US Army Corps of Engineers
Rock Island District Website

District Projects

Iowa Reservoir Regulation Plan Studies

Published March 8, 2019

Flood Risk Management Program Manager


Saylorville Lake, Lake Red Rock, and Coralville Lake and their associated watersheds

The Corps reservoirs located in Iowa were developed for multipurpose use, however the primary purpose is flood risk management. These reservoirs have reduced peak floods in Iowa and have greatly minimized flooding in communities located below the reservoirs. Environmental and land use changes have been observed since the projects went into operation. The U.S. Army Corps of Engineers, Rock Island District (The District) is looking to developed alternatives to the current Regulation Plans to manage flood risks along the Des Moines River and Iowa/Cedar River basins. The final Reservoir revision will produce revised Regulation Plans, Environmental Assessment and Real Estate Plans. The alternatives to be examined include but are not limited to: increasing or extending maximum spring (pre-planting) releases, relaxing of Mississippi River or other constraints, seasonal variations in pool levels to maximize flood storage and increasing the dam’s storage corridors. 

It is the District's priority to develop feasible alternatives to mitigate the risk of flooding along the Des Moines and Iowa/Cedar River basins. 

In July 2010, a reservoir study incorporating Saylorville, Red Rock and Coralville reservoirs was proposed to analyze alternatives to current Regulation Plans for water control and possible physical modifications to the projects. Over the last several years, the District has experienced significant flooding along the Des Moines and Iowa/Cedar rivers which resulted in levee overtopping, erosion, pump station damage and millions of dollars in personal property damage.

The results of the Des Moines River Regulated Flow Frequency Study indicated that flooding on the Des Moines River is higher and more frequent than previously estimated. Those results are also driving a need to comprehensively study Flood Risk Management alternatives for the flood control reservoir system, the SE Des Moines levee, other existing Federal and non-Federal flood risk management projects and the Des Moines and Raccoon Rivers in Des Moines, IA. 

In 2015, the District conducted an initial assessment and developed alternatives to the current Regulation Plans to manage flood risks along the Des Moines River. In 2017, the District began a comprehensive Regulation Plan update. The 2 year study is expected to have a final recommended plan selected by December 2018.

In 2016, the District conducted an initial assessment and developed alternatives to the current Regulation Plans to manage flood risks along the Iowa/Cedar River Basins. The final Reservoir Regulation revision for Iowa/Cedar Rivers will be conducted separately from the Des Moines River Study. The alternatives for the Iowa/Cedar Rivers Study will be similar to those of the Des Moines River Study.

In 2018, The District conducted public meetings to present the identified alternatives, tentatively selected plan, and draft report for the Des Moines River Study. The report was submitted to MVD for approval. The final report is expected to be complete in 2019.

OM - Operations and Maintenance

Summarized Project Costs

Estimated Federal Cost  N/A 
Estimated Non-Federal Cost N/A 
Estimated Total Project Cost  N/A 
Allocations Prior to FY 2019  N/A 
FY 2019 Allocation N/A 
FY 2019 Total Capability  N/A 

Major Work Item Current Year
FY 2019:
The District will initiate a 2 year effort to evaluate the Coralville Lake Water Control Plan Update Feasibility Study with Environmental Assessment. This effort is funded through O&M funding. Coordination Meetings with Local, State, Federal partners, and Public open houses will hosted. The results of these meetings will assist the District with identifying goals and objectives of the project. A list of alternative water management strategies will be identified and evaluated. 

The District is also finalizing the Des Moines River Study and working on incorporating the results into the Des Moines River Regulation Manual.