -97.92031 796.53 16-Jan-02 83.37 1.05 714.21 was 58-57-5CR 58-57-5J2 30.04950 -97.93567 913.48 04-Feb-02 200.43 1.49 714.54 58-57-5R5 30.07601 -97.95407 960.00 06-Feb-02 193.85 0.85 767.00 58-57-5R7 30.07612 -97.95426 960.00 06-Feb-02 194.55 0.40 765.85 58-57-5RR 30.04613 -97.95755 900.00 07-Feb-02 174.29 1.60 727.31 58-57-602 30.07421 -97.91580 798.18 04-Feb-02 95.50 1.00 703.68 58-57-6K1 30.07645 -97.88418 790.80 05-Feb-02 128.91 0.00 661.89 58-57-6R1 30.05508 -97.91069 805.12 08-Feb-02 124.95 2.00 682.17 58-57-6RF 30.07161 -97.91065 802.37 08-Feb-02 102.19 0.00 700.18 58-57-6RR 30.06606 -97.91080 840.15 08-Feb-02 153.15 0.00 687.00 58-57-76F 30.04068 -97.96017 940.00 04-Feb-02 229.96 0.00 710.04

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A-4 February 2002 High Flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-57-76G 30.04050 -97.96049 940.00 04-Feb-02 215.12 0.00 724.88 58-57-802 30.02667 -97.92778 838.00 04-Feb-02 160.43 0.00 677.57 58-57-807 30.01944 -97.95194 887.00 04-Feb-02 212.00 0.00 675.00 58-57-8DJ 30.02222 -97.92083 862.00 05-Feb-02 207.46 0.00 654.54 58-57-8RM 30.03547 -97.93542 842.00 07-Feb-02 178.26 0.00 663.74 58-57-8TH 30.03555 -97.93611 910.00 07-Feb-02 232.51 0.00 677.49 58-57-901 30.03275 -97.89030 836.91 05-Feb-02 184.04 0.00 652.87 58-57-902 30.00833 -97.89584 814.00 04-Feb-02 184.42 0.00 629.58 58-57-903 30.03850 -97.88617 824.02 04-Feb-02 174.90 0.00 649.12 58-57-911 30.01250 -97.88917 831.00 04-Feb-02 198.95 0.00 632.05 58-57-9A 30.03000 -97.89222 833.00 04-Feb-02 185.97 0.00 647.03 58-57-9PC 30.02778 -97.87917 805.00 04-Feb-02 160.01 0.00 644.99 58-58-101 30.08358 -97.84264 708.67 04-Feb-02 60.71 0.00 647.96 58-58-123 30.10943 -97.84173 700.89 05-Feb-02 74.90 2.80 628.79 58-58-124 30.11908 -97.84083 714.97 05-Feb-02 99.62 0.00 615.35 58-58-1AB 30.11337 -97.86055 770.00 05-Feb-02 142.90 0.00 627.10 58-58-1C1 30.10156 -97.85811 747.00 05-Feb-02 113.42 2.00 635.58 58-58-1DL 30.08587 -97.85644 759.75 05-Feb-02 100.87 0.00 658.88 58-58-1EG 30.10000 -97.87444 755.00 08-Feb-02 125.30 0.00 629.70 58-58-1KM 30.09347 -97.84483 715.60 05-Feb-02 71.40 1.50 645.70 58-58-1MC 30.09111 -97.84028 700.00 05-Feb-02 55.30 0.00 644.70 58-58-1PS 30.08919 -97.85257 747.53 05-Feb-02 101.91 1.32 646.94 58-58-1PW 30.11315 -97.87292 773.00 06-Feb-02 145.86 0.00 627.14 58-58-1WM 30.08540 -97.86787 768.80 05-Feb-02 124.92 0.00 643.88 58-58-211 30.08611 -97.82639 703.00 05-Feb-02 57.48 0.00 645.52 58-58-216 30.12277 -97.81532 685.33 07-Feb-02 61.08 1.30 625.55 58-58-218 30.09472 -97.81555 688.00 05-Feb-02 56.05 1.50 633.45 58-58-2KS 30.11056 -97.81889 670.00 07-Feb-02 42.90 0.00 627.10 58-58-2PM 30.12187 -97.82211 661.18 06-Feb-02 40.68 1.60 622.10 58-58-406 30.06203 -97.85601 752.79 05-Feb-02 100.44 0.70 653.05 58-58-410 30.06683 -97.83882 755.00 07-Feb-02 130.24 1.90 626.66 58-58-417 30.04694 -97.86750 764.00 05-Feb-02 112.77 0.00 651.23 58-58-418 30.07129 -97.85825 731.05 05-Feb-02 73.82 0.40 657.63 58-58-423 30.06781 -97.85912 745.00 05-Feb-02 91.96 0.00 653.04 58-58-424 30.07856 -97.87157 744.00 05-Feb-02 90.12 0.00 653.88 58-58-4BL 30.08000 -97.86987 734.51 05-Feb-02 85.23 0.00 649.28 58-58-4CT 30.06020 -97.86847 735.17 04-Feb-02 82.16 0.30 653.32 58-58-4DD 30.07717 -97.86132 714.95 05-Feb-02 52.55 2.00 664.40 58-58-4HO 30.07203 -97.84697 725.00 05-Feb-02 77.47 0.00 647.53 58-58-4ML 30.07515 -97.85528 699.32 05-Feb-02 52.63 1.80 648.49 58-58-4MM 30.08013 -97.84224 710.00 05-Feb-02 68.43 0.00 641.57 58-58-4NM 30.04582 -97.85100 754.00 07-Feb-02 113.13 0.00 640.87 58-58-4SG 30.08111 -97.84361 710.00 05-Feb-02 67.20 0.00 642.80 58-58-509 30.07611 -97.83000 712.34 05-Feb-02 98.20 1.83 615.97 58-58-704 30.02750 -97.85389 746.00 12-Feb-02 128.71 0.00 617.29 58-58-709 30.03860 -97.85139 765.00 07-Feb-02 150.64 0.42 614.78 58-58-7SH 30.00889 -97.86305 722.00 04-Feb-02 90.56 0.00 631.44 67-01-303 29.99000 -97.87556 719.23 1/31/2002 169.24 0.00 549.99 67-01-304 29.984722 -97.876389 717.55 1/14/2002 165.60 0.00 551.95 67-01-311 29.98139 -97.89139 768.00 29-Jan-02 196.47 0.00 571.53 67-01-801 29.89472 -97.93028 574.00 0 574.00 San Marcos Springs 67-01-809 29.91192 -97.92877 601.27 2/5/2002 20.59 0.00 580.68 67-02-104 29.98278 -97.87139 680.00 29-Jan-02 105.99 0.00 574.01 67-02-105 29.97472 -97.85694 647.00 29-Jan-02 67.10 0.00 579.90 67-02-106 29.95806 -97.84194 678.00 29-Jan-02 95.95 0.00 582.05 A-5: November 2002 High Flow Potentiometric Map of Southern Groundwater Divide area A-5: November 2002 High Flow data, Southern Divide area SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58502H1 30.23493 -97.81423 689.46 11/14/02 194.83 0.00 494.63 58502H2 30.23541 -97.81300 686.32 11/14/02 182.85 -1.10 504.57 5850704 30.13694 -97.85555 727.00 11/18/02 113.00 -0.70 614.70 5850718 30.13670 -97.84542 693.92 11/18/02 103.94 -0.85 590.83 5850730 30.14000 -97.83833 683.00 11/18/02 92.80 -0.80 591.00 58507PL 30.14581 -97.84589 717.22 11/18/02 128.60 -1.00 589.62 5850858 30.13111 -97.82166 630.00 11/18/02 14.35 -2.30 617.95 58572FR 30.09482 -97.93754 926.00 11/27/02 189.65 -0.60 736.95 58572RR 30.08858 -97.91692 789.89 11/18/02 110.00 -2.00 681.89 5857307 30.09986 -97.88229 790.51 11/18/02 168.05 -1.58 624.04 BSEACD Report of Investigations 2007-1201 53

