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Water Quality


With 11,800 lakes, 69,000 miles of rivers and streams, and 10.6 million acres of wetland, water is a major part of Minnesota’s culture, economy and natural ecosystems. Water quality nationwide has been severely degraded from intense industrial activity, sprawling development and lax protections of the natural environment. In the last 30 years water quality has continued to decline overall despite policies like the Clean Water Act.

In Minnesota, today nearly 6,000 bodies of water are considered impaired by one or more pollutant or stressor (see Figure 1). Further, there has been a sharp decline in wetlands found throughout the state.1 Wetlands are vital for storm water retention, water filtration, wildlife habitat and erosion control. The reduction in wetlands in the state has increased water quality issues as the natural protection they provided surface and ground water is no longer present in many areas of the state.

While local governments and industrial sites have taken steps to improve water quality, managing pollution from stormwater and other forms of runoff has continued to be a challenge. Transportation infrastructure and adjacent land development can increase the area impervious to water. This can result in pollutants flowing freely from these surfaces and stressing water quality. The transportation system can disrupt natural filtration systems, produce contaminants, drain polluted runoff and harm water quality in many ways. Salt used on roads and parking lots, for example, drains directly into surface water bodies demonstrating the direct role transportation plays in impacting water quality.

Both public and private sectors can innovate to minimize impacts on water quality. These efforts are collectively referred to as green infrastructure or low impact development. Examples include:

  • Planting native vegetative strips around impervious surfaces2 to capture the maximum amount of stormwater runoff
  • Limiting impervious surface by narrowing roadways
  • Introducing pervious surfaces and capturing water runoff on site

These are a few ways transportation can use green infrastructure or low impact development principles to help stabilize and improve Minnesota’s water quality.


  1. “Draft 2020 Impaired Waters List.” Minnesota’s Impaired Waters List. Minnesota Pollution Control Agency, November 12, 2019. https://www.pca.state.mn.us/water/minnesotas-impaired-waters-list.
  2. Impervious surfaces are defined as mainly artificial structures, such as pavement or buildings, which are covered by water-resistant materials like asphalt, concrete or building roofs. These surfaces disrupt and divert regular water flow and can cause flooding or pollution issues for surrounding areas.

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Archived Reports

Water Quality was previously included within Environmental Quality. The original Environmental Quality Trend Papers are below.

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