Study Indicates Need for Higher Flows in the Upper Delaware
Trout Unlimited report shows current flows inadequate for fish, aquatic ecosystem
4/12/2001 -- --
Hancock, NY -- Trout Unlimited today announced the completion of a report on flow needs for fish and other aquatic life in the Upper Delaware River and its three principal tributaries, the West Branch, the East Branch, and the Neversink River. The report, prepared by Dr. Piotr Parasiewicz of the Department of Natural Resources at Cornell University, concludes that higher year-round minimum flows are needed from New York City water supply reservoirs on all three tributaries. The report also recommends a long-term research effort to develop flow and water management policies that allow sustainable water supply for New York City and other users and for more natural flows in the three tributaries.
Water flows in the Upper Delaware are governed by a complex decision-making process that usually ignores the river’s aquatic ecosystem, its world famous wild trout fishery, and recreational opportunities on the river. The interstate compact that administers this process, the Delaware River Basin Commission (“DRBC”), is currently reexamining its flow management policies. The TU report indicates that significant changes are needed in order to restore the aquatic health of the Upper Delaware system.
“The Upper Delaware and its tributaries represent one of the most well-known fisheries in the East,” said Nat Gillespie, TU’s Catskills Coordinator, “but unfortunately these tailwaters currently achieve a fraction of their potential biological productivity. The rivers need more water and it must be better distributed. TU and its conservation partners intend to convince New York City and the other members of the DRBC that they can modify the existing flow regime in order to improve the health of the river and meet their water supply bottom line.”
Flows on the Upper Delaware River and its principal tributaries are controlled by three New York City water supply reservoirs: Cannonsville on the West Branch, Pepacton on the East Branch, and Neversink Reservoir on the Neversink. How much water New York City releases from these reservoirs is dictated by requirements of litigation that took place before the U.S. Supreme Court in the 1950s after downstream states sued New York City for taking too much water out of the Delaware system.
Under the system that resulted from that litigation, New York City must deliver water from its reservoirs if releases are necessary to meet a flow target measured at Montague, New Jersey. If releases are not necessary to meet the Montague flow target, the city has no obligation to release water except to meet minimum flow targets in the three tributaries established by New York State Department of Environmental Conservation in the late 1970s. This system is administered by the DRBC, which is made up of the four states in the basin (New York, New Jersey, Pennsylvania, and Delaware), New York City, and the federal government. Any changes to flow management in the Upper Delaware must be approved by the DRBC.
The flows out of the New York City reservoirs differ dramatically from natural flows in a number of respects. Total annual flows in the three upper tributaries are far below pre-reservoir levels, changes between high and low flows are much more abrupt than in a natural river, and the seasonal flow patterns are significantly altered from the typical natural pattern of high flows in the spring and winter. While minimum flows on all three tributaries are too low, often the West Branch receives higher flows in the summer, because New York City uses that water to meet the Montague flow target.
The TU report concludes that under the current regime, minimum flows out of the New York City reservoirs create ecological “bottlenecks” that impair the fisheries and ecosystems in the Upper Delaware and its tributaries. The most urgent problems identified were chronic low flows in the East Branch and the Neversink; reduction of high “peak” flows that play a critical role in moving sediment and maintaining the river channel; the regular occurrence of very high water temperatures caused by low summer releases; and severe limitation of aquatic habitat in the winter due to extremely low winter releases and the formation of anchor ice. When low flows and cold weather combine, ice can accumulate on the stream bottom and suffocate fish and other aquatic life.
“Many anglers focus on summertime flows,” said Gillespie, “and it is definitely true that summer flows in all three rivers do get too low and too warm periodically. However, anglers rarely see these rivers in the winter. When winter flows get low, a gray frosting of anchor ice can cover entire riffles and dramatically limit aquatic habitat. Anybody who wonders why the Delaware system does not produce more fish just needs to visit it during a cold winter.”
The report recommends higher year around flows in all three tributaries to address the thermal and habitat deficits that currently impact the aquatic ecosystem. It also recommends a long-term research program focused on developing a long-term flow strategy to quantify and develop more natural seasonal flows and allow a long-term water supply for New York City and downstream users.
On the West Branch, the report recommends increasing winter minimum flows from 45 cfs to 300 cfs and summer flows from 160 cfs to 600 cfs (in order to maintain cool temperatures on the main stem Delaware). On the East Branch, the report recommends increasing winter minimum flows from 45 cfs to 200-250 cfs, and summer flows from 95 cfs to 500 cfs. On the Neversink, the report recommends increasing winter minimum flows from 25 cfs to 150 cfs and summer flows from 53 cfs to 100 cfs. The report also recommends higher spring and fall flows for all three tributaries.
Trout Unlimited has led the way in forming the Delaware Coalition, a group of anglers, guides, and river related businesses united to fight for improved water flows in the Upper Delaware River basin. The main objective of the Delaware Coalition is to increase year-round flows in the East Branch and West Branch of the Delaware River and the Neversink River.