DU Biologist Josh Kavanagh inspects the recently installed high velocity tubes at Simon Lake

The project was completed after years of consultations with private landowners by the Minnesota Department of Natural Resources (DNR) field staff and DU staff, along with months of survey and design work by DU’s engineering staff.

Historically, shallow Simon Lake held thousands of migrating waterfowl that were attracted to its abundant wetland foods. Like so many other shallow lakes in Minnesota, Simon Lake was suffering from continuous high water levels, turbid water quality, lack of aquatic plants and an abundance of undesirable fish, including non-native carp. Although many factors can influence habitat conditions in a shallow lake, the presence of fish is the most likely culprit behind the decline of Simon’s waterfowl habitat and water quality.

Fortunately, Simon Lake is situated high in a well-managed watershed where many small wetlands and upland grass fields are still intact and nutrient runoff from agricultural operations is considered minimal.

An earlier attempt in the 1990’s to create a fish barrier was not successful, and both DNR and landowners asked DU to design and install a more permanent solution. The high-velocity, tube fish barrier limits fish movement into the lake using an outlet culvert with enough length and slope (approximately four feet of drop) that water passes at such high velocities, fish cannot navigate up the tube and into the lake.

“Essentially it’s creating a one way carp slip-and-slide,” said Josh Kavanagh, a DU biologist who helped coordinate the project. “High velocity tube fish barriers are the most effective and maintenance free fish barrier designs currently available to wildlife managers.”

DU engineers are further refining the design for outlet improvement projects on several additional shallow lakes around the state.

DU engineers developed the engineering design plans a couple of years ago, but DNR still needed to secure legal access to the lake’s outlet before construction could begin. In 2004 and 2005, DU’s Kavanagh assisted DNR Area Wildlife Managers Kevin Kotts and Dave Soehren as they met with Simon Lake property owners to discuss management options and establish an easement on the outlet, thereby allowing DU to legally place and maintain the outlet tube structure for the DNR.

“Simon Lake now has a well-designed and functioning high-velocity tube fish barrier at the outlet DNR will maintain in perpetuity,” said Matt Olson, DU construction manger for Minnesota.

DU and DNR also asked landowners to consider allowing a drawdown that would winterkill fish and rejuvenate aquatic plants in the lake. Unfortunately, the landowners could not form consensus on allowing a drawdown and preferred to focus on the implementation of the fish barrier as a first step. “We’re hoping that, through continued negotiations, landowners will ultimately form consensus to allow DNR to totally reclaim this shallow lake that is important for wildlife and humans alike,” Kavanagh said.

A cooperative partnership between DU, DNR and private partners around the lake made the Simon Lake fish barrier project possible. Funding was provided by DNR and a grant through the Habitat Corridors Partnership, of which DU is a key partner, from the Minnesota Environment & Natural Resources Trust Fund with approval from the Legislative Commission on Minnesota Resources (LCMR).

Establishing this line of defense at the outlet of Simon Lake is merely one goal for this and many other impaired shallow lakes around the state. In partnership with Minnesota DNR and other conservation partners, DU’s Living Lakes Initiative is improving waterfowl habitat in Minnesota for you and future generations. Your continued support and contributions to Ducks Unlimited is critically important and enable DU to fulfill our habitat mission in Minnesota and throughout North America.