PROJECT SUMMARY

The Koochiching Soil and Water Conservation District (KSWCD), in partnership with the Rainy Lake Property Owners Association (RLPOA), sought funding to restore nine (9) acres of wetlands on Rainy Lake, MN at the juncture of Koochiching County Road 134 (CR 134) and Elks Bay. The site has been significantly impaired by the infestation and dominance of non-native hybrid cattails. The infestation has been accelerated by loss of natural water flow from past road construction and a legacy of privately owned septic systems that were poorly suited to the soil conditions. The consequence has been the displacement of native aquatic plant species, degradation of habitat for waterfowl and fish, and the creation of floating navigational hazards.

Restoration of this 9-acre wetland will remove floating mats of invasive hybrid cattail, enhance natural aquatic habitat, and re-establish a more natural water flow. Left unchecked, non-native hybrid cattails will continue to dominate and spread through the area.

The proposed project comprises three main activities. To enhance water flow, an existing 48-inch circular culvert will be replaced by a 16’ x 10’ box culvert with the raising and widening of the roadway above the 2022 flood level. Next, utilizing methods tested at Voyageurs National Park, nine acres of hybrid cattails will be removed utilizing a combination of prescribed burning above ice during frozen lake conditions followed by mechanical removal of the remaining biomass during open water. Finally, approximately 2 acres of the restored area will be seeded with native aquatic vegetation and, if viable, wild rice.

PROBLEM STATEMENT

Shoreline access and habitat for native wildlife and vegetation on Rainy Lake have suffered in recent decades due to an overgrowth of non-native hybrid cattails. This project addresses environmental and ecological impairments on a nine-acre site located at CR 134 and Elks Bay. This site was largely open water prior to the emergence of hybrid cattails starting around 1980. Construction of CR 94, 134, and 135 to provide road access to islands did not consider openings for natural water flow. And until the creation of the East Sewer Sanitary District, private septic systems which were poorly suited to rocky shorelines added substantial nutrient loads into these waters. The loss of water flow, trapped nutrients, and loss of wave action accelerated the encroachment of hybrid cattails, ultimately resulting in an extensive, dense monoculture degrading the waterways adjacent to CR 94, 134, and 135 and the islands they connect.

Non-native hybrid cattails grow taller, faster and more densely than the native species that they out compete and displace. Dense stands of hybrid cattails block sunlight and reduce dissolved oxygen which makes poor habitat for fish spawning. The dense hybrid monoculture also provides poor habitat for predator fish like northern pike, poor cover for marsh waterbirds, poor nesting sites for waterfowl, and is a poor source of nutrition for wildlife. This project incorporates lessons learned from a similar project in the same area. In 2007, a 12-foot wide box culvert was placed under CR 94 allowing water to flow north out of Jackfish Bay. A channel to the culvert was dredged through dense cattails. Subsequent aerial imagery shows the channel widened significantly and cattails regressed as floating mats broke away. Unfortunately, these mats create floating navigational hazards, landing in and potentially infesting other parts of the lake including Voyageurs National Park. The 2007 project demonstrated the importance of enhanced water flow for sustainable cattail reduction but also created troublesome floating cattail bogs. This project proposes an integrated approach where cattails are initially removed to avoid the release of floating mat fragments and then creates a more sustainable native environment by enhancing water flow and seeding native species.

PROJECT OBJECTIVES

The project site includes the roadway of CR 134 where it crosses Elk Bay, and 9 acres of lake waters to the east and west of  CR 134, currently overgrown with dense mats of hybrid cattails. Three project objectives have been identified for this site which, collectively, will help restore and sustain a habitat for aquatic plants and wildlife native to the region.

Enhancing water flow beneath CR 134 is essential to sustain a native habitat. The limited water flow beneath CR 134 currently traps nutrients and blocks the effects of current and wave action. An existing 48-inch culvert will be replaced with a 16’x10’ box culvert, similar to what was done on CR 94. The culvert will significantly improve water flow, exposing a six to ten-fold increase in cross section for water flow.

A contractor will be hired to install 16’x10’ box culvert. The roadway will be raised and widen to accommodate the culvert, and to raise it above the 2022 flood level. The placement of a 12 culvert through CR 94 in 2007, which created water flow out of Jackfish Bay to the north, resulted in regression of cattails on either side of the culvert.   It also led to the creation of many floating bogs. We were encouraged by the result that restoring water flow led to the localized regression of cattails but were concerned that restoring water flow through the other county roads in the area without cattail removal would create more floating bogs. Without removing the non-native hybrid cattails initially, there would be little hope of restoring native plants or improving habitat for fish and wildlife.

OBJECTIVE PURPOSE: 

• Remove trapped nutrients which favor hybrid cattail growth
• Restore waterflow
• Promote regression of non-native hybrid cattails
• Accommodate new box culvert
• Provide Flood Mitigation

TIMELINE / TASKS

• Fall 2023 (UPDATE: Summer/Fall 2024)
  
  • Replace existing 48”culvert culvert with 10’ X 16’ box culvert
  • Raise elevation of CR134 by approximately 4 ½ feet
  • Construct bypass for continued access during construction

The final phase will be to restore native vegetation, including wild rice, to inhibit the return of non-native hybrid species and create a more resilient native aquatic habitat. Two acres of the site appear well suited for native aquatic vegetation. A seed list of 26 species native to Koochiching County, courtesy of Minnesota Wildflowers, has been assembled with the advice of Minnesota Native Landscapes. Wild rice seeding will be attempted following best practices recommended by Voyageurs National Park and Treaty #3 Communities which have successfully re-established significant wild rice growth within First Nation Communities on Rainy Lake.

Two acres in the project area will be seeded with a custom wetland seed mix, developed in collaboration with Minnesota Native Landscapes, containing 26 species which are native to Koochiching County. A similar seed mix was utilized by Voyageurs National Park following a hybrid cattail removal project. With guidance from Treaty #3 Community leaders, VNP, and MN DNR, 1 to 2 acres will also be seeded with native wild rice seed. If the guidance reveals that wild rice is not well suited to our project site, sedges and bulrush will be seeded instead.