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A-5: November 2002 High Flow data, Southern Divide area SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 5857313 30.11333 -97.88333 805.00 11/18/02 189.95 -1.65 616.70 5857314 30.11571 -97.89501 899.79 11/18/02 267.40 -2.35 634.74 58573BF 30.10760 -97.90590 849.71 11/18/02 167.37 -1.30 683.64 58573CR 30.12278 -97.88834 870.00 11/18/02 239.43 -1.00 631.57 58573DB 30.11445 -97.91221 810.35 11/21/02 90.47 -1.60 721.48 58573DD 30.11010 -97.88184 820.00 11/18/02 186.02 -1.25 635.23 58573GC 30.09758 -97.88686 824.50 11/18/02 186.91 0.00 637.59 58573KP 30.11150 -97.89209 861.08 11/18/02 217.12 -2.20 646.16 58573LU 30.11994 -97.88019 771.57 11/18/02 158.35 -1.00 614.22 58573NB 30.09937 -97.90118 833.03 11/18/02 157.00 -1.30 677.33 58573RF 30.09618 -97.90588 850.00 11/18/02 169.32 -1.20 681.88 58573SD 30.09278 -97.91444 830.00 11/18/02 139.65 -1.55 691.90 58573TA 30.10167 -97.87527 775.00 11/19/02 144.70 -1.45 631.75 58574AT 30.04320 -97.96113 915.12 11/27/02 180.00 -1.40 736.52 58574BD 30.04917 -97.97528 920.00 11/20/02 152.08 -1.30 769.22 58574R2 30.04792 -97.96568 908.91 11/27/02 158.00 -0.30 751.21 5857502 30.06635 -97.94447 890.00 11/27/02 171.52 -0.50 718.98 5857505 30.05164 -97.92097 857.01 11/26/02 161.40 -1.25 696.86 5857508 30.04346 -97.95557 879.93 11/20/02 164.10 -1.30 717.13 58575CR 30.07240 -97.92031 796.53 11/18/02 82.63 -1.05 714.95 58575CY 30.04352 -97.95052 874.97 11/20/02 159.40 -1.05 716.62 58575J2 30.04950 -97.93567 913.48 11/20/02 197.96 -1.49 717.01 58575JB 30.05111 -97.95583 865.00 11/20/02 129.60 -1.21 736.61 58575R3 30.07041 -97.94576 918.93 11/27/02 191.53 -0.85 728.25 58575R4 30.08269 -97.94820 887.19 11/27/02 116.70 -1.00 771.49 58575R5 30.07601 -97.95407 960.00 11/27/02 193.80 -0.85 767.05 58575R7 30.07612 -97.95426 960.00 11/27/02 194.50 -0.40 765.90 58575T4 30.05853 -97.92112 828.30 11/18/02 129.80 -1.95 700.45 5857605 30.05777 -97.90743 809.07 11/26/02 124.60 0.00 684.47 5857606 30.04773 -97.88367 820.38 11/19/02 173.00 -0.70 648.08 58576BF 30.04611 -97.88333 820.00 11/25/02 173.50 -1.75 648.25 58576DS 30.08139 -97.90945 790.00 11/18/02 96.45 -1.65 695.20 58576R1 30.05508 -97.91069 805.12 11/27/02 122.22 -1.70 684.60 58576RF 30.07161 -97.91065 802.37 11/27/02 102.27 -2.00 702.10 58576RH 30.04560 -97.89873 803.40 11/21/02 147.40 -2.35 658.35 58576RR 30.06606 -97.91080 840.15 11/27/02 149.85 -2.20 692.50 5857701 30.03969 -97.96465 931.00 11/20/02 207.00 -2.02 726.02 5857702 30.03865 -97.97967 949.17 11/20/02 187.10 -0.40 762.47 585776F 30.04068 -97.96017 940.00 11/20/02 228.74 -0.75 712.01 585776G 30.04050 -97.96049 940.00 11/20/02 213.78 -0.20 726.42 5857802 30.02667 -97.92778 838.00 11/20/02 156.58 0.00 681.42 5857807 30.01944 -97.95194 887.00 11/20/02 208.90 0.00 678.10 5857808 30.01139 -97.94417 738.00 11/20/02 72.50 -0.70 666.20 5857809 30.01032 -97.94487 738.00 11/20/02 81.50 -0.45 656.95 5857810 30.04117 -97.92059 817.58 11/26/02 122.90 -1.10 695.78 58578CY 30.04081 -97.95053 914.48 11/20/02 203.00 -1.21 712.69 58578RM 30.03547 -97.93542 842.00 11/20/02 170.51 -1.70 673.19 58578RP 30.03674 -97.92944 865.00 11/20/02 174.44 -1.45 692.01 58578SG 30.02337 -97.92108 875.04 11/20/02 212.25 -1.05 663.84 58578WM 30.01085 -97.94485 750.00 11/20/02 83.78 -0.70 666.92 5857902 30.00833 -97.89584 814.00 11/19/02 197.02 0.00 616.98 5857903 30.03850 -97.88617 824.02 11/19/02 178.82 0.00 645.20 5857911 30.01250 -97.88917 831.00 11/19/02 200.02 -0.30 631.28 5857913 30.03389 -97.89111 849.00 11/25/02 206.00 -1.10 644.10 58579A 30.03000 -97.89222 833.00 11/19/02 189.76 -2.05 645.29 58579MW 30.02038 -97.89897 840.00 11/21/02 196.40 -2.30 645.90 58579OL 30.02159 -97.90551 865.00 11/20/02 217.60 -0.30 647.70 58579PC 30.02778 -97.87917 805.00 11/19/02 161.73 -1.40 644.67 5858101 30.08358 -97.84264 708.67 11/18/02 68.28 0.00 640.39 5858115 30.12444 -97.87389 730.00 11/18/02 131.35 -1.60 600.25 5858121 30.10503 -97.86236 760.07 11/18/02 146.56 -1.47 614.98 5858123 30.10943 -97.84173 700.89 11/18/02 82.35 -2.80 621.34 58581BT 30.11235 -97.85900 765.00 11/19/02 157.23 -1.65 609.42 58581dL 30.08587 -97.85644 759.75 11/19/02 95.82 -0.40 664.33 58581EG 30.10000 -97.87444 755.00 11/21/02 137.92 -0.85 617.93 58581JK 30.08645 -97.85426 754.34 11/19/02 91.70 -0.50 663.14 58581KM 30.09347 -97.84483 715.60 11/19/02 70.35 -1.50 646.75 58581MC 30.09111 -97.84028 700.00 11/19/02 59.00 -0.70 641.70 58581PS 30.08919 -97.85257 747.53 11/19/02 103.60 -1.32 645.25 58581TW 30.10164 -97.87061 790.68 11/19/02 168.30 -1.65 624.03 BSEACD Report of Investigations 2007-1201 54

