Corps: Repeat of 2011 unlikely

Despite mountain snowpack above the level reached at the same time in 2011, the U.S. Army Corps of Engineers says there won’t be a repeat of the historic Missouri River flooding of 2011.

“Flood control remains our primary consideration,” said Jodi Farhat, Corps’ chief of Missouri River reservoir operations, Omaha, Neb., during a conference call with Missouri River interests Tuesday. “There’s news stories about the potential for flooding but a repeat of the 2011 flood is highly unlikely.”

Farhat explained that the Missouri River basin experienced “all three in the 2011 flood.” Farhat was referring to the combination of mountain snowpack, plains snowpack and spring rainfall.

“Currently only above mountain snowpack exists today,” said Farhat.

The current mountain snowpack is expected to produce well above normal runoff even without the influence of plains snowpack or spring rains. The most recent projections offered by the Corps call for 30.6 million acre feet of runoff into the Missouri River system this year, well above the 25.2 maf long-term average.

According to the Corps, the amount of runoff projected in the Missouri River basin this year occurs an average of once every four years and there is ample storage in three main Upper Missouri reservoirs to contain the expected runoff. The reservoirs are Fort Peck in Montana, Lake Sakakawea in North Dakota and Lake Oahe in North and South Dakota.

“The runoff is 121 percent of normal,” said Farhat. “We’d need seven to eight inches of water equivalent to reach 2011 conditions. We do not expect the reservoirs to completely refill this year.”

Peak mountain snowpack generally occurs about April 15. By March 15 approximately 87 percent of peak accumulation is reached.

The most likely forecast for Lake Sakakawea calls for a mid-summer elevation of 1,845.0 feet. Overflow level, which was reached in the flood year of 2011, is 1,854.0 feet. Lake Sakakawea stood at 1,831.48 feet Tuesday.

Releases from the Garrison Dam power plant averaged 17,900 cubic feet per second in February. The Corps says releases will be reduced to 16,000 in mid-March, with a variable being ice conditions on the Missouri downstream from Garrison Dam. Summer releases are projected to average about 26,000 cfs.

According to the Corps, a full service, eight month navigation season downstream on the Missouri is expected is 2014.