Amendments to the Human Health Methods for Developing Class 2 Chronic Standards

Kayaker on Minnesota RiverMPCA's 2008 Clean Water Act triennial review identified several areas of potential amendment to the state’s water quality standards. This rulemaking is one of several efforts that the MPCA will initiate as a result of that review process. The amendments in this rulemaking address:

  • Updated methods for developing human health–based water quality standards (HH-WQS)
  • Clarification of applicable Beaches Environmental Assessment and Coastal Health (BEACH) Act requirements

HH-WQS Methods

Minnesota’s HH-WQS provide protection for the beneficial uses of surface water, including drinking water, fish consumption, and recreation. HH-WQS were first adopted statewide in 1990 (Minn. R. ch. 7050) and updated in 1998 for the Lake Superior Basin only (Minn. R. ch. 7052). The methods we use to determine the HH-WQS need significant revision to incorporate the latest information and risk-assessment practices for ensuring that human users of Minnesota’s surface waters are fully protected. WQS methods, and subsequent numeric standards based on those methods, serve as the basis for setting wastewater discharge effluent limits, assessing water quality, and determining whether waters are impaired (i.e., do not meet WQS).

The proposed amendments to these methods incorporate new exposure and toxicity information to better protect infants and children from developmental effects. The improved exposure information includes higher rates of drinking water usage, incidental water intake (e.g., small amounts of water ingested while swimming), and fish consumption. The enhanced toxicological methods evaluate multiple durations of exposure and add adjustment factors to decrease the cancer risk associated with early-life exposure (birth to age 16).

The amendments also include new methods to develop HH-WQS for pollutants in fish tissue. The current HH-WQS have only one fish tissue–based standard for mercury. For pollutants that accumulate to high levels in the aquatic food chain (bioaccumulative chemicals), fish consumption can be a major route of exposure to humans. Therefore, applying HH-WQS to fish tissue provides more accurate and reliable data for protecting human health than evaluating these pollutants in water.

More information on the full scope of the amendments is available in the “Technical Support Documents” tab below.

Applicable BEACH Act Requirements

The MPCA is proposing to clarify which E. coli numeric WQS established under the BEACH Act specifically apply in the Lake Superior Basin. The MPCA considers this to be a housekeeping amendment because it incorporates existing federal WQS that have been in effect since 2004. The MPCA is also proposing a state-only clarification of the federal term “recreation season.”

Requests for comments

As part of its effort to obtain public input into this rulemaking, the MPCA has published two formal requests for comment and held several public meetings. The comments and information submitted in response to those requests are still part of the rulemaking record and continue to be considered in the development of the rule amendments. Requests for comment may be viewed in archived State Registers for July 28, 2008 and March 2, 2009.

Notice of intent to adopt rules

The MPCA provided an 80-day comment period for the proposed amendments, ending on September 4, 2014.


The MPCA has prepared a statement of need and reasonableness (SONAR) for the proposed amendments.

Notice of adoption

The MPCA published the notice of adoption on March 16, 2015, and they became effective March 23, 2015.

Requests for Comments

Completed (published July 28, 2008 and March 2, 2009)

Drafting of rule language/SONAR


Public comment period

Comment period closed on September 4, 2014.

Adoption of rules


U.S. EPA review and approval


Rules effective



Contact information

For technical questions about the content of the amendments:

Angela Preimesberger

For questions about the status of the rulemaking:

Katie Izzo