EFFECTS OF ARTIFICIAL RECHARGE ON GROUND-WATER QUALITY, LONG ISLAND, NEW YORK.

Artificial-recharge experiments were conducted at East Meadow in central Nassau County, Long Island, N. Y. , from October 1982 through January 1984, to evaluate the degree of ground-water mounding and chemical effects of artificially replenishing the ground-water system with tertiary-treated wastewater. Reclaimed water was provided by the Cedar Creek wastewater-treatment plant in Wantagh. Recharge with reclaimed water increased the concentration of sodium and chloride in ground water but lowered the concentrations of total nitrogen (nitrate plus nitrite) and some low-molecular-weight hydrocarbons. Reclaimed water was well within the New York State effluent standards for ground-water recharge. Specific-conductance measurements and Stiff diagrams of chemical analyses were used to help define the extent and shape of the plume formed by reclaimed water.