Water Quality Standards and Classifications
The Water Quality Standards and Criteria (WQS) (PDF) are an important element in Connecticut's clean water program. The WQS set an overall policy for management of Connecticut's surface and groundwaters in accordance with the directives provided by Section 22a-426 of the Connecticut General Statutes and Section 303 of the Federal Clean Water Act.
The WQS have several purposes:
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indicate the general types of discharges allowed;
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ensure the segregation of drinking water supplies from waters used for waste assimilation;
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show areas of conflict between usages, and areas where ground and surface waters are degraded;
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provide the standards for toxicity consideration to protect aquatic life;
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provide a framework for the establishment of priorities for pollution abatement, dispensation of State funding, remediation goals; and finally;
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provide clear guidance for location decisions for business and industry as well as other economic developments.
The WQS do not stand alone as a regulatory means of protecting public health and the environment. These standards are integrally related to, and applied by DEP simultaneously with, other statutory and regulatory requirements governing water and waste management. As an example of how these pieces fit together, the following may be of assistance.
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Section 22a-430 of the General Statutes allows and sets procedures for the permitting of discharges of treated wastewaters to the waters of the State.
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The WQS set forth the types of wastewater that can be discharged in various classifications in order to meet statutory goals. In addition, the WQS provide the guiding principles concerning waste assimilation, aquatic toxicity and the goals for receiving waters.
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If the type of discharge is allowed, then the details of application procedures and requirements for treatment, monitoring and reporting of the specific discharge are provided by Sections 22a-430-1 through 4 of the Regulations of Connecticut State Agencies.
Three Fundamental Elements
Element One. First, the water quality standards describe DEP's general policies and goals for maintaining or restoring specified levels of quality for each classification. The Standards describe discharges to ground and surface water consistent with DEP's goals for each classification. The Standards also define the concept of a zone of influence for such discharges; this concept is covered in more detail below. Other key provisions of the standards include policies for protecting ground and surface water whose actual quality exceeds that quality associated with its classification. These policies are known as the anti-degradation principles. There are also policies and procedures that define the methods by which DEP may alter an assigned classification. The Standards also include important appendices which provide guidance on anti-degradation, definitions, lake trophic classifications, bathing water standards and numerical criteria for aquatic toxicity.
Element Two. The second element is the water quality criteria which: (i), describes the uses DEP has designated as appropriate for each water quality classification, and, (ii), establishes narrative and numerical factors used by DEP to determine whether goals established in the standards are being met.
Criteria are divided into groups with surface fresh waters having the designations AA, A, B, C, and D. Saline waters are assigned classes SA, SB, SC and SD. It should be noted that C, D, SC, and SD are never acceptable goals; these classifications reflect certain problems, usually a distinct and difficult situation.
Element Three. Classifications and the classification maps are the third element. Classifications are assigned to surface and groundwater in all areas of the state. These assignments are based on both the use or potential use of such waters as well as on their known or presumed quality. The individual water quality classifications are described in more detail below.
Water Quality Classifications
Classifications are shown on water quality classification maps. In cases where the actual quality of groundwater does not meet the assigned classifications criteria, the water quality classification maps reflect that fact by means of color coding or a split designation on older maps, such as GA/GB, indicating that the existing groundwater quality in the subject area may be GB quality but the goal is the higher GA criteria.
Significantly, over 90% of the State is classified at the highest levels of protection, as suitable for drinking without treatment. A little more than 6% of the land area is classified as GB, indicating historically urbanized areas. A very small area of the State is classified as GC, having demonstrated hydrogeologic characteristics suited for waste disposal.
Inland surface water classifications.
Class AA
Designated uses: existing or proposed drinking water supply, fish and wildlife habitat, recreational use (may be restricted,) agricultural and industrial supply.
Discharge restricted to: discharges from public or private drinking water treatment systems, dredging and dewatering, emergency and clean water discharges.
Class A
Designated uses: potential drinking water supply; fish and wildlife habitat; recreational use; agricultural and industrial supply and other legitimate uses including navigation.
Discharge restricted to: same as allowed in AA.
Class B
Designated uses: recreational use: fish and wildlife habitat; agricultural and industrial supply and other legitimate uses including navigation.
Discharge restricted to: same as allowed in A and cooling waters, discharges from industrial and municipal wastewater treatment facilities (providing Best Available Treatment and Best Management Practices are applied), and other discharges subject to the provisions of section 22a-430 CGS.
Class C
Indicates unacceptable quality, the goal is Class B or Class A. Designated uses: same as for B. One or more of the class B uses is not fully supported due to problems that can and will be corrected by normal DEP programs. A good example is the intermittent water quality problems caused by combined sewer overflows.
Discharges restricted to: same as for Classes B or A .
Class D
Indicates unacceptable quality, the goal is Class B or Class A. Designated uses: same as for B. One or more of the designated uses for class B is not fully supported due to an intractable or very difficult pollution problem. An example is the PCB contaminated bottom sediments in the Housatonic River.
Discharges restricted to: same as for Classes B or A.
Coastal and Marine Surface Waters.
Class SA
Designated uses: marine fish, shellfish and wildlife habitat, shell fish harvesting for direct human consumption, recreation and all other legitimate uses including navigation.
Discharge restricted to: same as for AA or A surface waters.
Class SB
Designated uses: marine fish, shellfish and wildlife habitat, shellfish harvesting for transfer to approved areas for purification prior to human consumption, recreation, industrial and other legitimate uses including navigation.
Discharge restricted to: same as for B surface waters.
Classes SC or SD
Indicates unacceptable quality, the goal is Class SB or Class SA. Designated uses: same as for Classes C or D surface waters.
Discharge restricted to: same as for Classes C or D surface waters
Groundwater Classifications.
Class GAA
Designated uses: existing or potential public supply of water suitable for drinking without treatment; baseflow for hydraulically connected surface water bodies.
Discharges limited to: treated domestic sewage, certain agricultural wastes, certain water treatment wastewaters.
Class GA
Designated uses: existing private and potential public or private supplies of water suitable for drinking without treatment; baseflow for hydraulically connected surface water bodies.
Discharge restricted to: as for GAA and discharge from septage treatment facilities subject to stringent treatment and discharge requirements, and other wastes of natural origin that easily biodegrade and present no threat to groundwater.
Class GB
Designated uses: industrial process water and cooling waters; baseflow for hydraulically connected surface water bodies; presumed not suitable for human consumption without treatment.
Discharge restricted to: same as for A (Note; same treatment standards apply), certain other biodegradable wastewaters subject to soil attenuation.
Class GC
Designated uses: assimilation of discharge authorized by the Commissioner pursuant to Section 22a-430 of the General Statutes. As an example a lined landfill for disposal of ash residue from a resource recovery facility. The GC hydrogeology and setting provides the safest back up in case of technological failure.
Discharge restricted to: potential discharges from certain waste facilities subject to extraordinary permitting requirements.
Standards Adoption and Public Participation
Section 22a-426 of the General Statutes provides specific procedures for the adoption of all portions of the WQS. The Statute provides that any revision of the standards, criteria or classification map be subject to public notice requirements and a public hearing. Notice is printed in the Connecticut Law Journal, in newspapers of general circulation in the affected areas and is sent certified to the chief executive officer of any affected municipality.
Classification maps are reproduced through the DEP's Geographic Information System (GIS) and are available to the public in the DEP store.
Additional Information:
Guidance for the Submission of Applications to Lower Ground Water Quality Classifications to Class GB (PDF)
Federal EPA Water Quality Standards
For further information, contact staff at the DEP Bureau of Water Protection and Land Reuse: (860) 424-3020.
