Iowa Watersheds Project

In September 2016, the Iowa Watersheds Project ended with the completion of over 150 built structures including ponds, terraces, wetlands, water and sediment control basins, and on-road structures. The Iowa Flood Center received $4.5M from the U.S. Department of Housing and Urban Development (HUD) for the five-year project aimed at mitigating flood risk in select Iowa watersheds.

The specific goals of the project aimed to:

  •     Maximize soil water holding capacity from precipitation;
  •     Minimize severe soil erosion and sand deposition during floods;
  •     Manage water runoff in uplands under saturated soil moisture conditions;
  •     Reduce and mitigate structural and nonstructural flood damage

Phase I – Hydrologic Assessment

Hydrologic assessments were completed to further understand the hydrology, assess risk, and prepare a plan to minimize future losses in watershed participating in this study. The watersheds ranged in area from 500 to 1,500 square miles, representing Iowa’s varied topography, soils, and land use. The Iowa Flood Center developed HEC-HMS hydrologic models for each basin and ran simulations to understand the potential effectiveness of various hypothetical mitigation strategies.

The hydrologic assessments include a comparison of the water cycle across the watersheds and an analysis of hypothetical watershed scenarios that seek to reduce flood damages including changes to infiltration in the watershed and increased storage on the landscape.

Finalized Phase I Reports [pdf]

South Chequest Creek Hydrologic Assessment
Middle Raccoon River Hydrologic Assessment
Soap Creek Hydrologic Assessment
Turkey River Watershed Hydrologic Assessment
Upper Cedar River Watershed Hydrologic Assessment

Phase II – Construction of Projects

Watershed Management Authorities in each watershed selected pilot subwatersheds to construct and implement demonstration projects. Three HUC 12s were identified to receive funds for project construction.

The following subwatersheds were selected to receive $1.5M to fund the construction of small-scale flood mitigation projects:

A dense instrumentation network monitoring stream stage, precipitation, soil moisture, soil temperature, and water quality was deployed in each of the pilot watersheds to track watershed conditions.

Finalized Phase II Reports [pdf]

Beaver Creek Project Evaluation
South Chequest Creek Project Evaluation
Soap Creek Project Evaluation
Otter Creek Project Evaluation

As the Iowa Watersheds Project ended in the fall of 2016, the state of Iowa was awarded $96.9M for a new watershed project, The Iowa Watershed Approach. The IWA will work in nine new watersheds across the state and is built off the framework developed through the IWP. For more information, visit the IWA website here.

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