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BSEACD Report of Investigations 2007-1201 5558-50-3AS 30.24389 -97.78528 670.00 11/1/05 253.38 -1.00 415.62 58-50-3RS 30.24055 -97.78722 690.00 11/1/05 245.22 0.00 444.78 58-50-410 30.18022 -97.87550 783.00 11/3/05 142.60 -0.25 640.15 A-5: November 2002 High Flow data, Southern Divide area SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 5858211 30.08611 -97.82639 703.00 11/19/02 59.50 -1.35 644.85 5858218 30.09472 -97.81555 688.00 11/19/02 59.00 -0.80 629.80 5858406 30.06203 -97.85601 752.79 11/19/02 103.20 -0.85 650.44 5858410 30.06683 -97.83882 755.00 11/19/02 134.65 -1.90 622.25 5858417 30.04694 -97.86750 764.00 11/19/02 116.55 -1.50 648.95 5858418 30.07129 -97.85825 731.05 11/19/02 77.04 -0.40 654.41 58584CT 30.06020 -97.86847 735.17 11/19/02 86.70 -1.13 649.60 58584CW 30.08006 -97.87452 740.00 11/21/02 98.00 -1.60 643.60 58584HO 30.07203 -97.84697 725.00 11/19/02 79.65 -1.25 646.60 58584L 30.07083 -97.87473 740.00 11/21/02 87.10 -1.50 654.40 58584NM 30.04582 -97.85100 754.00 11/19/02 141.80 -1.28 613.48 58584SG 30.08111 -97.84361 710.00 11/19/02 67.57 0.00 642.43 5858509 30.07611 -97.83000 712.34 11/19/02 95.08 -1.83 619.09 5858704 30.02750 -97.85389 746.00 11/19/02 137.30 -0.34 609.04 5858709 30.03860 -97.85139 765.00 11/19/02 156.77 -0.42 608.65 58587SH 30.00889 -97.86305 722.00 11/19/02 93.60 -1.95 630.35 67-01-303 29.98972 -97.87527 715.00 11/15/02 133.90 0.00 581.10 67-01-311 29.98143 -97.89140 770.52 11/14/02 176.73 0.00 593.79 67-02-104 29.98279 -97.87153 674.32 11/14/02 87.77 0.00 586.55 67-02-105 29.95830 -97.84212 646.70 11/14/02 65.90 0.00 580.80 67-02-106 29.97474 -97.85712 678.28 11/14/02 92.06 0.00 586.22 67-09-113 29.83874 -97.99074 704.73 11/14/02 115.24 0.00 589.49 67-09-401 29.82925 -97.96236 642.51 11/14/02 48.85 0.00 593.66 67-01-809 29.91192 -97.92877 601.27 11/15/02 18.59 0.00 582.68 A-6: October and November 2005 Below Average A-6: October and November 2005 below average flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-42-619 30.29722 -97.78972 490.00 490.00 Bee Springs 58-42-711 30.25111 -97.83722 785.00 10/31/05 161.52 -1.80 621.68 58-42-811 30.25972 -97.82306 593.44 0.00 593.44 58-42-816 30.27750 -97.79389 620.00 11/1/05 189.35 0.00 430.65 58-42-819 30.26101 -97.81757 683.58 10/31/05 222.55 -1.94 459.09 58-42-821 30.26306 -97.81389 740.00 10/31/05 256.00 -2.00 482.00 58-42-825 30.26419 -97.81432 735.00 11/1/05 257.53 -2.45 475.02 58-42-8TW 30.26140 -97.79518 631.66 10/31/05 177.91 -2.00 451.75 58-42-913 30.26667 -97.78222 546.60 10/31/05 106.50 -1.60 438.50 58-42-914 30.26368 -97.77082 433.90 433.90 Main Barton Springs 58-42-915 30.25121 -97.78089 653.00 11/1/05 215.38 -1.94 435.68 58-42-921 30.26428 -97.77017 434.60 434.60 Eliza 58-42-922 30.26354 -97.76807 434.77 434.77 Old Mill Springs 58-42-927 30.25070 -97.75393 505.00 11/1/05 12.50 0.00 492.50 58-42-928 30.25631 -97.76955 580.00 10/29/05 129.51 0.00 450.49 58-42-9CL 30.27778 -97.78472 610.00 11/1/05 177.00 0.00 433.00 58-42-9NC 30.27083 -97.77472 505.00 10/31/05 76.11 -1.00 427.89 58-42-9SG 30.27482 -97.78076 569.00 11/1/05 128.20 0.00 440.80 58-49-916 30.27959 -97.78043 426.60 426.60 Cold Springs 58-49-926 30.12513 -97.90517 794.24 10/4/05 122.50 -0.22 671.52 58-49-937 30.15801 -97.88745 777.56 11/2/05 93.38 -1.30 682.88 58-49-9AN 30.16462 -97.87875 825.00 11/3/05 170.25 0.00 654.75 58-49-9BQ 30.12583 -97.90361 787.38 11/1/05 68.18 -0.90 718.30 58-49-9QL 30.12697 -97.90739 754.57 11/1/05 12.98 0.00 741.59 58-50-122 30.23839 -97.83824 740.00 11/3/05 205.25 0.00 534.75 58-50-127 30.22056 -97.87055 835.00 10/31/05 113.25 0.00 721.75 58-50-128 30.21556 -97.84722 745.00 10/31/05 113.00 -2.96 629.04 58-50-1CH 30.21071 -97.83421 720.47 11/3/05 196.02 0.00 524.45 58-50-1GR 30.22333 -97.83528 731.00 11/1/05 177.54 -1.90 551.56 58-50-1NF 30.23222 -97.85750 835.00 11/1/05 121.40 -1.50 712.10 58-50-1W2 30.22640 -97.84147 744.16 10/31/05 153.75 -1.45 588.96 58-50-211 30.24524 -97.82803 680.00 11/3/05 202.22 -0.70 477.08 58-50-212 30.22548 -97.80618 674.00 10/31/05 215.51 -1.70 456.79 58-50-216 30.23222 -97.79250 690.00 10/31/05 243.85 -3.17 442.98 58-50-222 30.21722 -97.81879 694.91 10/31/05 199.52 -2.30 493.09 58-50-231 30.20944 -97.79195 655.00 11/1/05 205.79 -2.15 447.06 58-50-2H1 30.23493 -97.81423 689.46 10/31/05 209.32 0.00 480.14 58-50-2JG 30.23972 -97.81445 693.00 11/1/05 235.40 -2.00 455.60 58-50-301 30.21035 -97.78159 658.66 11/1/05 161.85 -1.35 495.46

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BSEACD Report of Investigations 2007-1201 5658-50-8MG 30.13177 -97.82380 626.60 11/1/05 78.30 -1.00 547.30 58-50-8SM 30.16514 -97.79381 656.00 10/31/05 100.65 0.00 555.35 58-50-8SR 30.16565 -97.80952 665.00 11/1/05 138.47 -0.10 526.43 58-50-8ST 30.16503 -97.83125 705.00 10/31/05 193.67 -0.25 511.08 A-6: October and November 2005 below average flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-50-411 30.18670 -97.84917 770.00 11/1/05 228.05 -1.50 540.45 58-50-417 30.19536 -97.84640 804.00 11/1/05 261.70 -1.70 540.60 58-50-419 30.17303 -97.85028 752.00 11/3/05 201.69 0.00 550.31 58-50-420 30.18677 -97.86089 775.00 11/2/05 160.44 -3.20 611.36 58-50-421 30.17606 -97.87093 785.00 11/7/05 140.45 0.00 644.55 58-50-511 30.17159 -97.82578 698.59 11/1/05 195.75 -1.85 500.99 58-50-513 30.18263 -97.81969 751.53 11/3/05 259.68 -0.60 491.25 58-50-517 30.17437 -97.81892 683.96 10/31/05 186.10 -2.10 495.76 58-50-520 30.20764 -97.80213 704.75 11/3/05 243.80 0.00 460.95 58-50-521 30.19222 -97.79778 687.00 11/8/05 209.40 -1.85 475.75 58-50-5A 30.19084 -97.80651 746.56 10/27/05 257.91 -2.00 486.65 58-50-5BB 30.17843 -97.80962 730.00 10/31/05 221.80 0.00 508.20 58-50-5BL 30.20341 -97.80330 703.30 10/31/05 232.32 0.00 470.98 58-50-5CC 30.17629 -97.79716 713.80 10/31/05 196.50 0.00 517.30 58-50-5JA 30.19350 -97.79524 711.11 10/31/05 236.55 0.00 474.56 58-50-5JV 30.17072 -97.81287 694.39 10/31/05 182.00 0.00 512.39 58-50-5TC 30.17111 -97.82139 690.00 10/31/05 181.39 -1.50 