East Hampton planners, in cooperation with other town agencies, have generated detailed and color-coded maps showing the Lake Montauk watershed — actually watersheds, plural.
The maps show 10 sub-sheds that encircle the lake. A watershed is an area with geological boundaries within which water drains, in this case to Lake Montauk. The separate drainage areas were identified through studies done by the Cornell Cooperative Extension using data compiled by the county.
Bob Mason of the town’s Information Technology Department transformed the information into the colorful maps.
On their face, the maps would seem to be extremely useful to the Lake Montauk Advisory Committee, which met on March 14 at the Montauk Coast Guard station. Brian Frank, chief environmental analyst for the town’s Planning Department, led the meeting and explained how the maps would serve as a template for the watershed characterization report, a document required as a condition of state grant funding.
A priority of the Lake Montauk committee is to identify the sources of pollution and the tributary routes they take to the lake. Some trouble spots are well known: a culvert that empties into the south end of the lake, for instance. But, what might not have been fully realized, in that case, was the size of the sub-watershed in question.
A map shows watershed number five as extending from just east of South Lake Drive, then south through the Ditch Plain community to the ocean. Montauk Highway bisects it.
South of the highway, number five extends all the way to a point just east of Surfside Avenue. North of the highway, it extends even farther west. In short, the sub-shed drains water to the lake through a very large and relatively developed area.
Each sub-shed has its own personality and problems. The lakefront houses along Old Montauk Highway, for example, were built decades ago, before town water was supplied to the area. Because individual wells supplied the water, residents located their septic systems “down gradient” from them to preclude contamination. Good thinking, but now it’s realized that the septic systems (simple holding tank and leaching ring arrangements) are too close to the lake.
Mr. Frank spoke of Montauk’s unique, often mysterious, mixture of soil types. “It’s an interesting and complex watershed because of Montauk’s soil composition, the high clay and silt content. There was so much development around the lake, west and south, in the early 20th century. They just went through what was in their way — like at Ditch Plain and the golf course — instead of working around.”
Montauk’s large clay component often defies efforts to predict the course of a stream. But, finding and tracing each wetland and tributary within the sub-sheds is the next phase in the committee’s watershed characterization report.
Kevin McAllister, the Peconic Baykeeper, attended last week’s meeting. He spoke about the possibility of upgrading traditional tank and leaching field septic systems by way of a simple chemical process — the passage of effluent through a carbon-based membrane. In this way, nitrogen, the food that breeds shellfish-killing algal blooms, is removed.
Mr. McAllister said the process has been scaled to single-family households and restaurants.
Supervisor Bill Wilkinson, who attended the committee meeting, approved of the denitrification concept. “It’s the right thing to prove. It’s something we should do,” he said, agreeing that someone interested in building or upgrading a home or restaurant might be willing to give it a try.
“Montauk is a passionate community with a unique harbor that has different active and passive uses,” Mr. Frank said. “The watershed characterization report will be an important guidance document.”