New reports on Minnesota's wetlands

WetlandOwatonna-StraightRiverMarsh-WRPproject-NRCS-usdaA recent study by the Minnesota Pollution Control Agency (MPCA) measures the quality of all of Minnesota’s wetlands for the first time, and a second study documents quality trends of depressional wetlands. These help provide a more comprehensive status of Minnesota’s wetlands in conjunction with the Minnesota Department of Natural Resources (DNR) effort to measure wetland quantity.

Findings

  • Minnesota has 10.6 million acres of wetlands — which is nearly 20% of the state’s land cover, more area than than lakes and rivers combined.
  • Wetland acreage is stable — from 2006 to 2011 there was a slight gain of 2,080 acres.
  • Overall vegetation quality is high — roughly two-thirds of Minnesota’s wetlands are supporting healthy vegetation communities, due mostly to the large share of high quality wetlands in the northern part of the state.
  • Quality varies widely in different parts of the state — while most wetlands in northern Minnesota are in good condition, the opposite is true in the central and former prairie regions of the state, where degraded vegetation communities are predominant.
  • Depressional wetland quality is stable — from 2007 to 2012 in the central hardwood and former prairie regions, where most depressional wetlands (ponds and marshes) occur; there was no change in vegetation or macroinvertebrate quality.
  • Vegetation communities in more than half of these depressional wetlands are in poor condition (56%), with only 17% in good condition, similar to the quality of all wetland types in the central hardwood and former prairie regions.
  • Macroinvertebrate communities (aquatic invertebrates such as insects, leeches and snails) fared better — 43% good  and 29% in poor condition.
  • Non-native invasive plants are having the greatest impact — the non-native Reed canary grass and the Narrow leaved and Hybrid cattails have replaced native plant communities over the majority of the wetlands in the central and former prairie regions. Increases in non-native invasives are associated with all types of wetland impacts including: alterations of natural water movement, physical alterations such as plowing, nutrient enrichment, and increased pollutants such as chloride.
  • Recent wetland gains may be of limited quality — the majority of the new wetlands detected by DNR were pond like, which typically have limited wildlife value. Moreover, almost as many wetlands were converted to cultivated wetlands. While farming wetlands is not classified as a loss of wetland quantity, it is a loss of quality, even if farming ultimately stops. All of the wetlands sampled by the MPCA that have once been plowed but have been left to re-populate with wetland vegetation (or were passively restored) have degraded vegetation quality — with more than 80% in poor condition.

Why are wetlands important?

Wetlands provide valuable habitat for wildlife, filter out pollutants and sediment for the protection of downstream water quality in lakes and streams, recharge groundwater supplies and lessen the impacts of floods by storing water during intense rain storms and snow melt. In addition to benefits downstream, wetlands are important resources in and of themselves. “Even urban wetlands that look like they have nothing but cattails in them can harbor dozens of species of plants,“ said Glenn Skuta, MPCA Water Monitoring Manager.

In 1991, Minnesota passed the Wetlands Conservation Act. The goal is no net loss in the quantity, quality, and biological diversity of Minnesota’s existing wetlands. Minnesota now has monitoring programs that are able to more accurately evaluate whether the conservation goal is being met.

In 2006, the state started the wetland monitoring program to assess status and trends of both wetland quantity and quality. Sampling is done on a repeating, multi-year cycle. The results from the initial reports serve as a baseline that will allow the agencies to compare future data to reveal trends for wetland quality and quantity. The information will allow the state to begin to understand whether policies, regulations, and incentives are achieving their goals to protect wetlands.

More about wetlands.