507.11 58-50-5TP 30.17830 -97.80968 730.00 10/31/05 230.88 0.00 499.12 58-50-5ZB 30.20698 -97.83043 715.94 11/3/05 209.60 0.00 506.34 58-50-707 30.14041 -97.83871 670.00 10/28/05 162.49 0.00 507.51 58-50-718 30.13670 -97.84542 693.92 10/28/05 176.35 -0.90 516.67 58-50-730 30.14000 -97.83833 683.00 10/28/05 162.00 -0.80 520.20 58-50-731 30.15297 -97.85870 736.51 11/4/05 212.67 -1.36 522.48 58-50-734 30.13417 -97.85000 714.00 10/28/05 183.00 -2.15 528.85 58-50-739 30.13833 -97.84944 683.00 10/28/05 155.41 -2.00 525.59 58-50-743 30.15447 -97.85878 733.88 11/4/05 208.30 -1.95 523.63 58-50-744 30.14240 -97.84233 654.00 10/28/05 142.69 0.00 511.31 58-50-747 30.16098 -97.87471 800.00 11/2/05 160.25 -3.47 636.28 58-50-748 30.14617 -97.85970 720.00 11/2/05 170.44 0.00 549.56 58-50-7AD2 30.12967 -97.83661 650.00 11/1/05 104.90 -1.55 543.55 58-50-7BB 30.16573 -97.83470 714.10 10/31/05 202.00 -1.10 511.00 58-50-7BG 30.16221 -97.86037 762.00 11/4/05 211.75 -1.52 548.73 58-50-7CB 30.13664 -97.84186 660.00 10/28/05 148.31 -3.20 508.49 58-50-7CO 30.13976 -97.84605 692.00 10/28/05 176.55 0.00 515.45 58-50-7DF 30.14830 -97.84378 727.79 10/28/05 205.85 -1.85 520.09 58-50-7DR 30.14705 -97.84525 712.00 10/28/05 196.30 0.00 515.70 58-50-7DT 30.15528 -97.86182 755.00 11/4/05 191.30 -2.00 561.70 58-50-7EJ 30.13328 -97.84379 688.00 10/28/05 164.00 0.00 524.00 58-50-7FS 30.15954 -97.85764 750.00 11/4/05 194.30 -0.80 554.90 58-50-7GH 30.14484 -97.84625 682.00 10/28/05 156.65 -1.63 523.72 58-50-7HL 30.14745 -97.84647 699.00 10/28/05 202.10 -1.00 495.90 58-50-7LD 30.13239 -97.83894 630.00 10/28/05 109.64 -1.50 518.86 58-50-7MB 30.13944 -97.83583 690.00 11/1/05 165.40 -2.60 522.00 58-50-7ME 30.14272 -97.84134 676.00 10/28/05 170.43 -0.50 505.07 58-50-7ML 30.12487 -97.86229 695.00 10/28/05 171.35 -0.60 523.05 58-50-7MO 30.13194 -97.85500 711.82 10/28/05 171.58 -1.80 538.44 58-50-7PL 30.14581 -97.84589 717.22 10/28/05 183.90 -1.00 532.32 58-50-7RD 30.14792 -97.85992 760.07 11/4/05 216.34 0.00 543.73 58-50-7SC 30.15687 -97.86310 755.00 11/2/05 186.63 -2.00 566.37 58-50-7SP 30.13434 -97.85509 700.00 10/28/05 174.19 0.00 525.81 58-50-7TT 30.13917 -97.84139 660.00 10/28/05 140.08 -1.56 518.36 58-50-7WC 30.14209 -97.85368 702.00 11/2/05 166.00 -1.96 534.04 58-50-801 30.14281 -97.81076 663.82 11/1/05 105.70 -1.50 556.62 58-50-817 30.14000 -97.83222 700.00 11/7/05 177.65 -1.65 520.70 58-50-824 30.12692 -97.81834 636.18 11/1/05 73.14 0.00 563.04 58-50-830 30.16069 -97.81808 687.00 11/2/05 182.82 -2.10 502.08 58-50-840 30.13004 -97.79846 710.00 11/2/05 135.50 -1.75 572.75 58-50-842 30.15005 -97.83235 697.94 10/31/05 180.50 -1.50 515.94 58-50-845 30.12406 -97.82665 650.00 11/8/05 93.67 0.00 556.33 58-50-850 30.12590 -97.81580 620.87 11/1/05 59.81 -1.35 559.71 58-50-851 30.12582 -97.81564 621.76 11/1/05 60.57 0.00 561.19 58-50-852 30.16167 -97.81834 690.00 10/31/05 186.72 -1.50 501.78 58-50-856 30.13489 -97.82649 660.00 11/1/05 122.08 -1.75 536.17 58-50-861 30.14444 -97.83139 704.00 10/27/05 188.71 -1.80 513.49 58-50-8D5 30.13382 -97.81322 618.96 11/1/05 60.85 0.00 558.11 58-50-8DB 30.16142 -97.81152 650.00 10/31/05 121.03 -1.60 527.37 58-50-8JH 30.13876 -97.80353 630.77 10/27/05 70.52 0.00 560.25 58-50-8LB 30.13907 -97.82839 685.00 10/27/05 152.36 0.00 532.64 58-50-8LD 30.16139 -97.80972 663.00 10/31/05 135.92 -2.50 524.58

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BSEACD Report of Investigations 2007-1201 5758-58-1WM 30.08540 -97.86787 768.80 10/28/05 170.81 0.00 597.99 58-58-202 30.12459 -97.81374 651.13 10/31/05 100.95 0.00 550.18 58-58-208 30.11639 -97.81976 666.31 11/10/05 107.61 -1.75 556.95 58-58-219 30.09167 -97.81750 684.00 11/8/05 108.75 -0.93 574.32 A-6: October and November 2005 below average flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-57-201 30.10278 -97.93694 925.00 11/10/05 167.00 0.00 758.00 58-57-2RR 30.08858 -97.91692 789.89 11/10/05 143.23 -2.00 644.66 58-57-307 30.09986 -97.88229 790.51 11/4/05 209.00 -1.58 579.93 58-57-311 30.11246 -97.89114 857.70 11/10/05 236.41 0.00 621.29 58-57-312 30.10611 -97.90334 868.00 11/10/05 215.00 -1.45 651.55 58-57-3AM 30.08610 -97.91260 799.90 11/10/05 147.25 -2.00 650.65 58-57-3BF 30.10760 -97.90590 849.71 11/10/05 176.03 -1.30 672.38 58-57-3DB 30.11445 -97.91221 810.35 11/10/05 120.13 -1.60 688.62 58-57-3EG 30.10563 -97.88880 788.62 11/10/05 222.71 -1.60 564.31 58-57-3GC 30.09758 -97.88686 824.50 11/1/05 221.25 0.00 603.25 58-57-3H 30.11306 -97.88389 805.00 11/1/05 213.00 -2.00 590.00 58-57-3HF 30.11308 -97.87675 802.00 10/28/05 239.40 -2.00 560.60 58-57-3JC 30.08750 -97.91583 803.00 11/10/05 140.94 -1.00 661.06 58-57-3JF 30.09114 -97.90984 828.00 11/10/05 178.03 -2.45 647.52 58-57-3JP 30.11254 -97.88333 805.00 11/10/05 213.94 -3.50 587.56 58-57-3KD 30.08833 -97.91444 820.00 11/10/05 174.18 -1.60 644.22 58-57-3KF 30.09861 -97.89833 835.00 11/10/05 187.23 0.00 647.77 58-57-3NB 30.09937 -97.90118 833.03 11/10/05 178.33 -2.00 652.70 58-57-3ON 30.08889 -97.90833 800.00 11/10/05 173.45 -1.60 624.95 58-57-3RF 30.09618 -97.90588 826.00 11/10/05 188.45 -1.20 636.35 58-57-3RR 30.08833 -97.91500 805.00 11/1/05 142.67 0.00 662.33 58-57-502 30.06635 -97.94447 890.00 11/2/05 206.18 -0.50 683.32 58-57-503 30.06447 -97.92834 810.00 11/2/05 135.25 -0.50 674.25 58-57-509 