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Des Moines River

Studying river and tributary flows to offer potential benefit enhancements

Located along the Des Moines River in Iowa, Saylorville Lake, upstream from Des Moines, and Lake Red Rock, about 50 miles downstream provide flood risk reduction as well as recreation, water supply, drought management and fish and wildlife management. Altered flows to the river and tributaries as well as impounded water have an affect on resident and migratory fish and mussels as well as wildlife that depend on aquatic, riparian, and floodplain habitat.

By collaborating with many partners, the Corps and Conservancy aim to identify environmental flow requirements for the Des Moines River, and develop hypotheses for alternative water management that might establish more natural flow regimes and/or reservoir conditions to enhance multiple benefits within the program area. 

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Des Moines River

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Following a series of floods on the Des Moines River, Congress authorized construction of two major flood control dams and reservoirs. Saylorville Lake, upstream from Des Moines, was completed in 1977 and Lake Red Rock, 48 miles downstream of Des Moines, was completed in 1969 to intercept several more large tributaries of the lower Des Moines and Mississippi Rivers. Lake Red Rock is 142 miles upstream from its confluence with the Mississippi River. 

By the nature of public land involved for the reservoirs providing flood risk reduction, both have been further authorized to provide other benefits including recreation, water supply, drought management, and fish & wildlife management.

Construction and operation of dams resulted in potential implications for fish and wildlife habitat, water quality, and other natural resources. Operation of the dams including reduced peak flows, lower spring flows, increased summer flows and substantially modified/reduced floodplain inundation alters the flow regimes of the river and its tributaries. At the same time, the natural flow regime of the river has been significantly altered by upstream land use and drainage modifications as well as significant climate change trends over the past 100 years that have resulted in increased annual and seasonal flows.

The Des Moines River drains 25 percent of Iowa and is one of the most intensely farmed regions in the world. The intense cropping, large livestock facilities, and surface and tile drainage are responsible for creating some of the highest nitrogen and phosphorous loading to the Mississippi River, a major contributor to the Gulf of Mexico hypoxia condition. These changes have impacted resident and migratory fish and mussels, in addition to wildlife that depend on aquatic, riparian and floodplain habitat.

The Des Moines River Sustainable Rivers Program is designed to identify environmental flow requirements for the Des Moines River, and develop hypotheses for alternative water management that might establish more natural flow regimes and/or reservoir conditions that enhance multiple benefits within the program area. The goal of the program is to manage for a more “naturalized” flow regime that would benefit fish and wildlife populations, ecosystem function, river and floodplain habitat, and water quality. Restoring at least some aspects of the natural flow regime would be expected to benefit numerous species, including several ancient river fishes, such as paddlefish, shovelnose and lake sturgeon, as well as floodplain plant communities and terrestrial wildlife.

 

  • The Nature Conservancy in Iowa
  • U.S. Army Corps of Engineers, Rock Island District
  • Academia (list if possible)
  • Local water municipalities (list if possible)
  • Iowa Department of Natural Resources
  • Iowa Department of Ag & Land Stewardship
  • Natural Resources Conservation Service 
  • Partners and subject area experts have identified primary concerns for the Des Moines River, produced a literature review relating to the primary concerns, conducted an environmental flows workshop, and initiated work to further investigate recommendations for adoption.

  • Key data sets used include regulated flows (with dams) and unregulated flows (without dams) for the period of hydrologic record. The data sets were gathered and formatted by Rock Island Hydraulics Branch to use in in conjunction with HECRPT that further defined environmental flow definitions and recommendations by participants at the e-flow workshop. In addition, the current Des Moines River SRP task of conducting a rapid watershed threat assessment included several local and national GIS data sets available to the public and can be found in the References section of Saylorville Lake and Lake Red Rock Subwatershed Threat Assessment.

Publications

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TitleSiteDate
Des Moines - Environmental flows science summaryDes Moines River2017
Des Moines - Environmental flows workshop reportDes Moines River2017
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