Over the winter, lakes experience a decrease in dissolved oxygen (DO) levels that can lead to reduced numbers of fish that survive until spring. The concentration of DO in lake water varies from year to year based on winter conditions including when the lake freezes over and how soon (and how long) it is covered by a thick (sun blocking) layer of snow that prevents the natural processes of lake plants to generate dissolved oxygen through photosynthesis.

The Minnesota Department of Natural Resources (DNR) conducts periodic tests of DO level and water temperatures in Centerville, Coon, Martin and Peltier lakes to determine if the lake environment supports its fish. The DNR Fisheries Manager monitors the DO levels, deciding when to commence aeration of lakes to support aquatic life.

DNR Fisheries Specialist Jim Levitt angering a hole in a lake to collect samples and monitor water quality.

The goal of the DNR Lake Aeration Program is to ensure the safe winter operation of aeration systems and to ensure the appropriate use of aeration technology. In most cases, the use of aerators is to maintain existing populations of fish. It is important to realize that aerators are not the best option in all lakes. To view a brochure on how aeration may prevent winter-kill of fish, or to obtain a DNR aerator system permit application visit the DNR Lake Aeration Program (webpage).

DID YOU KNOW Cenaiko Lake (located at the Coon Rapids Dam Regional Park) is a designated trout lake and closed to fishing until the trout season (January 14, 2017 to March 31, 2017). See the fishing regulations for more details on designated trout lakes. DNR fisheries monitors and maintains Cenaiko Lake:

• 4,000 Rainbow Trout were stocked in December (size: 8-14 inches)
• 181 Adult Rainbow Trout were stocked in December (size: up to 5 pounds)
• Possession limit (5 combined – not more than 3 over 16″)