More than 5,000 fish died in the Beaver Dam River over the weekend, when the city lowered water levels in the river to aid an ongoing construction project.
According to the Beaver Dam Lake Improvement Association, walleye, northern pike and panfish were the main species that died.
"People are pretty outraged about it," said Jeannine Morris, who lives in Beaver Dam and noticed the dead fish on Thursday.
She says her family loves to fish and they were heartbroken to see this happen.
"There were some trophy fish in there, it takes a long time for a fish to grow that big, it's sad," Morris said.
According to the city, they starting bringing water levels down last week by closing off the dam. This was to dry out the concrete about four miles down the river where a delayed construction project is taking place on Cooper Street.
But a large amount of fish were still coming through the dam and there wasn't enough water for all of them.
"Unfortunately we had that fish loss in the meantime so there's the problem of now cleanup and looking forward to get the project done," said Beaver Dam Mayor Rebecca Glewen. "It's an important area for emergency service for our community."
She said the construction project involves a major thoroughfare for the city that needs to be fixed to aid emergency crews.
Bill Boettge, president of the Beaver Dam Lake Improvement Association says it's too early to assess blame but it wouldn't have been an issue if the city didn't lower the water levels.
"Why we got more fish going through this time we can't answer that right now," he said. "We're going to look at that and why did all those fish get through there and how can we prevent it in the future."
The city opened the dam back up early Friday morning and water levels are now what the city calls acceptable.
They are working with the Wisconsin Department of Natural Resources to prevent future fish loss as this construction project goes forward.
"There's got to be a balance," Glewen said. "It's not that we can just say we have to quit the construction project, that has to be finished."
Glewen says it's illegal to relocate the fish so the city couldn't have moved the fish beforehand into the lake. Local officials are looking at other methods in the future such as a prevention gate at the dam to keep large numbers of fish from entering the river.
Morris has organized a community cleanup effort near the dam to pick up trash along the river. She says anyone who wants to help can meet at 7 p.m. on Tuesday.