Although there are no direct significant environmental impacts associated with this project, issues have been raised concerning the total number of flood damage reduction projects along the lower Missouri River that have led to increased floodplain development and that may have cumulative impacts on aquatic and terrestrial resources. In general, the Missouri River floods from bluff to bluff upstream of the project area during flood events greater than the 100-year frequency. The project does not impact areas in the floodplain for water surface elevations at or below the 100-year frequency. However, given the limited accuracy of available topographic mapping, further surveys will be necessary to more accurately define the limits of these impacted areas during the design phase of the project. The benefits and costs for the 100-year plus five feet plan proved to be significantly lower than Plan C but generated only slightly lower net benefits.
All plans are feasible from an engineering, environmental and economic standpoint.
Plan C is the locally preferred plan.