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Water Quality Standards and Classifications

Water Quality Standards are the basis for programs to protect the state waters. Standards set forth the maximum allowable levels of chemical pollutants and are used as the regulatory targets for permitting, compliance, enforcement, and monitoring and assessment of the quality of the state's waters. Waters are classified for their best uses (fishing, source of drinking water, etc.) and standards (and guidance values) are set to protect those uses.

The water quality standards program is a state program with federal (U.S. EPA) oversight. New York's longstanding water quality standards program predates the federal Clean Water Act and protects both surface waters and groundwaters.

U.S. EPA defines a water quality standard to include the criteria, the designated (best) uses of the water, and an antidegradation policy.

Information regarding the New York State Water Quality Standards Program can be found in state regulation, specifically New York Codes, Rules and Regulations Title 6 (6 NYCRR) and guidance documents found in the Division of Water Technical and Operational Guidance Series (TOGS). Contact Alexander J. Smith at, Chief, Standards and Analytical Support Section.

Standards and Criteria

DEC establishes water quality standards and other criteria for many specific substances. These standards can be either narrative (e.g., "none in amounts that will impair ...") or numeric (e.g., "0.001 µg/L") and are found in NYS regulation 6 NYCRR Part 703. (link leaves DEC's website) In the absence of established water quality standards, numeric guidance values are derived and compiled in Division of Water guidance (TOGS 1.1.1 [PDF]). Ambient standards and guidance values are supported by technical documents called "Fact Sheets" that are also available upon request.

Water quality standards regulations (6 NYCRR Parts 700-706) are currently being revised. Nutrient criteria are also being developed.

Water Classifications and Reclassification

All waters in New York State are assigned a letter classification that denotes their best uses. Letter classes such as A, B, C, and D are assigned to fresh surface waters, and SA, SB, SC, I, and SD to saline (marine) surface waters. Best uses include: source of drinking water, primary contact recreation (i.e., swimming), secondary contact recreation (i.e., boating), fishing, and shellfishing. The letter classifications and their best uses are described in regulation 6 NYCRR Part 701. (leaves DEC website) The classification of individual bodies of surface water is in regulation 6 NYCRR Chapter X (Parts 800 - 941).

Surface waters of the State are reclassified through the formal rule making process. Requests for reclassification can be made by submitting a completed Water Reclassification Request Form (PDF) to DEC at the address on the form or by using the "E-Mail Form" button at the top of the form.

All fresh groundwater in New York State is Class GA. The best use of Class GA groundwater and Class A, A-Special, AA, and AA-Special surface waters is a source of potable water supply. Standards and guidance values of the Health (Water Source) Type are established for these waters to protect this use. Separate standards for drinking water are promulgated by the New York State Department of Health (NYS DOH).

Certain waters of the Lake Champlain and St. Lawrence River drainage basins are currently under consideration for reclassification.


New York has a statewide antidegradation policy as set forth in the September 9, 1985 Organization and Delegation Memorandum Number 85-40 (PDF). For the Great Lakes System, this statewide policy is supplemented by implementation guidance in TOGS 1.3.9 (PDF)

Other Resources

Standards and guidance values of other Types, including Health (Fish Consumption), Aquatic (Chronic), Aquatic (Acute), Wildlife, and Aesthetic are also established. Further information is provided in the Introduction to TOGS 1.1.1 (PDF).

Water quality standards and standard-setting procedures are in 6 NYCRR Chapter X, Parts 700-706.

Several Technical and Operational Guidance Series (TOGS) are relevant to water quality standards:

  • TOGS 1.1.3 (PDF) - Procedures for derivation of site-specific standards and guidance values for protection of aquatic life.
  • TOGS 1.1.4 (PDF) - Procedures for derivation of bioaccumulation factors.
  • TOGS 1.1.5 (PDF) - Procedures for deriving ambient water quality standards and guidance values for the protection of wildlife.
  • TOGS 1.1.6 (PDF)- Interpretation Guidance for Marine Dissolved Oxygen (DO) Standard.

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