A recent report from the Minnesota Department of Natural Resources (DNR) found that Minnesota gained roughly 43,000 acres of wetlands statewide between 2006 and 2020. Some of these new acres come from large-scale restoration projects, such as the recent Sunrise River Wetland enhancement project in Forest Lake that diverts water from an existing drainage ditch system into a 22-acre restored wetland. Other gains have been found in agricultural areas where landowners have removed drain tile or allowed natural wetlands to return. The Minnesota Wetland Conservation Act, in place since 1991, also prohibits draining, filling or altering wetlands and requires developers to make up for wetland impacts by creating or restoring wetlands somewhere else nearby.
Wetlands help to mitigate flooding, provide habitat for wildlife, and filter sediment, nutrients, and pollutants out of runoff before it flows into lakes and streams, but not all wetlands are created equally.
Wetland vs stormwater pond
Natural wetlands occur along the edges of lakes, rivers and streams, and within natural depressions in the landscape that were left behind by glaciers. Many of the ponds you see in residential and commercial developments, however, are actually stormwater ponds built to reduce flooding and downstream water pollution. Stormwater ponds can most easily be recognized by the presence of inlet and outlet pipes, and will usually only have vegetation around the edges.
Because stormwater ponds are designed to capture sediment and nutrients, they frequently turn green with algae in the summer and they also need to be dredged periodically to remove accumulated sediment. Though you might see ducks and geese landing in these ponds, they are not safe for fishing or swimming and they provide low-quality habitat for aquatic plants and animals.
Northern wetlands healthier than those in the metro and southern Minnesota
About 75% of all of Minnesota’s wetlands are located in northern and northeastern Minnesota. Most of these northern wetlands have high-quality, natural vegetation and they help to support the famously clear water of our northern lakes.
In comparison, 82% of the natural wetlands in the Twin Cities metro and central Minnesota have been degraded by non-native invasive species such as narrow-leaf cattail, phragmites, reed canary grass, and purple loosestrife. In southern Minnesota, only 5% of the original wetlands remain and most of those are degraded by invasive species as well.
Some wetland types are more at risk than others
In its report, the Minnesota DNR noted that the total acres of forested swamps statewide is actually declining, even as other types of wetlands return. Forested wetlands fill a completely different ecological niche than marshes and shallow open water wetlands and are more difficult to restore or artificially construct.
Calcareous fens are the rarest wetland ecosystem in Minnesota (only 200 remain statewide) and they require a constant supply of groundwater, making them particularly susceptible to drought, flooding, and changes in groundwater levels caused by over-pumping. Calcareous fens are found along the Minnesota River Valley and in karst geologic regions of southeast Minnesota. The closest calcareous fens to our area are located within Fort Snelling State Park and the Minnesota Valley Wildlife Refuge.
Another at-risk wetland type are ephemeral (seasonal) wetlands, which play a particularly important role as a birthing and breeding ground for salamanders, frogs, and dragonflies. Because these wetlands dry up in the summer, landowners often inadvertently mow them or fill them to create level ground. Despite their seasonality, it is important to note that ephemeral wetlands are still protected by law.
For questions about wetlands on your property, including how to manage invasive species, permits needed for building and grading, or how to restore wetlands on farmland, contact the Washington Conservation District or sign-up for a free site visit at www.mnwcd.org.
East Metro Water 