Ground-water resources of Kings and Queens counties, Long Island, New York

Abstract

The aquifers beneath Kings and Queens Counties supphed an average of more than 120 Mgalld (milhon gallons per day) for Industnal and pubhc water supply dunng 1904-4 7, but this pumping caused saltwater Intrusion and a detenoration of water quahty that led to the cessation of pumping for pubhc supply In Kings County In 194 7 and In western Queens County In 197 4 Since the cessation of pumping In Kings and westem Queens Counties, groundwater levels have recovered steadily, and the saltwater has partly dispersed and become diluted In eastern Queens County, where pumpage for pubhc supply averages 60 Mgal/d, all three maJor aquifers contain a large cone of depression The saltwater-freshwater Interface In the J ameco-Magothy aquifer already extends Inland In southeastern Queens County and IS moving toward this cone of depression. The pumping centers' proxinnty to the north shore also warrants monitonng for saltwater Intrusion In the Flushing Bay area Urbanization and development on western Long Island Since before the tum of this century have caused significant changes In the groundwater budget (total Inflow and outflow) and patterns of movement Some of the maJor causes are (1) Intensive pumping for Industnal and pubhc supply, (2) paving of large land-surface areas, (3) Installation of a vast network of combined (storm and sanitary) sewers, (4) leakage from a watersupply-hoe network that cames more than 750 Mgalld, and (5) bunal of stream channels and extensive wetland areas near the shore Elevated nitrate and chlonde concentrations throughout the upper glacial (water-table) aquifer Indicate widespread contannnabon from the land surface Locahzed contannnatlon In the underlyIng Jameco-Magothy aquifer IS attnbuted to downward nngratlon In areas of hydrauhc connection between aquifers where the Gardiners Clay IS absent. A channel eroded through the Raritan confimng unit provides a pathway for nngratlon of surface contannnants to the Lloyd aquifer sooner than anticipated Although ground water In the Lloyd aquifer IS still pnstlne, present pumping rates and potentlometnc levels In the Lloyd aquifer Indicate that It Is much more sensitive to Withdrawals than the other aquifers are and contains an extremely hnnted water supply Ground water has been a source of pubhc supply for western Long Island smce the mid-19th century Rapid Increases m populatiOn smce the tum of this century, and the attendant Increases In pumpmg for pubhc supply and mdustry, have resulted m severe water-level declmes and mtruswn of salme water from the surrounding bays As a result, pumpmg for pubhc supply 0 to 300

A Comparison of Methods for Assessing Groundwater Flooding Due to Sea Level Rise

“…Permeability testing determined the in-situ permeability to be approximately 30 m/day. These findings agreed with a previous USGS report detailing the hydrogeology of the area (Buxton and Shernoff, 1999). According to the USGS, bedrock depth in the study area is approximately 275 m below sea level, but the uppermost confining layer-the Gardiners Clay-is about 45 m below sea level.…”