SUMMARY 



PURPOSE OF THIS REPORT. To summarize present knowledge about the sources, 

 distribution and movement of water in the Long Island Sound Region. Clima- 

 tological factors such as temperature, wind and cloud cover that affect 

 elements of the hydrologic system are also discussed. 



HOW DOES WATER ENTER AND LEAVE THE SOUND? 



Long Island Sound holds about 16, 800 billion gallons of water 



but much more than this amount moves in and out each year estimated aver- 

 age quantities in billions of gallons a year (bgy) are: 



\H OUT 



Exchange with the ocean (east end) 64,000 79,800 



Net Exchange through the East River (west end) 9,200 



Runoff from streams 6,200 



Precipitation on the Sound 800 



Evaporation from the Sound 630 



Diversions into the region 130 



Ground-water outflow (Long Island) 100 



Many of these estimates rest on incomplete or poor data more 



accurate quantification is needed for planning and management. 



WHAT ARE THE PRINCIPAL CLIMATIC FEATURES? 



The climate of the Long Island Sound Region is characterized by: 

 four distinct seasons, little monthly variation in normal precipitation, 

 marked temperature contrasts over short distances, and the maritime influ- 

 ence which modifies air masses entering the region the climate may vary 



appreciably from one location to another and from one year to another 



distinctive climate events such as hurricanes, tornadoes, droughts and 

 blizzards occur in the region, resulting in floods, wind damage, crop 

 failure, and even loss of life. 



WHAT IS THE HYDROLOGIC SYSTEM IN THE REGION? 



The Region has an abundant supply of fresh water derived from 



precipitation and from inflowing streams. of the total precipitation 



falling on the land each year, about half returns to the atmosphere by 



evapotranspi ration the remainder ultimately discharges to streams and 



the Sound, either directly by overland flow or indirectly by downward per- 

 colation to the water table some 75 streams drain into Long Island Sound 



they are hydraul ical ly connected to adjacent ground-water reservoirs and 

 are tidal in their lower reaches--the Connecticut, Thames and Housatonic 



Rivers account for over 80 percent of total streamflow into the Sound 



about 16,500 square miles of land drains into the Sound, only 12 percent of 



this area is within the study region inflow is highest in the spring, 



lowest in the summer. 



I I 



