315,000 acre-feet, including input 

 from the Big Cypress, to maintain 

 the Everglades National Park. Of 

 this total, 260,000 acre-feet was 

 considered to be the average annual 

 flow required from Conservation Area 

 3A. This was just slightly less 

 than the 273,000 acre-feet estimate 

 of Van V. Dunn (1961). The latter's 

 estimate was a median value rather 

 than an absolute minimum (Tabb 

 1963). 



Klein et al. (1975) calculates 

 that the total annual inflow to the 

 park prior to conservation area 

 construction (1941-1962) was 947,000 

 acre-feet. Bear in mind that this 

 estimate includes rainfall and run- 

 off, and it reflects a relatively 

 low water condition compared to the 

 pre-drainage Everglades. As of 1941 

 Lake Okeechobee was diked and much 

 of what used to be Everglades sheet 

 flow was being bled off through 

 major drainage canals to the east 

 and west. After conservation area 

 construction (1963-1970) Klein esti- 

 mates average annual inflows to the 

 park at 1,384,000 acre-feet. Of the 

 437,000 acre-feet increase, approxi- 

 mately 250,000 was due to the water 

 control structures and the rest to 

 increased rainfall. 



Since 1972, the U.S. Geological 

 Survey (USCS) has been monitoring 

 the quality of surface waters and 

 sediment within the conservation 

 areas to the north of Tamiami Canal. 

 Moving south through the conserva- 

 tion areas, water quality character- 

 istics change significantly. In 

 particular, specific conductance, a 

 measure of the total ionic content 

 of water, decreases in a southerly 

 direction (Waller and Earle 1975, 

 Goolsby et al. 1976). A distinct 

 gradient of increasing specific con- 

 ductance also exists in the direc- 

 tion of the urbanized east coast 

 within Conservation Area 3 (Waller 

 and Earle 1975) . 



Mineralization of Everglades 

 surface waters is due primarily to 

 the closeness of highly soluble 

 calcium carbonate rock and leaching 

 from organic soils. Additionally, 

 groundwater to the south of Lake 

 Okeechobee is highly mineralized due 

 to contact with connate (entrapped) 

 seawater from ancient marine sedi- 

 ments (Parker et al. 1955). As 

 rainfall and runoff oscillate sea- 

 sonally, concentrations of major 

 inorganic ions respond accordingly. 

 Wet season concentrations are gener- 

 ally lower than dry season concen- 

 trations, due to relative dilution 

 (Table 13). 



Notable exceptions to the gen- 

 eral seasonal trend are color and 

 sulfate in both groups of stations 

 and calcium at the marsh sites. All 

 of these increase in concentration 

 with increased rainfall/runoff. 



Excess color in the marshes arises 

 from washout of organic tannins and 

 lignins, which are higher in concen- 

 tration during the wet season than 

 during the dry season. Sulfate 



concentrations decrease during the 

 dry season presumably because of 

 anaerobic reduction to sulfide 

 (Waller and Earle 1975). Calcium 

 concentrations decrease during the 

 wet season probably because of 

 enhanced precipitation under pH 

 conditions greater than 8.3. 



In contrast to the general sea- 

 sonal pattern, Lutz (1977) reports 

 no particular seasonal trends in the 

 major individual inorganic ions in 

 the Tamiami Canal to the east of the 

 study area; however, specific con- 

 ductance does show an increasing 

 trend during the dry season as well 

 as a slight increase with depth. 



Nitrogen, phosphorous, and 

 organic carbon are fairly high in 

 the conservation areas due to the 

 highly organic soils and productive 

 marsh environment. As with the 



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