WATER RESOURCES OF ORANGE COUNTY 87
with the depth to the water table, the porosity of the soil, the climate, the season and other factors.
The base flow of most streams in Orange County is maintained by seepage from the nonartesian aquifer. Seepage from the nonartesian aquifer also helps to maintain the levels of lakes and ponds during droughts.
Practically all natural recharge to the -Floridan aquifer in Orange County passes through the nonartesian aquifer. In the western part of the county, downward leakage is probably the principal form of discharge from the nonartesian aquifer. Seepage of nonartesian water out of the county is probably small.
Water is pumped from the nonartesian aquifer for lawn irrigation, stock watering, and domestic use. Most wells are small 11/- to 2-inch sand-point wells which yield about 5 to 10 gpm.
QUALITY OF WATER
Several factors influence the quality of the nonartesian ground water in Orange County. Rain recharging the aquifer dissolves soluble material contacted such as fertilizer and insecticides. Drainage from septic tanks percolates to the nonartesian aquifer. Harmful bacteria and color are usually removed if the recharge water percolates through sand. Some of the very shallow wells located in swampy areas yield water with high color. Most of the nonartesian ground water that is soft and low in mineral content has low pH indicating that it is corrosive. In areas where the piezometric surface is above the water table, upward leakage occurs and the nonartesian water is more highly mineralized.
The dissolved mineral content of water from wells in the nonartesian aquifer varies greatly depending on the composition of the aquifer. The -water from wells developed in clean quartz sand is usually very soft (hardness generally less than 25 ppm) and low in mineral content (about 25 to 50 ppm). The following is a typical analysis of water from a well in western Orange County (838-128-1) developed in clean quartz sand:
Silica (Si02) 2.5 ppm Dissolved solids 21 ppm Iron (Fe) .45 ppm Specific conductance 39 micromhos Calcium (Ca) .8 ppm at 25oC Magnesium (Mg) .7 ppm Bicarbonate (HC02) 5 ppm Sodium (Na) Sulfate (SO,) 2.8 ppm Potassium (K) .0 ppm Chloride (Cl) 5.5 ppm Fluoride (F) 0.1 ppm pH 5.2 units