Nassau County’s drinking water supply is threatened by salty ocean water. Coastal areas like Long Beach and Oyster Bay are at the highest risk and may need to find new water sources in the future.
Saltwater intrusion occurs when freshwater is pumped out of wells for everyday use and irrigation, leaving room for saltwater from the Long Island Sound and the Atlantic Ocean to creep in, increasing the salinity in groundwater.
The study by the U.S. Geological Survey was undertaken in 2016 to measure the sustainability of the sole-source aquifers that provide the island's freshwater supply. It shows that even if pumping freshwater stopped altogether, it could take generations to reverse.
"Saltwater increased during the 20th century and continues to increase to the present in the Lloyd-North Shore aquifer system in Great Neck and Manhasset Neck in northern Nassau County," the USGS wrote. "A major wedge of saltwater intrusion in the...aquifer in southwestern Nassau County appears to be increasing."
Several decades of population growth have increased the demand for fresh water, and warmer temperatures mean rain evaporates more quickly and seeps less into the aquifers.
