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Identifying factors that harm fish and other aquatic life is a key part of the state's watershed restoration and protection projects. The MPCA, Department of Natural Resources, and local partners study the following factors and relationships among them:

  • Aquatic connections, such as dams, culverts, and tile drainage
  • Hydrology, including stream flow and runoff
  • Aquatic biology, such as fish and bugs
  • Water chemistry, including oxygen levels, nutrient levels, and temperature
  • Stream channel assessment, mainly erosion
  • Lake shoreline assessment

Several conditions put stress on our waters:

  • Too much sediment. Soil and other matter in water can make it hard for fish and other aquatic life to breathe, feed, and reproduce. Sediment can also cover spawning areas and fill in parts of streams.
  • Low oxygen. Aquatic life needs oxygen dissolved in the water to breathe and survive.
  • Temperature. Water temperature affects metabolism and the ability to get oxygen, especially for species such as trout.
  • Lack of habitat. Habitat affects all aspects of survival for fish and other aquatic life. Habitat encompasses places to live, food to eat, places to reproduce and means of protection.
  • Too many nutrients. Excess nutrients, such as phosphorus and nitrates, can be toxic to aquatic life and cause algal blooms.

Technical guidance and reports

Local partners may find this technical guidance useful for stressor identification work.

Stressor reports are posted on the web pages of each watershed.