An aerial photo shows flooding and erosion at Jones Beach...

An aerial photo shows flooding and erosion at Jones Beach State Park, Thursday. (April 1, 2010) Credit: Kevin P. Coughlin

A season of heavy rain has lifted Long Island's water table to new heights, soaking basements and preventing floodwaters from receding as quickly as some might like.

Scientists with the U.S. Geological Survey said Thursday they had seen record-high or near-record-high groundwater levels in many parts of the region - part of an upward trend first noticed in 2005. Between the rising water table and the sheer volume of rain dumped this week, floodwaters in some parts of Long Island simply had nowhere to go.

"Probably more than 80 billion gallons of water fell on Nassau and Suffolk counties this past week and another 30 [billion] in NYC," said Stephen Terracciano, chief of the USGS office in Coram. "We are getting reports from folks that have reportedly never had basement flooding before."

At one monitoring well, just north of Lake Ronkonkoma, the water table is 7 feet higher than it was in 1995. The groundwater is now at ground level.

Neighborhoods near the Queens border have also seen increases. In Elmont, for example, measurements from one well show the water table has climbed by more than 30 feet since 1983, although the groundwater there is still about 36 feet below the surface.

Hydrologists think that rise may be linked in part to reduced pumping, as New York City shut off its drinking water wells in southeastern Queens in the 1990s.

Out east, geologists think an abundance of clay in North Fork soils may have hampered drainage at trouble spots such as Horton Avenue in Riverhead. USGS scientists have fanned out across the Island this week to check groundwater levels and take soil samples in those areas where flooding was particularly bad, Terracciano said.

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