Highlights of water management in the southwest Florida water management district

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Highlights of water management in the southwest Florida water management district

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Highlights of water management in the southwest Florida water management district
Parker, Garald G. (Garald Gordon)
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Box 2


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Aquifers -- Hydrogeology -- Florida ( lcsh )
Hydrology -- Florida -- Biscayne Aquifer (Fla.) ( lcsh )

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University of South Florida
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University of South Florida
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The University of South Florida Libraries believes that the Item is in the Public Domain under the laws of the United States, but a determination was not made as to its copyright status under the copyright laws of other countries. The Item may not be in the Public Domain under the laws of other countries.
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032968560 ( ALEPH )
891343127 ( OCLC )
G16-00678 ( USFLDC DOI )
g16.678 ( USFLDC Handle )

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Highlights of Water Management in the -Southwest Florida Water Management District by Garald G. Parker, C.P~G.a ABSTRACT Tl~e District, comprising 15 counties and nearly 10,000 square miles in central western Florida centering on the Tampa-St. Petersburg metropolitan area, is one of the. nation's most rapidly growing areas. Water-budget analyses _ compared with expected water d~nrnnds for water by the burgeoning population indicate that by about 1985, if the present population growth rates and water-use demands persist, we will be using as much water as nature supplies us with on the long-term average annual basis, for once-only uses. After that, to supply the water needed, we \Vill either "mine" water on a District-wide scale or bring about other remedies. Among these are, without attempting to list them in order of-priorities: 1. Reuse water again and again by cleaning it up and recharging the aquifers with both high-grade sewage effluent either by land-spreading or by injection _through recharge wells into the aquifers. 2. Engage in . desalination of r-he almost limitless quantities of brackish ground water, especially in the coastal areas where salt-water encroachment is occurring on a large scale. 3. Induce aquifer recharge by creating storage space in the aquifers in areas that are currently full to overflowing. In such areas . precipitation is no\v largely rejected as re charge and ground-water seepage is lost to evapotrans piration. 4. Effect economies of water use by both industry and agriculture-by far the largest users of water in our District-by regulation of amounts that may be used for irrigation and for various other industrial and agricultural processes. 5. Divert flood waters from direct runoff to the oceans to temporary flood detention areas from which water can be drawn off to aquifer recharge facilities . . 6. By permit processes reguiate the amounts of water that can be withdrawn for any purpose from either grou~dor surface-water sources in the District thus preventing overdraft and resultant lowered water levels and, in some areas additional salt:-water encroachment. 7. Eliminate waste of water, particularly the existing . large losses from thousands of existing . wild-flowing artesia n wells. a Chief Hydrologist and Senior Scientist, Southwest lorida Water Management District, Brooksville, Florida 33512. ,. Discussion . o).'.Jen until Octo__.bc:r L 197 3. 8. Develop new, large well fields u_pgradient from ihc larg t coastal springs that now are discharging along our Gulf Coast, a total of about 900 mgd, none of which is now used for water supply. 9. Space new well fiel~s for regional water-supply purposes widely over the District and arr.u:ige for o~aniza-tion of regional water-distribution and use systems : 10. As soon_ as feasible engage in rainmaking tQ augment nature's normal precipitation. Under nature's irrigation supply-deJ'!la d pattern and man's previously -unmanaged and all-too-often wasceftil usage growing beyond all previous expectations, the water . supply and the flood-and-drought situation have becorn~ impossible to live with. But with proper management of our . water and land resources the tide can be changed. and. it will be possible to live comfortably with in our available: resources. It will cost us more but the incrca cost is the price we must pay to live in an area w c dem nds on the• ,vater resources are rapidly outgrowing n the Southwest Florida Water Ma agemenr District comprises an area of nearly 10, _ 0 square , miles and 15 counties situa,ted in central-western. . I Florida (Figure 1). In fact, the District is almost as_ . large as -the State of Maryland and is larger ~an an-y: of the following States: Connecticut, Delaware , New Hampshire; New Jersey, Massachusetts, Rhode Island or Vermont. "Big" government is loathed in Florida just as it is generally elsewhere in the United States,. and .it: took a nearly catastrophic set of weathercircum~ . stances in 19 59 and 1960 to convince citizens of ' this reg_ion that local government is too small, too~; weak and generally too provincial in outlook co• prevent or alleviate such destructive floods , as those that plagued this region ,in March 19 59, and. again in . March and September 1960. . As a matter of fact, th. . alternatin ood and dt0U t thro ghout. both geologic and recorded n , • ' B .ut a ong as the_: popuLlti~n was ~a. rse . and the dema. ds for water_:. supply ,vere irtcons~quentiaL the people cGuld toler:ite the vagaries of nature. For .-ample the; great flood of. September 1933 might have been_ ' en moridisastrous rhan .. thos