30.07240 -97.92031 781.00 11/1/05 120.59 -0.60 659.81 58-57-510 30.06346 -97.94162 865.00 11/2/05 186.28 -3.90 674.82 58-57-512 30.05853 -97.92112 828.30 11/10/05 154.35 -1.95 672.00 58-57-5J2 30.04950 -97.93567 913.48 11/1/05 212.05 -1.49 699.94 58-57-5R5 30.07601 -97.95407 960.00 11/2/05 196.90 -0.85 762.25 58-57-5R7 30.07612 -97.95426 960.00 11/2/05 197.60 -0.40 762.00 58-57-5RR 30.04613 -97.95755 900.00 11/2/05 185.12 -2.10 712.78 58-57-606 30.04773 -97.88367 820.38 11/4/05 214.00 -0.70 605.68 58-57-610 30.04560 -97.89873 803.40 11/4/05 185.73 -2.35 615.32 58-57-6DS 30.08139 -97.90945 790.00 11/10/05 135.50 -1.65 652.85 58-57-6JC 30.08055 -97.91111 782.00 11/10/05 134.79 -1.60 645.61 58-57-6KW 30.08278 -97.91250 785.00 11/10/05 127.70 -1.80 655.50 58-57-6M3 30.07214 -97.91615 790.00 11/10/05 120.08 -1.50 668.42 58-57-6MZ 30.08361 -97.91261 790.00 11/10/05 132.47 -1.80 655.73 58-57-6SI 30.08194 -97.91333 790.00 11/10/05 139.95 -1.50 648.55 58-57-701 30.03969 -97.96465 931.00 11/3/05 210.02 -0.90 720.08 58-57-702 30.03865 -97.97967 949.17 11/3/05 197.60 -0.40 751.17 58-57-76F 30.04068 -97.96017 940.00 11/2/05 235.25 0.00 704.75 58-57-76G 30.04050 -97.96049 940.00 11/2/05 232.20 -0.20 707.60 58-57-802 30.02667 -97.92778 838.00 11/15/05 189.50 0.00 648.50 58-57-807 30.01944 -97.95194 887.00 11/15/05 214.30 0.00 672.70 58-57-8BW1 30.03833 -97.92834 851.00 11/3/05 177.84 -2.00 671.16 58-57-8JG 30.03494 -97.95198 856.00 11/3/05 167.45 -0.30 688.25 58-57-8SG 30.02337 -97.92108 875.04 11/2/05 236.17 -1.05 637.82 58-57-901 30.03275 -97.89030 836.91 11/1/05 229.22 -1.60 606.09 58-57-902 30.00833 -97.89500 815.00 11/2/05 219.50 0.00 595.50 58-57-903 30.03851 -97.88618 826.80 11/2/05 220.30 -0.70 605.80 58-57-9OL 30.02159 -97.90551 865.00 11/2/05 256.91 -0.30 607.79 58-57-9PC 30.02778 -97.87917 800.36 11/2/05 223.00 -1.34 576.02 58-58-101 30.08358 -97.84263 707.84 11/2/05 126.83 -1.15 579.86 58-58-115 30.12444 -97.87389 730.00 11/4/05 173.54 -1.60 554.86 58-58-122 30.09472 -97.84361 714.00 11/8/05 139.90 -1.00 573.10 58-58-123 30.10943 -97.84173 712.00 11/1/05 138.60 -2.80 570.60 58-58-124 30.11908 -97.84083 714.97 11/1/05 171.00 -2.00 541.97 58-58-128 30.08725 -97.85361 748.46 10/28/05 163.00 -1.50 583.96 58-58-1AB 30.11337 -97.86055 770.00 11/1/05 230.40 -1.10 538.50 58-58-1BC 30.08509 -97.85768 743.00 10/28/05 157.32 -0.73 584.95 58-58-1C1 30.10156 -97.85811 747.00 11/1/05 181.10 -0.95 564.95 58-58-1DD 30.11858 -97.87114 755.00 10/28/05 216.67 -1.78 536.55 58-58-1DL 30.08587 -97.85644 759.75 10/28/05 157.00 -0.40 602.35 58-58-1EH 30.11096 -97.87410 807.00 10/28/05 251.61 -1.60 553.79 58-58-1JS 30.10578 -97.87267 798.00 10/28/05 234.40 -2.10 561.50 58-58-1MC 30.09111 -97.84028 700.00 11/2/05 116.94 -0.70 582.36 58-58-1OS 30.10535 -97.87415 791.00 10/28/05 234.95 -2.00 554.05 58-58-1PS 30.08919 -97.85257 747.53 11/7/05 164.72 -1.32 581.49 58-58-1RD 30.10806 -97.87382 837.00 10/28/05 279.58 -2.10 555.32

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BSEACD Report of Investigations 2007-1201 5858-50-201 30.21958 -97.79373 657.81 8/11/06 219.64 0.00 438.17 58-50-212 30.22548 -97.80618 674.00 7/26/06 226.82 -1.70 445.48 58-50-214 30.21136 -97.80354 705.55 8/11/06 266.55 0.00 439.00 A-6: October and November 2005 below average flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-58-220 30.09333 -97.81445 693.00 11/8/05 109.80 -1.50 581.70 58-58-413 30.07051 -97.83549 752.43 11/1/05 174.73 -1.08 576.62 58-58-417 30.04723 -97.86748 763.07 11/4/05 164.51 -1.50 597.06 58-58-418 30.07129 -97.85825 731.05 11/2/05 125.53 -0.40 605.12 58-58-423 30.06781 -97.85912 745.00 11/2/05 143.10 -1.60 600.30 58-58-424 30.07856 -97.87157 744.00 11/4/05 140.78 -2.00 601.22 58-58-426 30.08000 -97.86987 734.51 11/4/05 141.90 -2.00 590.61 58-58-427 30.07717 -97.86132 709.43 11/4/05 99.45 -2.00 607.98 58-58-4BS 30.05167 -97.83417 692.00 11/2/05 107.08 -0.75 584.17 58-58-4CT 30.06020 -97.86848 734.80 11/2/05 133.57 -1.13 600.10 58-58-4HO 30.07203 -97.84697 725.00 11/2/05 130.47 -1.25 593.28 58-58-4LC 30.07083 -97.87361 710.00 11/4/05 125.83 -1.00 583.17 58-58-4SG 30.08111 -97.84361 710.00 11/2/05 126.60 0.00 583.40 58-58-4TC 30.06184 -97.85600 748.00 11/2/05 152.15 0.00 595.85 58-58-505 30.06807 -97.81940 753.20 11/2/05 21.90 -1.00 730.30 58-58-509 30.07611 -97.83000 712.34 11/2/05 142.22 -1.83 568.29 58-58-5JW 30.07193 -97.82836 736.99 11/8/05 155.79 -3.75 577.45 58-58-704 30.02750 -97.85389 746.00 11/2/05 173.96 -0.34 571.70 58-58-711 30.01677 -97.85932 696.62 11/2/05 122.07 -1.95 572.60 58-58-712 30.02917 -97.87000 780.00 11/4/05 216.17 0.00 563.83 67-01-203 29.96194 -97.92056 691.00 11/3/05 104.10 -1.00 585.90 67-01-301 29.96294 -97.89681 679.00 11/3/05 113.79 -1.00 564.21 67-01-303 29.98976 -97.87547 719.24 10/24/05 165.92 -1.10 552.22 67-01-304 29.98451 -97.87630 717.55 10/24/05 154.98 -0.25 562.32 67-01-4AA 29.92159 -97.96544 724.88 10/24/05 144.18 -0.90 579.80 67-01-5MD 29.94628 -97.93557 755.00 11/3/05 187.68 -1.30 566.02 67-01-5PL 29.91819 -97.93240 660.00 11/3/05 91.40 -2.05 566.55 67-01-5XN 29.92359 -97.94784 685.00 11/3/05 108.30 -0.50 576.20 67-01-6AW 29.93650 -97.91118 760.00 11/3/05 197.15 -1.00 561.85 67-01-6AW1 29.93141 -97.90462 675.00 11/3/05 105.50 -0.40 569.10 67-01-6AW2 29.93740 -97.91480 790.00 11/3/05 