REPORT: Reservoirs contributed to flooding along Delaware River
By FREDA R. SAVANA/The Intelligencer

The flooding that has devastated communities along the Delaware River in recent years could have been lessened if the water levels of four critical reservoirs had been lowered, according to an engineer's study.
Roger Ruggles, a professor of civil and environmental engineering at Lafayette College in Easton, conducted the analysis.

His findings support the belief of many who live and work near the river that reducing water levels at three New York reservoirs and Lake Wallenpaupack in Pennsylvania would dramatically reduce the severity of the flooding.

The Delaware Riverside Conservancy, a nonprofit organization that works for residents and business owners along the river and advocates for reduced reservoir capacity, hired Ruggles to conduct the study.

Ruggles' report estimated the crest level recorded at the Montague River gauge in Milford, N.J., in the northern part of the state, during the June 2006 flood would have been six feet lower if the reservoirs had been at 80 percent of capacity rather than 100 percent.

Clarke Rupert, a spokesman with the Delaware River Basin Commission, said he couldn't comment on the report since it has not been formally submitted to the commission. The study is expected to be entered into the public record Wednesday, when the DRBC will hold a public hearing to discuss its new river and reservoir management plan.

Historically, the DRBC has said the reservoirs play a relatively small role in mitigating flooding.
However, Rupert did say it is “universally accepted” that a comprehensive flood analysis is needed to better understand the role of the region's rivers and reservoirs in flooding. That study, conducted in conjunction with the National Weather Service, the U.S. Army Corps of Engineers and the U.S. Geological Society, is under way and is expected to be completed early in 2009, he said.

“That will provide some very, very useful information,” Rupert said.

Efforts to reach Ruggles for comment were unsuccessful because he's out of the country. In his report, he supported the need for such a study.

His research examined water levels at the Cannonsville, Pepacton and Neversink reservoirs in New York's Catskill Mountains. The reservoirs and Lake Wallenpaupack hold a combined total of 270 billion gallons of water and account for almost half of New York City's water supply.

Lake Wallenpaupack also generates hydroelectric power for Pennsylvania Power and Light and is a tourist attraction.

Ruggles concluded that keeping the reservoirs lower than capacity so they could store storm water would “result in a significant decrease in flood water during each of the three studied storms.”
“This proves the reservoirs are the cause of excessive floods,” said Gail Pedrick, a conservancy member, a New Hope resident and a flood victim.

During the June 2006 flood, she said, “109 billion gallons or the equivalent of 37 hours of Niagara Falls poured into the Delaware from the reservoirs.”

Ruggles found that four days before each flood, each of the reservoirs was either full, near full or exceeding its capacity.

“The relatively high storage volumes ... provided little control on the total outflow. Voids of approximately 20 percent of the total volume would have been sufficient to make a significant difference in the water surface elevations in the reach of the Delaware River between Montague and Belvidere, N.J.,” Ruggles' report said.
Coordinated control of reservoir releases is also vital to controlling flooding, Ruggles said.

Freda R. Savana can be reached at 215-345-3061 or fsavana@phillyBurbs.com.
January 15, 2008 4:27 AM