Local Fishing Waters With Aeration Systems

Almost all our local fishing waters are productive aquatic ecosystems, reflecting the fertile lands (watersheds) surrounding them. To maintain fish populations in shallow, soft-sediment lakes where wintertime oxygen drops to levels threatening survival (a condition known as winterkill), aeration is sometimes used to mix in atmospheric oxygen.

Aeration systems used to maintain fish populations are operated by local organizations under permit from MN DNR Section of Ecological and Water Resources. Details of the Lake Aeration Program, including local aerated lakes, can be found here.

Notes About Aeration Systems / Aerated Waters Related To Fish Management:

  • Thin ice is present when systems are operating; unsafe ice can spread beyond signed areas.
  • Aerators can create a refuge of adequate oxygen but typically do not replenish oxygen throughout an entire lake; fish die-offs can still occur in aerated lakes. Beginning aeration late in a season, or once oxygen levels are below 4 parts per million, might not maintain sufficient oxygen.
  • Winter aeration start times and duration depend on ice and weather conditions; during mild or short winters, aerators might not be run at all.
  • Permittees (operators) are responsible for running aeration systems safely (including sign posting/moving) and effectively. Inexperience, desire to limit costs, annual variations in ice formation, and other factors can compromise running a system optimally.
  • Aerators can stir bottom sediments and create cloudy water or suspended nutrients. Waters and aerator location need to be deep enough so enough water volume can be oxygenated.
  • Aeration systems are one lake management tool and not a "cure-all." Aeration cannot change fundamental problems of shallow, fertile waters (such as thick vegetation/algae, odors, high summer temperatures, and spikes in harmful bacterial levels).
  • Once an aeration system is established, advocates resist ever ceasing operation, even when allowing an occasional winterkill could benefit gamefish populations. This MN DNR Fisheries research study describes when leaving an aerator off might improve fishing more than sustaining unbalanced fish communities.

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