Presented below are water quality standards for the state of Maine in effect for Clean Water Act (CWA) purposes.

EPA is posting these standards as a convenience to users and has made a reasonable effort to assure their accuracy.

Documents marked with an asterisk (*) are not part of the official Maine CWA-WQS docket and therefore not subject to review under the Clean Water Act.

• State Standards in Effect for CWA Purposes
• Federally Proposed or Promulgated Standards

State Standards in Effect for CWA Purposes

Since 2015, EPA has taken several actions on Maine’s WQS.  Please refer to EPA’s action letters below for more information.

• [See Action Letter: Review and Action on Maine Water Quality Standards, 06-096 Chapter 584 - June 23, 2020 ]
• [See Withdrawal of Certain of EPA’s February 2, 2015 Decisions Concerning Water Quality Standards for Waters in Indian Lands ]
• [See Action Letter: Review and Approval of Maine's Sustenance Fishing Designated Use Subcategory and the Assignment of that Subcategory to the Waters Identified - November 6, 2019 ]
• [See Action Letter: Withdrawal of Disapprovals, and Issuance of Approvals, of Maine's Human Health Criteria for Multiple Pollutants - April 11, 2016 ]
• [See Action Letter: Withdrawal of Disapprovals, and Issuance of Approvals, of Maine's Human Health Criteria for Copper, Asbestos, Barium, Nitrates, Iron and Manganese - January 19, 2016 ]
• [See Action Letter: Review of and Decisions on Maine Water Quality Standards - June 5, 2015 ]
• [See Action Letter: Review and Decision on Water Quality Standards Revisions - March 16, 2015 ]
• [See Action Letter: Review and Decision on Water Quality Standards Revisions - February 2, 2015 ]

The following statutes are from the Maine Revised Statutes, Title 38, Chapter 3, Subchapter 1: Environmental Protection Board.

Article 1: Organization and General Provisions

• [See 38 MRSA 361-A: Definitions ]
  (Effective April 17, 2006)
• [See 38 MRSA 363-D: Waiver or modification of protection and improvement laws ]
  (Effective August 19, 2009)

Article 1-F: Nonpoint Source Pollution Program

• [See 38 MRSA 410-H: Definitions ]

Article 2: Pollution Control

• [See 38 MRSA 414-A: Conditions of licenses ]
• [See 38 MRSA 414-B: Publicly owned treatment works ]
• [See 38 MRSA 414-C: Color pollution control ]
• [See 38 MRSA 417: Certain deposits and discharges prohibited ]
• [See 38 MRSA 418: Log driving and storage ]
• [See 38 MRSA 418-A: Protection of the lower Penobscot River ]
• [See 38 MRSA 419-A: Prohibition on the use of tributyltin as an antifouling agent ]
• [See 38 MRSA 419-B *: Goals for dates of removal of transformers containing polychlorinated biphenyls ]
• [See 38 MRSA 420: Certain deposits and discharges prohibited ]
  (Effective January 25, 2005)
• [See 38 MRSA 423: Discharge of waste from watercraft ]
• [See 38 MRSA 423-A: Discharge of waste from motor vehicles ]

Article 3: Enforcement

• [See 38 MRSA 451: Enforcement ]
• [See 38 MRSA 451-A: Time schedule variances ]

Article 4-A: Water Classification Program

• [See 38 MRSA 464: Classification of Maine Waters ]
• [See 38 MRSA 465: Standards for classification of fresh surface waters ]
  (Effective August 19, 2009)
• [See 38 MRSA 465-A: Standards for classification of lakes and ponds ]
  (Effective August 19, 2009)
• [See 38 MRSA 465-B: Standards for classification of estuarine and marine waters ]
  (Effective August 19, 2009)
• [See 38 MRSA 465-C *: Standards of classification of groundwater ]
• [See 38 MRSA 466: Definitions ]
• [See 38 MRSA 467: Classification of major river basins ]
  (Effective May 19, 2010)
• [See 38 MRSA 468: Classification of minor drainages ]
  (Effective May 19, 2010)
• [See 38 MRSA 469: Classification of estuarine and marine waters ]
  (Effective July 20, 2011)
• [See 38 MRSA 470 *: Classification of groundwater ]
• [See 38 MRSA 470-H *: In-stream flow and water level requirements; rules ]

