Cost-efficient rock fishways have been constructed at the Arborg Dam on the Icelandic River, the Dominion City Dam on the Roseau River and the Rapid City Dam on the Little Saskatchewan River. To ensure that these fishways work, the department monitored use of the fishway at the Rapid City Dam in 1993. Spawning migrations of fish were observed using the fishway the following spring. Lake Eutrophication Many lakes in southern Manitoba are shallow and productive. This is most common where the waters are rich in nutrients.
Nutrients encourage growth of aquatic vegetation in summer.
In winter, the vegetation decays and uses up oxygen. High nutrient content sometimes occurs naturally, but can be added from domestic sources such as sewage lagoons or septic fields and from agricultural sources such as animal waste and crop fertilizer. If shoreline vegetation is removed, it can no longer serve as a buffer that filters the flow of nutrients to the water. They release air bubbles into the water to prevent winter kills of fish. Most often these systems are purchased, installed and operated by local interest groups and governments with biological and technical assistance from Manitoba Natural Resources.