MANITOWOC (NBC 26) — About six months ago, a fish kill at Silver Lake prompted the Wisconsin Department of Natural Resources to test the water and fish population. The results are in, and it is now clear what caused the kill — and what comes next.
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The search for answers began last winter, when the DNR drilled 12 holes through the ice to test water samples. Those tests found low oxygen levels everywhere they sampled.
Jason Breeggemann, a DNR fisheries biologist, said the lake has a troubled history with this problem.
"Silver Lake has a history of fish kills from low oxygen during wintertime," Breeggemann said.
Biologists say a large algae bloom last fall, followed by plants decaying under the ice, depleted the oxygen fish need to survive.
"We knew there was going to be some level of mortality as a result of low dissolved oxygen," Breeggemann said.
The tests also ruled out neighbors' biggest fear — that runoff or a contaminant had entered the water. I asked DNR water quality biologist Claire Hetzel whether anything in the water shouldn't have been there.
"Correct. There was no indication of any acute spill, which was good news," Hetzel said.
An electrofishing survey revealed the extent of the damage. Crews caught 33 black crappie, 3 yellow perch, 4 bluegill, just 1 largemouth bass, and no walleye.
The DNR says panfish should start rebuilding, but the process could take 3 to 5 years. Walleye stocking is set to begin next year.
For people who live on the lake, the results are hard to accept. Brett Hubbartt, Silver Lake president, said he had hoped the damage was less severe.
"I was disappointed. I was hoping we didn't have such a severe kill," Hubbartt said.
Hubbartt said he has already noticed the difference firsthand.
"I've lived here 14 years now, and this was the first year I didn't have any bluegill spawning on the shoreline," Hubbartt said.
To prevent this from happening again, the DNR is looking into adding an aerator — a system that pumps oxygen into the water — which could prevent or reduce winter fish kills in the future.
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