218.32 -0.70 570.98 67-01-6EN 29.93216 -97.90456 670.00 11/3/05 95.75 -0.70 573.55 67-01-7BB 29.90860 -97.97154 767.83 10/24/05 188.13 -0.77 578.93 67-01-801 29.89472 -97.93028 574.00 0.00 0.00 574.00 San Marcos Springs 67-01-809 29.91192 -97.92877 601.27 11/3/05 26.83 0.00 574.44 67-01-812 29.89048 -97.92837 580.89 10/25/05 4.70 -2.89 573.30 67-01-813 29.89113 -97.93188 581.12 10/25/05 5.51 -3.08 572.53 67-01-8BB 29.89444 -97.92945 585.03 10/26/05 10.05 -1.25 573.73 67-01-8CC 29.89361 -97.93204 632.70 10/26/05 57.47 -2.12 573.11 67-01-8DD 29.88717 -97.94962 750.96 10/26/05 175.39 -1.00 574.57 67-01-9EG 29.91359 -97.91647 650.00 11/3/05 69.80 -0.85 579.35 A-7: July and August 2006 Low Flow A-7: July and August 2006 low flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-42-619 30.29722 -97.78972 490.00 0.00 490.00 Bee Springs (flowing?) 58-42-711 30.25111 -97.83722 785.00 7/26/06 161.35 -1.80 621.85 58-42-811 30.25972 -97.82306 593.44 0.00 593.44 58-42-819 30.26101 -97.81757 683.58 7/26/06 221.30 -1.94 460.34 58-42-8TW 30.26140 -97.79518 631.66 8/11/06 185.03 -2.00 444.63 58-42-914 30.26368 -97.77082 433.90 0.00 433.90 Main Barton Springs 58-42-921 30.26428 -97.77017 434.60 0.00 434.60 Eliza 58-42-922 30.26354 -97.76807 434.77 0.00 434.77 Old Mill Springs (trickle flow) 58-42-927 30.25070 -97.75393 505.00 7/31/06 21.40 0.00 483.60 58-42-928 30.25631 -97.76955 580.00 7/19/06 136.52 0.00 443.48 58-42-9NC 30.27083 -97.77472 505.00 10/31/05 76.11 -1.00 427.89 58-42-9SG 30.27482 -97.78076 569.00 8/15/06 131.68 0.00 437.32 58-42-9XN 30.26704 -97.78812 617.00 7/31/06 199.24 -2.20 415.56 58-49-916 30.27959 -97.78043 426.60 0.00 426.60 Cold Springs 58-49-9BQ 30.12583 -97.90361 787.38 7/25/06 77.15 -0.90 709.33 58-49-9RP 30.14727 -97.88963 783.90 8/30/06 110.10 0.00 673.80 58-49-9SR 30.16354 -97.90721 824.10 0.00 824.10 58-49-9TO 30.15106 -97.87583 770.90 8/19/06 171.50 0.00 599.40 58-50-127 30.22056 -97.87055 835.00 7/26/06 112.80 0.00 722.20 58-50-128 30.21556 -97.84722 745.00 7/26/06 112.45 -2.96 629.59 58-50-1GR 30.22333 -97.83528 731.00 7/26/06 176.33 -1.90 552.77 58-50-1W2 30.22640 -97.84147 744.16 7/26/06 153.24 -1.45 589.47

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BSEACD Report of Investigations 2007-1201 5958-57-3RR 30.08833 -97.91500 805.00 8/2/06 147.48 0.00 657.52 58-57-3XN 30.11759 -97.88125 771.00 8/18/06 194.28 0.00 576.72 58-57-3Z2 30.11573 -97.89489 899.74 8/2/06 284.45 -2.00 613.29 58-57-3Z4 30.11672 -97.89369 869.08 8/2/06 267.19 -2.50 599.39 A-7: July and August 2006 low flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-50-216 30.23222 -97.79250 690.00 7/26/06 255.80 -3.17 431.03 58-50-222 30.21722 -97.81879 694.91 7/26/06 218.60 -2.30 474.01 58-50-231 30.20944 -97.79195 655.00 8/11/06 221.23 -2.15 431.62 58-50-2H1 30.23493 -97.81423 689.46 7/26/06 216.39 0.00 473.07 58-50-301 30.21035 -97.78159 658.66 7/26/06 191.80 -1.35 465.51 58-50-411 30.18670 -97.84917 770.00 7/26/06 228.53 -1.50 539.97 58-50-414 30.18028 -97.83889 762.66 8/2/06 248.18 0.00 514.48 58-50-417 30.19536 -97.84640 804.00 7/26/06 262.36 -1.70 539.94 58-50-419 30.17303 -97.85028 752.00 7/27/06 208.00 0.00 544.00 58-50-420 30.18677 -97.86089 775.00 8/2/06 160.35 -3.20 611.45 58-50-421 30.17606 -97.87093 785.00 7/27/06 141.80 0.00 643.20 58-50-4MC 30.17826 -97.84862 745.22 8/2/06 219.50 -1.54 524.18 58-50-511 30.17159 -97.82578 698.59 8/2/06 210.65 -1.85 486.09 58-50-513 30.18263 -97.81969 751.53 8/2/06 267.00 -0.60 483.93 58-50-520 30.20764 -97.80213 704.75 8/11/06 263.51 0.00 441.24 58-50-521 30.19222 -97.79778 687.00 8/11/06 220.40 -1.85 464.75 58-50-5A 30.19084 -97.80651 746.56 8/2/06 269.30 -2.00 475.26 58-50-5BB 30.17843 -97.80962 730.00 8/2/06 258.04 0.00 471.96 58-50-5CC 30.17629 -97.79716 713.80 8/2/06 237.15 0.00 476.65 58-50-5JA 30.19350 -97.79524 711.11 8/11/06 250.55 0.00 460.56 58-50-5JV 30.17072 -97.81287 694.39 8/2/06 210.10 0.00 484.29 58-50-5ZB 30.20698 -97.83043 715.94 7/28/06 214.76 0.00 501.18 58-50-718 30.13670 -97.84542 693.92 8/16/06 200.70 -0.90 492.32 58-50-730 30.14000 -97.83833 683.00 8/15/06 188.15 -0.80 494.05 could be 58-50-707 58-50-734 30.13417 -97.85000 714.00 8/16/06 210.01 -2.15 501.84 58-50-739 30.13833 -97.84944 683.00 8/16/06 176.53 -2.00 504.47 58-50-743 30.15447 -97.85878 733.88 7/28/06 241.05 -1.95 490.88 58-50-747 30.16098 -97.87471 800.00 7/27/06 159.49 -3.47 637.04 58-50-748 30.14617 -97.85970 720.00 7/27/06 171.33 0.00 548.67 58-50-7AD 30.12942 -97.83694 640.00 7/28/06 136.35 -1.55 502.10 58-50-7BB 30.16573 -97.83470 714.10 8/2/06 214.02 -1.10 498.98 58-50-7BG 30.16221 -97.86037 762.00 7/25/06 217.39 -1.52 543.09 58-50-7DF 30.14830 -97.84378 727.79 7/28/06 227.61 -1.85 498.33 58-50-7DR 30.14705 -97.84525 712.00 7/28/06 218.84 0.00 493.16 58-50-7DT 30.15528 -97.86182 755.00 7/28/06 207.18 -2.00 545.82 58-50-7EJ 30.13328 -97.84379 688.00 8/16/06 191.35 0.00 496.65 58-50-7HR 30.14648 -97.84503 734.00 7/28/06 223.78 -1.80 508.42 58-50-7ME 30.14272 -97.84134 676.00 8/16/06 195.61 -0.50 479.89 58-50-7PL 30.14581 -97.84589 717.22 7/28/06 205.60 -1.00 510.62 58-50-7RG 30.14939 -97.87416 766.11 8/19/06 173.13 -2.39 590.59 58-50-7SC 30.15687 -97.86310 755.00 7/28/06 189.74 -2.00 563.26 58-50-7SP 30.13434 -97.85509 700.00 8/16/06 192.23 0.00 507.77 58-50-7TT 