Yellowstone Flooding Won’t Impact Lower Missouri River Basin

It’s a dry year in the Midwest along the Missouri River Basin, but many fear the amount of water coming out of the Yellowstone River into the Missouri River system. John Reemus, Army Corps Missouri River Basin Water Management Chief, says that floodwater will be captured by the reservoir system.

“The bulk of the flooding or water from the flooding on the Yellowstone River has already reached the Garrison reservoir, that accounts for the increase in the pool level there that we’ve seen over the last month. The Yellowstone River still has a lot of water coming out of it. The water has been captured or will be captured in the Garrison reservoir and management there. We would like to balance the storage in those upper three reservoirs. So, it’s going to take several weeks to several months to do as we move that water out of Garrison downstream. Right now, the amount of water from that flooding will not impact how much water released from Gavins Point Dam.”

Kevin Low of the National Weather Service Missouri River Basin Forecast Center confirmed the outcome, adding that the mountain snowpack melt is complete. The Yellowstone storm cleared what was left.

“And this rain on snow event during June 11 through the 13 resulted in catastrophic flooding centered on the Yellowstone National Park. Widespread two to four inches of rain coupled with a melt out of about seven inches of higher elevation snow was the cause of it. However, even with that historic flooding event in mid-June, our most recent water supply forecast continued to indicate that we will see a much below normal runoff season this year in the mountainous west.”

As for the three-month outlook, Doug Cluck from the National Center for Environmental Information, says it’s going to be hot and dry.

“In July-August-September, the seasonal outlook for temperature for those three months shows the bullseye over the west, the intermountain west, just slightly leaning towards above normal in terms of temperatures from Montana down through the Dakotas and Missouri. As you go west though, that probability gets a little stronger. And then in terms of precipitation, there’s this kind of big area of below normal, again the probabilities aren’t extremely high, slightly elevated chances of below normal precipitation for, basically, much of the Missouri basin there.”

Gavins Point Dam, the most downstream location in the reservoir system, will likely maintain minimum outflows for the rest of the season and into next year.