WESPEN Online Order Form print this page
US Fish & Wildlife Service FieldNotes
Fish Protection installed at Prairie Du Sac Hydroelectric Dam on the Wisconsin River
Region 3, August 25, 2009
View looking upstream at the Prairie du Sac Hydroelectric Dam. This is the lowest dam on the Wisconsin River and is located near Madison, Wisconsin. USFWS photo by Nick Utrup.
View looking upstream at the Prairie du Sac Hydroelectric Dam. This is the lowest dam on the Wisconsin River and is located near Madison, Wisconsin. USFWS photo by Nick Utrup. - Photo Credit: n/a
View from the upstream side of the Prairie du Sac dam powerhouse looking at the new trash racks installed at the intake of the powerhouse. USFWS photo by Nick Utrup.
View from the upstream side of the Prairie du Sac dam powerhouse looking at the new trash racks installed at the intake of the powerhouse. USFWS photo by Nick Utrup. - Photo Credit: n/a
Close-up view of one of the newly installed trash racks showing the vertical bars with one-inch clear horizontal spacing. This new design will help reduce fish entrainment and turbine mortality. USFWS photo by Nick Utrup.
Close-up view of one of the newly installed trash racks showing the vertical bars with one-inch clear horizontal spacing. This new design will help reduce fish entrainment and turbine mortality. USFWS photo by Nick Utrup. - Photo Credit: n/a

Fish entrainment and turbine mortality has always been a problem and an issue of concern at hydroelectric power plants throughout the Midwest.  Numerous studies conducted at hydropower dams in Wisconsin have shown that thousands of fish are entrained annually and that many of these fish are killed by the turbines.  Further, the results show that predominantly small fish (i.e., less than 6 inches) pass through these dams on an annual basis with mortality rates ranging from 10 to 20 percent.  Over the course of several years, this mortality rate can have a profound impact on fishery resources.

 

The Federal Energy Regulatory Commission  regulates and licenses all non-federal hydroelectric dams in the United States.  As part of the licensing process, the FERC must refer to the U.S. Fish and Wildlife Service and other state and federal agencies to make recommendations relative to the impact these hydro dams have on the environment, including fishery resources.  During recent relicensing of the Prairie du Sac Hydroelectric Project (FERC Project No. 11162; located near Madison, WI), state and federal resource agencies, including the Service, recommended that the licensee (Alliant Energy) install fish protection structures at this project to minimize fish entrainment and mortality.  Subsequently, as part of the license requirement and pursuant to Section 18 of the Federal Power Act, the FERC ordered Alliant Energy to install fish protective devices in the intake area of the project.

 

Starting in 2004 the Service, along with Wisconsin Department of Natural Resources and the River Alliance of Wisconsin, has worked closely with Alliant Energy to design and construct fish protective devices that would reduce or eliminate fish mortality associated the hydroelectricity production.  After several months of research and negotiation among the parties involved, it was determined that Alliant Energy would need to install new trash racks in front of the intake area of the powerhouse.  To minimize fish entrainment and mortality, these trash racks were to consist of vertical bars with no greater than one inch clear horizontal spacing between the bars.  These were to replace the old trash racks, which were wide enough to allow many fish to pass through.

 

Following final approval from the FERC and resource agencies, Alliant Energy began replacing the trash racks in 2008.  The new "fish friendly" trash racks were completed in 2009 and are currently in operation.  The successful completion of this project will most certainly minimize or eliminate turbine mortality for the fishery resources in the vicinity of the dam. This project is an example of how the U.S. Fish and Wildlife Service, through collaboration with partners, can effectively reduce the impact hydroelectricity production has on the environment.  Careful review of FERC hydropower projects, by the FWS and partners, is imperative to reducing any detrimental impacts that these projects may have on the aquatic environment, especially as demand for hydroelectricity increases.

Contact Info: Nicholas Utrup, 920-866-1736, Nick_Utrup@fws.gov