Ninety-nine percent of the 79.72 million gal/d of water used in Pasco County, Florida is groundwater from the Upper Floridan aquifer. In addition, 53.5 million gal/d is exported for use in Pinellas County. Chemical quality of the water generally falls within recommended limits for drinking water except near the coast. A groundwater flow model was used to predict drawdowns in water levels under five different development plans for west Pasco County. One of these plans was incorporated in an estimated groundwater development plan for 2035 for Pasco, Pinellas, and part of Hillsborough County. Reduction in evapotranspiration accounts for nearly all the water required for each development plan. Two plans showed less effect in drawdown and potential of saltwater intrusion than the other three. For the overall groundwater development plan for Pasco, Pinellas, and parts of Hillsborough Counties, the average potentiometric surface in 2035 would be from 8 ft higher to 20 ft lower than the average 1976-77 potentiometric surface. Reductions in head would increase the potential for infiltration of contaminants in areas where surficial materials are thin, sinkhole development in sinkhole prone areas, and upconing and lateral intrusion of saltwater. The potential for dewatering the surficial aquifer is great in the Cross Bar Ranch and Cypress Creek well-field areas. Evapotranspiration of groundwater would be reduced by 19% between 1976-77 and 2035. Exchange of water between the rivers and the aquifers will be reduced by 13%. Springflow will be reduced by 6%, and three springs will cease to flow. Model boundary inflow and outflow also will be reduced.
