LAKE DELTON — Before the water began flowing into Lake Delton this week, a series of moves were made involving the Mirror Lake and Lake Delton dams so the state Department of Natural Resources could rid the lake basin of carp.

Officials last week first lowered the level of Mirror Lake and then closed the Mirror Lake dam so no water was flowing into Dell Creek. The gates of the Lake Delton dam were closed Wednesday morning.

That allowed DNR officials to add rotenone Wednesday and Thursday to any standing water left in a series of pools and to Dell Creek. The chemical kills the fish and will allow the DNR to start with a clean lake when restocking begins this spring.

"This is a fairly common treatment," said Andy Morton, lower Wisconsin River basin supervisor for the DNR. "If you remove as much carp as possible, you give the sport fishery a chance to re-establish itself."

On Thursday, with the Lake Delton dam closed, water began pouring over the Mirror Lake dam and filling Lake Delton. The lake could be filled in the next two months, depending on the weather, Morton said.

And while pleasure boaters, water skiers and swimmers will likely return this summer to the lake, anglers will likely stay away for several years.

Lake Delton was a prime destination for walleye and bass anglers, but it will have to be stocked with fish, all of which will have to grow to legal size.

A large rock bar on the lake's northeast side has been added, and the coffer dam will also be submerged once the lake refills. Both will provide structure to attract fish.

"It's a great opportunity because we hope to bring it back to what it once was and also it could be improved," Morton said. "This is the first step in the fishery restoration."

— Barry Adams