Competition for available water supplies will continue into the future 

 and will likely be one of the most pressing environmental issues in Southwest 

 Florida (Milliman et al . 1981). 



Impoundments as a Source of Groundwater Pollution 



One of the most pressing problems concerning the quantity and quality of 

 surface water in Southwest Florida is the impoundment of freshwater streams to 

 supply water for industrial and mining purposes, for municipal sewage treat- 

 ment, and irrigation. Waste waters contaminated with bacteria and toxic 

 materials often are released by users into the impoundments. Not only are the 

 impoundments contaminated, but according to a Department of Environmental 

 Regulation study in 1980, some of the water retained temporarily in the 

 impoundments seep into shallow underground aquifers and contaminate public 

 supply water there. Nearly all the drinking water used in Southwest Florida 

 comes from these aquifers (the larger are called subsurface impoundments) and, 

 without proper treatment, are a threat to public health. 



Major aquifers in Southwest Florida that are affected are the Floridian 

 aquifer, the shallow caustic acquifer, the sand ridge water table aquifer, and 

 the Bay of Biscayne aquifer. Evidence is that these aquifers will be further 

 threatened as the demand for clean water and wastewater disposal accelerate 

 into a major conflict. Unless aggressive State action is taken, the quality 

 of the water supply will degrade unchecked. 



4 



Insufficient treatment of waste waters discharged into surface impound- 

 ments will increase the cost of drinking water treatment. Continued degrada- 

 tion of the groundwater quality may eventually limit economic growth in the 

 area. The 1980 report recommends steps that can be taken to minimize this 

 threat. Currently the Department of Environmental Regulation is developing a 

 series of groundwater and permit standards to protect shallow freshwater 

 drinking water supplies from pollution. 



Southwest Florida has a relatively large number of small impoundments. 

 Hillsborough County has the largest number of mining related impoundments 

 which are primarily holding areas for phosphate slime operations. It also has 

 the largest number (224) of municipal impoundments, agricultural impoundments 

 (82), and industrial impoundments (72). Lee County has a large number (238) 

 of municipal impoundments, as do Sarasota, Manatee, and Collier Counties. 

 Lee County has 66 industrial impoundments and 2 agricultural impoundments, and 

 Pinellas County has 62 industrial impoundments. The risks involved with these 

 impoundments were described earlier in the hazardous waste section of this 

 report. 



The Florida State Department of Environmental Regulation (1980b) com- 

 pleted a study in January 1980 that reported that "surface impoundments dis- 

 charge pollutants into shallow aquifiers." These pollutants travel undetected 

 through the subsurface. This study (referred to as a Surface Impoundment 

 Assessment) reported thousands of subsurface impoundments that have the same 

 potential as surface impoundments for contaminating groundwater supplies. The 

 study further reported that more intense conflicts between clean water and 

 waste water disposal will develop unchecked unless aggressive State action is 

 taken. The current rate of degradation of drinking water supplies from 

 groundwater pollution is likely to continue. 



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