Thousands of fish killed in Long Grove pond

When thousands of dead fish started surfacing on Salem Lake in Long Grove earlier this month, it was unlike anything longtime resident Casey Komperda had ever seen.

"It was fish on top of fish," recalled Komperda, who lives on the east side of the lake. "There were piles and piles. And wherever there was still ice, they would gather."

The fish, about 6,000 in all, likely were killed by a wintertime oxygen deficiency, said an official with the Lake County Forest Preserve District, which owns about two-thirds of the lake.

Salem Lake was covered by snow and ice for so long this winter, the oxygen supply for the fish was cut off, said Jim Anderson, the forest district's natural resource manager. Additionally, sunlight couldn't reach the plants in the lake, which would have helped create oxygen, he said.

The forest district's decision to turn off mechanical aerators that increase underwater oxygen levels, prevent algae growth and promote healthy living conditions for fish and other wildlife may have contributed to the fish kill, Anderson said.

The district may activate the aerators next winter to prevent more fish deaths, he said.

The 38-acre lake is near Route 22 and Old McHenry Road, at the southern end of Heron Creek Forest Preserve.

The preserve was established in 2004, but the section containing the lake was acquired in 2008. The land formerly belonged to CF Industries.

A man-made feature, Salem Lake averages only about 31/2 feet in depth and drops to 7 feet at its deepest point, Anderson said.

"What we're dealing with is a very shallow pond, comparatively speaking," he said.

About one-third of the lake is owned by the lakeshore residents, including Komperda. He was disturbed and saddened when the fish - including bluegills, largemouth bass and tiger muskies - started surfacing a few weeks ago.

"It's depressing because we fish on this lake," Komperda said.

He said CF Industries ran the lake's aerator system during the winter when it controlled the site.

Forest district officials opted to turn off the aerators this winter because they often attract geese that defecate in the area, Anderson said.

Although fish kills happen sporadically throughout the county and have happened at Salem Lake before, Anderson admitted the recent situation was "pretty significant."

Forest district staffers and local residents removed the dead fish over the course of the month.

Fish still live in the lake, Anderson said, but he didn't know how many. A survey would be needed to determine the fish population, he said.

Next winter, officials will deactivate the aerators while geese are migrating through the area and then turn them back on when the birds are gone, Anderson said.

Additionally, forest district officials will examine the lake and determine if it should be restocked, he said.