.. SQl.:T"'W~!>T FU>fll WATE~ MA •~MC>IT O , o ?0 40 1,0 60 100 SC.,._\..E IN M \LES Fig. 1. Index map showing the 1ocation of the Southwest Horida Water Management mstrict. but i~ 193 3 the population was small and homes and business e tablishments generally were not in flood prone areas. Today the population is fife, expanding rapidly, and much of it is develop ing in hazardous, flood prone areas. The counties of Florida ha\ c the authority to enact flood plain .zoning regulations but, with rare exceptions, have . failed to do so. .,,-~ -Historically, this area has experienced numer_ .ous droughts of 1 or 1-to 2-years' duration but people had always been able . ."to make out" because their small needs for water could be met by nearby sources. Now we are experiencing, generally over the entire District, a drought of unprecedented proportions with 10 years of -subnormal precipitation out of the last 12, and with an accumulated rainfall deficiency of about 100 inches or more (Figure 2). With a long-term aver . age annual pre-cipitation for the District of about 5 5 inche _ s, the deficiency is almost that of 2 years of expected rainfall. Such conditions of extreme drought and flood, complicate d by an exp loding populatjon \\ irh a va-st thirst for water, have created watersupply and flood .protection problems of suc h large m a gnitudes that l oca l governmentsvillage, city a_a county-cannot successfully combat them. . • Accordingly "Big Government" in the form of a regional flood control agenc y was demanded by loc a l citizens in 1960. The. State Legislature re-sponded by enacting Chapter 61-691, Florida Statutes, which established the Southwest Fl~rida Water Management District. The Act became law . on July 1, 1961. Its Section 1 states: "For the purpose defined in Chapter 3 78, Florida Statutes, a nd to facilitate the creation and initial operation of a district under said Chapter, Southwest Florida Water .Management District is hereby created a public corporation for carrying out and effectuating the provisions of said Chapter. Other than as herein provided, Southwest Florida Water Management District shall operate under and be governed by the provisions of Chapter 378, Florida Statutes, as amended from time to time." Chapter 378, Florida Statutes, is known as the Flood Control Act. It prescribes rules and regulations governing the establishment of flood control and water management districts. Among other things this Act provides for cooperation with agen . cies of the federal government to effect flood .control management (378.01) and establishes a water resources development account (378.03) in the general revenue fund of the State which is to prov ide financial assistance to districts established under its authority, including the funds as grants. in-aid to purchase lands required for such purposes as water storage areas, canal or reservoir sites and bridges. The members of the Board of Governors, as 25 20 1 0 5 0 5 10 1 5 20 2 5 Departure From Normal Rainfall For Tampa, Fla . 8/

. ) • provided in Chapter 61-691, were appointed by the Governor an d met for their organizational meeting on August 28, 1961, at the Capitol in Tallahassee, Florida. By March 6, 1962, the entire District w a s organized into 11 River B as ins (Figure 3), each with its own B as in Board opera ting at the grassroots level to levy taxes, build and operate flood control and other water management structures within limits of their river basin boundaries , and to b e r esponsible for carrying out the provisions of Ch apter 61-691 within their respective bounda ries. Each Basin Board, however, is r e ~ponsible for its actions to the 9-member Board of-Governors of the District. In the meantime, members of the Florida delegation to the U.S. Congress were busy arranging through the Committees on Public Works in both the House and the Senate for aid of the U.S. government under the provisions of both the River and Harbor and Flood Control Acts. This resulted in the establishment of the Four River Basins, Florida, Project as described in House Document No. 585, 87th Congress, 2nd Session, 1962 (Figure 4). Under this authority and with funds provided by e U.S. Congress, the State of Florida's water resources development account and local ad valorcm taxes, the U.S. Army Corps of Engineers and the Southwest Florida Water Management District began work on the Four River B a sins' Project on October 23, 1962. The District staff at that time consisted of only 3 persons, but additional personnel were adde d as work progressed on the flood control aspects of the Four Rive r Basins' Project. Early in .the Proje .ct emphasis w a s placed on starting construction of the Tampa Bypass Canal with its system of channels and water control structures designed to route damaging floods around the periphery of Tampa instead of through it; on developing the outdoor recreation plan to allow and provide for citi ze n use of flood control properties and other works of the District such as reservoirs and flood detention areas for such activities as hunting, fishing and camping; beginning work on the Lake Tarpon project to prevent flooding and to seal off salt water from access to the lake, thus allowing it eventually to become a fresh-wate( lake; to acquire l a nds within the 850 square miles of the Green Swamp for flood detention purposes and, hopefully, either for direct aquifer recharge or for l ater downstream release as water supplies to the rapidly growing coa tal urban areas; to improve navigation and water conservation on the Withlacoochee River by construction at the 18 CRYSTAL HOMos•s BP. '5\ ;J , .. ~ ! : .. ... ,.;~;, : ti ~ )(:;. Pl'TMLACHA!>C.O 1' -B:::ac• -~J r~~ C) "" I/ ~e:tEf. S0-.. ~0.Art V O F sou,,_ .-.EST FLO~•OA WATER "'..:.>..>C,EME .. T Q 1 ~ TRICT 10 4 v /4 -E OK~CH084E . • . -" Fig. 3. Map of Southwest Florida Water Management Dis• trict showing the 11 river basins which comprise-the District . Fig. 4. Map of Southwest Florida Water Management Dis ~ trict showing works of the Four River Bas ins' Project of the U.S. Army Corps of Engineers and the Southwest, . Florida Water Management District.


