Funding is running out for a program that protects Long Island's drinking water, according to the two groups that pay for it.

Nassau County already dropped part of its funding for a program to monitor groundwater levels, so the Long Island Water Conference and the Nassau Suffolk Water Commissioners' Association temporarily stepped in.

But now they say they can't afford to continue on their own.

The wells monitor groundwater levels. Experts say the levels are important, especially in coastal communities, because when water levels drop too low, saltwater can seep in and contaminate the water supply.

The vulnerable areas include Montauk, Great Neck and Port Washington. Port Washington Water Commissioner Mindy Germain says the monitoring is essential for managing the area's wells. There have been occasions where salt contamination has forced officials to close certain wells.

If wells do need to be shut down, it could also affect water pressure for firefighters, experts say.