The Green Swamp: Should it be in Public Ownership?

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The Green Swamp: Should it be in Public Ownership?

Material Information

The Green Swamp: Should it be in Public Ownership?
Garald G. Parker
Physical Description:
1 online resource (1 paper)


Subjects / Keywords:
Floridan Aquifer ( lcsh )
Green Swamp (Fla.) ( lcsh )
Flood control ( lcsh )
Water supply ( lcsh )
Land tenure ( lcsh )
Text ( sobekcm )
Time Period:
1973 - 1973
North and Central America -- United States -- Florida -- Green Swamp


A paper discussing the impact of the Green Swamp on the water supply of peninsular Florida.
Original Location:
Box 3 Folder 12
General Note:
April 1973

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
This object is protected by copyright, and is made available here for research and educational purposes. Permission to reuse, publish, or reproduce the object beyond the bounds of Fair Use or other exemptions to copyright law must be obtained from the copyright holder.
Resource Identifier:
G16-00003 ( USFLDC DOI )
g16.3 ( USFLDC Handle )

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THE GREEN SWAMP: SHOULD IT BE IN PUBLIC OWNERSHIP? . BY GARALD G. PARKER, C.P.G. !/ Peninsular Florida, south of a hydrologic divide that crosses the peninsula in a roughly arcuate line from Cedar Key northeast to Putnam Hall. and Florahome, thence southeast to New Smyrna Beach, is a "hydrologic island." No rains that fall, no streams that flow, and no ground water that courses through the rocks, crosses this line southward. Therefore, all water that is available for any use whatsoever south of thls line originates as rainfall south of the line. Of the rain thatfalls in the area south of this line, averaging about 55 inches a year, about 73% or more is lost to evapotranspiration piocesses. This is the water that evaporates from all wet surfaces, such as rivers, lakes, swamps, wet soils, wet leaves, wet roofs, and roadways, etc. and that is transpired, or "breathed" by living organisms, chiefly plants. This loss,about 40 inches per year, subtracted from the precipitation, leaves about 15 inches for recharge to the aquifers and eventual runoff from the streams. Fifteen inches of annual recharge on one square mile of land surface amounts to about 718,000 gallons per day and this is roughly the measure of the potential water crop from each square mile of land in all areas of recharge. In other words, starting with our aquifers full, we could harvest 15 inches or 718,000 gallons per' day per square mile and not diminish storage in the aquifers at all. But we could he using up all the water in the strenms a.nd before long thev would dry up! So we have to settle for some lower yield, perhaps about one-third the runoff, or 5 inches per square mile. This would yield us roughly about 24 .0,000 gallons per day per square mile. But much of the land area of Florida south of the peninsular hydrologic divide either water (as most of our river and coastal swamp lands do) or the Floridan aquifer is so deeply buried beneath overlying impermeable deposits of dense clay, silt, and marl, that no local recharge takes place. As a result we depend upon three main (but not sole) recharge areas, namely: (1) the Green Swamp High; (2) the Pasco High, which centers about 40 miles due west of the Green Swamp; and (3) the Ai'achua-Putnam High, which centers about 110 miles north of the Green Swamp and is dissected by the peninsular hydrologic divide. The Pasco. High furnishes most of the water supply to the coastal area from Tampa (including about one-half of Tampa's supply) north to and beyond Weeki Wachee. The Alachua-Putnam High serves a vast area including part of Suwannee Basin, part of the Silver Springs Basin, part of the Rainbow Springs Basin, and much of the Upper St. Johns Basin. The Green Swamp serves ari even larger area, including in part the Upper St. Johns Basin, the Peace River Basin, and the coastal area from Charlotte County north to Tampa. !/ Chief Hydrologist and Senior Scientist, Southwest Florida Water Management District, Brooksville, Florida