30.13917 -97.84139 660.00 8/16/06 166.60 -1.56 491.84 58-50-7TY 30.13095 -97.85670 693.00 8/16/06 184.29 -1.45 507.26 58-50-7WC 30.14209 -97.85368 702.00 7/26/06 184.24 -1.96 515.80 58-50-7XN 30.13821 -97.87484 728.00 8/19/06 177.71 0.00 550.29 58-50-801 30.14281 -97.81076 663.82 7/28/06 142.07 -1.50 520.25 58-50-824 30.12692 -97.81834 636.18 7/28/06 112.08 0.00 524.10 58-50-827 30.13639 -97.81944 682.00 7/28/06 181.60 -1.35 499.05 58-50-836 30.14501 -97.81313 661.85 7/28/06 142.60 -2.20 517.05 58-50-856 30.13489 -97.82649 660.00 7/28/06 156.45 -1.75 501.80 58-50-8JW 30.13562 -97.83194 683.00 7/28/06 179.90 -1.50 501.60 58-50-8LB 30.13907 -97.82839 685.00 7/28/06 184.87 0.00 500.13 58-50-8LD 30.16139 -97.80972 663.00 8/15/06 171.80 -2.50 488.70 58-50-8MG 30.13177 -97.82380 626.60 7/28/06 111.00 -1.00 514.60 58-50-8MU 30.14000 -97.83222 700.00 7/28/06 201.10 0.00 498.90 58-50-8XN 30.14658 -97.82452 670.00 7/28/06 184.60 0.00 485.40 58-57-312 30.10611 -97.90334 868.00 8/19/06 227.28 -1.45 639.27 58-57-313 30.11333 -97.88333 805.00 8/19/06 216.05 -1.65 587.30 58-57-317 30.11772 -97.90820 805.00 8/2/06 101.05 0.00 703.95 58-57-318 30.12378 -97.90764 800.00 7/21/06 128.37 -1.92 669.71 58-57-3AM 30.08610 -97.91260 799.90 8/22/06 153.95 -2.00 643.95 58-57-3DD 30.11010 -97.88184 820.00 8/19/06 271.28 -1.25 547.47 58-57-3GC 30.09758 -97.88686 824.50 7/31/06 233.93 0.00 590.57 58-57-3H 30.11306 -97.88389 805.00 8/2/06 232.50 -2.00 570.50 58-57-3HO 30.12341 -97.88333 772.00 8/18/06 187.30 -1.50 583.20 58-57-3JF 30.09114 -97.90984 828.00 8/22/06 187.05 -2.45 638.50 58-57-3NB 30.09937 -97.90118 833.03 8/19/06 189.13 -2.00 641.90 58-57-3RF 30.09618 -97.90588 826.00 8/19/06 197.91 -1.20 626.89

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BSEACD Report of Investigations 2007-1201 60 A-7: July and August 2006 low flow data SWN DDLat DDLong LSD Elev Date Meas WL MPH WL Elev Comment 58-57-4R2 30.04797 -97.96564 908.91 8/3/06 192.30 -0.30 716.31 58-57-502 30.06635 -97.94447 890.00 8/3/06 209.30 -0.50 680.20 58-57-503 30.06447 -97.92834 810.00 8/9/06 135.38 -0.50 674.12 58-57-509 30.07240 -97.92031 781.00 7/25/06 124.35 -0.60 656.05 was 58-57-5CR 58-57-510 30.06346 -97.94162 865.00 8/3/06 187.41 -3.90 673.69 58-57-511 30.04950 -97.93567 913.48 7/21/06 216.45 -1.49 695.54 58-57-512 30.05853 -97.92112 828.30 6/28/06 169.70 -1.95 656.65 was 58-57-5T4 58-57-5RR 30.04613 -97.95755 900.00 8/3/06 198.80 -2.10 699.10 58-57-606 30.04773 -97.88367 820.38 8/22/06 244.95 -0.70 574.73 58-57-608 30.08045 -97.91660 793.18 6/28/06 176.20 -1.60 615.38 58-57-610 30.04560 -97.89873 803.40 8/22/06 208.80 -2.35 592.25 58-57-6JC 30.08055 -97.91111 782.00 8/22/06 138.18 -1.60 642.22 58-57-6MZ 30.08361 -97.91261 790.00 8/22/06 135.92 -1.80 652.28 58-57-6XN 30.04236 -97.90179 825.00 8/21/06 265.00 0.00 560.00 58-57-701 30.03969 -97.96465 931.00 8/3/06 219.80 -0.90 710.30 58-57-702 30.03865 -97.97967 949.17 8/3/06 199.90 -0.40 748.87 58-57-76G 30.04050 -97.96049 940.00 8/3/06 218.59 -0.20 721.21 58-57-802 30.02667 -97.92778 838.00 8/2/06 192.90 0.00 645.10 58-57-807 30.01944 -97.95194 887.00 8/2/06 214.85 0.00 672.15 58-57-8DC 30.03601 -97.93889 900.00 8/30/06 213.60 -1.60 684.80 58-57-8HR 30.02378 -97.92594 825.00 8/2/06 182.53 -1.30 641.17 58-57-8JG 30.03494 -97.95198 856.00 8/3/06 170.80 -0.30 684.90 58-57-902 30.00833 -97.89500 815.00 7/31/06 241.86 0.00 573.14 58-57-903 30.03851 -97.88618 826.80 7/28/06 246.30 -0.70 579.80 58-57-9OL 30.02159 -97.90551 865.00 8/3/06 281.82 -0.30 582.88 58-57-9PC 30.02778 -97.87917 800.36 7/31/06 240.27 -1.34 558.75 58-58-115 30.12444 -97.87389 730.00 8/2/06 188.14 -1.60 540.26 58-58-122 30.09472 -97.84361 714.00 8/22/06 158.08 -1.00 554.92 58-58-123 30.10943 -97.84173 712.00 7/28/06 173.08 -2.80 536.12 58-58-124 30.11908 -97.84083 714.97 7/28/06 203.56 -2.00 509.41 58-58-1AB 30.11337 -97.86055 770.00 7/28/06 257.63 -1.10 511.27 58-58-1C1 30.10156 -97.85811 747.00 7/28/06 213.50 -0.95 532.55 58-58-1DH 30.11685 -97.87302 770.00 8/17/06 253.55 -1.50 514.95 58-58-1DL 30.08587 -97.85644 759.75 8/22/06 179.38 -0.40 579.97 58-58-1EH 30.11096 -97.87410 807.00 8/22/06 270.28 -1.60 535.12 58-58-1JG 30.10000 -97.86250 735.00 8/16/06 207.85 0.00 527.15 58-58-1MC 30.09111 -97.84028 700.00 7/28/06 151.75 -0.70 547.55 58-58-1OS 30.10535 -97.87415 791.00 8/16/06 250.08 -2.00 538.92 58-58-1PM 30.08556 -97.86028 762.00 8/22/06 220.25 -2.00 539.75 58-58-1WM 30.08540 -97.86787 768.80 8/22/06 199.50 0.00 569.30 58-58-219 30.09167 -97.81750 684.00 7/28/06 141.11 -0.93 541.96 58-58-220 30.09333 -97.81445 693.00 7/28/06 140.30 -1.50 551.20 58-58-301 30.092221 -97.789444 734.00 8/17/06 173.52 -2.30 558.18 58-58-417 30.04723 -97.86748 763.07 8/21/06 201.05 -1.50 560.52 58-58-418 30.07129 -97.85825 731.05 8/22/06 167.75 -0.40 562.90 58-58-426 30.08000 -97.86987 734.51 8/22/06 148.40 -2.00 584.11 58-58-427 30.07717 -97.86132 709.43 8/22/06 120.00 -2.00 587.43 58-58-4BS 30.05167 -97.83417 692.00 7/31/06 134.92 -0.75 556.33 58-58-4CT 30.06020 -97.86848 734.80 7/28/06 166.86 -1.13 566.81 58-58-4HO 30.07203 -97.84697 725.00 7/28/06 165.20 -1.25 558.55 58-58-4SG 30.08111 -97.84361 710.00 7/28/06 164.41 0.00 545.59 58-58-4TC 30.06184 -97.85600 748.00 7/28/06 186.05 0.00 561.95 58-58-508 30.07917 -97.83099 731.45 6/21/06 175.40 