Much above average runoff continues in the upper Missouri River basin.
The US Army Corps of Engineers says April runoff in the upper basin was the third highest April runoff (7.8 MAF. Average in April is 2.9 MAF.) in the 121 years of record. The Corps expects releases from all System projects will be above average for the next several months, and possibly as late as November.
Chief of the U.S. Army Corps of Engineers Missouri River Basin Water Management Division John Remus says releases from Gavins Point are nearly double (55,000 cfs) the average for this time of the year. He says they’ll maintain Gavins Point releases at this rate to reduce the pool levels in Oahe and Fort Randall a few feet. Remus says that will provide flexibility should they need to reduce Gavins Point releases for short periods over the remainder of the spring and summer.
About 47% of the total flood control storage for the upper basin remains available to store runoff this spring and summer. The plains snow has melted. Mountain snowpack has peaked and is melting.
As of April 30, the reservoir level at the Oahe Dam had risen 1.7 feet during the month to 1616.4 feet. The pool level at Big Bend went down two-tenths of a foot to 1420.5. Big Bend will have a scheduled powerplant outage this week from tomorrow through Friday (May 7-10). All turbines will be offline for maintenance so releases will be made through the spillway.
Big Bend Dam
- Average releases past month – 30,800 cfs
- Forecast average release rate – 38,100 cfs
- Forecast reservoir level – 1420.0 feet
- Notes: Spillway releases will occur May 7-10 while maintenance is performed on all turbines.
Oahe Dam
- Average releases past month – 30,200 cfs
- Forecast average release rate – 37,600 cfs
- End-of-April reservoir level – 1616.4 feet (rising 1.7 feet during April)
- Forecast end-of-April reservoir level – 1615.9 feet
The near-record April runoff, which was nearly 3 times average, increased the 2019 upper basin runoff forecast to 42.3 MAF. If realized, this runoff total will be the third highest runoff in 121 years of record-keeping, only surpassed by 1997 (49.0 MAF) and 2011 (61.0 MAF). Runoff in 2018 was 42.1 MAF, which is currently third highest.
Beginning on May 7, updates on basin conditions, reservoir levels and other topics of interest will be updated each Tuesday. The updates are posted to Facebook and Twitter at NWDUSACE and can be viewed here: http://www.nwd-mr.usace.army.mil/rcc/reports/pdfs/weeklyupdate.pdf.
To view the detailed three-week release forecast for the mainstem dams, go to http://www.nwd-mr.usace.army.mil/rcc/reports/twregfcast.pdf.
All US Army Corps managed dams–reservoir levels, inflows and releases:
http://www.nwd-mr.usace.army.mil/rcc/reports/pdfs/MRBWM_River_Daily.pdf.
