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II
FIGURE 10.-Areas of recharge to the Floridan aquifer.
The aquifer is replenished by infiltration of rain over about 13,000 square miles. In the darkly-shaded areas almost all. the rainfall is offered to the aquifer but some is rejected when the aquifer becomes full. In the lightly shaded areas the aquifer is blanketed by watertight material but receives recharge through sinkholes that penetrate the blanket.
This aquifer is the source of Florida's many large springs, such as Silver Springs, whose discharge averages 500 mgd, or 775 cfs. It is also the source of water from many thousand wells. In Seminole County alone it yields water to more than 2,500 irrigation wells. The natural flows of some of the wells are quite large; one well at Jacksonville, in Duval County, yielded a flow of almost 10 mgd, enough water to nsuppnly a city of 75,000 people.