Wysong Locks and Dam of the inflatable "Fabridam "; on the purchase of a huge flood detention area in the lo,\ er Hillsborough River to serve also • a site for a big, ~e,v well field to serve the creasing needs of the City of Tampa; on the replacement of an antiquated and worn-out dam on the Oklawaha at .Moss Bluff with a bigger, new locks and dam; on the construction of the Masaryktown Byp. ass Canal to prevent a recurrence of some of the worst flooding experien.ced in .the District during the 1960 floods; on the construction of the Jumper Creek Flood Detention Area and the Tsala Apopka Outfall Canal on the Withlacoochee River in Citru: County; and on numerous other projects such as the Big C} press Creek Flood Detention Area including a regional well field. Works such as these, including the building and occupancy of a new heaqquarters office and -service center on a beautiful oak and pine forested site 7 mile s south of Brooks\ ille (Figure 1) occupied the chief attention of the staff until early 1969. At that time, owing to growing pressure on the Disrrict's Governing Board to regulate the drilling of \\el ls and the uncontrolled development of ground \\'ater, the decision was made to establish a Ground-Water Hydrology Division for these purposes. This was done in lv\arch 1969, but was • kl } reoriented to a Hydrologic Division when ecame understood by the administrative and executive officers of the District-that ground water and surface water in this District are only different sides of the same hydrologic coin and must be n_1~naged as a single resource. Upon the activation of the new Hydrologic Division, the nucleus was available for the establishment, under Chapter 3 73 .142, Florida Statutes, of a Water Regulatory District. This was accomplished in July 19~9, with the new organization having the same Board of Governors and the same District boundaries as the original District. The staff wrote the draft of a proposed regulatory law and on October 1, 1969, Chapter 357R-1, Florida Administrative Code, "Orders of the Southwest Florida Water Management District (Regulatory)" became effective. Ch apter 3 5 7 R-1 defined the rnles and regulations for the development, use, control_ , and conservation of water and related land resources, with p;rticular referei 1ee to ground-water resources in the District. Its several sections provided for: ( J) Purposes and definitions; (2) Regis~-~n of , ,. II drillers; (3) Construct ion of wells; . nvenro r y of wells and water uses; ( 5) Civil action for damages; and (6) Penal provisions. Un e r these regubtions the registration of all well drillers and engineering laboratories drilling holes of 2 inches. in diameter or larger was begun on January 1, 1970; all drillers@f good repute and adequate experience were "grandfathered" in during this first year but any not registered by January 1, 1971, were required to take both a written test in the office and a demonstration test of drilling skills using their own rigs "on the job." In the office,. 11;3M card systems were set up for data control, filing, retrieving and processing. Before many months had passed the staff was processing an average of nearly 1,000 vvell permits and well completion reports each month and to date have registered 297 well drilling contractors and l,107 drillers. A total of 22,939 well drilling permits have been processed from January 1, 1970 to December 1, 1972. Owing to unforeseen weaknesses and incomplete coverage of our initia~ rules and regulations , I (3 57R-1 ); revisions were made and adopted as Chapter 16CC, Florida Administrative Code, effective February 3, 1972. Later, on July 1, 1972, the Hydrologic Division was given broader functions• and entitled the Water Resources Division; simultaneously the biologists of the Environmental Team, previously a unit loosely attached to the Office of the Executive Director, were made the nucleus of our newly established Environmental Department. This rearrangement allows for-better use of personnel, equipment and facilities, and the organization as needed from time to time of ad hoc teams of hydrologists, geologists,. biologists and engineers to attack practically any problem of environmental, water resources, or engineering con-_ cern. Currently, a Planning Division is being established. Other Divisions, ~hose titles suggest their areas of responsibility are: Administrative, Legal and Office of the Senior Scientist-Chief Hydrologist, Engineering, Environmental, Field Operations, Finance and Accounting, Real Estate, Technical Services and Water Resources. Although the Four River Basins' Project is still the largest in terms of money and manpower expended on District programs, the problems relating to water supply have taken over the major emphasis of our present planning. Scarcely a day passes-if ever-that water or water-related problems somewhere in the District do not make newspaper, TV and radio headlines. Or saying it another way, water and water-related problems are always in the news and by far the most of these relate to water supply. In order to find s olutions to these water problems and to manage water adequately, it .is neces-19 , . . . I ..


