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Grayling

Attempts to keep arctic grayling alive in Upper Red Rock Lake over the winter is proving difficult.

Testing of a solar-powered windmill to aerate Upper Red Rock Lake to help grayling survive ran into some problems this winter.

Snow partially buried the aerator’s solar panel, according to Matt Jaeger, fisheries biologist for Montana Fish, Wildlife & Parks in Dillon.

Heavy ice buildup on Upper Red Rock Lake, where grayling overwinter, is believed to be one of the reasons the fish’s populations haven’t grown in the Centennial Valley. Heavy ice means when vegetation dies in the shallow lake — about 5.5 feet deep — oxygen is depleted and the grayling suffocate.

Wind generation was considered for the aerator as an alternative to solar, but wind is more inconsistent than sunshine, Jaeger said.

One other option federal and state agencies are considering to keep fish in the lake alive over the winter is to pipe in fresh water. A final option, if nothing else works, is to dredge the lake’s inlets, which would take several seasons of work. Removing sediment is considered the last option because the lake’s sandy bottom could quickly fill in any dredged areas when wind whips up waves on the water body.