F19 Kootenay Lake nutrient restoration
This project includes the coordination, oversight, and implementation of nutrient additions to the North Arm of Kootenay Lake, and the associated monitoring and reporting. Nutrient additions (nitrogen and phosphorus in the form of liquid agricultural grade fertilizer) support phytoplankton populations that are suitable for the production of Daphnia, a main food source for Kokanee.
Final report: executive summary
Dams upstream of Kootenay Lake have altered the natural cycle of nutrient inputs into the lake (Daley et al. 1981). Nutrient retention from the Duncan Dam to the north, which began operation in 1967, and Libby Dam in Montana, which began operation in 1973, caused Kootenay Lake to shift from an oligotrophic to an ultra-oligotrophic system. This effect was observed following the remediation of a fertilizer plant upstream in the 1970s (Binsted and Ashley 2006). There was a concern, based on simulation modelling and population declines, that the dominant North Arm Kokanee (Oncorhynchus nerka) stock might collapse and sport fish such as Gerrard Rainbow Trout (O. mykiss) and Bull Trout (Salvelinus confluentus) would decrease significantly, as Kokanee are their main food source (Walters et al. 1991). A costbenefit analysis of using fertilizer to improve the fisheries concluded that the monetary benefits of the program would more than off-set the costs (Korman et al. 1990).
Click the provincial database link below to read the full final report for this project.