I • ) . s ary th a t .we understand the nature and occurre nce of our water resources. B asic to this understanding i s rhe d etermination of how mucb of w hat kind of wt1ter is where and bow it mries in quantity a n d q uulity, both in spac e . and in time. To gain thisessential knowledge we r el : : heavily upon a compre hensive, cooperative arrangement with the U.S. G eo logical Survey to d evelo p b o th the systematic and speci a l basic data ne eded for management p ur poses. This is suppl emented by gener a lized geologic a nd hydrologic studies of florida by the Florida Department of Natu ral Re s ources in cooperation with the U.S. Ge olog ical Survey and the Southwest florida Water M a nagement District. The information supplied as a result of these coopera tive -agreements covers such areas as: (1) flows and st age s of streams; (2) flows and stages of ground w ~t e r; (3) study and description of both the chemical and biologic quality of ground and surface waters; ( 4) investigation and description of lakes, aquifers and aquicludes; (5) preparation of water table and potentiometric maps for various places at di fferent times of the year; (6) evalu ation and d escription of the water resources of areas of particular interest, such as for example, the Green Swamp, the Gulf Coastal zone of salt-water encroachment, the "world's biggest orange grove," an area of 62 square miles in DeSoto County, and the phosphate-mining _district in the upper Peace and Al afia River basins; and (7) others such as one or more contiguous counties not previously studied in detail . Topical cooperative studies include such subjects as: (1) deep well disposal of waste waters; (2) the effects of spray irrigation disposal of sewage effluent; (3) the artificial recharge of aquifers; (4) salt-water encroachment; (5) the development of aquifer and river basin digital models; (6) groundwatersurface-water relationships; and (7) forecast ing the formation of sinkholes. This is far from being a complete list of areas and topics of study but is fairly representative of the scope of our cooperative program with the U.S. Geological Sur vey. This cooperative arrangement, covering fiscal ye a rs 1963 through 1972, has amounted to a total of $4,220,300 of which the District has contributed one. half and the Survey the other half. The pro gram h . as steadily grown from its inception and is now funded ( 197 3 FY) at $607,000 (both sides included), but it is still inadequate to cover our needs of data for water m a nagement purposes. To supplement the U.S . Geological Surve y cooperative program, special studies are contracte d with consulting firms of e ngineers, hydrologists and environmentalists; and b asic to all our field studies is a progr a m of m apping the Districtt pi ece by piece as funds b eco me avai l able, bv photognmmetric methods. Most m ap pi ng i s done on a scale of 1 inch equ a l s 200 feet an d with 1-foot contour intervals. This m app~ng is done by contract \\ it h firms specializing in photogramme t ry . In addition to the work done a nd d ata assembled b y the U.S. Geological S urv ey, the consult ants and the ph otogra mmetric firms , the District staff of 24 water resources p rofessionals a nd 9 subprofession als gathers a vast amount of fie ld inform ation both pe rsona lly and from the well compl eti on reports requ i red b y l a\v to be completed an d sent in by th e well driller s operating within . the District. Such d ata a re filed, -rared and. -~ l ater retrieved as needed by us . e of IBM computer • facilities supplemented with standard filing and storage systems. Special studies of all available data are combined to make managemen t decisions on all levels ranging from the regi1lation of pumping regimes and quantities of water pumped from existing wells and well fields to the gra nting or denial of a permit for a new well;the plugging-and abandonment of an old one, the t aking of water from any surface-water source, or the di-edgin g, filling or building of structures in can a ls or streams of the District. Like\.vis e , decisions are made. re garding whether or not a proposed n e,\ well field may be developed and if so-how,where, an d when. Conditions of its drilling, completion a nd subsequent operation are carefully re gulated to avoi d o ve rd evelopment of the resource or d amag e either to the environment or to existing water-supply de\ elopments. Additionally, operations of e xisting we ll fields ' and all other l a rge sources of withdrawal are being strictl y monitore d and . controlled. This has already led to orders fo; the reduction of pumping from ' existin g well fields of the Cit y of St. P etersburg, of the County of Pinell as , a nd s pecific \Yells of the phosph ate industry . . Ord ers for reductio n of exist ing l a rge sca le pumping r elat ed to e:\:cessive o r inefficient use of indu s tri al and agricultu yal waters are no\v being finalized. Currently our k nowledge of w a ter use a nd withdra wals l a rgely d epe nds upon un v erified reports from the operator.. The new orders will require the meteri ng of all water from i l a rge cap acity wells or other sources~ and quarterly reporting b y the operators of their withdrawals and fin a l disposition of the withdrawn waters . . Thus , for the. first tim e in any l a r ge area of Florida, total me asured withdrawals and tota l consumptive u es will be known. Such information i s esse ntial f ,r p ro p er mamgement a n d e \ entu:1l a loca tion of


