The new Des Moines River Water Control Plans were approved in February 2019 for Lake Red Rock and Saylorville Lake. The Water Control Plans consist of operational parameters defining how and when water is stored and released. These include a schedule of releases, conservation pool levels to be maintained during non-flood or drought conditions, and downstream water level constraints.
The following key issues informed the primary need to update the Des Moines River Basin Master Reservoir Regulation Manual:
- The Des Moines River has experienced a significant increase in the magnitude and frequency of flooding.
- Sedimentation within the reservoirs has negatively impacted available conservation (water supply) storage capacity at Saylorville Lake.
- Deviations from the approved water control plans, approved and conducted from 2016-2018, demonstrated the need to permanently update the water control plans for each reservoir.
The Des Moines River Basin has experienced significant land use changes. These changes influence runoff rates into the Des Moines River and its tributaries resulting in increased flood risk within the Des Moines River Basin. Following the 2008 Des Moines River flood, the District re-evaluated regulated flow frequencies on the Des Moines River. The Regulated Flow Frequency Study, completed in early 2010, concluded the frequency of flooding on the Des Moines River had increased and indicated major flood events, like 1993 and 2008, are more likely to occur than previously estimated.
The purpose of the study was to update the Des Moines River Basin Master Reservoir Regulation Manual to better meet mission objectives based on changes in flood frequencies, land use, and reservoir sedimentation. The selection of new water control plans will result in a revised Des Moines River Basin Master Reservoir Regulation Manual, which includes the Saylorville Lake and Lake Red Rock Water Control Plans. The final feasibility report with an integrated environmental assessment is available on this website, and provides a detailed account of the planning, regulatory and environmental considerations resulting in the new water control plans. The District began operating under the new plans in February of 2019. The completed Des Moines River Basin Master Reservoir Regulation Manual and Appendices for Lake Red Rock and Saylorville Lake, are scheduled to be completed later in 2019. Standing instructions, which include the regulation tables for the updated water control plans can be found in the links below.