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Letter: Brown tide not fault of septics

This appeared to be red or brown tide

This appeared to be red or brown tide in Flanders Bay, just inside Great Peconic Bay. The Riverhead Business District is just visible in the upper left of the frame on Aug. 14, 2013. Credit: Doug Kuntz

Long Island's septic systems have been named as a source of polluting nitrogen that causes brown tide ["Trouble blooming on LI's waterways," News, Oct. 23]. If this is true, it may be necessary to spend billions of dollars to replace or upgrade the current waste handling systems.

Before we commit massive resources to this problem, we should first test this hypothesis. If it were possible to prevent polluted groundwater from entering our bay, would the brown tide cease to bloom? This test has already been done.

The flow of groundwater that carries nitrogen from septic systems into our bays is controlled by rainfall. Because almost no rain has fallen on the South Shore since the last week in September, groundwater and the nitrogen that is carried by it have been drastically reduced.

A natural variation in rainfall has given us the test to determine the effects of reducing nitrogen in our bays. However, the result does not confirm the hypothesis. The reduction of nitrogen from septic systems did not eliminate brown tide. I believe the reduction caused brown tide.

Most algae are important to a healthy ecosystem, but brown tide is not. What causes brown tide? Years of research have confirmed that brown tide has a competitive advantage over other algae when groundwater nitrogen is low, not high. Why then are we aiming to reduce it?

Roger C. Tollefsen, Hampton Bays

Editor's note: The writer is president of the New York Seafood Council, which represents the seafood industry, including harvesters and processors.