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regulatory programs

phosphorus-restricted basins

Program Summary

Maps

Phosphorus comes from a variety of sources. Some sources are natural and contribute to the background level of phosphorus necessary for a healthy ecosystem. Some sources are man-made and this additional phosphorus can tip the balance to excessive algae growth and impairment of the water body. Man-made sources include: wastewater treatment plants, failing septic systems and stormwater runoff from the land.

In an effort to protect the New York City reservoirs from the harmful effects of high levels of phosphorus, the 1997 Watershed Regulations limit new man-made sources of phosphorus into reservoirs that already exceed the phosphorus water quality guidance value. The 2002 list of phosphorus-restricted basins contains eight reservoirs and two controlled lakes in the Croton System: Amawalk Reservoir, Bog Brook Reservoir, Croton Falls Reservoir, Diverting Reservoir, East Branch Reservoir, Middle Branch Reservoir, Muscoot Reservoir, Titicus Reservoir, Lake Gleneida and Lake Gilead. No Catskill or Delaware System reservoirs are currently phosphorus restricted.

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