WINDOM, Minn. – March 21, 2012 – Spring migration is underway and ducks and geese are finding Wolf Lake Waterfowl Production Area (WPA) in Cottonwood County a great place to stop and refuel. The once-degraded shallow lake and nearby wetlands were enhanced by Ducks Unlimited and its partners to reveal a healthy wetland system with abundant vegetation, clear water and improved habitat for waterfowl and other birds.
"At the height of the migration we had several thousand ducks and geese come through Wolf Lake. The bird use is greater than any other year that our staff remembers," said Scott Ralston, wildlife biologist with the U.S. Fish and Wildlife Service (USFWS) and Partners for Fish and Wildlife program. "With new improvements, we also hope to hold more birds as local breeders and see many more broods using the restored wetlands this summer."
The key to shallow lake enhancement is the periodic, temporary removal of water from the lake. This simulates natural droughts and causes beneficial fish winterkill events. Active water-level management also simulates natural wetland hydrology that rejuvenates the aquatic ecology. This is exactly what DU and the USFWS Windom Wetland Management District set out to do when they collaborated in 2009. DU designed three water control structures, a pump station and a fish barrier for the three-wetland system on the WPA. Crews completed construction in July 2011 and water was removed from the wetlands to initiate the rejuvenation process.
Throughout the winter, water levels remained low to help remove invasive fish, such as the common carp, from Wolf Lake. However, the mild winter this year posed some management challenges. "This winter was abnormally mild and, by February, which should have been our coldest month, we bored some test holes and found only 4-6 inches of ice over about 18 inches of open water in South Marsh. We knew we still had surviving fish with that much water left under the ice and we knew we had to act fast to remove them before spring melt when remaining fish could then move back upstream into Wolf Lake," Ralston said.
To solve the problem, the USFWS and the Minnesota Department of Natural Resources (DNR) applied rotenone under ice to ensure a complete fish kill. With the system fish free, managers can focus on using the new water control structures to raise or lower water levels on any of the three wetlands to maximize conditions for waterfowl.
"Our partners and the public users of Wolf Lake WPA are excited to see the habitat and bird response to our enhancement efforts," said Josh Kavanagh, DU regional biologist. "When we get the right infrastructure in place and develop a sound management plan, we often see immediate results."
"It is amazing how these systems can bounce back after years of stagnant water and unproductive habitat; the vegetation response from the drawdown on Wolf Lake last summer was phenomenal, and migrating waterfowl are finding abundant food resources in the newly flooded basin this spring," said Rob Baden, assistant area wildlife manager with the Minnesota DNR.
Managers are now letting water fill the basins on the WPA through snowmelt and runoff. As predicted, spring migrating waterfowl are using the basins to rest and feed as they travel to the breeding grounds. Arrowhead tubers and invertebrates are providing the fuel these birds need to arrive on the breeding grounds in good health and ready to nest. The downstream fish barrier will prevent carp and other rough fish from recolonizing the basins and negatively impacting the system.
Funding for construction of the Wolf Lake project was provided by a state grant from the Outdoor Heritage Fund as recommended by the Lessard-Sams Outdoor Heritage Council, as well as a federal grant through the North American Wetlands Conservation Act. Additional support was provided by Ducks Unlimited, USFWS, Minnesota DNR, Cottonwood County Game and Fish League, Fox Lake Conservation League and Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources.
Ducks Unlimited is the world’s largest nonprofit organization dedicated to conserving North America's continually disappearing waterfowl habitats. Established in 1937, DU is celebrating its 75th anniversary this year, with special events, projects and promotions across the continent. Ducks Unlimited has conserved more than 12 million acres thanks to contributions from more than a million supporters across the continent. Guided by science and dedicated to program efficiency, DU works toward the vision of wetlands sufficient to fill the skies with waterfowl today, tomorrow and forever. For more information on our work, visit www.ducks.org. Connect with us on our Facebook page at facebook.com/ducksunlimited, follow our tweets at twitter.com/ducksunlimited and watch DU videos at youtube.com/ducksunlimitedinc.