Lake Alice - Fergus Falls

Problem:

Lake Alice is a 39 acre prairie pothole lake in the heart of Fergus Falls. Prior to urban development, Lake Alice supported a diverse array of vegetation and wildlife. Presently, a significant storm water system flow is discharged into the lake, carrying runoff from the upstream residential area that carries sediment which includes significant amount of phosphorus. A report by the City of Fergus Falls and MPCA identified excessive phosphorus, sediment loading, cyanobacteria, and fecal coliform in receiving waters as water quality concerns. As an extreme case of hypereutrophy, Lake Alice offers relatively little in terms of beneficial uses or ecosystem services. Stakeholder awareness of the degradation of the lake ecosystem continues to draw attention to remediation of the lake's degraded condition, but true understanding of the lake's unique role in the watershed is lacking amongst the public. An education campaign accompanying remediation attempts is due. A goal of altering the contemporary trophic state and attendant elimination of harmful algal blooms and odors associated with decaying plant material may be accomplished by achieving a condition of mesotrophy in Lake Alice that supports aquatic and wetland plant communities similar in abundance and diversity to those of other prairie pothole lakes in the region.

Scope:

This project, an initial phase of a larger remediation and education project, will remove the primary source of phosphorus and total suspended solids before stormwater enters the lake through two major storm sewers. This phase is critical to the overall remediation project as it eliminates the primary source of pollutants entering the lake so subsequent clean up efforts ca n be effective in the long term. The City of Fergus Falls will construct two sediment traps "upstream" of Lake Alice in the storm water system flow in order to collect sediment from the two major storm sewer inputs that discharge into the lake. Each sediment trap will consist of a 6 ft by 10 ft by 60 ft precast concrete box culvert. The trap has a series of baffles that slow down the flow of water and allow the sediment to settle out. The sediment can then be removed from the trap and disposed of. The City is also seeking funding through this project to replace three storm inlets with catch basins containing sumps and porous baffles for capturing sediments. The catch basins replaced will be connected to smaller storm sewers which discharge to Lake Alice as a smaller, less expensive sediment collection option.

Priority/ Urgency:

Having failed to meet one or more water quality standards, Lake Alice was finally placed on the TMDL List under Section 303d of the Clean Water Act in 2022 and is predicted to meet its TMDL by 2025. The Section 303(d) list also acts as a "trigger", signaling the need for immediate management actions to address water quality impairments and making this project a high priority to begin to remediate the damage caused by the discharge of sediment into Lake Alice in order to meet federal requirements.