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Patrick Springer, Published January 31 2011

Water retention reduces Red’s flow

A goal of reducing peak flows on the Red River enough to drop flood stages 2 feet in Fargo during a 1997 magnitude flood appears realistic.

An analysis for the Red River Basin Commission identified water storage sites throughout the valley from Wahpeton, N.D., to Emerson, Manitoba, to reduce river flows by 20 percent, with one exception.

The lone area that fell short of that goal involved three tributaries that feed the Red River near Grand Forks and Drayton, N.D., where retention sites identified so far could reduce flows by 14 to 16 percent.

But the hydrologist who conducted the study, Charles L. Anderson of Alexandria, Minn., believes further study will allow the 20 percent reduction goal to be met for the three tributaries – the Red Lake, Sand Hill and Marsh rivers.

“I think there’s potential there,” Anderson said. “This is a first cut.”

If the goal of 20 percent reduction in Red River flows and stages is met for a 1997 flood, it would reduce the level in Grand Forks by 2.7 feet,” he said.

To reach that goal, “I don’t think it will be particularly difficult,” he added.

Importantly for the Fargo-Moorhead area, he said significant storage potential exists in North Dakota’s Wild Rice River and Sheyenne River watersheds.

Retention projects could include tributary dams, such as the Maple River Dam, impoundments or restored wetlands. They also could include culvert sizing and using roads to temporarily hold water, he said.

“That can be applied basically everywhere,” he said.

Lance Yohe, executive director of the Red River Basin Commission, said the study confirms that retention has real potential as one means of flood control under a comprehensive approach.

“It’s going to take a little more work to nail it down,” he said. “But it does tell us that we can move in that direction; we can make a difference.”

The Red River Basin Commission, which plays an advisory role, plans to release some of its findings in public meetings, perhaps as early as late February and early March, Yohe said.

The commission’s retention recommendations will be general and will stop short of endorsing individual projects. Those decisions will fall to individual water boards on both sides of the river, which have united under the Red River Retention Authority.

Retention projects that offer benefits both locally and downstream will find the greatest support, Yohe said. “This will help us identify those win-win projects,” he said.

Water officials agree retention alone will not protect Fargo-Moorhead from severe flooding, but is an important component of comprehensive flood control, and can help to mitigate impacts from a project to protect Fargo-Moorhead.

The U.S. Army Corps of Engineers is studying a diversion channel – which it identified as the best solution – to protect the metro area.

The largest permanent levee that could be built would provide protection against a 50-year flood, with a crest of 41 feet, a flood similar to the record 2009 event, 40.84 feet.

Storage options the corps identified could reduce flooding in Fargo-Moorhead by 1.6 feet, from 42.4 feet to 40.8 feet. By contrast, a diversion could reduce a 100-year flood, 42.4 feet, by almost 12 feet, resulting in a stage of 30.6 feet, according to corps figures.

Readers can reach Forum reporter Patrick Springer at (701) 241-5522