Caused by an unusually heavy blue-green algal bloom, depleted oxygen levels led to a large fish kill in north-central Iowa's Crystal Lake. This was followed by another fish kill at Black Pit, a 16-acre pond in Lester Milligan Park in Mason City, which was caused by a similar algal bloom.
"When it really looks scummy (stay out), because a lot of times pets will go in there and ingest the water and they can get sick," said Iowa DNR Spokesman Kevin Baskins, speaking about the recent blooms. "In some cases we've even had pets dies." Officials will monitor Black Pit to see if it will recover on its own, or need restocking.
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