oahe dam releases

On Aug. 26, 2019, the U.S. Army Corps of Engineers began releasing water from Oahe Dam through the regulating tunnels on the west end of the dam, into the “stilling basin,” seen here, to handle increases release levels. The diversion of some of the dam releases from the power plant on the east end of the dam is to facilitate maintenance work on the power plant, which houses seven turbines, which will go on until nearly Christmas. (Patrick Callahan/OaheTV)

In a teleconference on Thursday, Oct. 10, federal managers of the upper Missouri River said it will take record releases until into December to get the reservoirs down enough to handle next year’s flooding and runoff.

The U.S. Army Corps of Engineers is forecasting that the runoff this year into the upper Missouri River Basin above Sioux City will total 61 million acre-feet by Dec. 31. That’s big: 3.5 times the average and it would equal the 121-year record set in 2011 when flooding caused billions of dollars of damage.

Eileen Williamson, spokeswoman for the Corps’ river management division based in Omaha, pointed out that runoff is the rain and snow melt that flows into the Missouri River, not the same as the releases made at the six main stem dams by Army Corps’ river managers.

That release amount, while above average this year, will not equal the release amounts needed in 2011 when the dams were filled to the brim.

But releases from Gavins Point Dam, the southern-most of the big six dams on the Upper Missouri, are at 80,000 cubic feet per second, on average each day and will remain at that high rate until early December, John Remus said Thursday during the teleconference with 66 “stakeholders” representing Congressional, legislative and local government offices from several states, and reporters.. Remus is chief of the Corps’ Northwestern Division’s water management office in Omaha for the main stem reservoirs on the Missouri River north of Sioux City, including Lake Oahe eight miles north of Fort Pierre and Pierre.

He and other Corps’ officials will be in Fort Pierre at 10 a.m., Oct. 23, to give a report of this year’s management and their plans for next year.

The Gavins Point releases, described as sort of the bottom of the bag that is the Upper Missouri River storage system of the six reservoirs, will be reduced to 22,000 cfs by late December, where it will remain until late January or early February, Remus said.

The Corps can’t release high amounts of water from the dams during the winter because icing up along the river can cause flooding if the river level is raised much.

As of Thursday, the six reservoirs had a total of 63.4 MAF stored. That includes, including 7.3 MAF, or 45 percent, of the 16.3 MAF of “flood control storage,” at the “tops” of the reservoirs, which still needs to be evacuated over the next eight weeks. Remus says that the Corps aims to have enough water evacuated from the six-dam system so that at least all of the 16.3 MAF of flood control storage will be available for use once the 2020 runoff comes.

Soils across the Upper Basin are extremely wet, except in Colorado, and precipitation is expected to be above normal in the next couple of weeks. If the land across the Upper Basin goes into the dead of winter still saturated or wetter than normal and is frozen in place, that could mean higher runoffs in the spring because there won’t be any “storage” in the ground itself across the region, Army Corps officials say.

Meanwhile, south of Gavins Point, in Nebraska, Kansas and Missouri, people are dealing with still-broken levees from early this summer, while worrying about the increased river levels from the way-above-normal releases from Gavins Point.

The concern was reflected in questions from reporters and local government officials in those states on Thursday, asking when the water levels would get low enough for more substantive repairs to be made to the Missouri River dikes and levees that failed this summer.

It’s a late season drama that has made things worse: runoff into the Missouri above Sioux City in September almost doubled the previous record for the month, set in 1986. Between Gavins Point and Sioux City, runoff was more than 16 times the long-term average and more than double the previous record last month. September runoff between Lake Oahe and Lake Randall downstream was over 12 times the average runoff and set a new record, Army Corps officials said.

The runoff across the entire Upper Missouri River Basin which includes several states, from Jan 1 to Oct. 1 was 53.6 MAF, or million acre-feet, which is already well above the previous record set for the entire 12 months in 1997 of 49 MAF, with three months remaining.

To get more and the most up-to-date information on the Army Corps’ management of the six reservoirs, including releases, go online to www.nwd-mr.usace.army.mil/rcc/reports/twregfcast.pdf

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