556.05 58-58-704 30.02750 -97.85389 746.00 7/31/06 201.25 -0.34 544.41 58-58-711 30.01677 -97.85932 696.62 7/25/06 144.10 -1.95 550.57 67-01-203 29.96194 -97.92056 691.00 7/24/06 112.40 -1.00 577.60 67-01-301 29.96294 -97.89681 679.00 7/24/06 116.98 -1.00 561.02 67-01-3AT 29.96739 -97.87622 697.00 8/30/06 121.10 -2.00 573.90 67-01-5BH 29.92472 -97.93833 712.30 7/24/06 111.00 -0.50 600.80 67-01-5MD 29.94628 -97.93557 755.00 8/3/06 190.42 -1.30 563.28 67-01-5MW 29.95156 -97.93530 770.00 8/2/06 203.23 -0.70 566.07 67-01-5PL 29.91819 -97.93240 660.00 7/24/06 93.28 -2.05 564.67 67-01-6XN1 29.94111 -97.89156 630.00 8/2/06 27.10 -2.00 600.90 67-01-6XN2 29.94058 -97.89103 630.00 8/2/06 26.44 -1.50 602.06 67-01-801 29.89472 -97.93028 574.00 0.00 0.00 574.00 San Marcos Springs 67-01-9EG 29.91359 -97.91647 650.00 7/24/06 72.40 -0.85 576.75

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A-8: Trinity Potentiometric Data A-8: Trinity Potentiometric Data SWN Inferred Aquifer DDLat DDLong MP LSD Date 99 DLW 99 WL Elev 99 Date 2002 DWL 2002 WL Elev 2002 Date 2005 DWL (ft) 2005 WL Elev 2005 Date 2006 DWL (ft) 2006 WL Elev (ft) 2006 5849406 Middle 30.17833 -97.96278 -1.00 1015.00 11/08/05 49.75 8/13/06 49.93 964.07 5849509 Lower 30.1722222 -97.9441667 -1.60 978.00 12/19/05 360.82 615.58 5849511 Middle 30.19397 -97.92458 -1.35 991.46 2/13/02 220.20 769.91 08/02/06 350.10 640.01 5849601 Upper 30.20537 -97.89588 -2.6 796 2/13/02 32.10 5849602 Upper 30.20708 -97.89520 -2.5 805 2/13/02 7.58 5849603 Upper 30.20679 -97.90495 0 827 2/13/02 24.79 5849604 Middle 30.20650 -97.90521 -0.28 827.07 2/13/02 140.92 685.87 5849606 Upper 30.17507 -97.90086 0 885 9/24/99 122.96 5849608 Middle 30.19938 -97.87556 0.00 838.52 6/22/99 175.21 663.31 5849609 Upper & Middle 30.17917 -97.89750 0.00 870.00 6/22/99 148.71 721.29 5849704 Middle 30.13828 -97.96912 0.00 974.25 2/19/02 242.68 731.57 5849706 Middle 30.14570 -97.96701 -2.45 981.96 2/19/02 236.20 743.31 08/02/06 367.98 611.53 5849707 Middle & Lower 30.13875 -97.95889 -1.75 1093.00 2/19/02 317.05 774.20 5849903 Upper 30.14644 -97.91629 -0.5 837 2/11/02 5.39 831.39 5849913 Middle 30.13278 -97.88944 -2.10 827.00 8/5/99 224.00 600.90 5849918 Upper 30.13778 -97.89261 -1.69 769 8/5/99 107.90 5849925 Upper & Middle 30.12594 -97.90382 -1.35 789.86 2/3/02 150.92 637.59 11/01/05 153.26 635.25 08/01/06 170.00 618.51 BSEACD Report of Investigations 2007-1201 615849928 Middle 30.14532 -97.87984 -1.45 745.00 8/5/99 210.45 533.10 06/26/06 184.75 558.80

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A-8: Trinity Potentiometric Data SWN Inferred Aquifer DDLat DDLong MP LSD Date 99 DLW 99 WL Elev 99 Date 2002 DWL 2002 WL Elev 2002 Date 2005 DWL (ft) 2005 WL Elev 2005 Date 2006 DWL (ft) 2006 WL Elev (ft) 2006 5849933 Upper 30.14515 -97.87982 -2 745 8/5/99 265.52 5850120 Lower 30.23497 -97.87321 0.00 832.00 2/13/02 268.45 563.55 09/24/05 289.37 542.63 08/01/06 332.95 499.05 5850121 Middle 30.22018 -97.86961 -2.00 830.00 2/7/02 244.40 583.60 10/31/05 252.55 575.45 07/26/06 255.63 572.37 5850125 Lower 30.24594 -97.85099 -0.90 843.60 02/01/02 270.29 572.41 07/26/06 326.25 516.45 5850409 Upper 30.17428 -97.87479 -0.70 714.50 8/9/99 182.13 531.68 2/7/02 185.93 527.87 11/03/05 181.98 531.82 07/26/06 185.60 528.20 5850415 Middle 30.18944 -97.87361 0.00 830.00 2/7/02 195.14 634.86 10/05/05 190.62 639.38 5851102 Lower 30.24055 -97.74639 0.00 530.00 2/4/02 143.78 386.22 5857507 Upper & Middle (+/-Ked) 30.06358 -97.94252 -3.20 837.00 2/6/02 198.10 635.70 11/02/05 224.53 609.27 08/03/06 235.38 598.42 5857809 Upper 30.01032 -97.94487 -0.45 738 2/4/02 82.80 11/15/05 84.60 652.95 57569CB Middle 30.12961 -98.01430 -2.40 963.13 4/3/02 60.00 900.73 11/08/05 83.56 877.17 08/13/06 125.46 835.27 58494FR Lower 30.19806 -97.98028 -2.00 1083.00 3/8/02 410.00 671.00 58495F1 Upper 30.18761 -97.93945 0 953 2/19/02 60.65 58495F2 Middle 30.18816 -97.94017 -1.20 938.76 2/19/02 65.30 872.26 58495IH Middle 30.18180 -97.92930 -1.45 966.36 08/02/06 372.50 592.41 58495KR Middle 30.18748 -97.93740 -0.95 924.72 2/19/02 42.48 881.29 58495MH Middle & Lower 30.17986 -97.94807 -0.95 954.73 11/08/05 331.85 621.93 08/13/06 372.25 581.53 58495RW Middle 30.18431 -97.93494 -1.70 930.54 2/19/02 48.50 880.34 58496BM Middle 30.20053 -97.90720 -0.15 936.02 2/13/02 263.55 672.32 BSEACD Report of Investigations 2007-1201 6258496H2 Upper & Middle 30.20702 -97.89436 -0.10 808.71 2/13/02 203.40 605.21

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CD Report of Investigations 2007-1201 63 Potentiometric Data Inferred Aquifer DDLat DDLong MP LSD Date 99 DLW 99 WL Elev 99 Date 2002 DWL 2002 WL Elev 2002 Date 2005 DWL (ft) 2005 WL Elev 2005 Date 2006 DWL (ft) 2006 WL El ev BSEAA-8: TrinitySWN 58496H58497G58574AR58574R (ft) 2006 4 Upper & Middle 30.20554 -97.90504 -2.15 823.12 2/13/02 220.90 600.07 4 Middle 30.13838 -97.96915 -1.70 963.16 2/19/02 277.60 683.86 Upper 30.04639 -97.97472 -1.40 956.00 7/22/99 224.18 730.42 1 Upper 30.05237 -97.99522 0.00 1013.52 9/22/99 216.00 797.52

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BSEACD Report of Investigations 2007-1201 64 Compact Disk The compact disk contains dig ital copies of all maps and fi gures in this report and a simple Microsoft Excel-based database with potentiometric data.