Long Island Sound –
By the Numbers

Area of Long Island Sound
1,194 square miles*
Area of the drainage basin or watershed
16,820 square miles
Average Depth
63 feet
Water Volume
18 trillion gallons
Length of Coastline
600 miles
No. of Harbors, Bays, and Coves
Salinity range at the western end
23 parts per thousand
Salinity range at the eastern end
35 parts per thousand
% of fresh water that comes from three major rivers
Avg. winter and summer water temperatures (2011)
37°F winter/69°F summer
No. of tides each day (greatest tides in the west)
4 tides (2 high, 2 low)
Population living within 50 miles
more than 23 million people
Estimated value to the local economy per year
$9.4 billion (2015 dollars)
No. of finfish species found in the Sound
More than 120 finfish species
No. of tropical species that stray here seasonally
21 tropical species
No. of species that spawn in the Sound
at least 50 species

Data Note

*The area of the Sound includes all the major embayments of the Sound. When Fishers Island Sound (surrounding Fishers Island) is included the area is 1,220 square miles.

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