PFAS Monitoring in Surface Water and Fish Tissue

Per- and polyfluorinated alkyl substances, or PFAS, are a group of thousands of human-made chemicals that have been used widely in consumer products and industry since the 1940s. Due to their unique chemical structure, PFAS are extremely stable and repel oil, grease, water, and heat. Unfortunately, these same properties that make PFAS desirable for industrial processes, also make them extremely resistant to breaking down in the environment (i.e., 'persistent'), earning them the nickname “Forever Chemicals.”

PFAS easily migrate in the environment and cause contamination of soil, sediment, groundwater, and surface water.  Because of this, humans and animals can be exposed to PFAS by drinking contaminated water or eating contaminated food, including plants and animals.  Beginning in 2016, CT DEEP began conducting fish tissue analysis and, more recently, surface water monitoring to evaluate PFAS levels in Connecticut. Information about the studies conducted to date is provided below.

U.S. EPA National Lakes Assessment (2022)

DEEP participates in the U.S. Environmental Protection Agency's National Lakes Assessment (NLA).  The NLA is conducted every five years and is designed to provide statistically valid national and regional estimates of the condition of lakes. It uses a probability-based sampling design to represent the condition of all lakes across the coterminous United States.  Data collected are shared with State agencies and serve as a valuable source of lake fish tissue information.  For the first time, in 2022, fish tissue sampling for PFAS analysis was added to the study design.  Connecticut lakes from which fish tissue was collected during 2022 included Billings Lake (North Stonington), Crystal Lake (Winchester), Halls Pond (Willington), Lake Zoar (Newtown) and Whites Pond (Suffield).  Target species included predator species commonly targeted by recreational anglers such as Largemouth Bass, Smallmouth Bass, and Yellow Perch.  Samples were shipped to EPA and will be analyzed for PFAS, PCBs, and mercury.  Results will be reported here as soon as they are made available by EPA.

Quinebaug Valley State Fish Hatchery (2022)

The DEEP owned and operated Quinebaug Valley State Fish Hatchery, located in Plainfield, CT, is responsible for the production of the majority of the trout stocked into Connecticut waters by the DEEP Fisheries Division. Hatchery fish, which are reared in a controlled environment, have historically been used by DEEP as field blanks in fish tissue contaminant studies.  In June 2022, in order to verify the suitability of hatchery fish use as field blanks in PFAS studies, Brown Trout were collected from the Quinebaug Hatchery and submitted to the University of Connecticut's Center for Environmental Science and Engineering (UConn CESE) for analysis of 28 PFAS compounds. Samples were non-detect for all PFAS except for very low levels of PFOS (2.4 ppb), indicating that it is appropriate to continue to use these fish as field blanks in aquatic tissue contaminant studies. Based upon the most recent DPH guidance, these results also indicate that CT DEEP hatchery-raised Brown Trout, in general, remain safe to consume in unlimited quantities. However, because trout can absorb PFAS from contaminated surface waters after stocking, the public is reminded to always consult the CT DPH 'If I Catch It, Can I Eat It?' Guide to Eating Fish Safely for waterbody-specific consumption guidance.

PFAS Surface Water Study: Select Waste-Receiving Waters (2021)

In September 2021, fish tissue and surface water samples were collected from eight waste-receiving waterbodies in Connecticut.  The effort was part of a larger study to characterize PFAS levels in environmental media entering and discharging publicly owned treatment works (POTWs) in Connecticut.  Sample locations included a total of ten sites on the Connecticut River (Cromwell and Hartford), Farmington River (Farmington and Windsor), Hockanum River (Vernon), Naugatuck River (Beacon Falls), Pequabuck River (Bristol), Quinnipiac River (Wallingford), Scantic River (Somers), and Still River (Winsted).  Fish tissue and surface water analysis results are provided below.  Due to quality control concerns data collected from the Hockanum River were discarded and are not available below.  A final report for the project is forthcoming. 

Natchaug River and Quinebaug River (2019)

In October 2019, Smallmouth Bass, Fallfish and White Sucker were collected from the mouth of the Natchaug River in Windham, CT.   The sampling location is a site situated adjacent to an active regional fire training school and PFAS contamination was previously discovered in the vicinity.  

Crews also collected fish in November 2019 from the Quinebaug River in Putnam, CT for PFAS analysis.  The sampling location is a site downstream of an industrial discharger is known to use PFAS in their operations.  Fish collected at the Quinebaug site included Fallfish, White Perch, Yellow Perch, Redbreast Sunfish, Fallfish and White Sucker. 

Fish tissue samples were analyzed by SGS Axys in British Columbia for 27 PFAS analytes using an updated proprietary method.  The sampling plan and results are available for download below. 

Long Island Sound (2019) 

In 2019, CT DEEP Fisheries Division staff supported New York State Department of Environmental Conservation (NYS DEC) efforts to collect Striped Bass from Long Island Sound for tissue analysis.  A total of eight fish were collected and analyzed for analysis of 11 PFAS along with total mercury, total PCBs, and selected organochlorine pesticides.  Levels were below detection limits for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS).

U.S. EPA National Rivers & Streams Assessment (2008-2019) 

DEEP participates in the National River and Stream Assessment (NRSA) component of the U.S. Environmental Protection Agency's (U.S. EPA) National Aquatic Resource Surveys (NARS). NARS is a collaborative program between EPA, states, and tribes to assess the quality of the nation’s coastal waters, lakes and ponds, rivers and streams, and wetlands. The NRSA is a national probability-based survey of rivers and streams based on physical, chemical and biological data collected and analyzed using standardized field and laboratory methods by state, EPA and contractor crews across the USA. NRSA surveys are conducted over a two-year period, every four years.  Since the 2008-2009 survey, a subset of sites from each NRSA survey are selected for tissue sample collection and analysis. In order to allow for comparison to previous years, typically, a number of these sites are sites that have been previously monitored for tissue contamination.  Connecticut NRSA fish tissue monitoring sites have been located on the Connecticut River, Farmington River, West Branch of the Farmington River, and Housatonic River, Pawcatuck River, Quinebaug River, and Shetucket River. 

Housatonic River (2017)

In June 2017, White Perch, Yellow Perch, and Largemouth Bass were collected for PFAS analysis from the Housatonic River in Derby, CT, just upstream of the confluence with the Naugatuck River.  The peninsula formed by the confluence of these two rivers is known locally as “O’Sullivan’s Island”.  This property was historically used as a fire training site, suggesting that PFAS-containing fire fighting foam may have been discharged at the site.  Samples were analyzed by SGS Axys in British Columbia for 13 PFAS analytes using proprietary methods.  The results as well as the associated DPH Health Consultation are available for download below. 

Connecticut River (2016)

In October 2016, Smallmouth Bass and Yellow Perch were collected from the Connecticut River in Middletown, CT, south of the confluence with the Mattabassett River.  This location was selected for investigation because it is located downstream of a publicly owned treatment facility. Emerging research at the time suggested that waste treatment facilities could be a potential discharger of PFAS to surface waters.  Bass samples were analyzed as individual fillets while Yellow Perch samples, which were smaller in size, were filleted and composited for analysis.  Samples were analyzed by SGS Axys in British Columbia for 13 PFAS analytes using proprietary methods.  The results are available for download below. 

Contact for More Information

Meghan Lally
PFAS Project Lead / Fish Tissue Contaminant Project Lead


Content last updated on January 11, 2024.