Reservoir voids would not have prevented flooding

But they might have reduced some damage

By FRITZ MAYER

RIVER VALLEY — The record floods in 2004, ’05 and ’06 have sparked an ongoing argument about whether the New York City reservoirs could have been used to mitigate the flooding in some degree, by creating voids that could hold back some of the torrential rain waters.

On December 15, the Delaware River Basin Commission (DRBC) released a flood-analysis model that showed what the results would have been if the Cannonsville, Neversink and Pepacton reservoirs had 10 percent or 20 percent voids.

According to Carol R. Collier, director of the DRBC, the results “indicate that operational changes to reservoirs alone will not substantially reduce flooding if we experience storms similar to the three major events in September 2004, April 2005 and June 2006.” She added that “No single approach will eliminate flooding along the Delaware River and that we must continue to focus efforts on implementing a combination of flood-loss reduction strategies.”

Still, there are a number of voices pushing for establishing year-round voids in the reservoirs as a way of ensuring flood protection. Diane Tharp, executive director of the NorDel Conservancy said, “The preliminary results of the model confirm that our longstanding position that voids do reduce the flood crest, and that the people who live along the Delaware River remain in danger until the DRBC comes up with a plan to create year-round voids.”

Tharp said, for instance, that if there had been voids of 20 percent in the reservoirs, the crests in the ’05 and ’06 floods would have been three feet lower where she lives near the Delaware Water Gap. That, she said, would have prevented water from going into the second floor of her home and would have lessened the damage to her home by about $50,000.

While Tharp and others will continue to lobby for year-round voids, they are likely to continue to be strongly resisted by the New York City Department of Environmental Preservation, which has argued that such voids would make the city more likely to run out of water during a time of drought.

The flood analysis model did not reflect crests at locations such as Narrowsburg, NY, Callicoon, NY and Barryville, NY, but it did have crest levels for Harvard, NY on the East Branch, Hale Eddy, NY on the West Branch, Bridgeville, NY on the Neversink River and Montague, NJ on the Delaware River.

Some of the results in the upper reaches of the basin would have made a substantial difference in crest levels. For instance, a 20 percent void in the reservoirs in the ’04 flood would have resulted in the crest being nearly seven feet lower at Harvard. The same void in the ’06 flood would have resulted in a four-foot lower crest at Hale Eddy, a five-foot lower crest at Bridgeville and a three-foot lower crest at Montague.

The presentation presented by the DRBC projected scenarios for nine points along the Delaware River Basin from Hale Eddy to Trenton, NJ and, in most cases, the waters would have risen to flood stage even if the reservoirs had been empty. The exceptions to that were the Hale Eddy, Harvard and Bridgeville locations.

Go to www.state.nj.us/drbc/ to view to flood model and related documents.