t,ater resom es for whatever us es man needs to make of them. Emironmental assessmen: t of proposed l a nd • elopment , drainage proposals, eutrophication . 1tro1 schemes for lakes and reservoirs, and many other imilar or related studies are a regular part of our a ctivities. The staffers making these studies and management decisions, some of which are in the form of recommendations for action either to the Di trict GO\ erning Board or any of the 11 District Ba in Boards, consist (as of J 2-1-72) of 3 biologists, 11 engineers, 3 geologists, 4 hydrologists, 3 hydrogeologi ts, and 9 h drotechnicians. The staff also engages in a wide variety of ;,people-ervice" functions. These include such matters as: 1. Preparation and publication of The Hydroscope, _the monthly journal printed to keep the public informed not only of current important happenings affecting the water resources of the .District but enlightening our nonprofessional readers on interesting or current technical matters (Vol. 1, o. 1 \\as issued in January 1970). Recent topics ha, e included articles on. salt-water encroachment, how to interpret and utilize potentiornetric maps, the meani ng and value of hydrographs, the nature ~our water-supply problems and how to use the 9t:r budget approach tQ determine the adequacy of our water resources for future population gro\ th, the size and location of new well fields, .and any others. 2. Participation in meetings of learned and scientific ocieties, engineering and professional as ociations, public forums, seminars and the giving of talks or speeches before Boards of County Commissioners, City Councils, scholastic groups ranging from uni\ersity level to the elementary school, and active membership in citizen-sponsored action . groups -seeking such objectives as new and improved \ \.ater treatment and/or sewage treatment plants, or the end to a drainage scheme or one of land de elopment t hat could be damaging to the water re ources or to the em ironment. 3. Planning for the acquisition of new flood water detention areas and/or new well fields that , ould be integral parts of a region a l water-supply system for selected p arts of our urbanizing areas and their conjuncti, e use for citizen enjoyment, • in . eluding camping, fish in g, hunting, bird-lore, . ol "Outdoor Classrooms," nature trails, canoecourses, and oth rs. ow at this point, it may be well to describe the nature of some of the water-supply problems we are working on and some of the solutions to these problems that are either proposed or have been determined: The number one problem relates to how much water is available for water-supply purposes and how much water can be withdrawn from what sources for consumptive use. Currently we can only derive "ball-park" values, because, with the kinds of basic data available to work with, this is the best that can be done at the present time. To quantify the water-supply situation we make use of the water budget method. HO\vever, we must use the results we obtain with caution, recognizing that they are only "ball-park" values because all the factors we plug into our equations arc themselves only approximations. Precipitation, for example, is measured at widely scattered stations over the District and most of the records are short, in the order of 10 years or less; few exceed 50 years. Thus, precipitation values are not nearly as good as needed. The Jong-term average rainfall over the District appears to be about 5 5 inches per year. Runoff, the discharge measured in . surface streams, is perhaps even . less we11 defined than precipitation. Runoff records are shorter, few exceeding 40 years; and, to avoid tidal conditions in the estuarial sections of our coastal streams, gaging stations are generally several miles or more inland from the stream mouths. Thus rhe runoff increment in the stretch between the gaging station and the stream mouth is unmeasured and must be estimated. Total, long .-term average runoff the District over, is apparently about 15 inches per year. Ground-water discharge into the lower, tidal portions of the streams and into the Gulf of Mexico via shore zone seeps and submarine springs cannot be measured directly so must be determined in directly. Likewise, storage and flow of ground \\"ater in the aquifers cannot be measured directly as is srreamflow; therefore, such information must be derived indirectly from study of pumping test data that give us approximate values of the co efficients of transmissibility, storage , and leakance, an d from potentiometric and water t a ble maps that provide us with gradients and lengths of flow sections through the saturated thickness of the aquifers. Adding to our quantification problem is the fact that there is no direct way of me:i uring evapo transpiratioi1 lo sses . Generally, evapotranspiration (Et) values are derived as a residual by subtracting 21 , . . .. !-'


