124 CONSERVATION OF GROUND WATER 



ground-water reservoir under Brooklyn, at the western end of 

 Long Island, New York, but the water table has been rising 

 in recent years and may eventually rise sufficiently to be a prob- 

 lem in some basements and subways constructed several years 

 ago. Provincetown, on Cape Cod in Massachusetts, has solved 

 a similar problem of salt-water encroachment by pumping at 

 reduced rates, especially when the water table is low. Thus 

 controlled, the wells furnish a continuous supply of fresh 

 water, although some are within 800 feet of the ocean. 



Brooklyn, N.Y. 55 Brooklyn occupies the western tip of 

 Long Island, which has an areal extent of about 1,300 

 square miles and is bordered on all sides by salt water. The 

 ground-water reservoir underlies practically all the island 

 and is dependent for its natural replenishment upon the 

 precipitation that falls on the island. So humid is the climate 

 and so permeable the surficial materials of the island that 

 the replenishment is estimated to average a billion gallons 

 a day or more. The ground water moves toward the edges 

 of the island and is discharged into the ocean, either directly 

 from the sands and gravels or through the numerous streams 

 fed from the ground-water reservoir. Fresh water has been 

 obtained from wells right along the strand line of the island, 

 and even along the barrier beaches. 



In Brooklyn, the island is only 6 to 8 miles wide between 

 the East River and Jamaica Bay. Here, too, water levels were 

 originally above sea level, as shown by a water-table map 

 based on data collected in 1859. By 1932, however, heavy 

 draft for industrial and public use had lowered water levels 

 below sea level under the northern half of Brooklyn. The 



ss References: Brashears, M. L., Artificial Recharge of Ground-water on 

 Long Island, N.Y., Econ. Geo/., vol. 41, pp. 503-515, 1946. 



Jacob, C. E., The Water Table in the Western and Central 

 Parts of Long Island, New York, N.Y. Water Power and Con- 

 trol Commission Bull. GW T -12, 1945, 24 pp. 



Lusczynski, N. J., "Withdrawal of Ground Water and Pond 

 Water on Long Island from 1904 to 1949," U.S. Geol. Sur- 

 vey, Typed rept., 1950, 3 pp. 



