Effects of Small, Removable, Modular Hydropower Generating Units on Downstream Passage of Freshwater Fish

This is a unique hydropower project that uses a new technology incorporating a matrix of small, submersible, and removable turbine-generating units that are stacked one on top of the other like box fans.  It is the only one of its kind operating in the United States.  The 9.2-megawatt project began operating in December 2011 at a Corps of Engineers dam located on the upper Mississippi River in Minneapolis, Minnesota.  The placement of the generating units in several of the spillways in the dam meant fish had an option of  moving  through the generating units or through a gated spillway structure located immediately above the units.  Studies conducted on the success of fish moving downstream through the new generating units combined field studies with desktop analyses.  These study results estimated 714,000 fish would be entrained annually at the project with an expected 72 percent mortality for small fish less than 4 inches in length.    More refined studies are needed to better gage the project effects on downstream movements of fish.  The technological advances shown by this project have positive economic and environmental advantages over traditional hydropower projects.