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
Natural

Resources (DNR),

Ducks Unlimited (DU), and local conservation organizations,
Lake

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

Lake in Murray County are undergoing reclamations.

“These degraded lakes are typical of most of the remaining
shallow

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

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

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

Service, Minnesota Waterfowl Association and local clubs,
restoring

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
is

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

sediments, resulting in turbid water that reduces sunlight
penetration

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
waters.

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

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
fish.

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
Currant

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

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

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

and erodes shorelines.

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

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
an

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
partial

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

a rotenone treatment.

Once fish populations have been eliminated, preventing them
from

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

reclamation project. Toward that end, a fish barrier was
recently

installed in the outlet downstream from Lake Augusta in a
cooperative

project between DNR and DU. A recently added water control
structure

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

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
working

together, we are making progress.”

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