New elevation data shows building dams in the James River watershed to regulate flooding would be less cost-effective than originally thought, said a project manager for the Army Corps of Engineering.
Steve Rothe reviewed some preliminary findings from a Light Detection and Ranging study at the James River Water Development District Meeting in Aberdeen on Sept. 11. The data shows that hypothetical dams at different sites would hold less water than estimates using older technology.
A possible dam near Westport along the Elm River, which feeds into the James River, would hold only 29,000 acre feet of water compared to a previous estimate of 45,000 acre feet, Rothe said.
Similar drops in acre feet were noted for other possible dams such as one at Maple River, 11,000 acre feet instead of 17,000, and Dry Branch, 7,600 acre feet instead of 11,000.
The dams would be expensive for the amount of water they would hold and how much land they would protect, he said.
Federal funding for these types of projects would be unlikely because they are basically protecting farmland, he said.
"It is not the best news," he said. "It is all negative from a proposal point of view, but it is informative."
The land next to the James River and its tributaries is too flat to make dams that trap water into deep reservoirs, he said. The lakes created would be shallow.
"It is not really news to us," said Dave Bartel, James River Water Development District manager. "It is like when I talk to a community group about the James River. It is like pouring a glass of water on a table. The water just spreads out."
Bartel said bigger dam projects aren't the answer, but there are a lot of smaller projects, such as small dams and shore stabilization, that help protect land and improve water quality.
"There are a lot of little things we can do to help," he said.
Rothe, who works out of the Army Corps of Engineering office in Omaha, Neb., said the study showed that channel impediments and obstructions in the James River were not a major source of flooding.
The final report will be forwarded to the development district after it is completed. Some of the data in the report will be helpful for projects, he said.