Releases from Gavins Point Dam are forecast to increase to 60,000 cfs beginning Thursday, May 23.
The decision comes after precipitation totaling between 2 to 5 inches, fell over central Nebraska and much of South Dakota over the last 2 to 5 days.
Because of the rain, inflows into Oahe, Big Bend, Fort Randall, and Gavins Point Dams have been increasing and causing pool levels to rise.
The forecast rise at Oahe Dam and Fort Randall Dam includes storing runoff in their exclusive flood control pools. Releases from Gavins Point Dam will allow more water to pass through the system and slow the rise in the pool levels at these projects.
The 3-week forecast was updated today and reflects the following changes:Fort Peck Releases: Increase May 24 from 9,500 cfs to 10,000 cfs Garrison Releases: Decrease May 24 from 30,000 cfs to 27,000 cfs Oahe Releases: Increase to May 27 to 42,000 cfs
Note: Oahe is forecast to enter the exclusive flood control pool on May 25 Big Ben Releases: will average about 50,000 cfs Fort Randall Releases: Increase May 26 to 52,000 cfs
Note: Fort Randall is forecast to enter the exclusive flood control pool on May 26 Gavins Point Releases: Increase May 23 to 60,000 cfs
“Although the mountain snowpack is normal, we still have a little more than 8 inches of snow water equivalent coming from the mountain snowmelt and want to ensure we have storage available to capture and manage that runoff,” said John Remus, Chief of the Missouri River Basin Water Management Division.
The travel time from Gavins Point Dam to the lower Missouri River and the large uncontrolled drainage area diminishes the effects of releases at locations further downstream.
“We are monitoring conditions along the length of the Missouri River and this increase at Gavins Point will not reach Kansas City until after Monday, May 27. By then, the peak flooding from the recent rain should be declining,” said Remus.
“There is no estimate on how long releases will remain at 60,000 from Gavins Point,” said Remus.
Additional precipitation, lack of precipitation or other circumstances could cause adjustments to the reservoir release rates.
Releases will remain higher than average into the fall because the reservoirs have to be at the base of the annual flood control pool by the beginning of the 2020 runoff season.
“We will continue to monitor conditions and make adjustments as necessary,” said Remus.
The National Weather Service issues official stage forecasts for the Missouri River and the public should monitor their nearest upstream gage as fluctuations to river stages will occur with regional precipitation along the rivers and creeks that join the Missouri River downstream from Gavins Point Dam. More information about releases and river stages downstream from Gavins Point Dam is available here http://www.nwd-mr.usace.army.mil/rcc/reports/pdfs/GRFT.pdf and from the National Weather Service, Missouri Basin River Forecast Center https://www.weather.gov/mbrfc/.