Project No. 56, Manston Slough Restoration

MINNESOTA ENVIRONMENTAL INITIATIVE AWARDS: 2015 Partnership of the Year and Natural Resources

Manston Slough Wins Top Honors at Environmental Initiative Awards Program 

Wilkin County, Minn. – The Buffalo-Red River Watershed District and their partners were recognized with top honors at the 2015 Environmental Initiative Awards for the Manston Slough Restoration project. The project won the evening’s highest honor, 2015 Partnership of the Year, and also received the Natural Resources category award. 

This statewide awards program annually honors innovative projects that have achieved extraordinary environmental results by harnessing the power of partnership. Winners were announced at the Environmental Initiative Awards celebration on Thursday, May 21, in Minneapolis. 

Manston Slough is a more than 2,500-acre shallow wetland complex located in Wilkin County, Minnesota, in the Red River Basin. Before this project began, more than 75% of the historic wetland in the area had been completely drained. 

State agencies, federal agencies, a nonprofit organization and more than 33 private landowners collaborated over many years to restore the Manston Slough wetland and surrounding area. The entire project encompasses over 7,000 acres providing countless hunting and recreational opportunities for the general public.

 “Collaboration isn’t always easy. This project is a wonderful example of what can be accomplished for our environment and for all Minnesotan’s when we choose to work together,” says Environmental Initiative’s Executive Director, Mike Harley. 

About Environmental Initiative

Environmental Initiative is a nonprofit organization that builds partnerships to develop collaborative solutions to Minnesota’s environmental problems. The organization brings together leaders from nonprofits, businesses, and government agencies to find consensus on critical issues and respond with actions that have measurable, positive environmental outcomes. http://www.environmental-initiative.org/

ABOUT THE PROJECT:

Location: On Wilkin County Ditch No. 13-Lateral, a tributary to the South Branch of the Buffalo River, in northern Wilkin County
Client: Buffalo-Red River Watershed District
Date:5/6/2008

Background:
The Manston Slough project was initiated after the Minnesota Department of Natural Resources (DNR) began looking at enhancing wetlands in the E½ of Section 19, Manston Township, in the Manston Wildlife Management Area (WMA). After review of the site by the Buffalo-Red River Watershed District (BRRWD) and their Engineer, Houston Engineering, Inc., the BRRWD and their Mediation Project Team (PT) decided that a larger, more comprehensive project would restore historic wetland water levels while providing additional flood control. The final Manston Slough project extends across almost seven square miles and includes parts of Mitchell, Manston, and Meadows Townships in Wilkin County. The project site is located near the bottom of the beach ridge on very flat topography. Runoff from the east drops quickly through the landscape upstream of the site and then enters the Manston Slough area, spilling out of various waterways that drain into the historic basin. The area was initially drained in the late 1800s with the construction of Ditch No. 15 by the State of Minnesota. The project site is approximately two miles wide in the east-west direction and four miles long in the north-south direction. A large portion of the Manston Slough project area includes land owned by the United States Fish and Wildlife Service (USFWS) and DNR. During meetings with personnel from the DNR and the USFWS, it became evident that, in addition to flood control, the site also had great potential for wildlife habitat enhancement.

LIDAR aerial and GPS ground survey was conducted on the project site in order to obtain ground elevations for the site. A geotechnical investigation was also started to determine the subsurface conditions. The NRCS and Ducks Unlimited (DU) supported the project by encouraging property owners in the flood pool and wetland areas around the project site to sign up for Wetland Reserve Enhancement Program (WREP). In 2003, the Governor’s Clean Water Cabinet selected this site as one of their Pilot Project Initiatives.

The Project:
The project drainage area is 26.5 square miles and extends approximately 7 miles east of the site. The project includes:

  • A low hazard classification dam with 4,340 acre-feet of storage below the Emergency Spillway Crest
  • 1,147 acres of wetland restoration
  • A water level control structure to manage wetland elevations
  • Upland watershed treatment to control erosion 

The dam embankment has a maximum height of approximately eight feet and primarily consists of modifications to existing roads. The principal spillway consists of a reinforced concrete culvert through the dam embankment and a reinforced concrete box drop inlet. Stop logs in the side of the box inlet allow management of the wetland pool,  operation and maintenance of the project, and provided drawdown capability for access to the site during construction. The 300-foot vegetated emergency spillway is designed to convey discharges in excess of the principal spillway capacity at nonerosive velocities. The U.S. Army Corps of Engineers’ HEC-HMS and HEC-RAS computer programs were used extensively to simulate runoff events and aid in the design of spillway features. Wilkin County Ditch No. 13-Lateral will serve as the outlet channel.

Benefits:
A preliminary cost-benefit analysis was conducted for the project. Final  project costs were $6.3 million. Project benefits are expected to exceed $15 million.

  • Floodwater storage and retention.
  • Natural resource enhancement – 1,147 acres of new restored wetland in addition to enhancement of existing wetlands.
  • Nutrient assimilation, resulting in improved water quality.
  • Sediment entrapment, resulting in improved downstream water quality.
  • Buffalo Aquifer groundwater recharge.
  • Improved nesting habitat for waterfowl and improved habitat for breeding, brood rearing, feeding or cover purposes for other species.
  • Provides an educational opportunity for watershed managers, engineers, agency employees and the public, due to the diversity and uniqueness of the project. 

Funding:

  • Buffalo-Red River Watershed District (M.S.A. 103D.905, Subd. 3) – $1,257,267
  • State of Minnesota DNR Flood Damage Reduction Grant – $3,765,742
  • Project Assessments per Benefited Party (M.S.A. 103D.725) – $628,633
  • Minnesota Board of Soil and Water Resources-Reinvest In Minnesota (RIM) – $347,000
  • Lessard-Sams Outdoor Heritage Council (LSOHC) CPL Grants Program – $350,000