Impact of the Birch Lake Outlet Dam on the Water Levels of Birch Lake and Ten Mile Lake, Cass County, Minnesota

The Birch Lake outlet dam, located in Hackensack, Minnesota, is a small concrete dam used to maintain water levels on Birch Lake (Figure 1). The Birch Lake outlet dam is owned and operated by Cass County and was authorized by a Department of Natural Resources Permit (76- 3435). This permit authorized the operation of the dam and defined the conditions of operation. On July 18, 2001, representatives of Ten Mile Lake Association, Birch Lake Association, Pleasant Lake Association, Cass County and the Minnesota Department of Natural Resources met to discuss concerns related to the Birch Lake outlet dam and water levels on Ten Mile Lake and Birch Lake. At the time of that meeting, Ten Mile Lake water levels were near the highest recorded in 25 years. During the course of that meeting, DNR Waters agreed to conduct a two-year study to investigate the operation of the Birch Lake outlet dam and the effects that dam has on water levels on Ten Mile Lake and Birch Lake. It was also decided that the four-inch stoplog, installed since August 1999, would remain in the Birch Lake outlet dam during the course of the two-year study. On July 20, 2001, Cass County formally requested that the Birch Lake outlet dam be converted to a fixed crest structure and that the permit be modified to reflect that configuration.