The Pomme de Terre River Association has partnered with the Minnesota Department of Natural Resources to replace the Crissy Dam with a safer, more environmentally friendly structure called a “rock arch rapids.” The project is currently still in the design and planning phase, and once a design is finalized it will undergo extensive modeling to ensure it is the best option. A similar project on the lower Pomme de Terre river was completed with great success.
The project will address several key issues:
Water flowing over low-head dams creates a dangerous roller (sometimes called a “Drowning Machine”) that can trap and drown swimmers, fisherman, boaters, and kayakers.
The current structure makes it incredibly difficult for some fish and mussel species to move up and down the Pomme de Terre River. The Minnesota Pollution Control Agency identified 15 fish species and eight mussel species absent upstream of the current structure in their Watershed Biotic Stressor Identification study. This barrier was also noted by the DNR in their Minnesota River Fisheries Management Plan 2023–2027 (pg. 6 and 23).
Completed projects revealed that removing dams increased the percent of gamefish caught near project sites.
Dams slow stream flow causing sediment to drop out of the water in the upstream reservoir. Looking at the initial plans for the dam from 1935, it was stated that the average water depth was going to be 6-7′ deep in the reservoir. Currently most of the reservoir is less than 1.5’ deep, with no river channel to be found upstream of CR 10.
Downstream waters are often sediment deprived, resulting in excess erosion of the streambed and streambanks below dams. The upstream reservoir is very shallow and will continue to fill in as sediment comes down the river. Over time, the reservoir upstream will fill in and a river channel will form through it.
Proactively addressing the sediment accumulation gives us control over where the river channel will form. It also takes advantage of resources available; 20 years from now, the reservoir will still be filling in and getting shallower, but there might not be funding available to address it and the organisms limited by the barrier (walleye, sturgeon, various endangered mussels) may not be here.
Replacing the dam will allow kayakers and canoers to pass through the Pomme de Terre without having to portage around. There are also large, flat rocks strategically placed in the design to allow anglers to stand on, and current project designs include ADA accessible fishing platforms.
