EUREKA – First they drained most of the lake. Then they killed all the fish left in it. This week, the lake begins its comeback.
"We tested the water and its good enough for the fish to arrive," commented fish biologist Rob Hilsabeck of the Illinois Department of Natural Resources (IDNR). "We're ready for restocking."
Eureka Lake was choking on a dominant and overabundant population of grass carp, the surviving and unwelcome species of a low-oxygen, harsh winter, fishkill that all but wiped out a healthy game fish population five years ago. To reclaim the health of the lake, the IDNR executed a program this summer and fall that collected and transplanted to other lakes as many catfish, redear sunfish, bluegill and bass as possible, then killed the remaining fish in the lake three weeks ago with a fish-killing compound called rotenone.
The fish died in less than an hour of the application of the rotenone. This past week, a small cage that contained a half dozen bluegill was lowered into the lake -- the piscine version of the proverbial canary in the coal mine -- to check the viability of the water to sustain fish life.
"The rotenone had dissipated," Hilsabeck said. "The fish all lived."
On Friday, IDNR began to restock the 30-acre lake with baby fish, starting with about 9,000 four-inch channel cats raised in the Jake Wolf Memorial Fish Hatchery in rural Mason County.
Hilsabeck will return this next week and restock the lake with 22,500 bluegill and 7,500 redear sunfish. Fishing will be allowed on the lake next spring, although caught fish will likely not be big enough to keep for a couple of years. The lake will be stocked with fingerling largemouth bass in the spring.
According to Hilsabeck, there's no guarantee that carp will never return to Eureka Lake although the hope is always to avoid the kind of imbalance that resulted in the grass carp takeover following the natural fish kill of 2013.
Hilsabeck praised local staff for keeping the water level of the lake down during the reclamation process.
"Their work was very impressive," he said.
The town took advantage of the lowest lake level in decades to do some work.
"We are grateful to the DNR for all of the expertise and assistance they have given the city in restoring Eureka Lake," Administrator Melissa Brown said. "And gratitude to the (city) employees that have worked diligently to make repairs and improve the lake while the opportunity of exposed shoreline has presented itself.”
Local officials made repairs to the dam, placed rock around the perimeter to prevent erosion, made extensions and repairs to pipes for "dry hydrants" that serve as fire protection sources of water and placed donated PVC pipe in areas to promote fish habitats.
According to Brown, the lake should refill this fall.
"It is really dependent on rainfall that will bring water from surrounding watershed," she said. "During the last rains we got this past weekend, the lake rose four feet, according to (public works director) Rusty (Klaus). He feels if October continues to bring this type of rain, the lake could be back to normal levels by the end of October or November."
The refill should also eliminate the stench of rotting fish.
"We got a couple of calls and e-mails (about the smell)," Brown said.