The following statutes are from the Maine Revised Statutes, Title 38, Chapter 5, Subchapter 1: Mills and Dams:

• Article 1: Erection and Flowage Rights
  Subarticle 1-B: Permits for Hydropower Projects Heading: PL 1983, C. 458, §18
  [See 38 MRSA 636 (hydropower projects): Approval criteria ]

Rules

• [See 06-096 CMR 450 and 06-061 CMR 11: Administrative Regulation for Hydropower Projects ]
• [See 06-096 CMR 514: Regulations Concerning the Use of Aquatic Pesticides ]
• [See 06-096 CMR 519: Interim Effluent Limitations and Controls for the Discharge of Mercury ]
• [See 06-096 CMR 530: Surface Waters Toxic Control Program ]
• [See 06-096 CMR 550: Discontinuance of Wastewater Treatment Lagoons ]
• [See 06-096 CMR 570: Stormwater and Combined Sewer Overflows ]
• [See 06-096 CMR 573: Snow Dumps: Exemption from Waste Discharge License ]
• [See 06-096 CMR 579: Classification Attainment Evaluation Using Biological Criteria for Rivers and Streams ]
  (Effective January 25, 2005)
• [See 06-096 CMR 581: Regulations Relating to Water Quality Evaluations ]
• [See 06-096 CMR 582: Regulations Relating to Temperature ]
• [See 06-096 CMR 584: Surface Water Quality for Toxic Pollutants ]
  (Effective September 18, 2006)
• [See 06-096 CMR 585: Identification of Fish Spawning Areas and Designation of Salmonid Spawning Areas ]
• [See 06-096 CMR 586: Rules Pertaining to Discharges to Class A Waters ]
• [See 06-096 CMR 587 *: In-stream flow and water level requirements ]

[See Letter from Maine DEP to U.S. EPA clarifying provisions of Maine water quality standards related to dam impoundments ]

Federally Proposed or Promulgated Standards

• 40 CFR §131.43  Maine
  • Federal Water Quality Standards Applicable to Maine (December 3, 2020)
• 40 CFR § 132  Water Quality Guidance for the Great Lakes System

