Title: Supplemental Environmental Assessment & Finding of No Significant Impact - Fawn Island Shallow Water Habitat Repairs, Harrison County, Iowa
Summary: In 2010, Fawn Island was constructed near river mile 673.6 as a flow-through chute to function as shallow water habitat intended to benefit the federally endangered pallid sturgeon and other native fish and wildlife species. The unprecedented flood of 2011 eroded the east bank of the chute beyond the designed construction footprint, and the chute has become deeper and faster than desired.Proposed repairs include the construction of four stone revetments, totaling approximately 2,612 linear feet. Approximately 7,000 cubic yards of material would be removed in order to securely entrench the revetment toes. Seventeen spur dikes would be created along these revetments to direct flows away from the bank and relieve pressure on the revetment. Approximately 24,260 tons of new quarried rock riprap would be required.
Geographic Scope: Left descending bank of the Missouri River near river mile 673.6 in Harrison County, Iowa.
Impacts: None
Decision/Date: Made following close of public comment period.