Flood Mitigation Projects
Phase I: Hydrologic Assessment
A hydrologic assessment of each watershed will be conducted by the Iowa Flood Center to understand the hydrology, assess flood and water-quality risks, and evaluate scenarios to maximize results. This step will take place at the full watershed scale in the target watersheds (Upper Iowa River, Upper Wapsipinicon, Middle Cedar, Clear Creek, English River, North Raccoon River, East Nishnabotna, and West Nishnabotna). The watersheds range in area from 500 to 1,500 square miles and represent Iowa’s varied topography, soils, and land use.
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.
Phase II: Project Construction
Watershed Management Authorities in each watershed will identify eligible subwatersheds to construct and implement built projects. The location, type, and number of projects in each watershed will be based on the hydrologic assessment, watershed plan, and stakeholder input. Projects may include the following:
- Farm ponds
- Stormwater Detention Basins
- Sediment Detention Basins
- Floodplain Restoration
- Channel Bank Stabilization
- Buffer Strips
- Saturated Buffers
- Perennial Cover
- Oxbow Restoration
- Prairie STRIPS
Volunteer landowners will be eligible to receive 75% cost share assistance on constructed projects, with the remaining 25% being covered by the landowner or through local match. Projects are designed using NRCS specifications and guidelines and are required to have a 20 year maintenance agreement.
A dense instrumentation network monitoring stream stage, precipitation, soil moisture, soil temperature, and water quality will be deployed in each watershed to track project benefits before and after implementation.
In 2010, the Iowa Flood Center was awarded $4.5M of HUD funding for the creation of the Iowa Watersheds Project (IWP) that’s goal was to reduce flood damage in select Iowa watersheds. The IWP provided funding to five watersheds across the state (Upper Cedar River, Turkey River, Soap Creek, Middle Raccoon, and Chequest Creek) to establish a WMA, develop a hydrologic assessment and watershed plan, and construct practices similar to those mentioned above. The IWP ended in 2016 with the construction of over 150 built projects that will reduce flooding and improve water quality. The success of the IWP served as leverage to secure funding for the Iowa Watershed Approach and provided a framework to build off to create a vision for Iowa’s future.
Landowners enjoy the built projects for the multiple benefits they provide, which include improving the accessibility of their farm, decreasing erosion, increasing widlife habitat, providing water for livestock, adding aesthetic beauty to the landscape, and providing areas for recreation and personal enjoyment.
For more information on the Iowa Watersheds Project, visit: