The quality of ground water has been locally altered by (1) dis- 

 posal to the ground of sewage and industrial effluent and landfill disposal 

 of solid wastes, (2) leaching of fertilizers and deicing compounds, and (3) 

 induced recharge of water from streams and salt-water encroachment in areas 

 of ground-water development. Most cases of pollution are apparently local, 

 but there is no continuing program of monitoring ground-water quality to 

 evaluate long-term changes. 



The existing pattern of development on the north shore of Long 

 Island Sound consists of: 



(1) Surface-water reservoirs and well fields tapping stratified- 

 drift deposits that provide water for urbanized areas. Waste disposal is 

 principally by sewage treatment plants that discharge to streams, estuaries 

 and the ocean. 



(2) Individual wells principally tapping bedrock provide water 

 for rural and many suburban parts of the area. Waste disposal is to septic 

 tanks and cesspools. 



Both of the above patterns of development may produce hydrologic 

 problems. Large scale ground-water development reduces streamflow in adjacent 

 streams and by lowering the water table can affect lake levels and swamps. 

 During periods of low streamflow, the pumping may even dry up a reach of stream. 

 In the coastal urban centers of New Haven and Bridgeport, Connecticut pumping 

 over a long period resulted in widespread salt-water encroachment of the 

 strat if ied-dr if t aquifers and subsequent abandonment of many wells. In the 

 less developed areas, septic tank disposal may be inadequate and require sewer- 

 ing or the effluent may deteriorate the ground-water quality. 



The development and management of ground-water resources must 

 take into account the hydrologic balance between inflow and outflow within 

 each ground-water reservoir. Only small local imbalances exist at the present, 

 primarily because of the small amount of development. 



Future large scale ground-water development will occur principal- 

 ly in valleys containing thick permeable deposits of stratified drift. In 

 most areas, these deposits are hydraul ical ly connected to adjacent streams 

 and may be termed stream-aquifer systems. The sustained yield of these stream- 

 aquifer systems may vary considerably depending on the scheme of management. 

 For example, estimated yields of several stream-aquifer systems in Subregions 

 1, 4 and 5 shown on maps prepared for this study (see Appendix C) range from 

 less than 0.5 to over 15 million gallons per day. These yields were predica- 

 ted on a management scheme, the essential elements of which are (1) the water 

 pumped is not returned to the ground-water reservoir or stream near the site 

 of withdrawal, (2) minimal effect on streamflow, and (3) fairly constant rate 

 of pumping. Several alternative management schemes would significantly alter 

 the estimated long-term yields. 



A continuous program of hydrogeologic investigations is necessary for 

 planning the optimal development and management of both ground- and surface- 

 water resources on the north shore of Long Island Sound. Such a program should 



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