Ducks Unlimited’s Living Lakes: Improving Minnesota’s shallow lakes one by one
BENSON, Minn., Dec. 29, 2005 - Ducks Unlimited (DU) believes a temporary modification to the outlet of Minnesota’s Frank Lake will result in improved migration habitat. The modification will lower the water level of Frank Lake this winter to increase the likelihood of undesirable fish winterkill and enhance vegetation on which waterfowl feed.
With permission from Frank Lake landowners and assistance of Minnesota Department of Natural Resources (DNR) Wildlife Division field staff, DU installed two new water siphons and a fish barrier grate on the outlet of Frank Lake this fall. The water siphons are lowering lake levels faster and to a greater depth than would naturally occur due to a dam on the outlet of the lake. Lower lake levels this winter should reduce populations of rough fish, such as black bullheads and fathead minnows, and the fish barrier will prevent fish from re-entering the lake next spring.
The Frank Lake project is part of DU’s Living Lakes initiative. Living Lakes has a goal of restoring or enhancing 400 shallow lakes in Minnesota and Iowa during the next 10 years to benefit migrating waterfowl.
“Installation of both the barrier and siphon were time consuming and expensive and only made possible through the cooperation of landowners and significant help from DNR field staff, “said Josh Kavanagh, DU biologist in Minnesota. A grant from the Minnesota Environment & Natural Resources Trust Fund provided DU with funding for the project. The Legislative Commission on Minnesota Resources approved the grant to DU through the multi-organizational Habitat Corridors Partnership.
Like so many other Minnesota shallow lakes, 130-acre Frank Lake, near Benson in Swift County, has suffered in recent years from high water levels, nutrient loading, and a dense population of undesirable fish that negatively affect waterfowl habitat quality. By temporarily lowering water levels, wildlife managers can simulate drought and winterkill conditions, thereby resetting the ecological characteristics of shallow lakes and restoring conditions preferred by ducks: clean and clear water with low fish populations and abundant aquatic plants and invertebrates such as fresh water shrimp.
DU and DNR began the cooperative project in 2003 after several years of declining waterfowl use on Frank Lake. DU and DNR conducted an ecological survey of the lake’s condition and held an informational meeting in 2004 to review improved management ideas with the lake’s six adjacent property landowners. The landowners gave their permission to conduct a temporary, partial drawdown of Frank Lake during the winter of 2004-2005 using the lake’s existing water control structure. DU also installed a barrier on the outlet of the structure to bar the re-entry of fish.
“Unfortunately, too many fish survived last year because the dewatering process was slow and didn’t reduce the water level enough,” Kavanagh said. In addition, the 2004-2005 winter was very mild. Although lower water levels did allow rooted aquatic plants to increase in spring 2005, they were set back by untimely heavy rain that deeply flooded the lake inhibiting full potential growth.
The new equipment DU installed will bring better results, Kavanagh says. “With a little cooperation from Mother Nature this winter, we should be able to meet our habitat goals,” he said. “Complex, yet important shallow lake improvement projects such as Frank Lake can succeed, one lake at a time, when we work together with our partners and private landowners.”