bottom to top to effectively stop this senseless waste of water. D. Augment present supplies . 1. Reus e of water (C 2 and C 3 abov e) is a means of augmenting current supplies. 2 . Pr e venting salt-water e ncro achment is an augmentation of existi ng supplies. 3. Recycling cleaned-up sewage wastes is one of our bi gges t sources of "new,, water. Most municipa l sewage is 99% reusable water. Being replaces it, allow no more l arge-scale water . d eve lopments and work to elim i nate waste and extravagant u ses of water supphes in such areas. run through "tertiary,, (extended secondary) treatment to reduce impurities of all kinds and re sult in a product that is at least as good as ,\. w ater naturally available in the aquifers and ~a~ strea ms of the area, would make such water av aila ble for human reuse after being artifi-~ cially recharged to our aquifers or mixed with streamflow. Just one reuse of a year's water\,)-.\ crop would allow the water crop to go twice 7. ln the shore zo ne r eg i o n whi ch h as been in vade d by salt-water encroachment and in some inland are a s rntaining brackish gro und water, imm ense supplies . of b racki h . w ater are available, particul arly in the upper parts of the Florid an Aquifer of sou t hern Florida. . . This.water r a ng es from nearly as salty as the ocean to only slightly more salty than normal ground , water. Much of it a mil e or so inl a n _ d is onl y mildly saline (1,000 to 7,000 mall) and can be economically reclaimed for u se . This will : be more costly _than us e of fresh water (if it . were locally available), but is comparable to_. the cost of developing and transporting . fresh water from distant well fields. Som e d ay we will do this on a large sc a le, and it may not.: as far. Or, saying it another way, it would serve twice as many people. This can be done, but at a cost. It is a cost that, eventually, we . must p a y. _The question isn't if we should do it, the question is oniy when and how sh a ll we d o it? 4. ~,:Pture as much flood flow as we can an.d inject it into the only available large storage reservoir -the Floridan Aquifer: This can be accomplished best by developing flood detention reservoirs with discharge works lead ing to those parts of the District where large drawdowns of water level have created billions or trillions of gallons of available storage volume. Some such large storage capacity exists in the areas of pumping influence that surround every large well field in the District, but the largest potential storage is in the areas of lar ge drawdown around the phosphate and citrus production areas, mostly in Polk, eastern Hillsb o rough and eastern M a natee Counties where, over more than a thousand square miles, water levels . in the FloridanAquifer hav e declined 20 to 60 feet or more in the last 20 years. 5. Locate and operate regional well fields and r echarge facilities so as to manage withdrawals and repla _cements (re-charge) scientific a lly. Well fields should be hooked up into regional system s much as the electrical industry has done their generator plants a nd powe r distribution sys tems. 6. In areas where wate r is now being "mined," that is pump~d out at a rate faster th an nature be far off, p a rticul a rly if the coa t J! C ~nties ' cannot import the fresh w ater they ~viU n eed.~~ to obtain from outside their county bound aries. We must remembe r that the -co a sta l ' counties are at the dowm tr eam end of n ature's pipeline; the upstrea m end is in those inl an d counties mostly to the ea t, and i included within the boundaries of the Southwest Flor:. ida .Water Management D ist rict. 8 . Import water from dist ance s up to several hundred miles, such as from the aquif r upgradient from Weekiw a chee Springs, Chass a howitzka Sp r ings, Homosassa Spri ngs , Crystal River Springs and o'thers, or even farther, from such large north Florida streams as the Suwannee OL Apa l ac hicola. But this will be costly, probably much more costl y than any other mea ns previously mentioned. 1 onethe less, it has been done elsewhere in p laces such as Boston, New York, Los Angeles, San Francisco a nd Den ve r; it could also be done here. Hydrologic and engi-neering studi es will have to be m ade b y the District to evaluate just how mu.ch th ese alternatives \vill cost. Then, with such knowledge, the taxpayers will be in a position to make the necessary choices . E. Mine the aquifers. The Floridan Aquifer and its overlying shallow system of water t able and low pressure a rtesi a n z0.n es contain fa r more water in storage tha n all the Great Lake combined. In' the District, for exa.rnple, the upper 1,000. feet or more 1 gene r al : ly filled with fresh, :iter inland