Although the Green Swamp is thus not the only recharge area in Central and South Florida, is one of the three most important and likewise up to now one of the least developed. It is essential to protect it from "ditchers, 11 "drainers, 11 and "developers," who could ruin it as a source of water. lhe Green Swamp as defined by the U. S. Geological Survey, comprises about 870 square northern Polk and southern Lake Counties, with smaller 'Sc?"-f..n e.i4'1 ..,,t-e.,..-parts inieastern asco and Hernando Counties. About 710 square miles or nearly 82% of the 870 square miles is drained (rather poorly) by the Withlacoochee River. Tite remainder is divided between the Hillsborough, Peace, and Oklawaha River Basins, and a smaller part goes to the Kissinnnee River Basin. But these streams are less sources of water supply than they are sources of floodcontrol problems. The huge Floridan Aquifer acquires much of its recharge here, and it is the ground water from the Floridan Aquifer that supplies more than 90% of all water supplies utilized in peninsular Florida. Thus, as described, the Green Swamp is not only the springhead of five major rivers in peninsular Florida, it is also the largest of the three major ground water recharge sources in the peninsula. Recent hydrologic studies of water available for use in the Southwest Florida Water funagement District have shown that, with all potential sources accounted fo.r, we will, for once-only uses, be using all of nature's annual fresh water replenishment by about 1985. Beyond that, if we are to supply the burgeoning population and industry with needed water, other sources will need to be developed, and these are costly. It behooves us to protect, develop, and conserve the fresh water resources nature has provided for us. And among these, perhaps the most important of all is the Green Swamp. As part of the Four Rivers Basin project, Florida, Southwest Florida Water Management District has acquired, or is in the process of acquiring, 133 square m-Lles of the Green Swamp for flood detention areas. This is divided between the Little Withlacoochee Flood Detention Area (36.4 square miles) and the Green Swamp Flood Detention Area (96.6 square miles) and amounts to a total of 15.3% of the Green Swamp area (as defined by the U. S. Geological Survey in Florida Geological Survey Report of Investigations No. 4, dated 1966). But this acquirement by Southwest Florida Water Management District is only about one-seventh of the total Green Swamp area. Would it be necessary and proper for the government (statec , federal, or distri.ct) to own all the 870 square mi.les of the defi.ned Green Swamp? The answer is but the government should own and use for water recharge and conservati.on purposes as much of the 870 square miles as are normally flooded by the 25-year flood. In other words, the Green Swamp land that should be allowed to remain in private holdings for development, should be only those lands that are normally not flooded by the 25-year flood. How much land is thus normally flooded? Or saying i.t in another way, how much land in the Green Swamp should be developed without resorting to drainage and related flood control works? This is the crux of the problem. To date there are large areas of the Green Swamp that have never been surveyed to determine land ownership boundaries, much less to determine the areas that generally are not flooded and, to be developed, would require drainage, roads, water supplies, sewage, and other public services. -2-


.. Lacking the necessary survey data one can only estimate the area, based on study of the most useful available maps --the United States Geological Survey Topographic Quadrangles --for the area. These maps have ten-foot contour intervals and show areas of swamp, wooded, and open lands. The ten-foot contour intervals are almost useless for our present purposes --one needs onefoot contours, not ten-foot intervals. The Green Swamp area is not even covered with modern aerial photos that would allow, by study of the plant assemblages and topographic features, the discrimination of generally non-flooded from flooded lands. A study of the U. S. Geological Survey maps, plus some supplementary knowledge gained from brief trips through the Green Swamp area and surveillance flights over it, indicates that perhaps one-fourth to one-fifth of the Green Swamp area may be suitable for limited development. This would be in excess of the 133 square miles in the two flood detention areas in the Green Swamp. Thus, 870 133 = 737 x 1/4 = about 184 square miles; or, if one-fifth is suitable, then only about 147 square miles is suitable for private development, chiefly as scattered residences and farmsteads. The rest, about 553 to 590 square miles, should be retained for water supply and conservation purposes chiefly, but would also serve as public park land, wild life pre$.erve, and a green belt to serve the urbanized areas. The remainder, 147 to 184 square miles is widely scattered through the Green Swamp, generally as isolated islands or narrow, linear ridges of no great individual size. There is no really large block of "high land" that could be developed for new towns or similar land developments, without extensive drainage that would be harmful to the swamps and marshes needed for recharge purposes to supply water to the thirsty, growing population outside of the Green Swamp. Further, allowing urbanization or municipal type developments in .the Green Swamp would carry with it the seeds of destruction to the water supply even if were not the cause. The problem is how to dispose of the human, industrial, conunercial, and agricultural wastes that would accumu1a.te from deve1opment of the Green Swamp lands. Lacki_ng streams to carry away and dilute wastes, the poorly drained Green Swamp could well become huge noisome sump of human and i .ndustrial wastes that would ruin the recharge source for the major water supply of Central Florida. As this essay concludes, based on the best evidence now available, the state, federal, or district governments should acquire about 5'i0 to 590 additional square miles of the Green Swamp. At current inflated values of About $250 per acre, this would cost $90 million to $100 million and market demands are risir.g rapidly. These are relatively large sums of money. But we are talking of protecting one of the major sources of water supply for all of southern, peninsular Florida. It is a cost that we must somehow manage to pay, and soon, for the developers are rapidly usurping the land and if allowed to proceed unchecked will ruin the Green Swamp for all time. 04-15-73 --3-


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