DNR, partners, restoring three southwest Minnesota lakes

Work is underway on three more southwestern Minnesota shallow
lakes to

improve water quality and waterfowl habitat.

In a partnership effort between the Minnesota Department of

Resources (DNR),

Ducks Unlimited (DU), and local conservation organizations,

Augusta in Cottonwood County, Teal Lake in Jackson County, and

Lake in Murray County are undergoing reclamations.

“These degraded lakes are typical of most of the remaining

lakes basins here in the prairie pothole region of Minnesota,”

to Windom Area DNR Wildlife Manager Randy Markl. “For the DNR

numerous other organizations such as DU, the U.S. Fish and

Service, Minnesota Waterfowl Association and local clubs,

these basins is a high priority.”

Destruction of aquatic vegetation caused by carp and black
bullheads is

a common cause of impaired water quality and eliminating them

essential, Markl said. Carp, in particular, root up lake

sediments, resulting in turbid water that reduces sunlight

necessary for vegetative growth. Aquatic vegetation helps
improve water

quality by tying up nutrients that contribute to algae growth
and also

provides an important food source for waterfowl.

The DNR is banking on a winterkill to eliminate fish from these

To encourage such an event, the DNR used a recently installed

control structure to lower Lake Augusta. Teal Lake is currently
in a

naturally low water condition and appears ripe for a winterkill.
In the

event a complete winterkill does not occur, the DNR could apply
a fish

toxicant (rotenone) later this winter to eradicate any remaining

Hjermstad Lake, which is one of several interconnected basins,
poses a

more difficult challenge, according to Wendy Krueger, DNR
Slayton Area

Wildlife Manager. Water from these basins eventually flows into

Lake, a 377-acre fishing lake with a fixed crest dam. That

contributes to chronically high water in the upper basins,
allowing fish

to over-winter and causing wave action that stirs up bottom

and erodes shorelines.

To counter effects of the dam, the DNR worked with DU and

organizations to install variable crest structures at Hjermstad
and its’

connected basins to allow for water drawdowns that would
encourage a

winterkill. However, the relative depth of Hjermstad Lake poses

additional challenge, Krueger noted.

“We’re not sure whether enough water can be removed from
Hjermstad to

result in a complete winterkill,” Krueger said. If only a

winterkill occurs, Krueger said the agency would have to follow
up with

a rotenone treatment.

Once fish populations have been eliminated, preventing them

re-entering the treated basin is critical to the long-term
success of a

reclamation project. Toward that end, a fish barrier was

installed in the outlet downstream from Lake Augusta in a

project between DNR and DU. A recently added water control

downstream of Teal Lake acts as a fish barrier there and two

barriers have been installed on the Hjermstad basin outlets.

“We have a lot of work to do in this region of Minnesota to

significantly improve water quality and habitat for waterfowl
and other

wildlife,” Krueger said. “But by forming partnerships and

together, we are making progress.”

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