US Army Corps of Engineers
Northwestern Division

News Releases

Spillway flows at Garrison Dam scheduled for Monday, June 17

Northwestern Division
Published June 12, 2019
On Monday, August 6, releases of 9,000 cubic feet per second were transitioned from the regulating tunnels to the spillway at Garrison Dam near Riverdale, North Dakota.

On Monday, August 6, 2018 releases of 9,000 cubic feet per second were transitioned from the regulating tunnels to the spillway at Garrison Dam near Riverdale, North Dakota. The spillway had not operated since 2011. The transition allows an operational test of the repairs made following 2011 the release amount is consistent with the flows released through the regulating tunnels and would not be noticeable downstream. Each gate was opened 1 foot.

On Monday, August 6, releases of 9,000 cubic feet per second were transitioned from the regulating tunnels to the spillway at Garrison Dam near Riverdale, North Dakota.

On Monday, August 6, 2018, releases of 9,000 cubic feet per second were transitioned from the regulating tunnels to the spillway at Garrison Dam near Riverdale, North Dakota. The spillway had not operated since 2011. The transition allows an operational test of the repairs made following 2011 the release amount is consistent with the flows released through the regulating tunnels and would not be noticeable downstream.

Garrison Dam and Lake Sakakawea near Riverdale, North Dakota. Higher-than-average lake levels in the upper Missouri River Basin in 2018 are the result of runoff from heavy mountain snowpack and late spring rainfall in the Yellowstone River basin.

Garrison Dam and Lake Sakakawea near Riverdale, North Dakota.

As releases are increased to a targeted 46,000 cubic feet per second (cfs) from the Garrison Dam, in Riverdale, North Dakota, some flows will be transferred to the spillway beginning on Monday, June 17.

The updated 3-week forecast from the Missouri River Basin Water Management Division released today shows releases from Garrison Dam increasing to 32,000 cfs over the weekend reaching a rate of 35,000 cfs on Monday. To meet the targeted release of 35,000 cfs, crews will be opening three spillway gates.  

“The release capacity of the powerhouse is just over 40,000 cfs, but some flows will be transferred to the spillway allowing us to proceed with previously scheduled maintenance and construction work at our switchyard, power plant and intake structure.” said Operations Project Manager for the Garrison Dam, Todd Lindquist.

The spillway will be used to avoid delays to previously scheduled work. Flows through the spillway will fluctuate based on when generating units are scheduled to be offline. This will result in varying flows through the spillway between approximately 3,000 and 16,000 cfs over the next two months. 

Once all work in the power plant is complete and all five generators are available for use, the majority of releases will be run through the power plant to maximize power generation.

Total releases from Garrison are currently not forecast to exceed 46,000 cfs. Comparatively, releases during last year's high runoff reached 60,000 cfs in late June and continued for much of July. At the 46,000 cfs release rate, river stages in Bismarck are not expected to be above 11.4 feet.


Contact
Eileen Williamson
402-996-3802
eileen.l.williamson@usace.army.mil
or
Todd Lindquist
(701) 654-7702

Release no. 19-044