Even though an inch of rain or more fell overnight Monday in parts of the Upper Devils Lake Basin, the mammoth lake may have peaked in elevation for the year.
The lake reached a record elevation of 1,452.05 feet above sea level in late June, but since has leveled off. Unofficially, the lake reached 1,452.10 feet on June 27. The elevation was at 1,451.89 feet Tuesday morning.
"Typically, it peaks this time of year," said Mike Lukes, hydrologist with the National Weather Service in Grand Forks. "Considering our rains recently, there's that chance that we could get more rain and peak again later. But based on our long-range outlook, we have it pretty much going down from here."
The major reason is that with warmer temperatures this time of year, water is evaporating faster than it is entering the lake from the upper basin. In addition, the state-owned Devils Lake Outlet is releasing as much as 250 cubic feet of water per second toward the Sheyenne River. The capacity of the outlet was raised from 100 cfs earlier this summer.
"We could be proven wrong by a big rain," Lukes said, adding that it likely would take a basinwide rain event of about 2.5 to 3 inches to cause any significant rises in the lake elevation for the remainder of 2010.
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Independent reports of rainfall in the Devils Lake Basin overnight Monday totaled 1.06 inches south of Starkweather, N.D., 0.93 inches about six miles northwest of Devils Lake, and 0.82 inches in the city of Devils Lake.
While the ground is saturated throughout much of the basin, inflows to Devils Lake from upper basin coulees have decreased significantly in recent weeks.
Devils Lake has risen by about 29.4 feet in the past 17 years. It was at an elevation of 1,422.62 in the early summer of 1993. The lake level has risen by 5 feet in the past two years.
Engineers say the lake will spill out of its banks at Stump Lake at an elevation of 1,458 feet, about six feet higher than this summer's elevation.
Some engineering estimates say that if Devils Lake spills from its banks, the amount of water running toward downstream communities could be 14,000 cfs for nearly 100 days. The peak flow of the Sheyenne River in Valley City during a major flood in 2009 was about 8,500 cfs.
A federal Devils Lake interagency task force is under a mandate to report to Congress by September on potential solutions and costs of preventing a catastrophic flood. It recently launched a website -- www.devilslake.noaa.gov -- to provide support for response, preparedness and mitigation efforts resulting from the ongoing flooding of Devils Lake.
The site, which is being managed by the National Oceanic and Atmospheric Administration, also will facilitate the interagency effort to develop options and recommendations to address flooding issues.
Historical data indicates the lake has spilled to the Sheyenne at least twice in the past 4,000 years, the last time less than 2,000 years ago.
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At 1,452 feet, Devils Lake and the combined Stump Lake cover about 182,200 acres and contain about 3.7 million acres of water.
"We compare it with a glass of water or a soup bowl," he said. "We consider it a soup bowl now, and that contributes to more area from which it can evaporate."
In 1993, when the glass-of-water-sized lake was at 1,422.6 feet, it covered 44,231 acres and contained 565,900 acre-feet of water.
At that time, Stump Lake was a small lake covering about 9,043 acres and containing about 214,750 acre-feet of water.
In 1999, Devils Lake started spilling into Stump Lake, which rose by more than 43 feet before the two lakes equalized in elevation at 1,447.15 feet in 2007. The two have been rising simultaneously since.
Engineers estimate the combined lake will have to grow by another 1.3 million acre feet from today's elevation before it overflows. At its spill elevation, Devils Lake will cover an estimated 261,000 acres.
Reach Bonham at (701) 780-1110; (800) 477-6572, ext. 110; or send e-mail to kbonham@gfherald.com .
