A chain of shallow lakes forms the headwaters of the Shell Rock River Watershed in Albert Lea, Minnesota. Several of these lakes were considered impaired waterbodies by the Minnesota Pollution Control Agency, and a comprehensive approach was needed to solve significant water quality issues.
One of the primary contributors to the poor water quality was the over-abundant populations of bottom-feeding invasive carp. Carp re-suspend sediment and phosphorus into the water as they disturb the lake bottom when feeding. The impacts of this behavior negatively affect aquatic vegetation, damage habitat, contribute to algal blooms, and make the water cloudy. Many recreational activities were limited by the impaired water quality classification and conditions.
Smith-Root engineered and installed electric fish barriers in existing culverts at three tributaries to the Shell Rock River Chain of Lakes: Mud Lake, Wedge Creek, and White Lake between 2009 and 2010. Electric fish barriers create electric fields that prevent fish passage. Following installation and activation of the barriers, all carp were removed from upstream habitats, and the barriers maintain the carp-free areas.
Water quality in the watershed is dramatically improving each year, and downstream lakes are seeing marked improvements because of reduced nutrient loading from carp-free headwater areas. Additional barriers are in the planning stage to further improve the aquatic habitats and water quality in the Shell Rock River Watershed.