Impaired waters viewer (IWAV)

The interactive IWAV map displays impaired waters around Minnesota in the 2020 Impaired Waters List.

Glossary of abbreviations used in the map


Impaired waters: Waters failing to meet one or more water quality standards.

Delisted waters: These are previously listed waters now determined to meet water quality standards based on new and reliable data. Delistings may occur as a result of watershed actions or other factors. Shown are all delistings since 2002.

Corrective actions: Y = Delisting was a result of actions in the watershed that resulted in improved water quality. N = Delisting was not a result of corrective actions.

List corrections: Corrections are determinations that a water is not impaired but which are not considered delistings. Corrections can occur when new water quality standards are adopted and the original listing data now show support, the original assessment methodology was not appropriate, or the original listing data were found to be invalid and current data indicate support. Shown are all corrections to the 2020 Impaired Waters List.

AUID: Assessment unit identifier

Reservation: Defined by the U.S. Census Bureau’s 2019 spatial data on tribal lands except with respect to the Mille Lacs where the state disagrees with the tribe and the federal government on the boundaries of the reservation. See the tribal designation section: File Draft 2020 Impaired Waters List (wq-iw1-65)

Use class: See Minn. Rule 7050.0220 for definitions

Impaired uses:

  • AQC: Aquatic consumption, see Minnesota Dept. of Health for more information
  • AQL: Aquatic life
  • AQR: Aquatic recreation
  • DW: Drinking water
  • LRV: Limited resource value

TMDL: Total maximum daily load. The maximum amount of a pollutant that a waterbody can receive and still meet water quality standards. TMDL also refers to the process of allocating pollutant loadings among point and nonpoint sources.

  • TMDL approved: Impairments for which a TMDL plan has been developed and approved by the U.S. EPA.
  • TMDL not required: Impairments for which a TMDL is not appropriate; the impairments are cause for non-pollutants and reflect natural background conditions.
  • Additional impairments: Impairments for which a TMDL is underway or not yet developed.


  • Ace: Acetochlor
  • Al: Aluminum
  • Amm-U: Ammonia, unionized
  • As: Arsenic
  • Cl-: Chloride
  • Clpyr: Chlorpyrifos
  • Cu: Copper
  • Coldwater: Lack of cold water assemblage
  • DDT (Dichlorodiphenyltrichloroethane)
  • Dieldrin
  • Dioxin (including 2,3,7,8-TCDD)
  • DO: Dissolved oxygen
  • E. coli: Escherichia coli (E. coli)
  • FC: Fecal coliform
  • FishesBio: Fish bioassessments
  • Hg-F: Mercury in fish tissue
  • Hg-W: Mercury in water column
  • InvertBio: Benthic macroinvertebrate bioassessments
  • Nitrate
  • Nutrients
  • PCB-F: Polychlorinated biphenyls (PCBs) in fish tissue
  • PCB-W: Polychlorinated biphenyls (PCBs)
  • PFOS-F: Perfluorooctane Sulfonate (PFOS) in fish tissue
  • PFOS-W: Perfluorooctane Sulfonate (PFOS)
  • pH
  • PlantBio: Aquatic plant bioassessments
  • T: Turbidity
  • Temp: Temperature
  • Toxaphene
  • TSS: Total suspended solids

TALU: Tiered aquatic life use

  • E - Exceptional: High quality waters with fish and invertebrate communities at or near undisturbed conditions
  • G - General: Waters with good fish and invertebrate communities that meet or should meet minimum goals
  • M - Modified: Waters with legally altered habitat that prevents fish and invertebrate communities from meeting minimum goals.