CARONDELET PARK – Normally, Horseshoe Lake is a good place to catch channel catfish, bluegill and largemouth bass.
But lately, a covering of green gunk has coated the five-acre lake on the western end of Carondelet Park and made life miserable for fish and anglers alike. Kevin Meneau, a fisheries management biologist for the state Department of Conservation, said things got so bad that about 300 fish died in the lake in late August.
The city Parks Division started working last week on a fix for the problem.
But anglers fishing in the park’s other lake said over the weekend that conditions were too bad to toss a line into Horseshoe Lake. A photographer for The SouthSider and Metrostl.com found several dead fish on the side of the lake’s north end.
“It was good fishing until I don’t know what happened over there,” Demir Dedic of south St. Louis County said as he stood next to Boathouse Lake in the center of the park. Whatever happened, things have gotten pretty bad, he said.
“I heard there was a problem with it smelling really bad, fish kill,” said Ray Scheumbauer, who was out fishing with his son John Scheumbauer. Before that happened, Ray Scheumbauer said, he liked Horseshoe Lake. “It’s a little bit nicer, kid-friendly.”
The change came after an overflow drain in the north side of the lake blocked up. The lake filled with nutrients, which led to the rapid growth of duckweed and watermeal. The plants, not algae, covered the top of the lake and robbed fish below of oxygen. That led to the fish kill, Meneau said.
According to city Parks Commissioner Kim Haegele, pipes connected to a grated inlet had deteriorated and weren’t draining well. That cut the amount of aeration.
A contractor was hired to dig up the old pipe and replace it, Haegele said. As of Friday, the inlet was mostly clear of duckweed and watermeal. Over the weekend, about two-thirds of the lake north of a stone footbridge was free of the weed. It covered more of the lake south of that bridge.
The tiny plants flow on the top of the water, Haegele said.
According to the website of the U.S. Forest Service, duckweeds are the smallest known flowering plants and grow almost everywhere in the United States and the lower part of Canada. Their flat, oval leaves are no more than a quarter-inch thick and float on the top of ponds, lakes and sloughs. Flies, mites, bees and small spiders can spread the pollen. The plants can grow quickly.
Watermeal is smaller than duckweed, Meneau said.
Haugele said Friday that within the next two weeks, the park division would install a new water source at the south end of the lake. That will naturally push the duckweed northward into the inlet. There are flowing water sources at the north end of the lake, but they’re too close to the inlet.
“We suspended stocking until the city parks folks could get this fixed,” Meneau said. “They fixed it, so now they can renew fish (stocking).” The department will do that some time this month, he said.
A photographer for The SouthSider and Metrostl.com found several dead fish along the lake’s north shore. Meneau said that was about typical at this stage.
Dead fish first sink to the bottom. They fill with gas as they decompose, and float to the top. Then wind will blow them to the side. Sometimes birds will eat them.
The state conservation department stocks fish in several lakes in the area under its St. Louis Urban Fishing Program. For information on stocking, call the Fish Stocking Hotline at 636-300-9651.