A comprehensive study about to be released by the Suffolk County Department of Health Services brings grim news about Suffolk's water supply.   Its findings are of urgent concern to all Long Islanders.   First, some brief background. Back in 1987, the Suffolk County Comprehensive Plan revealed disturbing levels of contamination in Long Island's aquifers-the sole source of all our drinking water. The findings served as a catalyst for countywide efforts to protect these precious supplies.   The reforms, including groundbreaking land preservation and other programs, certainly helped. But--the new report reveals--not enough.

• The study, covering the years from 1987 to 2005, finds a continual decline in water quality. This includes:Rapid rises in the levels of harmful nitrates: A 40% increase in the Upper Glacial aquifer, and a 200% spike in the Magothy. Even the lower rate, if continued, would raise nitrates to unsafe levels by 2050.
• Nitrates are already degrading our coastal environment. To the point where the New York State Department of Environmental Conservation has declared the entire South Shore Estuary Reserve system an "impaired water body." This region stretches more than 60 miles, all the way from South Oyster Bay to Shinnecock Bay.
• Volatile organic compounds (VOCs) are also increasing. They now are present in four times as many wells as they were in 1987.
• Pesticides now are found in almost one out of every four community supply wells.

These trends pose an existential threat to Long Island, endangering our children's health, our island ecosystem, our tourism and fishing industries.

Ask how things stand in Nassau County, and the answer is, in a way, even more shocking: nobody knows. Some testing is done, by the County and by some local water authorities. But given our patchwork of dozens of separate local water systems, comprehensive findings do not exist.

What's certain is that we need action. Employing the language of government reports, the study says that its findings show "the need for increased water resource protection efforts." That's the understatement of the year.

What we actually need is a major new commitment to protecting our water. For if our supplies are declining now, after decades of regulation and oversight, then clearly we must do much, much more. The public is strongly committed to water protection, as it has demonstrated over and over. And Suffolk County has a history of bold and effective action. Starting now, Long Island leaders have to uphold that tradition.

And not just environmental groups. A threat to our water is a threat to us all. If ever we needed leaders from across the spectrum of business, civic and public-interest groups, and academia to step up and join in common cause, this is the time.

Our region's survival is at stake. We need an effort equal to the threat.