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Water Condition Lists

Impaired Waters, Restoration Waters and Healthy Waters

Every two years, Sections 303(d) and 305(b) of the Clean Water Act (CWA) requires states to publish a list of all waters not meeting water quality standards and an overall report on surface water quality status of all waters in the state. To comply with this reporting requirement, Wisconsin produces three lists.

  1. Impaired Waters: This is the official CWA 303(d) list. It contains waters with no cleanup plan in place (TMDL, alternative restoration).
  2. Restoration Waters: These are impaired waters with a restoration plan in place. This list was created during the 2020 cycle.
  3. Healthy Waters: These are waters assessed for at least one metric and show no impairment. Waters have been identified since 2014. The list was created during the 2018 cycle.

Prior to the 2018 cycle, the only list generated was the Impaired Waters list. For the 2020 cycle, this list was separated into two separate lists: the impaired waters list and the restoration waters list. This change was to align more closely with the listing methods of other midwest states.

Wisconsin's 2020 lists

U.S. Environmental Protection Agency (USEPA) approved Wisconsin’s 2020 303(d) List on October 13, 2020. With this approval the 2020 assessment cycle is completed.

Public water quality data was received from four entities from Jan. 22 - March 1, 2019. This information was uploaded to the SWIMS database and utilized in the assessments. Regional biologists reviewed list changes in the spring and summer of 2019. A 30-day public comment period on the draft lists was held from Oct. 15 - Nov. 22, 2019. Comments postmarked or received by Nov. 22, 2019, were considered before the DNR submitted the final draft lists to the U.S. Environmental Protection Agency (USEPA) for approval on April 1, 2020.

Below are the approved list, USEPA approval letter and decision document, response to public comments, and the public comments received.


Restoration prioritization

Restoration actions can only occur on a subset of Wisconsin’s waters at any given time due to the large number of water resources in the state. When the impaired waters list is created a priority ranking of high, medium or low is given to a listing. This ranking, also known as TMDL Status, is based on the current prioritization framework document. For more information on this framework document and TMDL prioritization, visit Surface water quality restoration.

Data viewing tools

The Impaired Waters Search Tool may be used to search DNR's database current and previous impaired waters, as well as listing update proposals. 

The Surface Water Data Viewer can be used to search for impaired waters listings and proposed listings in an interactive mapping application. To view impaired waters on the map, click the "Show Layers" button to expand the "Impairments and Assessments" grouping and check the "Impaired Waters Status" layer. The definitions of the listing status categories are provided in the Impaired Waters Search Help Tool.

EPA 5-part categorization

Assessed waters are placed in one of five categories depending on if there is an impairment and if there is a restoration plan in place.

Wisconsin further divides categories 4 and 5 into subcategories.

Categories and descriptions

1 Attains all uses. Healthy Waters
2 Attains at least one use; no use impaired.
3 Insufficient information for an attainment decision.
4 An impairment exists and a cleanup plan (TMDL or alt.) has been approved by the EPA. Restoration Waters
5 An impairment exists but a cleanup plan (TMDL or alt.) is still needed. Impaired Waters

Category 4 (Restoration Waters) subcategories

Sub-category Description Key Defining Factor
4A A state-developed TMDL has been approved by EPA or a TMDL has been established by EPA for any segment-pollutant combination. TMDL approved by EPA.
4B Other required control measures are expected to result in the attainment of an applicable water quality standard in a reasonable period of time. Alternative to TMDL approved by EPA.
4C The non-attainment of any applicable water quality standard for the segment is the result of pollution and is not caused by a pollutant. No pollutant.

Category 5 (Impaired Waters) subcategories

Sub-category Description Key Defining Factor
5A Available information indicates that at least one designated use is not met or is threatened, and/or the anti-degradation policy is not supported, and one or more TMDLs are still needed. This is the default category for impaired waters. TMDL needed. Default subcategory.
5B Available information indicates that atmospheric deposition of mercury has caused the impairment and no other sources have been identified. Mercury only.
5C Available information indicates that non-attainment of water quality standards may be caused by naturally occurring or irreversible human-induced conditions. Natural or irreversible conditions.
5P Available information indicates that the applicable total phosphorus criteria are exceeded; however, biological impairment has not been demonstrated (either because bioassessment shows no impairment or because data are not available). Phosphorus only.
5W Pollutant/impairment a low priority for a TMDL because the impaired water is included in a watershed area addressed by at least one of the following WDNR-approved watershed plans:  adaptive management plan, adaptive management pilot project, lake management plan, or Clean Water Act Section 319-funded watershed plan (i.e., nine key elements plan). Alternative cleanup plan.
Previous lists

The following table contains previous years' impaired water lists and related documents.

EPA Approval column: Before an impaired waters list is official, it needs approval from the U.S. EPA. These are the approval documents from the EPA to the DNR for each assessment cycle.

Public Comments and DNR Response column: Prior to sending an impaired waters list to the EPA for federal review, the list is sent out for a public comment period. These are the DNR's responses to public comment for each cycle. For additional information, visit Public participation in water quality assessments.

Year List EPA Approval Public Comments and DNR Response Additional Supporting Documents
2018 PDF;
Cover letter;
Decision doc;
Tribal consult
Public comments;
DNR response
Fact sheet
2016 PDF;
Cover letter;
Decision doc;
Tribal consult
Public comments;
DNR response
Fact sheet
2014 PDF;
Cover letter
Decision doc
Public comments;
DNR response
Public webinar slides
2012 Excel Cover letter and decision doc DNR response 1;
DNR response 2;
DNR response 3;
DNR response 4
Justification for adding Yahara Lakes to Rock River TMDL (Category 4A justification)
2010 Excel Cover letter;
Decision doc
2008 Excel Partial approval letter and decision doc;
Full approval letter and decision doc
2006 Excel Cover letter and decision doc    
2004 Excel      
2002 PDF;
1998 Excel