The Knife River fish trap, which has provided valuable information on migrating strains of rainbow trout for 16 years, was severely damaged by recent flooding, Department of Natural Resources officials said.
"It pretty much tore the heck out of it," said Deserae Hendrickson, DNR area fisheries supervisor at French River.
The trap is just below the Minnesota Highway 61 expressway.
The recent high water on the Knife, caused by a high volume of rain, tore away about half of the steel grating in the trap and now lies downstream. The water destroyed a drum screen where the fish enter the trap, ripped away all of the electrical connections, filled much of the trap with boulders and gravel, bent the gate controls and washed out part of a road that provided access to the trap.
The trap captured Lake Superior steelhead and Kamloops rainbow trout bound upstream each spring to spawn and also captured young trout downbound to the lake.
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The trap was constructed in 1996 at a cost of about $550,000, DNR officials said. It has been instrumental in monitoring the rainbow trout population and the effectiveness of stocking strategies, Hendrickson said.
The DNR now must decide whether to repair the trap, said Don Schreiner, DNR Lake Superior area fisheries supervisor.
"The big question is, how much money will it cost to get it functional again, and is it worth it?" Schreiner said. "You have to ask yourself, should we keep investing in something that has provided the reason for its being?"
The trap also was damaged severely by flooding in July 1999, Schreiner said.
As for how juvenile steelhead might have fared in the Knife River and other streams after recent flooding, Schreiner said it's too soon to tell.
"I don't know what's going to happen this time around, but in 1999, we thought initially we had sustained huge losses, and it turned out to be one of the best year classes we ever had," he said. "I think that's because we ended up with water in the streams all summer."
