DNR seeks to improve

Lake Hanska fishing

By FRITZ BUSCH

Journal Staff Writer

NEW ULM -- Like ice anglers and snowmobilers, the Minnesota Department of Natural Resources is hoping for a very cold winter with lots of snow.

The DNR has its own selfish reasons, but sports enthusiasts should agree.

In an effort to reclaim Lake Hanska by ridding it of a large population of carp and black bullhead as well as decay at the lake bottom, the DNR plans to activate the aeration system at a later time than it would if it was aerating.

Aeration is typically used to keep fish alive by providing oxygen to dead areas of shallow lakes.

This time, the DNR wants to turn on the bubblers at each end of the lake's bottom when there is enough ice and snow on top so open water areas are created.

"We hope this winter is real severe," said DNR Fisheries Manager Huon Newburg of New Ulm. "We want it (Lake Hanska) as dead as possible under the ice."

Timing is of the essence.

There are no guarantees.

If the process works, it will save Minnesota taxpayers hundreds of thousands of dollars.

Killing off rough fish in a lake with a chemical costs between $300,000 and $400,000.

The same result could be accomplished for about $5,000 with reverse aeration.

The chemical rotenone is typically used to kill undesirable fish species like carp and black bullhead in a lake before it is restocked.

Those types of fish feed on the lake bottom, stirring up sediment, impairing water quality and making it difficult for beneficial plants to grow.

Lake Hanska was treated with rotenone in 1987 and restocked.

The fishing was very good for several years until carp and bullhead returned.

The DNR thinks the rough fish returned because somebody put them in the lake. Fertilizer run-off also helped recreate the problem.

This time, the process is designed to drop the Lake Hanska's oxygen levels too dramatically and quickly for fish to be able to adjust.

Reverse aeration has worked on Clear Lake near Waseca and Wagonga Lake south of Willmar, Newburg said.

Next spring, the results of the plan will be obvious.

"If there are a lot of dead fish on the shore when the snow and ice melts, we'll know it worked," Newburg said. "We'll set nets in April or May and restock the lake. We are working closely with the Lake Hanska Association."

If the plan works, the DNR will restock the lake with a diverse fish population.

If reverse aeration does not work, the DNR will consider treating the lake with rotenone.

The Lake Hanska Reclamation is part of a concerted effort to manage the lake and its watershed, according to Ken Varland, DNR Regional Wildlife Manager of New Ulm.

Varland said the DNR met earlier this month with several area organizations.

"We had a very positive and encouraging meeting with the local groups," Varland said. "We believe we'll be able to continue to work well together to achieve better recreational opportunities for everyone at Lake Hanska."

Other plans for Lake Hanska include:

* Designing and installing a new mechanical fish barrier on the grade stabilization structure on the south side of County Highway 6, and on the Lake Hanska outlet water control structure.

* Designing and installing a drop inlet structure to enhance lake drawdown capabilities and lake level manipulations.

* Installing a second aeration system in the western part of the lake.

*Starting an immediate, full drawdown of the lake to promote the growth of aquatic vegetation critical to good water quality and fish and wildlife habitat. The lake is currently undergoing a gradual drawdown.