KIRKWOOD, Mo. — Some 650 dead fish, mostly bluegill, washed up recently at Kirkwood Park's Walker Lake over the weekend, the Missouri Department of Conservation confirmed with 5 On Your Side.
Multiple parkgoers said they encountered hundreds of fish carcasses floating on top of the lake and lying on the lake's shore, according to the community's Nextdoor page. Many said a "horrible" smell accompanied the mass of bodies.
Conservationists confirmed the deaths and attributed them to equipment failure and extreme temperatures.
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"The cause was an aerator pump failure last month combined with recent extremely high temperatures which depleted O2 in the water, stressing fish and resulting in a die-off," MDC Metro Media Specialist Dan Zarlenga at the St. Louis Regional Office said. "This is a common issue this time of year (July-September) as warmer water does not hold as much O2. The event was then triggered by the aerator failure and amplified by high population density in the lake."
Zarlenga said Kirkwood city officials are responsible for cleaning up the dead fish. The job was seemingly completed by Wednesday, as 5 On Your Side crews that arrived at the scene found no dead fish.
Around 2,000 fish are stocked in the lake annually for public fishing through MDC and Kirkwood. The department is currently working on an agreement with the city for each to pay half the cost for a replacement aerator.
"The pump failure did have an impact, but its effects were made worse by the temperatures, so if the pump had failed at a different time, the impact might have been less," Zarlenga said. "Had it not failed, the O2 levels would still be higher even with the heat, but fish may still have died due to the super-hot temps."