Dissolved Oxygen Investigation Coon Rapids Hydroelectric Redevelopment Project

Abstract

The Coon Rapids Dam is located in Hennepin County, Minnesota, on the Mississippi River approximately four miles downstream from the City of Anoka and approximately twelve miles upstream from the downtown section of Minneapolis. The structure was transferred to the Hennepin County Park Board by Northern States Power Company in 1969. Since 1969 the structure has undergone considerable modifications to make the facility meet its new recreational role, with the installation of walkways and observation platforms. The hydropower redevelopment at Coon Rapids will send between 1,000 and 8,000 cfs (the range of discharge for the turbines), which previously passed over the spillway, through the turbine units. This will have an impact on downstream D.O. concentrations because the spillway is an excellent aerator, increasing D.O. concentrations, while the turbines do not add any air to the water.