Restoration Efforts at Houghton Lake
The Nature Conservancy's restoration goals for Houghton Lake were deceptively simple. To the maximum extent possible, we want to restore groundwater flow and quality to the lake and wetlands. To accomplish this we had to remove buried tiles from the agricultural fields and fill in many of the ditches that in the past had intercepted groundwater before it discharged to the lake. This change moves more water through the lake itself, helping to flush out chemicals and nutrients from adjacent farm fields that have accumulated over the decades. Now that the restoration is complete the annual flush of algae the lake experiences should decrease as nutrients leach out of the system over the years. This will improve habitat for native fish, amphibians and reptiles as the water clears over time.
There is one disruption that we did not restore: the natural lake water level. Although the outlet of the lake is man-made and has dropped the lake several feet, we did not manipulate it. The wetland habitats that have developed on the exposed lake bottom are too valuable and it would be foolish to drown out these high-quality habitats.
The adjacent fields have been restored to appropriate native wetland and grassland communities. The hydrologic restoration created very wet muck soils in the valley bottom, which we hope to restore to sedge meadows, wet prairies and fen communities. This will increase habitat for many wetland species, especially rare snakes and turtles at the site. The rolling uplands were planted to prairie to reduce agricultural runoff to the wetlands and to create additional habitat.
Preparing the Land at Houghton Lake
As we mentioned before, preparing the tract for restoration has been a long, arduous task. Eradicating the invasive species from the land has been our first task. In the spring/summer of 2007, stewardship worked to remove reed canary grass from the ditch and field edges. Attention will soon be turned to common buckthorn and the native cottonwood trees lining the ditches. Though a native species, cottonwoods must be downed to reduce the number of seeds that shower the landscape and potentially turning our restoration into a dense thicket.
In the spring of 2009, our invasive specie removal efforts shifted towards purple loosestrife. Efforts to fight it and stem its invasion are costly, time-intensive and often unsuccessful. To help battle purple loosestrife at Houghton Lake, we turned to some unlikely partners. European beetles, Galerucella calmariensis and G. pusilla, have been used since the early 1990s in Indiana as biological control agents for purple loosestrife. In Indiana and numerous sites throughout the Great Lakes, biocontrol programs have been reported to have significantly reduced dense infestations, generally within five years of the initial release. Extensive research and testings has shown that these beetles would not pester other plants. Therefore , once populations of purple loosestrife start to decline, so will the beetles.
A Great Success
Since we started preparing for this restoration in 2006, we've:
- plugged three ditches to restore the hydrology of the site and create 8 acres of wetlands
- installed a water control structure at the south end of the lake to control the water level
- collected 56 pounds of seed to plant with volunteers
- purchased an additional 852 pounds of seed to plant
- planted 135 acres with seed from 140 native species
- planted 4,500 native plant plugs
- treated invasive plants (reed canary grass, cottonwoods, Phragmites, Canada thistle, buckthorn, and cattails) on 402 acres, 22 miles of ditches, and 11 miles of field borders, including many retreatments
- burned 191 acres of habitat with three burns
Volunteers donated a total of 360 hours, getting their hands dirty to help with the restoration. Full-time and seasonal staff, along with AmeriCorps members, spent over 3,800 hours in the field working on the restoration.
This restoration is finished in the sense that all the necessary pieces – restored hydrology and diverse seed mix – are in place to develop into diverse habitats, but we’ll continue to manage the site to control invasive plants and to introduce fire management.