Agenda - Council - 12/08/2015 - Laserfiche WebLink

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Executive Summary Starting in the winter of 2012-2013, the water levels in the Coon Rapids Dam Pool will remain raised all year long as a way to keep invasive carp species from traveling upstream. Landowners along the river were concerned about how the higher water level may affect their shoreline through ice damage and erosion. The purpose of this project was to gather information about current bank conditions in the pool in order to better address residents' concerns about the future and to direct the use of available public bank stabilization funding. A total of 16.2 miles of riverbank was inventoried leading to the identification of 13 project sites, which if stabilized, would reduce sediment loading to the river by 5,220 tons per year. Methods Preparation • Anoka nProject Scope • • Dayton Coon Rapids Champlin Brooklyn Park Field Work The project scope was determined primarily by the extent of the pool with the dam fully raised. According to the Army Corps of Engineers, the pool extends 7.1 miles north of the dam when the pool is fully raised. In order to include all potential changes, the current inventory extends 7.5 miles to the Champlin -Dayton border. The Rum River was also inventoried nearly to the dam in Anoka because it could also potentially be affected by the rise of the pool. An atlas of the river was printed for note -taking purposes. The inventory was conducted on October 16th and 17th, 2012. The pool was still raised to its full height. Four staff members were on the inventory crew. The first person recorded erosion conditions and estimated a lateral recession rate for the bank. Using the Wisconsin NRCS Direct Volume Method, the entire shoreline was given a 1-4 ranking, ranging from slight to very severe erosion. These erosion classifications were converted to lateral recession rates for use in soil loss calculation (see next page for detailed descriptions). A second staff member recorded any structures on or near the shoreline and gave them a ranking as either stable, slumping, or failing. It is important to note that the erosion conditions near a structure do not necessarily indicate the stability of a structure. For example, the soil behind a