Coon Rapids Dam Fish Barrier and Improvements Preliminary Design

The primary goal of this preliminary design effort was to identify the improvement measures required to meet the Minnesota Department of Natural Resources' objectives for the Coon Rapids Dam which primarily consists of preventing the migration of invasive fish species for decades to come. The most practical and economic method to impede the upstream migration of invasive fish was determined to be a physical barrier that utilizes the natural fall and velocity of water over the existing spillway. The existing Dam and existing upstream pool level operating procedure would serve as an effective barrier approximately 89.1 percent of the time1. An improved dam structure coupled with a modified upstream pool level operating procedure that maintains the summer recreational pool year-round would serve as an effective barrier approximately 99.9 percent of the time. Preliminary design of improvements necessary to provide an improved invasive fish barrier and to prolong the overall life of the Dam was completed. Major improvements include replacement of the main spillway inflatable gate system and implementation of downstream scour protection measures. The estimated capital cost for improvements totals $16.9 million (2011). It is recommended that the proposed dam improvements and modified pool operating procedure be considered by State and Federal agencies as part of an overall plan for control of invasive fish species migration into the waters of the State of Minnesota including the Upper Mississippi River Watershed.