Geology topics

Research about Pasco County, Florida

Source-linked reports with geographic coverage including Pasco County, Florida.

2 recordsLinked to original sources

USGS1985

Hydrogeology of the Cross Bar Ranch well-field area and projected impact of pumping, Pasco County, Florida

The hydrogeology and development of a groundwater flow model are described for a 121-square-mile area in Pasco County, Florida. The hydrogeologic framework consists of the surficial aquifer--a thin blanket of sand--and the underlying carbonates of the upper Floridian aquifer. The aquifers are separated by a leaky sand and clay confining unit. The Cross Bar Ranch well field occupies 13 square miles and contains 17 production wells averaging about 700 feet deep and tapping the upper Florida aquifer. Procedures to calibrate, test sensitivity to input parameters, and validate the model 's accuracy are described. Pumping at 30 million gallons per day should result in 5 feet of decline in the water table of the surficial aquifer over an 8-square-mile area and in the potentiometric surface of the Upper Florida aquifer over a 15-square-mile area. Under the 45-million-per-day maximum permitted rate, drawdown should be 5 feet or more in the water table and potentiometric surface over areas of 16 and 28 square miles, respectively. At the center of pumping, water levels could decline 15 to 25 feet. The surficial aquifer could possibly be completely dewatered in a small area of the well field when pumping is at the maximum rate.

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USGS1980

Ground-water hydrology of the Dade City area, Pasco County, Florida, with emphasis on the hydrologic effects of pumping from the Floridan aquifer

The Dade City area, northeast Pasco County, Florida, is an area of about 260 square miles. Of the approximately 32 million gallons per day pumped from the Floridan aquifer in the area in 1975, about 16 million gallons per day were pumped from an area of about 0.25 square miles by a citrus processing plant. There are essentially two producing zones in the Floridan aquifer in the Dade City area. The upper zone is from about 10 feet above to about 150 feet below National Geodetic Vertical Datum of 1929 , and the lower zone from about 300 to about 500 feet below NGVD of 1929. There is evidence of hydraulic interconnection of the upper and lower zones of the Floridan aquifer. This appears to be highly significant in terms of the geohydrology of the Floridan aquifer in the area, particularly with regard to its ground-water flow pattern, water quality, and aquifer hydraulic characteristics. In the immediate vicinity of the citrus processing plant, aquifer transmissivity may range from 200,000 to as much as 400,000 feet squared per day. It is probable the Floridan is only semiconfined in the immediate vicinity of the citrus processing plant. High aquifer transmissivity in the area is the reason why there are only a few feet of drawdown of the Floridan 's potentiometric level even near the center of the well field.

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