What is the in-river west bank fish passage and how does it impact the river?

The in-river west bank fish passage, located upstream from the dam, is a design alternative developed to address concerns shared during the first public information meeting held in January 2019. The design includes parallel sheet pile walls that extend 350 feet along the upstream riverbank and pools that step the level of the water above the dam to the level of the water below the dam. The fish passage will be located in a 23.5-foot notch on the west side of the dam. 

Since this project CANNOT impact the floodplain by law, hydraulic modeling was completed on the preliminary plans to ensure that the fish passage will have NO effect on the floodplain. Final design will verify this impact and structural engineers will be involved in any dam modification. 

Steel was identified as the passage wall material for several reasons: steel walls are easier and quicker to construct; they can be built with less disruption to the existing channel bottom; and existing steel passage structures in Wisconsin have been successful in the past.   

The fish passage will be integrated into the existing spillway structure to ensure stability of both the existing dam and the passage. Additionally, the separation wall between the passage channel and the main river channel will be constructed to withstand forces from river flow and ice loading. Construction of the fish passage will likely take between 60-120 days to complete, pending weather conditions impacting the flow of the river.