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Posted 4/26/2018

Release no. 18-029

Jeff Rose
(515) 276-4656
Saylorville Reservoir Manager


Brett Call
(641) 828-7522
Red Rock Reservoir Manager

ROCK ISLAND, Ill. – The U.S. Army Corps of Engineers, Rock Island District, will initiate temporary modifications to the water control plans at Saylorville and Red Rock reservoirs.  The goal is to preserve flood storage capacity by increasing outflows from the reservoirs during normal flood operations.  Meanwhile, the Corps will identify impacts as it evaluates the modifications for potential permanent changes to the reservoirs’ water control plans.

The temporary modifications will be in effect from Tuesday, May 1, 2018 through December 15, 2018.  These temporary modifications to outflows are the same as those conducted in 2016 and 2017, and are in coordination and concurrence with city and county officials from the cities of Des Moines, Johnston and Polk City;  Mahaska, Marion, and Wapello counties.

Under the current water control plans, normal flood operations during the growing season are to release outflows between 12,000 cubic feet per second (cfs) up to a maximum of 16,000 cfs at Saylorville (depending on Red Rock’s pool level) and a maximum of 18,000 cfs at Red Rock.  Under the temporary modifications, outflows will be a maximum of 16,000 cfs at Saylorville (regardless of Red Rock’s pool level) and a maximum of 22,000 cfs at Red Rock when reservoir levels and inflows permit.

The purpose of the temporary modifications is to increase outflows in order to preserve reservoir storage, thereby reducing the possibility of higher release rates for additional excessive rainfall. If rainfall increases reservoir elevations to require release rates above these thresholds, higher outflow releases will be made in accordance with the existing water control plans.


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NOTES: Cubic Feet per Second (cfs): The rate of flow past a given point, measured in cubic feet per second.  One cubic foot of water equals about 7 1/2 gallons.