Water Quality Standards Regulations: Maine

Presented are water quality standards in effect for Clean Water Act (CWA) purposes for this state.

EPA is posting these standards as a convenience to users and has made a reasonable effort to assure their accuracy. For each document listed under "State Standards in Effect for CWA Purposes", EPA has made a reasonable effort to identify parts of the standards that are disapproved or are otherwise not in effect for CWA purposes. Additionally, please note the documents may also contain provisions that EPA does not have the authority and duty to act on under the Clean Water Act because the provisions are not water quality standards.

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

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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 for more information.

• Action Letter: State of Maine's Surface Water Quality Standard Revisions Contained in Chapter 584 and P.L. 2021, Ch. 551 and Chapter 584 – May 4, 2023 (pdf) (129.95 KB)
• Action Letter: Review and Action on Maine Water Quality Standards, 06-096 Chapter 584 - June 23, 2020 (pdf) (553.8 KB)
• Withdrawal of Certain of EPA’s February 2, 2015 Decisions Concerning Water Quality Standards for Waters in Indian Lands - May 27, 2020 (pdf) (3.1 MB)
• 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) (454.07 KB)
• Action Letter: Withdrawal of Disapprovals, and Issuance of Approvals, of Maine's Human Health Criteria for Multiple Pollutants - April 11, 2016 (pdf) (566.31 KB)
• 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) (269.34 KB)
• Action Letter: Review of and Decisions on Maine Water Quality Standards - June 5, 2015 (pdf) (443.79 KB)
• Action Letter: Review and Decision on Water Quality Standards Revisions - March 16, 2015 (pdf) (2.56 MB)
• Action Letter: Review and Decision on Water Quality Standards Revisions - February 2, 2015 (pdf) (1.2 MB)

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

Article 1: Organization and General Provisions

• 38 MRSA 361-A: Definitions (pdf) (179.44 KB)
  (Effective November 16, 2022)
• 38 MRSA 363-D: Waiver or modification of protection and improvement laws (pdf) (146.3 KB)
  (Effective August 19, 2009)

Article 1-F: Nonpoint Source Pollution Program

• 38 MRSA 410-H: Definitions (pdf) (149.51 KB)

Article 2: Pollution Control

• 38 MRSA 414-A: Conditions of licenses (pdf) (180.72 KB)
• 38 MRSA 414-B: Publicly owned treatment works (pdf) (156.47 KB)
• 38 MRSA 414-C: Color pollution control (pdf) (157.97 KB)
• 38 MRSA 417: Certain deposits and discharges prohibited (pdf) (151.33 KB)
• 38 MRSA 418: Log driving and storage (pdf) (154.51 KB)
• 38 MRSA 418-A: Protection of the lower Penobscot River (pdf) (150.03 KB)
• 38 MRSA 419-A: Prohibition on the use of tributyltin as an antifouling agent (pdf) (157.03 KB)
• 38 MRSA 419-B *: Goals for dates of removal of transformers containing polychlorinated biphenyls (pdf) (155.1 KB)
• 38 MRSA 420: Certain deposits and discharges prohibited (pdf) (176.4 KB)
  (Effective January 25, 2005)
• 38 MRSA 423: Discharge of waste from watercraft (pdf) (154.18 KB)
• 38 MRSA 423-A: Discharge of waste from motor vehicles (pdf) (146.7 KB)

Article 3: Enforcement

• 38 MRSA 451: Enforcement (pdf) (154.7 KB)
• 38 MRSA 451-A: Time schedule variances (pdf) (169.51 KB)

Article 4-A: Water Classification Program

• 38 MRSA 464: Classification of Maine Waters (pdf) (217.04 KB)
  (Effective May 4, 2023)
• 38 MRSA 465: Standards for classification of fresh surface waters (pdf) (169.31 KB)
  (Effective November 16, 2022)
• 38 MRSA 465-A: Standards for classification of lakes and ponds (pdf) (165.74 KB)
  (Effective November 16, 2022)
• 38 MRSA 465-B: Standards for classification of estuarine and marine waters (pdf) (160.79 KB)
  (Effective November 16, 2022)
• 38 MRSA 465-C *: Standards of classification of groundwater (pdf) (148.19 KB)
• 38 MRSA 466: Definitions (pdf) (172.56 KB)
  (Effective November 16, 2022)
• 38 MRSA 467: Classification of major river basins (pdf) (221.75 KB)
  (Effective November 16, 2022)
• 38 MRSA 468: Classification of minor drainages (pdf) (176.05 KB)
  (Effective November 16, 2022)
• 38 MRSA 469: Classification of estuarine and marine waters (pdf) (70.02 KB)
  (Effective July 20, 2011)
• 38 MRSA 470 *: Classification of groundwater (pdf) (145.79 KB)
• 38 MRSA 470-H *: In-stream flow and water level requirements; rules (pdf) (149.55 KB)

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
  38 MRSA 636 (hydropower projects): Approval criteria (pdf) (164.63 KB)
   

Rules

• 06-096 CMR 450 and 06-061 CMR 11: Administrative Regulation for Hydropower Projects (pdf) (111.2 KB)
• 06-096 CMR 514: Regulations Concerning the Use of Aquatic Pesticides (pdf) (59.85 KB)
• 06-096 CMR 519: Interim Effluent Limitations and Controls for the Discharge of Mercury (pdf) (82.39 KB)
• 06-096 CMR 530: Surface Waters Toxic Control Program (pdf) (127.21 KB)
• 06-096 CMR 550: Discontinuance of Wastewater Treatment Lagoons (pdf) (64 KB)
• 06-096 CMR 570: Stormwater and Combined Sewer Overflows (pdf) (95.44 KB)
• 06-096 CMR 573: Snow Dumps: Exemption from Waste Discharge License (pdf) (63.34 KB)
• 06-096 CMR 579: Classification Attainment Evaluation Using Biological Criteria for Rivers and Streams (pdf) (155.43 KB)
  (Effective January 25, 2005)
• 06-096 CMR 581: Regulations Relating to Water Quality Evaluations (pdf) (64.67 KB)
• 06-096 CMR 582: Regulations Relating to Temperature (pdf) (60.19 KB)
• 06-096 CMR 584: Surface Water Quality for Toxic Pollutants (pdf) (515.67 KB)
  (Effective May 4, 2023)
• 06-096 CMR 585: Identification of Fish Spawning Areas and Designation of Salmonid Spawning Areas (pdf) (117.08 KB)
• 06-096 CMR 586: Rules Pertaining to Discharges to Class A Waters (pdf) (65.26 KB)
• In-stream Flows and Lake and Pond Water Levels (pdf) (177.11 KB)

Letter from Maine DEP to U.S. EPA clarifying provisions of Maine water quality standards related to dam impoundments (pdf) (287.24 KB)

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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