Regulation 314 CMR 4: The Massachusetts Surface Water Quality Standards

These regulations implement provisions of the federal Clean Water Act, which protects the nation's waters. The Surface Water Quality Standards designate the most sensitive uses of Massachusetts waters and provide criteria for evaluating water quality to support those uses.

Contact for 314 CMR 4: The Massachusetts Surface Water Quality Standards

314 CMR 4.00 Contact Information

Table of Contents

Current Regulation

On November 12, 2021, MassDEP promulgated amendments to the Massachusetts Surface Water Quality Standards (the SWQS), 314 CMR 4.00. Subsequently, MassDEP published two sets of corrections, effective December 10, 2021 and January 7, 2022. MassDEP has posted an unofficial version of the regulation as amended and corrected online, which is now enforceable by the Commonwealth. However, federal Water Quality Standards regulations promulgated at 40 Code of Federal Regulations Part 131, 40 CFR 131, pursuant to the federal Clean Water Act (CWA), 33 USC 1251 et seq., require that state water quality standards be approved by the U.S. Environmental Protection Agency (EPA) to be federally enforceable for CWA purposes such as water quality assessments, total maximum daily loads, and National Pollutant Discharge Elimination System permits. On March 31, 2022, EPA approved the majority of the amendments to the SWQS, disapproved six amendments, and deferred action on others. Additional information on the status of the amendments to the SWQS is available here.


Software to derive freshwater aluminum and copper criteria: Aluminum Criteria Calculator, V. 2.0 and Copper Biotic Ligand Model, V. 2.2.3.

Supporting Documents

Adjustment of Criteria Using the Streamlined Water Effect Ratio (Copper Only):

Adjustment of Criteria Using the Water-Effect Ratio (Specified Metals):

Ammonia Criteria:

Technical Guidance Documents:


Presentations and Reports:

Revisions Summary and Response to Comments

A summary of amendments to 314 CMR 4.00 and MassDEP's response to public comments are available here.

Previous Regulation

The previous regulation, 314 CMR 4.00, became effective as of December 6, 2013.

This is an unofficial version of Commonwealth regulations and is posted here for the convenience of the public. It is not an official statement of the regulations.

Proposed Amendments & Public Comment

There are no proposed regulations out for public comment at this time.

Contact for 314 CMR 4: The Massachusetts Surface Water Quality Standards