The municipal council of Crescent Lake in Portage la Prairie, Manitoba are reviewing options to improve water quality of Crescent Lake.
The lake serves as the receiving environment for the city’s storm water runoff, provides year-round habitat for aquatic organisms, seasonal habitat for large numbers of migratory waterfowl and other birds, recreational opportunities for people, and a water supply to a local golf course and vegetable farm.
The city commissioned a study to assess the current conditions the lake and options to improve water quality, including cost estimates. The water quality issues identified for Crescent Lake are primarily related to eutrophication.
The mayor of Crescent Lake, Irvine Ferris told Portage Online that, “We do work on water quality, and that includes herbicides, vegetation and a lot of other things. There’s certainly been a lot of talk in our community over the years about how the (lake’s) water quality could be improved and how it could be utilized more by our citizens.”
Nutrient management options explore include: strategies to reduce external nutrient inputs to Crescent Lake (i.e., from the Assiniboine River, land drainage, geese), options to reduce internal nutrient loading (e.g., dredging to remove nutrient rich sediments) options to remove nutrients from the lake (e.g., removal of macrophytes), or changes to lake hydrology or morphology (e.g., increased flow through the lake, increase depth of the lake).
Options examined to address waterfowl-related issues included implementation of scare tactics to keep geese from sidewalks, habitat modifications to reduce goose access to sidewalks, parklands, and residential lawns, provide alternate grazing and loafing areas, and population management for resident geese.
In general, there was no single strategy that, if implemented, would address the majority of water quality issues. The report concluded that lake flushing, would potentially have positive effects to water quality, but may not be feasible with existing conditions.
Due to the lake’s shallow depth, lack of water movement, and elevated nutrient levels, the lake currently exhibits algal blooms, excessive growth of aquatic vegetation, and unpleasant odours.
The mayor said that many of the options explored are not financially feasible for the community. For example, one of the possibilities was dredging, and the estimated cost was $20-million.
No decisions have been made by the council yet. The full report is available here.