It's not clear what caused thousands of fish to die on the south branch of the Whitewater River this week, but investigators hope lab tests will help reveal an answer.
A DNR official tells the Winona Daily News the fishkill affected more than a mile of the southeastern Minnesota river, killing several species including brown and rainbow trout, chubs, suckers, and dace.
Ron Benjamin, the fishery supervisor for the area tells KTTC: "In that section of stream, we believe it took out everybody. Including the crayfish, including probably the insects, everything."
No other parts of the Whitewater were affected and the fishkill area is back to normal now, Benjamin tells the station.
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The fishkill was discovered Thursday and officials estimate the fish died Tuesday and Wednesday.
The Pollution Control Agency and Minnesota Department of Agriculture have joined the DNR in the investigation and Benjamin tells KTTC laboratory results are expected early next week.
The station notes that more than an inch of rain fell within a few hours late Monday and early Tuesday and investigators are looking at whether that may have contributed.
Whatever killed the fish dissipated before reaching the DNR's Crystal Springs fish hatchery.
Benjamin told news outlets southeastern Minnesota trout streams typically see three to five fishkills per year, but this one is larger than most.
The DNR says the Whitewater is safe for recreation but notes that anglers won't catch any fish there, the Daily News says.
Restocking of the river in that area will begin in a few weeks, Benjamin tells KTTC.