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Water Quality Standards Rule Updates

The DNR is conducting rulemaking on several topics related to surface water quality standards, outlined below.

Surface water criteria for PFAS (WY-23-19)

This rule focuses on creating surface water quality criteria for two types of poly- and perfluoroalkyl substances (PFAS) to protect human health: perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). This rule also includes updates to the procedures for implementing the new criteria in Wisconsin Pollutant Discharge Elimination System (WPDES) permits. More information about this rule package can be found on the NR 105 rule changes page.

Site-specific phosphorus criteria for lakes in the Wisconsin River Basin (WY-09-18)

The proposed rule will create site-specific phosphorus criteria for three waterbodies, Petenwell Lake located in Wood, Juneau, and Adams Counties, Castle Rock Lake located in Adams and Juneau Counties, and Lake Wisconsin located in Columbia and Sauk Counties. Analyses during the development of the Wisconsin River Basin Total Maximum Daily Load (TMDL) have concluded that the current statewide phosphorus criteria for Petenwell Lake and Castle Rock Lake are more restrictive than needed to protect the lakes’ recreation and aquatic life designated uses, and the current phosphorus criterion for Lake Wisconsin is not sufficiently protective of its designated uses.

The public comment period closed in August 2019, and this rule was submitted to the legislature in late 2019. The DNR expects the rule to take effect on June 1, 2020.

Process for developing site-specific criteria for phosphorus (WT-17-12)

This rule package establishes protocols for developing site-specific criteria (SSC) for phosphorus. SSC can be applied to individual waterbodies where the statewide phosphorus criteria are over- or under-protective of a waterbody's designated uses. The protocols for developing SSC refer to the rules described in package WY-23-13 because the SSC process relies on biological metrics and phosphorus response indicators to determine when an SSC is needed and to develop the appropriate phosphorus criterion for a waterbody.

An external advisory committee met from 2016 to 2018 to help develop the draft rules. The public comment period closed in September 2019, and this rule was submitted to the legislature in early 2020. The DNR recalled the rule for further review and expects to resubmit the rule in 2021.

Assessing waterbodies using biological metrics (WY-23-13)

This rule covers a range of topics related to assessing waterbodies using biological metrics, including the following:

  • "Narrative biocriteria" set expectations for the level of health of aquatic communities like fish, insects and plants.
  • Biological "phosphorus response indicators" for use in conjunction with phosphorus criteria to evaluate whether or not phosphorus-related impacts are occurring. This will enable impairment listing decisions to be based on whether an actual phosphorus-related biological response is occurring within the waterbody.
  • Algae criteria (measured using chlorophyll-a) to protect the recreation and health of aquatic communities.
  • Criteria to protect lakes that have coldwater fish, based on the temperature and oxygen needs of these fish.
  • An overview of the department's obligations under the Clean Water Act to assess Wisconsin's waterbodies every two years and report to U.S. EPA.

An external advisory committee met from 2016 to 2018 to help develop the draft rules. The public comment period closed in September 2019, and this rule was submitted to the legislature in late 2019. The DNR recalled the rule for further review and expects to resubmit the rule in 2021.

Bacteria criteria for surface waters (WY-17-15)

Revisions to the state's bacteria criteria were promulgated and became effective May 1, 2020. The rule revises Wisconsin’s bacteria criteria to better protect recreation and public health. It changes the bacterial indicator from fecal coliform to E. coli, because E. coli better predicts the risk of human illness caused by exposure to human fecal contamination. The rule also revises the permit effluent limit calculation procedures for wastewater treatment facilities discharging bacteria.

Designated uses for classifying surface waters

This rule is under development to refine existing designated use categories to more appropriately represent the variety of Wisconsin's surface waters. The updated use categories will better represent the state’s aquatic systems. It will also clarify the process used for assigning or updating designated uses.