Wisconsin's Water Quality Report to Congress

Every two years section 305(b) of the Clean Water Act requires states to publish an overall report on the quality of all surface waters across the state. This report, called the Integrated Report of Water Quality, is submitted to the EPA on April 1 of every even-numbered year.

Wisconsin's 2026 Report to Congress

Wisconsin's Water Quality Report to Congress 2026 was created based on water quality monitoring and restoration work done from 2023 – 2024. The Water Quality Report to Congress, Water Condition Lists, DNR response to public comments, and public comments on the draft Water Condition Lists were all submitted to the EPA on April 23, 2026. Below are copies of these documents:

Report pieces:

Appendix A - 2026 Impaired Waters List
Appendix B - 2026 Waters in Restoration List
Appendix C - 2026 Proposed Listings
Appendix D - 2026 Proposed Listing Removals
Appendix E - 2026 Waters Attaining Standards List
2026 Water Condition List [xlsx] (Impaired, Restoration and Healthy Waters Lists spreadsheet; this version is preferable for screen readers)

The EPA approved Wisconsin's submittal on Aug. 4, 2025. Below are copies of the approval documents:

2026 EPA Approval Letter and Decision Document

2026 Water Quality Report Key Points

81% of evaluated waters are healthy, by waterbody/assessment unit (AU) count (see Figure 2 below).
102 listings on 93 waters were added to the Impaired Waters List and Restoration Waters List.
The top four newly listed pollutants were: phosphorus (40%), E. coli (16%), PFOA (15%) and “Unknown” (evidence of degraded aquatic vegetation; 12%).
10 new pollutant listings were covered by existing TMDLs
16 listings were removed and 8 waterbodies were moved to the Waters Attaining Standards list.