~west of Punta Gorda. This new pl ant was installed in 1972 a t a cost of $385 ,000, includin g pump , wells and rreatment plam. Rotunda pl a ns to expand plant to 2 mgd in the near future. Co s t of ~ating br .ckish water from wells at the site an d reducing the 7,000 ppm chloride in the untreated \\ 'ell v,ater to less than 250 ppm \V ith only one p ass throu gh the exchange m ed ium is exp ecte d to be about 50 cents per thou. and gallons. Rotunda's engineers c alculate that such water can be profitably d eli ered to their con.sumers at 85 cents per thousand g allon. The s a lty waste water produced . is piped to the nearby Gulf of Mexico -where it is swept away by the tides to mingle h armlessl y with the ast saln waters of the Gulf. In summary, water management controls are needed to prevent this region and our District from becoming hydrologically bankrupt. It appears that . by about 19 8 5 we will be using all of the ,n-erage annu a t water crop and, as a conseque nce, unless action is take n in time to forestall it, we will be mining water on an increasing scale. Water is already beiJ1g mined on a l arg e scale in the phos. phate field of the upper P eac e River basin where the potentiometric surface of the artesian water in the Florid a n Aquifer has dropped 20 to 60 feet o er an area in e x ce s s of "1,000 square miles during . ~ last !0 years. Some of the prev~ntative and . ~ ervat10n n:easures we may employ include: A. Reduce R (runoff) losses to the Atlantic Ocean and the Gulf of Mexico . 1. Establish and utilize additional flood retention re serv oirs. 2. Create recharge facilities in association with such reservoirs to hurry flood waters into aquifer storage. 3. Establi s h salt-water control dams on tidal can als an d streams and place these d ams as near the shoreline as feasible . Hold a fre s hwater hea

