Cold may be behind large die-off of fish in Sloan's Lake

Hector Gutierrez, Rocky Mountain News

Published October 18, 2007 at midnight

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A large fish die-off at Sloan's Lake may be linked to cold weather killing algae, which leads to oxygen being absorbed from the water, authorities said Wednesday.

While scores of dead fish were bobbing in the west Denver lake, catfish, crappie, coy, bluegill and perch were gasping on the lake's southwestern shore where an inlet from Edgewater releases fresh, oxygenated water.

Such die-offs are natural seasonal events when abundant algae killed by a cold snap decompose and drift to the bottom of the shallow lake, absorbing oxygen, officials from Denver's Department of Environmental Health said.

Samples from the lake are being tested, but so far officials don't believe the water was contaminated by a toxin, said Ellen Dumm, the city's environmental health communications director.

"It's a sizable die-off," Dumm said.

Staff from the Colorado Division of Wildlife also scooped up a handful of dead fish and took them for testing to their fish lab in Brush, said Jennifer Churchill, the division's spokeswoman. The wildlife division is responsible for stocking the lake with fish.

Maintenance workers for the city's Parks and Recreation Department were attempting to remove the dead fish, but by afternoon many remained in the lake uncollected.

City crews posted "no fishing" signs and were notifying fishermen to release any fish they catch until the source of the problem is determined, said Jill McGranahan, parks and recreation marketing director.

Fisherman David Rice waded into the water near the inlet on the west side of Sheridan Boulevard and tossed a few dead catfish onto the bank.

"To kill catfish, it's got to be pretty harsh," said Rice, 43. "They survive a lot of things."

Rice managed to scoop up a live but lethargic goldfish and took it home to put in his pond near Sloan's Lake Park. The goldfish seemed to regain its energy in the pond, he said.

"I'm a nature person, and I don't like seeing fish dying," Rice said. "This is sad. I've been here 22 years, and I've never seen anything like this. When fish come up to you asking for help, you know there's trouble."

Actions under way

• Samples of lake water are being tested, but so far officials don't suspect a toxin.

• Crews have posted "no fishing" signs and are telling anglers to release fish they catch.

gutierrezh@RockyMountainNews.com or 303-954-5204 Staff writer Alan Gathright contributed to this report

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