Indian Lake Restoration

Restoring Indian Lake

Restoration of Indian Lake began not with water but with a bypass. In 1988, the Blue Earth County Public Works Department determined that growth and corresponding traffic shifts in the City of Mankato warranted construction of a roadway that would skirt the city on the south. A federal Environmental Impact Statement evaluated several alternatives and ultimately recommended the construction of CSAH 90, known local as the Mankato South Route. The project involved encroachment on 2.5 acres of wetland, which Blue Earth County was required to mitigate by either creating a new wetland or restoring a degraded wetland.

About the Lake

Indian Lake was a natural choice for mitigation efforts. Located approximately one mile south of Mankato, the Indian Lake basin is set in the floor of a valley that is currently a drainage way that discharges into Indian Creek which, in turn, discharges directly into the Minnesota River. The 50-acre basin has been drained and farmed since the 1920's. While a few area residents could remember fishing and swimming in Indian Lake, for the most part, the only remaining vestiges of the lake were old photographs and periodic flooding of the cornfield.

A Unique Opportunity

The setting of the project impressed project planners as a unique opportunity to provide much more than mitigation for wetland impacts. The forested valley surrounding the drained lake basin is an uncommon sight in southern Minnesota, where the landscape is characterized by flat cultivated fields. Recognizing that the ecological success of the lake restoration would be dependent on the preservation of the surrounding uplands, Blue Earth County acquired 70 acres of forested valley uplands surrounding the lake basin. The resulting restoration project is a new 120-acre regional park and provides an outstanding recreational and environmental resource for generations to come.

Restoring a Wetland Ecosystem

In addition to providing a regional park and wetland mitigation for the South Route and for future projects, the project restores a small portion of the wetland ecosystem that once dominated most of southern Minnesota. Ecological benefits of the project include habitat for aquatic invertebrates, amphibians, reptiles, birds, and mammals. Water quality improvement and protection is also a primary ecological goal for the project. Water quality of the Minnesota River is among the worst in Minnesota. Restoring wetlands along the river and in concentrated drainage ways (such as Indian Lake) will filter water entering the river and, in the long run, improve the water quality of the Minnesota River.

Wetland Mitigation Banking

Once the project was conceptualized and the land acquired, Blue Earth County proceeded through project design and the regulatory process for wetland mitigation banking. The mitigation site is located on the urban fringe of Mankato near rural residential neighborhoods. Public involvement was a key part of planning and design of the Indian Lake project.

Building a Restoration Team

Restoring Indian Lake demanded a diverse project team of technical experts and significant involvement of residents to resolve the myriad questions posed by this unique project. The water level of the restored lake was a key issue. Technical advisors and regulators favored a lower water level primarily because it would increase biodiversity due to more aquatic vegetation growing in shallower water. Local residents preferred a higher water level for boating, fishing, and aesthetic reasons. The team evaluated 13 management objectives to determine the lake depth that would best meet the project's environmental and recreation objectives. Environmental planners and hydrologists also estimated the lake's original scope and depth based on soils data and historical information.

Landscape architects worked with engineers and planners to design a park facility that melds environmental and recreational amenities. A trail system was designed to circle the restored basin and to connect with other regional trails. An interpretive display and pamphlets are describe the history of the basin, the restoration process, and ecological benefits of wetlands.

A Model for Success

In addition to being a model for the successful cohabitation of improved transportation facilities and environmental stewardship, the Indian Lake Restoration project also stands as a model for cooperation among a wide number of agencies. An Advisory Committee comprised of residents and technical experts assisted the Design Team throughout the project and a Technical Evaluation Panel was charged with assessing alternatives from the standpoint of mitigation banking. The Technical Evaluation Panel included representatives of the Blue Earth County Highway Department, the Minnesota Board of Water and Soils Resources, and the Blue Earth County Soil and Water Conservation District.

The Advisory Committee included residents and representatives of the Minnesota Department of Natural Resources, Minnesota Pollution Control Agency, and the City of Mankato. Construction of the South Route is underway and Indian Lake is becoming a lake once again. An outlet control structure was installed in late 1997 and the lake basin began filling. The summer of 1998 marked the first year of a 5-year monitoring plan designed to ensure the success of the project. Seeds of wetland plants that have lain dormant for the past 70 years are sprouting and aquatic organisms are finding new homes in the lake. Before the proud eyes of the community, a lake is reborn.