The biggest threat to wetlands is losing them to draining and filling. The overall goal at both state and federal levels is to maintain and even increase wetland acreage, along with maintaining wetland quality, which is affected by pollutants, water fluctuations, and other factors.
Alterations in water movement
Changing water levels or alterations in the movement of water (e.g., when storwater is directed to a wetland) can cause invasive plant species can take over. About 80% of Minnesota wetlands that have experienced even moderate water alterations now have abundant invasive plants growing in them — permanently replacing the native plant communities. This can change wildlife habitat and the wetland's ability to provide water quality benefits.
Wetlands: Critical to watersheds
Wetlands are highly interconnected with lakes, streams, and groundwater, providing water for streams and supporting flow through gradual release of water. Wetlands can remove excess sediment and nitrogen from water, though they may become overwhelmed and degraded in the process. Losing wetlands to urban development, agriculture, or other activities, or overloading them, can contribute to water quality problems in other parts of watersheds.
There is a long history of draining and filling Minnesota wetlands to accommodate settlement and development. Nearly 40% of the state was some form of wetland 150 years ago; now that percentage has been cut in half. The loss of wetlands has meant a loss of water quality benefits and has contributed to the degradation of streams, lakes, and groundwater.
Excess phosphorus means wetlands have less food for birds
Statewide, we’ve found elevated levels of phosphorus in 31% of our “prairie pothole” wetlands, negatively affecting the insects, snails, and leeches that live there. These macroinvertebrates are a vitally important food source for ducks and other birds that depend on wetlands during breeding or migration.