runoff (R) from precipitation (P), all in inches of water. This is more reliable the longer the period of record and should b e at least a year long. By starting and stopping each water budget period at the same time of year the annual cycle of wet and dry periods will be complete, and no accounting may therefore have to be made of changes in storage in ground-or surface-water bodies, or in the soil moisture above the water table. If significant chang es in storage have occurred, these then must be plugged into the. right-hand side of the equation. Runoff is essentially the measure of the total potential water crop, but it is only a potential, not an actual measure of what can be taken for consumptive use. Some water must be left to maintain the flow in the streams and to prevent lakes, swamps and marshes from drying out. For onceonly use, as is the common current practice here in _ the Southwest Florida Water Management District, it a p pears that we'd be lucky indeed if W{;. could cap~ 1re and use more than 1h R. How much would this be, and how many people would it supply with the amount of water-they will need? First, let's calculate the yield possible to obtain from the 15 inches of R. One inch of R from one .square mile for one year is approximately 17 .4 million gallons. 1/3 X 15" = 5", the expected water crop, and 5" X 17.4 mgy/mi2 = 87 mil. gal/mi2/yr.. From 10,000 sq. mi. the "ball-park" value of the water crop would be 870 billion gallons, or 0.87 tgy (trillion gallons per year). Current District water use data are still in the process of being computed and in the absence of actual values, we shall estimate that the usage i s about 1,000 gpcd (gallons per capita per day). This compares with U.S. Geological Survey figures for the 1970 national use at 1,800 gpcd. Our rate of use here is lower than the national use inasmuch a s we have fewer heavy industries and smaller agricultural uses in the District than in the industrial Ea s t and the irrigated West . Nonetheless, our huge phosphate and citrus industries are very large users of water and run the gpcd figures up from around 175-250 gpcd for our larger cities, and 100 gpcd for village uses, to this higher estimated Districtwide value. The population of the District is now about 1. 7 5 million people and it is generally forecast by demographers _that this will double by about 1985. Gi ve n 1. 7 5 million persons and 1,000 gpcd once only usages, our current water demand is about 365,000 gpcy (gallons per capita per year). This totals 638.75 bgy (billion gallons per year) or 0.64 to:.v _fr_U.J nded.' Wit h . an estimated availab f e aver .tge annual water crop of 0 .8 7 tgy and a water. use of 0.6 + tgy, we currently" have a sur plus of 0.23 tgy, or enoug h water for a population in creas of about 630,000 persons. Thus, on the b asis of these estim ation s, we will b e using all of the avai-lable water crop before 19 8 5 an d water min in g v ill begin on a l arge, incre ased scale unle.s w ay s are found either to augment the water crop r d ecrease us ag e, or both. So we h av e c a use for concern, but not for alarm. Even if before 1985 we use all the annual .. water crop, we will not be running out of fresh water. The great Floridan Aquifer (our huge "water barrel") underlies the State everywhere and: here ranges in thickness from about a thousan d feet to. more than 2000 feet. Totally, under the nearly 10,000 square miles of the District, the Floridan Aquifer stores far more fresh water tha n is stored in all of the Great Lakes combined. However, there is a limit to the amount that we may "mine" from this great aquifer, for much of its fresh water is in dea d storage , a dea d storage. imposed by the Ghyben-Herzberg principle of salt waterfresh water relations h i p . The Floridan peninsula is surrounded by ocea n w a ter a nd ever y where, at some depth, it is underla in b) salt water some. of which is more than 3 times a.s alty as the ocean. So, except fot relativel y short periods of timet _ we d a re not draw the regional water l evel down to or below sea level. Thus we c a n only safely use that part of this huge lens of fresh water that is above sea le el and this is a comparativ ely small part of the total volume in storage. If we were to manage our ground-water withdrawals so poorly as to deplete the top storage (the part abo e sea level), the bottom storage (the p art b elow sea level) will _ slmvly shrink in dir ec t proportion to top-storage depleti~n and as a conseq~ence salt w ater would move both inl and from the Gulf and upwa rd from below. Once this h appens it would be practically impossible to get ~he salt water pushed back out. However, even salt-\vater encroachment is not all b ad, for it furnishe s us with a n abundant supply of brackish water that c a n b e sweetened for watersuppl y purposes. R ecent breakthroughs in the reverse osmosis (RO) method h av e apparently made this method competitive with development and transport of fresh-water supplies via pipe lines from distant well fields. The n ewest~ and probably th~ most efficient desalination plant in the U .S., is the 500,000 gpd RO phnt at Rotunda \ ' '1:: ton Char-


from the 2 5-fo o t contour on the potentiometric urface. However, s alt water underlies this aqui f er system every\\'here and bounds it on the -st all along 'th shore. If the aquifer is over~mped, salt-water encroachment slowly but e\ entually follows. Tampa and St. _ Petersburg, to name only 2 large users, lost their original coastal zone well fields to salt-water encroach .ment in the 1920's; now other coastal cities, such as New Port Richey, .are undergoing the same loss. Addirionally, thousands of private wells in the shore zone that extends generally inland from the Gulf of Mexico to about the 10-foot contour on the potentiometric surface either have been ruined by salt-water encroachment or are in imminent dang_er of the same fate. And this is extremely serious because this zone includes most of our rapidly urbanizing area wh e re the largest amounts of wate r 'Nill be . needed to supply its burgeon _ ing' popula t ion. Great care must be taken that the aquifer not be mined of its fresh water with resultant salt water encroachment. Detailed research is cur rently underway to develop better knowledge of the aquifer's hydrologic characteristics . o that realistic, effective management decisions can be reached. Right now we have considerable generalized and some specific information and hydrologic understandings that will serve to guide us until better and more detailed data are available. We can make do, then, for awhile. But, we can't afford to dally. The situation is_upon us now. .r • Technical oivision NWW A • ' . . Membership is open to: "tho-se who are engaged in occupations pertaining to the supervision, regulation, or investigation of _. ground water or ground-water supply installations _ or who are teachers or students at recognized institutions in academic fields related to the study of ground water." The purposes of this Division are: "to cooperate with other Divisions of the N.W.W.A. in fostering ground-water research, educat~on, standards, and techniques; to advance knowledge in enginering and science, as related to ground water; and to promote harmony between the water well industry and scientific agencies relative to the proper development and protection of ground water supplies." Individual membership dues in the Technical Division ($18.00 per year) include a subscription to Ground Wa"ter in addition to the Water Well ' . I Journal. Membership application forms avai"lable , upon request. National Water Well Association, Inc. 88 East Broad Street Columbus, Ohio 43215 25 -,~.• ... -!. '


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