Devils Lake gets a drain for overflowing water

TOLNA, N.D. — With the mid-morning sun glistening off the water nearby, federal and state officials Thursday dedicated the $9 million Tolna Coulee Control Structure, a project designed to help much of eastern North Dakota deal with a two-decade-old flood in the Devils Lake Basin.

“That thing behind me is not a dam. It’s a control structure,” said Col. Michael Price, commander of the U.S. Army Corps of Engineers, St. Paul District. “It’s a remarkable accomplishment.”

The 800-foot-structure, built between Stump Lake and a natural rise in the Tolna Coulee, is designed to prevent a catastrophic spill from the Devils Lake Basin to the Sheyenne River Valley. The unique design mimics the natural erosion that likely would occur in the coulee, while restricting downstream flows.

Maj. Gen. John Peabody, commander of the Corps’ Mississippi Valley Division, noted that the control structure is among 19 completed or substantially completed projects of the 22 action points recommended 18 months ago by what later became the Devils Lake Executive Committee, a collaborative group of federal, state and local officials initiated by Sen. Kent Conrad, D-N.D., to address Devils Lake flood issues.

“This project is a key component of the master plan,” Peabody said.

Preventing damage

Devils Lake has risen by more than 30 feet and quadrupled in size since 1992, reaching a record elevation in June 2011 of 1,454.4 feet above sea level. That’s just 3.6 feet below the 1,458-foot natural spill elevation.

The lake elevation is at 1,452.8 feet this week.

The Corps expects to officially hand over the project to the North Dakota State Water Commission later this summer.

Without the control structure, State Engineer Todd Sando said, an overflow at 1,458 feet likely would cause catastrophic damage downstream. Engineers have estimated the maximum outflow would be 14,000 cfs, remaining above 12,000 cfs for 19 consecutive days.

That’s about twice the volume of water that passed through Valley City during its record flood of 2009 and roughly equivalent to a 500-year flood event in Valley City and other downstream communities.

The Sheyenne River flows into the Red River north of Fargo, which continues northward into Manitoba, emptying into Lake Winnipeg.

Record inflows into Devils Lake of nearly 600,000 acre feet of water in 2009 and more than 600,000 acre feet in 2011 prompted state and federal officials to expedite plans to put emergency flood protection measures into place by this spring.

Foot by foot

Meanwhile, a couple of miles from Thursday’s dedication, Devils Lake water at a volume of 350 cubic feet of water per second was running downstream from the new $85 million East Devils Lake outlet, gushing through culverts under roads and flowing steadily over the spillway at Tolna Dam to the southeast.

Together with the recently expanded 250-cfs state-owned West End Devils Lake outlet, a total of 600 cfs is being discharged from Devils Lake to the Sheyenne River. At that rate, it is estimated that the lake could be lowered by about 1 foot annually.

Under the state’s operating plan, the discharges will continue at that level from spring through fall, as long as the water volume and quality remain within accepted guidelines listed in the operating plan.

At 1,453.4 feet, the combined Devils Lake and Stump Lake contain about 4 million acre feet of water. The U.S. Geological Survey estimates the basin has about 1 million acre feet of storage remaining.

Because of the dry period over the past 10 months, the risk of the lake reaching 1,458 feet this year is less than 1 percent. At the spill elevation, the lake would cover more than 261,000 acres.

The combined Devils Lake and Stump Lake now cover about 200,000 acres. It was about 49,000 acres in 1992.

About $1.5 billion has been spent to deal with Devils Lake flood issues in the past two decades, during that time, more than 1,000 buildings have been moved or destroyed and about two dozen people have died in flood related traffic accidents.

Kevin Bonham is a reporter

at the Grand Forks Herald, which is owned by Forum Communications Co.

Tags: devils lake, news, flood, water