2019 Triennial Review of the Connecticut Water Quality Standards

The Connecticut Triennial Review Final Document is now available and has been submitted (transmittal letter) to the Environmental Protection Agency. 

 The Connecticut Department of Energy and Environmental Protection (Department) is initiating a review of Connecticut Water Quality Standards (“WQS”). This review is being conducted to evaluate the need to update or revise the WQS in order to remain consistent with State and federal law and to ensure that Connecticut’s WQS continue to reflect the best available science and support sound water quality management policies to improve and protect the water resources of the state.

With this notice the Department is requesting input from all interested parties on any aspect of the WQS that a person believes the Department should consider for potential revision. The comment should include the topic of concern, whether it is currently covered by the WQS, and if so where, any suggested revision and the basis for the suggested revision. Any technical information or reports supporting the comment should be included. Comments on the WQS will be accepted from March 4, 2019 through April 5, 2019. Comments should be provided via email to DEEP.WQS@ct.gov.

While the Department will accept comments on any provision of the WQS, the Department is particularly interested in comments on the portions of the WQS which the Department is evaluating for revision. The need to revise the WQS to address these topics was identified during the previous Triennial Review which was conducted in 2014. Prior to proposing formal changes to the Water Quality Standards, the Department is once again providing an opportunity for public review and comment on the current WQS through this Triennial Review process. After reviewing any comments received during this Triennial Review, the Department will develop recommended updates to the WQS and initiate a formal regulatory revision process.

The topics under consideration for change within the WQS are identified below. Additional topics may be identified during this Triennial Review process and included in subsequent proposed changes to the WQS. The regulatory process to revise the WQS also includes a formal public review and comment process.

Topics under Consideration for Revision within the WQS Regulations

Updates to Numeric Water Quality Criteria
Since the WQS were last revised, EPA has updated recommendations for water quality criteria. The Department is currently reviewing the water quality recommendations from EPA and will either propose adoption of the federally recommended criteria or provide a reason for not doing so in accordance with section 304(a) of the federal Clean Water Act. These include updates to federal water quality criteria recommendations for toxics, bacteria and ammonia. Information about the current federal recommendations for water quality criteria can be found on the EPA web site at: https://www.epa.gov/wqc.


Revise the Low Flow Statistic Applicable to Fresh Waters

The 7Q10 flow is currently identified as the low flow condition in freshwater rivers and streams. The Department intends to recommend changing the low flow statistic for fresh waters from the 7Q10 flow to the Q99 flow. The Q99 flow represents the daily low flow rate that is expected to occur approximately 1% of the time. For daily stream flows, the Q99 flow is roughly equivalent to the 7Q10. The benefit of using the Q99 flow is that information on Q99 flows for waterbodies in Connecticut is easily accessible through the USGS StreamStats web site for all locations, not just those served by gaging stations. The USGS StreamStats web site for Connecticut is available at: https://water.usgs.gov/osw/streamstats/connecticut.html.

Extended Disinfection Period

The current Water Quality Standards contain requirements for disinfection of treated sewage discharge to surface waters at section 22a-426-4(a)(9)(E) of the regulations. This section requires continuous disinfection for all sewage treatment plants located south of Interstate Highway I-95. Disinfection is currently required for all sewage treatment plants north of Interstate Highway I-95 from May 1 to October 1, unless an alternative schedule, including continuous disinfection, is approved to protect those using the waterbody. Based on public comments which identified contact recreational activities within Connecticut that occur outside the current disinfection period, the Department intends to propose an extension of the disinfection period for all sewage treatment plants located north of Highway I-95 to include the period from April 1 through November 1, unless an alternative schedule, including continuous disinfection, is approved to protect those using the waterbody.

Define Highest Attainable Use

Recent revisions to federal regulations pertaining to Water Quality Standards (40 CFR 131.3(m) and 131.10(g)) have included a new term, Highest Attainable Use. The Highest Attainable Use is evaluated during a study of how a waterbody is used and pertains to identifying the highest use level for a waterbody should environmental conditions permanently preclude certain uses of that resource. The Department is reviewing the recently revised federal regulations and anticipates proposing language to insure consistency with these federal requirements.

Downstream Protection

Water quality in a particular section of a waterbody maybe affected by activities in the upstream watershed which contribute pollutants to the waterbody that are then transported downstream, affecting water quality in that downstream portion of the waterbody. The Clean Water Act requires consideration of these impacts on downstream waters when addressing water quality concerns. The Department believes that this concept is currently included within the WQS but is reviewing federal recommendations and may propose changes to the regulations for clarification, as needed.

Water Quality Classification Maps

The Department is evaluating the need to make changes in order to reconcile the water quality classification designation with shellfishing classification for specific water quality segments, as needed. Additionally, the Department expects to update ground water classification designations for consistency with Aquifer Protection Areas.

Public Comments Received on the 2019 Triennial Review of the Connecticut Water Quality Standards
 Exhibit  Submitted by
 1 Jay Kulowiec, Industrial Water/Wastewater Consultancy, LLC    
 2 William Milardo, Durham Health Department
 3 Hugh Rogers
 4 Rivers Alliance of Connecticut
 5 Richard Harris
 6  Amy Valasquesz, South Central Connecticut Regional Water Authority
 7  Louise Washer, Norwalk River Watershed Association, Inc.
 8  Ken Lerman
 9  Joseph Schnierlein, Norwalk Mayor's Water Quality Committee
10   Valerie Rossetti, Save Our Water Connecticut
11    Patricia Sesto, Town of Greenwich
12  Thomas Tyler, The Metropolitan District
Margaret Miner & Tony Mitchell, Rivers Alliance of Connecticut 2
14      Mary Rickell Pelletier, Park Watershed
15  Mary Mador & Mary Mushinsky,  River Advocates of South Central Connecticut
16  Ralph W. Abele, EPA Region 1
Alicea Charamut,  Connecticut River Conservancy
18   Arthur G. Simonian,  The Mattabassett District
 2019 Triennial Review Presentation         
Content updated on July 20, 2022