The Michigan Department of Natural Resources says large amounts of dead fish are being reported in Lake Macatawa near Holland.
The fish are being found near the outlet channel of the lake.
The reports began in mid-April.
Experts say a virus responsible for causing viral hemorrhagic septicemia, or VHS, is responsible for the die-off.
The DNR says the virus was first reported in 2005 and can go years without causing problems.
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