WETLANDS
Seven Mile Creek Watershed


Publications
An Historical Perspective of Hydrologic Changes - 2004 (pdf 474 k)

An Historical Perspective of Hydrologic Changes (Powerpoint presentation 16,524 k)

Farming a Different Crop - Wetlands (pdf 413 k)

Featured Articles
Restored Marsh Helps Clean Creek - November 11, 2004 (pdf 23 k)


Website
Wetlands in the Seven Mile Creek Watershed



 
  Learn how the extent of wetlands have changed through time in the Seven Mile Creek watershed. Let's Go

Wetlands were once a dominant feature of the prairie landscape in South-Central Minnesota. Today, fewer than 10% of the original wetlands exist as a result of our intensive efforts to drain the fertile land for agricultural production. Although not all of the consequences of these changes are understood, they are thought to include water quality degradation, increased flood frequency and intensity along rivers and major tributaries, and loss of critical habitat and diversity for wildlife.

  Today, wetland restoration is increasingly favored as a means of providing multiple natural resource and socioeconomic benefits including flood abatement, water quality enhancement, and wildlife habitat restoration. Landowners and farmers are restoring wetlands as a means of treating water from drainage systems before it is released into nearby rivers or streams. Biological activity in wetlands can be effective at removing nitrate by converting it to nitrogen gas through a process called de-nitrification. Researchers in Iowa suggest that wetlands can remove from 20 to 80 percent of the annual nitrate in subsurface drainage water depending on the ratio between the areas of drained land and wetland.

Recently, the Seven-Mile Creek Watershed Project with funding from the McKnight Foundation are exploring ways to restore wetlands while maintaining agricultural productivity and profitability. Innovative solutions include linking wetlands to subsurface drainage systems for the purpose of filtering agricultural runoff before entering streams or ground water.

Prairie pothole landscape - poorly drained
clay loam soils
Restored wetland - scroll over image for
more information
 

For instance, in one project, a 12-inch public ditch tile (CD 58) draining 200 acres of cropland was petitioned by the Brown-Nicollet-Cottonwood Water Quality Board and Nicollet Soil and Water Conservation District through Minnesota Drainage Law 103e.227 to be routed into a newly restored 50-acre wetland. The wetland is expected to remove 4,400 lbs. of nitrate-N per year and act as downstream flood control by storing up to 55-acre feet of water during a 100-year, 24-hour storm. (Scroll over image at left for more information)

This approach to "treating" drainage water using restored wetlands presents some challenges in South Central Minnesota watersheds. Site topography may pose difficulties in getting subsurface drainage waters to the surface and into wetlands. Land requirements and the cost of construction are also important economic factors. Finally, the bulk of nitrate losses from drained lands in Minnesota occur in early spring when wetlands are not functioning at their peak capacity to remove nitrate, because of low temperatures and high water flow rates. Through the help of the McKnight Foundation and Minnesota’s Clean Water Partnership, programs are being implemented to help address these issues while making it easy for a landowner or farmer to plant a different crop—a wetland.

As an example of our efficiency to drain the land, take a look at the Seven Mile Creek Watershed Historical Wetlands. Historical aerial photos from seven different periods were scanned and geo-rectified to produce digital data for use in a Geographic Information System. Examples of how the information is being used:

• Educate watershed residents and policy makers
• Help explain current water quality conditions
• Help set realistic water quality goals for the watershed
• Identify potential wetland restoration areas
• Improve restoration designs
• Help located existing drainage tiles
• Identify abandoned water wells

 
Farming a Different Crop:
Using Wetlands to Farm Nitrogen out of Agricultural Tile Systems

The project is a cooperative project by the BNC Water Quality Board and other partners in South Central Minnesota with funding provided by the McKnight Foundation and Clean Water Partnership Program. The project focus is to reduce the nitrate concentrations to the Minnesota River and subsequently Gulf of Mexico by intercepting subsurface drainage systems to drain into restored wetlands. A voluntary program through the Conservation Reserve Program (CRP) will be used to retire the cropland for 15 years.

Performance will be monitored through water quality sampling to show NO3 reductions and measurement of production impacts to demonstrate any enhanced economic returns. The designs and cost/benefits will also be used to assess the extension of this technology and practice across the Middle Minnesota River Basin. Learn more about
wetlands in the Seven Mile Creek watershed.

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Brown Nicollet Cottonwood Water Quality Board
322 South Minnesota Avenue | St. Peter, MN 56082 | Phone: 507-934-4140 | Fax: 507-934-8958

             
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