Cleanup, testing continue after massive fish kill at Lake Iroquois

LAKE IROQUOIS — If there was a silver lining to last weekend’s massive fish kill at Lake Iroquois near Loda, it was that the 80-acre lake had not yet been stocked with new fish this year.

Thousands of fish were found dead Sunday morning — everything from carp to bass to catfish to walleye to crappies and blue gill.

“I saw some of every species that I’m aware of that were still in Lake Iroquois that were part of the kill. It didn’t discriminate based on species at all,” said Lake Iroquois resident Mike Johnson, head of the Lake Iroquois Association (LIA) Bass Club.

What caused the fish kill remained unknown Monday. An inspector for the Illinois Environmental Protection Agency (IEPA) collected water samples at the lake Monday to be tested later this week.

“I believe he’s primarily looking at the outfall area of the lake to determine if there was something that entered the lake that could have caused the fish kill, or otherwise looking to see if it was lake turnover that reduced the oxygen levels,” said IEPA spokesman Kim Biggs.

Lake Iroquois resident Jim Shearl, chairman of the LIA board’s recreation committee, said that “as best as we can determine,” the fish kill was caused by the fish not getting enough oxygen due to a phenomena called “inversion,” also known as “lake turnover.”

Shearl said the lake’s surface layer likely became “very hot” during recent “extremely hot and humid weather.” Then on Friday, a cold snap occurred, causing the surface water to cool down, become more dense and sink, in turn causing the water and sediment on the lake’s bottom to rise.

“The oxygen was not available in the water for the fish,” Shearl said, because “the lake turned over.”

Shearl noted that following the fish kill, the lake’s water appeared “very muddy,” which lines up with that theory.

A group of marine biochemists that the LIA uses to maintain the oxygen and PH levels in the water at the LIA’s smaller, 5-acre fishing pond, Shearl said, checked the pond on June 29. Around that same time, the group had received reports of lake inversion elsewhere, Shearl said.

“So this is something that doesn’t happen very often, but it is common,” Shearl said.

Ironically, when the marine biochemists tested the oxygen levels at the small fishing pond, they predicted that the pond would “turn over.” Yet the lake, not the pond, did.

Shearl said the fishing pond likely avoided a fish kill of its own because mechanical aerators had been installed in the pond this past spring. The lake does not have any aerators, Shearl said.

“There’s motors that create air that emits out into the (pond) that causes the water to move,” Shearl explained. “And that aeration was enough to keep that fish population (in the fishing pond) safe.”

Shearl noted that the fishing pond is not connected to the lake itself and is also “above the lake,” meaning that any chemical runoff from nearby farms would be deposited in the pond first.

The fish kill was discovered Sunday morning. Later that morning, Shearl organized volunteers to help remove the dead fish.

“By 10 a.m., we had 30 people at our swim beach volunteering and cleaning up, picking up fish and putting them into an end-loader on a tractor,” Shearl said. “Then we put (the fish) into a dump trailer and hauled them away to a proper disposal area.

“The volunteers worked for four hours on the swim beach. Then, after lunch, they moved to another cove and worked another four hours.”

Shearl estimated that about 30 volunteers helped Sunday morning and 20 that afternoon. The cleanup continued Monday with about a dozen volunteers, Shearl said.

“It’s just amazing how much people have stepped up to help us,” Shearl said.

Shearl estimated the cleanup would likely continue for another week, noting that he expects more dead fish to surface in coming days. Larger dead fish often take longer to float to the surface.

“It’s not done yet,” Shearl said.

Shearl said he thinks there are “still plenty of fish” in the lake despite the fish population being depleted “substantially.”

“We’re going to be working with biologists later on to check and see what the population is and what fish we need to add this fall to restore the fish population,” Shearl said.

Shearl said the LIA Bass Club helps the LIA board decide how many fish and what species of fish to stock the lake with each year. This year, the stocking of the lake was delayed until this fall — “which is, I guess, a little bit of a silver lining,” Johnson said.

Johnson said he would like a more accurate assessment of the fish population that remains before deciding how to proceed with stocking the lake this fall.

“We were actually looking at stocking options (for this fall) that would help to limit those populations (of some of the ‘trash’ fish that were killed) anyway,” Johnson noted. “But without having an assessment of the population that remains after this event, it’s kind of hard to say what we should do exactly.”

To help accurately determine the remaining fish population, it has been suggested that the Illinois Department of Natural Resources visit the lake and perform what is called “electro-fishing,” Johnson said. It involves shocking the fish — but keeping them alive — so that they float to the surface and a survey of their numbers and sizes and general health can be taken, Johnson said.

“It would be nice to get that done sometime after this event’s kind of over — and before we make any final decisions on stocking,” Johnson said.

Whether the fish kill prompts the LIA board to buy more fish than it normally does remains to be seen, as well. Johnson said that due to budget constraints, it has been suggested that a fundraiser be undertaken to raise enough money to “expand the fish stocking given this major kill.”

Also in question is whether the LIA Bass Club’s annual kids’ fishing derby will go on as scheduled at the lake on Aug. 18, Johnson said.

“It’s in question, pending what we find out about the condition of the lake and the fish population,” Johnson said.

Johnson said that if the lake is not deemed suitable for the fishing derby, the event may be held at the fishing pond instead.

Categories (2):News, Environment
Location (3):Local, Iroquois County, Loda

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