The Lake Byllesby Dam is located on the southern edge of Dakota County. The dam is owned by Dakota County with an exempt license to operate from the Federal Energy Regulatory Commission and water levels regulated by the Minnesota Department of Natural Resources.
Dakota County operates the turbines that produce electricity. The energy produced is sold as part of an agreement with Xcel Energy.
In a year, Lake Byllesby Dam generates enough electricity to power about 2,400 homes.
Dakota County regulates the surface use of the waters of the Lake Byllesby Reservoir and the Cannon River. Read County Ordinance 128.
The Lake Byllesby Dam was built in 1910 when Henry M. Byllesby Company constructed it across the Cannon River on the border of Dakota and Goodhue counties. Using mostly hand labor, a crew of 500–600 began work in April 1910 and completed the work in just nine months.
The dam was operated by Northern States Power until 1969 when it was sold to Dakota and Goodhue counties. Dakota County became sole owner in 2009.
The dam created the Lake Byllesby Reservoir, a 3.5–mile long, 1,432–acre lake.
The concrete dam is more than 1,100–feet long and more than 60–feet high from its base with nearly 400 feet of spillway. The crest of the spillway is 854 feet above sea level.
The dam is regulated as a high-hazard dam because of it size and location near Cannon Falls.