Top of Page

• 38 MRSA 361-A: Definitions (PDF)(5 pp, 158 K)
• 38 MRSA 363-D: Waiver or modification of protection and improvement laws (PDF)(2 pp, 150 K)
• 38 MRSA 410-H: Definitions (PDF)(2 pp, 153 K)
• 38 MRSA 414-A: Conditions of licenses (PDF)(7 pp, 185 K)
• 38 MRSA 414-B: Publicly owned treatment works (PDF)(3 pp, 160 K)
• 38 MRSA 414-C: Color pollution control (PDF)(3 pp, 162 K)
• 38 MRSA 417: Certain deposits and discharges prohibited (PDF)(2 pp, 155 K)
• 38 MRSA 418: Log driving and storage (PDF)(3 pp, 158 K)
• 38 MRSA 418-A: Protection of the lower Penobscot River (PDF)(2 pp, 154 K)
• 38 MRSA 419-A: Prohibition on the use of tributyltin as an antifouling agent (PDF)(3 pp, 161 K)
• 38 MRSA 419-B *: Goals for dates of removal of transformers containing polychlorinated biphenyls (PDF)(3 pp, 159 K)
• 38 MRSA 420: Certain deposits and discharges prohibited (PDF)(6 pp, 181 K)
• 38 MRSA 423: Discharge of waste from watercraft (PDF)(3 pp, 158 K)
• 38 MRSA 423-A: Discharge of waste from motor vehicles (PDF)(2 pp, 150 K)
• 38 MRSA 451: Enforcement (PDF)(3 pp, 158 K)
• 38 MRSA 451-A: Time schedule variances (PDF)(5 pp, 174 K)
• 38 MRSA 464: Classification of Maine Waters (PDF)(15 pp, 231 K)
• 38 MRSA 465: Standards for classification of fresh surface waters (PDF)(6 pp, 177 K)
• 38 MRSA 465-A: Standards for classification of lakes and ponds (PDF)(6 pp, 159 K)
• 38 MRSA 465-B: Standards for classification of estuarine and marine waters (PDF)(3 pp, 162 K)
• 38 MRSA 465-C *: Standards of classification of groundwater (PDF)(2 pp, 152 K)
• 38 MRSA 466: Definitions (PDF)(4 pp, 168 K)
• 38 MRSA 467: Classification of major river basins (PDF)(22 pp, 248 K)
• 38 MRSA 468: Classification of minor drainages (PDF)(7 pp, 176 K)
• 38 MRSA 469: Classification of estuarine and marine waters (PDF)(8 pp, 72 K)
• 38 MRSA 470 *: Classification of groundwater (PDF)(2 pp, 149 K)
• 38 MRSA 470-H *: In-stream flow and water level requirements; rules (PDF)(2 pp, 153 K)
• 38 MRSA 636 (hydropower projects): Approval criteria (PDF)(4 pp, 169 K)
• 06-096 CMR 450 and 06-061 CMR 11: Administrative Regulation for Hydropower Projects (PDF)(14 pp, 114 K)
• 06-096 CMR 514: Regulations Concerning the Use of Aquatic Pesticides (PDF)(2 pp, 61 K)
• 06-096 CMR 519: Interim Effluent Limitations and Controls for the Discharge of Mercury (PDF)(7 pp, 84 K)
• 06-096 CMR 530: Surface Waters Toxic Control Program (PDF)(13 pp, 130 K)
• 06-096 CMR 550: Discontinuance of Wastewater Treatment Lagoons (PDF)(3 pp, 66 K)
• 06-096 CMR 570: Stormwater and Combined Sewer Overflows (PDF)(10 pp, 98 K)
• 06-096 CMR 573: Snow Dumps: Exemption from Waste Discharge License (PDF)(3 pp, 65 K)
• 06-096 CMR 579: Classification Attainment Evaluation Using Biological Criteria for Rivers and Streams (PDF)(19 pp, 159 K)
• 06-096 CMR 581: Regulations Relating to Water Quality Evaluations (PDF)(3 pp, 66 K)
• 06-096 CMR 582: Regulations Relating to Temperature (PDF)(2 pp, 62 K)
• 06-096 CMR 584: Surface Water Quality for Toxic Pollutants (PDF)(24 pp, 281 K)
• 06-096 CMR 585: Identification of Fish Spawning Areas and Designation of Salmonid Spawning Areas (PDF)(3 pp, 120 K)
• 06-096 CMR 586: Rules Pertaining to Discharges to Class A Waters (PDF)(3 pp, 67 K)
• In-stream Flows and Lake and Pond Water Levels (PDF)(11 pp, 181 K)
• Letter from Maine DEP to U.S. EPA clarifying provisions of Maine water quality standards related to dam impoundments (PDF)(6 pp, 294 K)
• Action Letter: Review of and Decisions on Maine Water Quality Standards - June 5, 2015 (PDF)(34 pp, 454 K)
• Action Letter: Review and Decision on Water Quality Standards Revisions - March 16, 2015 (PDF)(10 pp, 3 MB)
• Action Letter: Review and Decision on Water Quality Standards Revisions - February 2, 2015 (PDF)(6 pp, 1 MB)
• Action Letter: Withdrawal of Disapprovals, and Issuance of Approvals, of Maine's Human Health Criteria for Copper, Asbestos, Barium, Nitrates, Iron and Manganese - January 19, 2016 (PDF)(2 pp, 276 K)
• Action Letter: Withdrawal of Disapprovals, and Issuance of Approvals, of Maine's Human Health Criteria for Multiple Pollutants - April 11, 2016 (PDF)(3 pp, 580 K)
• Action Letter: Review and Approval of Maine's Sustenance Fishing Designated Use Subcategory and the Assignment of that Subcategory to the Waters Identified - November 6, 2019 (PDF)(8 pp, 465 K)
• Withdrawal of Certain of EPA’s February 2, 2015 Decisions Concerning Water Quality Standards for Waters in Indian Lands - May 27, 2020 (PDF)(41 pp, 3 MB)
• Action Letter: Review and Action on Maine Water Quality Standards, 06-096 Chapter 584 - June 23, 2020 (PDF)(28 pp, 567 K)