TABLE k. WATER BUDGETS OF THE NORTHERN AND SOUTHERN PARTS OF THE 

 "WATER BUDGET AREA" OF LONG ISLAND, WATER YEARS 19^0-65 



[In millions of gallons per day] 



' The quantities in this table were derived with the assumption that no significant 

 change in ground-water storage occurred in the water-budget area during the period, 

 water years 1940-66. Independent quantitative estimates were made for all compon- 

 ents in the table unless otherwise noted. None of the values in this table are accurate 

 to more than 2 significant figures, and many values are accurate to less. 



Where more than 2 significant figures are shown, the entry was derived 

 from other entries in the table, and an additional significant figure was retained to 

 balance inflow and outflow. (See footnotes below.) 



2 The estimate of ground-water recharge was obtained by adding components 4, 6, 

 and 8. 



» The estimate of ground-water discharge to streams was obtained by subtracting 

 component 2 from component 7. 



* The estimate of evapotranspiration of precipitation was obtained by adding 

 components 6, 7, and 8 and subtracting the total from component 1. Therefore, the 

 subtotal of components 5, 6, 7, and 8 (total outflow) equals component 1 (total inflow) . 



• These values may be in error by as much as 100 percent or more. Values are in- 

 cluded mainly to indicate order of magnitude. 



After Franks and McClymonds (1972) 



Artificial recharge to the ground-water reservoir is from cess- 

 pools, septic tanks, recharge basins, injection wells and leaky water and 

 sewer pipes. The total artificial recharge in Nassau and Suffolk Counties 

 is estimated at 310 mgd in 1965; approximately 68 percent (210 mgd) of which 

 is from cesspools, septic tanks and recharge basins (10) . 



The quality of ground water has been affected primarily by waste 

 disposal practices that include disposal of sewage and industrial wastes 

 into the ground through septic tanks, cesspools and recharge basins. Dete- 

 rioration of quality has also resulted from the injection of heated water 

 through recharge wells, the discharge of smoke and other particulate matter 

 into the atmosphere, the leaching of fertilizers and salt-water encroachment 

 in areas of overdevelopment. 



Cohen and others (5) outlined the progressive pattern of ground- 

 water development in Long Island in three stages: 



30 



