Troubled Waters

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Troubled Waters

The attention paid to waterfront development on Tarrytown’s western boundary has diminished the focus on the Tarrytown Lakes, at its eastern boundary.

The Lakes, as they are known in and around the Village, have become a neglected treasure both beneath and above the surface of their waters. According to an official at Village Hall the 2006/2007 budget does not include expenditures for the rehabilitation of either the upper reservoir (the smaller of the two) or the lower reservoir.

For the sake of clarity, the issues threatening the Tarrytown Lakes can be assessed scientifically and visually. In reverse order, the dilapidated, former pump station at the end of the lower lake, the small stone house in the lake itself, and silt retention curtains are all in disrepair. Broken windows, peeling paint and three-foot holes in its roof make the pump station an eyesore for anyone driving, riding or walking by it. The small stone house in the lower lake has over half of its roof missing and large diameter pipes that originally transported Tarrytown’s drinking water have been left at the base of the house, rather than being removed. Silt retention curtains installed during the 1990’s to reduce siltation and nutrient flow from inlet streams, have not been cleaned or repaired, making them virtually ineffective, except as resting places for sunbathing turtles. In the smaller lake, the island where swans nested and raised their cygnets year after year has lost its umbrella of evergreens, along with the swans themselves. This small and exacting picture of nature, is the most revealing "before and after" visual of the lakes.

In January of this year the Mayor and Board of Trustees received a report on the status of and recommendations for the "Tarrytown Reservoirs." It was prepared by Professional Consulting, LLC located in Parsippany, New Jersey. The introduction noted that, "Since the late 1890’s, the reservoirs were used as a drinking water source." It also mentioned that, "Due to extensive renovation required at the Eastview Filter Plant, the Village transitioned over to New York City supplied water from the late 1980’s to the early 1990’s." By 1992, the Village of Tarrytown became totally dependent on the Catskill System water supply owned by New York City — effectively losing the 40% capacity that the Lakes had provided.

Beneath the waters of both the upper and lower lakes a process of eutrophication is taking place. Simply stated, there is an abundant accumulation of nutrients that are supporting a dense growth of plant life that die and decay, depleting shallow waters of oxygen, particularly in the summer months. Eutrophication, according to the report "is the process of lake aging." One of the indicators of an aging lake is the presence of phosphorous, which in and of itself, is an essential element in both plants and animals. It occurs naturally in rocks and soils. Usually present in low concentrations found in nature, phosphorous can also be introduced into freshwater bodies of water from man-made activities such as fertilizer runoff, septic system leaching and improperly treated waste-water. Accordingly high concentrations of phosphorous promote extensive algae growth and algae blooms, visible on the water surface during the summer. Water samples taken in 2005 reveal phosphorous levels 3 times higher than the "standard for a typical lake environment" in the upper lake and 7 times higher in the lower lake.

Nitrates, or the chemical compounds made up of nitrogen and oxygen, are also indicators of lake aging. Like phosphorous, their introduction into a body of water can be man-made in the form of fertilizer runoff, septic leaching and industrial discharge. In elevated levels, nitrates "can promote excessive aquatic plant and algae growth."Samplings taken from both lakes last year revealed nitrogen levels over 3 times higher in the upper lake and over 5 times higher in the lower lake, as compared to a "typical freshwater lake environment."

The gas, carbon dioxide "is very soluble in water." High levels of it "can induce stress in fish, as they need to expend more energy to remove oxygen from the water."Water samples from both lakes revealed levels of carbon dioxide 5 times higher than the "standard for a typical freshwater lake environment."

With regard to aquatic plants that thrive in nutrient rich waters, the upper reservoir supports an abundance of Curly-leaf Pondweed, Coontail and Eurasian Water Milfoil. Eurasian Water Milfoil "is an exotic invasive macrophyte of highest concern in the northeast." It is heavily concentrated near the south end of the lake by the parking lot. With the cyclical growth and death of Curly-leaf Pondweed its nutrients are released into the lake and promote algae growth. This is evidenced by the water turning pea-soup green in the summer.

There are remedial programs for the Tarrytown Lakes and the recommendations range from short-term measures like dredging/sediment removal and aquatic herbicide treatments, to a long-term "comprehensive water quality monitoring plan" which could introduce aeration methods. In the past ten to fifteen years Village efforts have been "on and off attempts" to remedy the relentless decrease in water quality. What has been lacking is a vision and commitment to institute and monitor an ongoing program that will pay more than lip service to these man-made recreational treasures. Without funds specifically earmarked for the restoration of the Tarrytown Lakes they will continue to deteriorate. It’s not debatable. It’s a scientific fact.

For additional information on the formation of the Tarrytown Lakes visit www.riverjournalonline.com and in the Past Times section read Richard Miller’s, "How The Tarrytown Lakes Came To Be."

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About the Author: Robert Bonvento