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Emerging Contaminants in NY's Waters

New! DEC Issues Ambient Water Quality Guidance Values - Learn about the Water Quality Guidance Values to Regulate PFOA, PFOS, and 1,4-Dioxane.

Emerging Contaminants, or contaminants of emerging concern, can refer to a number of different types of chemicals, including those found in medicines, personal care products, household cleaning products, cookware, and agricultural products. These chemicals are often detected in our waterways and may have harmful effects on humans, fish and other species. DEC's Division of Water is committed to identifying these emerging contaminants, developing water quality standards or guidance values where appropriate, and working towards minimizing their impacts to our environment.

Per- and Polyfluoroalkyl Substances (PFAS)

Per- and Polyfluoroalkyl Substances (PFAS) are a group of chemicals used to make fluoropolymer coatings and products that resist heat, oil, stains, grease, and water. Fluoropolymer coatings are blends of resins and lubricants used in products such as water-repellent clothing, furniture, adhesives, paint and varnish, food packaging, heat-resistant non-stick cooking surfaces and insulation of electrical wires.

Chemicals in this group include perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS).

1,4 Dioxane

1,4-Dioxane is a compound that has historically been used a solvent stabilizer and has been found in trace amounts in some cosmetics, shampoos, detergents, and cleaning products.

SPDES Permittee's Monitor for PFAS and 1,4-Dioxane

Some wastewater dischargers have been targeted to begin monitoring for PFAS and 1,4-Dioxane in accordance with the Departments "Permitting Strategy for Implementing Guidance Values for PFOA, PFOS, and 1,4-Dioxane" (TOGS 1.3.13), available below. If your facility's State Pollutant Discharge Elimination System (SPDES) permit has been modified to include this additional monitoring or if you've received a request for information requiring additional monitoring for these contaminants, please utilize the below links to fulfill the requirement:

Water Quality Guidance Values to Regulate PFOA, PFOS, and 1, 4-Dioxane

The finalized guidance values (GVs) are shown in the table below. The Department of Health (DOH) maximum contaminated levels (MCL) for finished drinking water are displayed for informational purposes.

Chemical DOH - Finished Drinking Water DEC - Raw Water Source
Adopted MCLs Human Health Aquatic Life
Chronic Acute
PFOA 10 ppt 6.7 ppt N/A N/A
PFOS 10 ppt 2.7 ppt 160 ppb (fresh)
41 ppb (saline)
710 ppb (fresh)
190 ppb (saline)
1,4-Dioxane 1 ppb 0.35 ppb 18,000 ppb (fresh)
7,000 ppb (saline)
160,000 ppb (fresh)
63,000 ppb (saline)

The GVs were derived by procedures established in Title 6 of the New York Codes, Rules, and Regulations (NYCRR) Part 702.

On March 15, 2023, NYSDEC announced the issuance of final water quality guidance values to regulate Perfluorooctanoic acid (PFOA), Perfluorooctane sulfonic acid (PFOS), and 1,4-Dioxane (1,4-D). The finalized GVs support the State's ongoing efforts to protect public health and the environment and prevent exposure to emerging contaminants through the protection of drinking water sources. Additionally, the new guidance values for PFOS and 1, 4-Dioxane also provide protection for aquatic life.

The new GVs are established in an addendum to TOGS 1.1.1: Ambient Water Quality Standards and Guidance Values and Groundwater Effluent Limitations (PDF). 1 The TOGS 1.1.1 addendum is supplemented by the finalized revision to TOGS 1.3.7: Analytical Detectability and Quantitation Guidelines for Environmental Parameters (PDF) and a new TOGS 1.3.13: Permitting Strategy for Implementing Guidance Values for PFOA, PFOS, and 1,4-Dioxane (PDF).

TOGS 1.3.7 guides the selection of analytical testing methods in situations, such as when monitoring emerging contaminants, where methods approved by State and/or Federal oversight bodies are limited or unavailable. TOGS 1.3.13 establishes how the GVs for PFOA, PFOS, and 1,4-D are applied to State Pollutant Discharge Elimination System (SPDES) permits to optimize environmental protection and minimize financial impacts. In addition to the final guidance implementing actions to control industrial discharges, DEC is actually working on proposing draft guidance to address emerging contaminants discharged through Publicly Owned Treatment Works (POTWs).

In 2020, New York formally adopted among the nation's lowest MCLs for drinking water for PFOA and PFOS at 10 parts per trillion (ppl)m and the first national standard for 1, 4-Dioxane at 1 part per billion (ppb). The MCLs were promulgated by the State's Drinking Water Quality Council, a body of water quality experts and scientists charged with setting limits in absence of federal standards for these emerging chemicals that have been pervasive in drinking water systems nationwide.

While MCLs adopted by the DOH provide protection for finished drinking water, DECs guidance values will provide complementary protection of ambient waters used as drinking water sources. The guidance values will initially be incorporated into requirements for industrial discharges needing a DEC State Pollutant Discharge Elimination System (SPDES) permit, so facilities do not contribute to harmful levels of emerging contaminants in the environment and these contaminants are appropriately controlled at industrial sources rather than downstream treatment systems.


Below are the finalized TOGS documents and Assessment of Public Comments. Also provided are the facts sheets detailing the derivation of the GVs.

1 TOGS 1.1.1 was last issued in June 1998, with addenda in 2000 and 2004 to add protection for specific chemicals. TOGS 1.1.1 is the DOW's mechanism to establish guidance values.Ambient Monitoring for PFAS and 1,4-Dioxane

DEC continues to monitor ambient water quality in lakes and streams for PFAS and 1,4-dioxane as part of the Rotating Integrated Basin Studies (RIBS) Screening Network. The monitoring is conducted at 3 to 4 of the state's 17 major drainage basin each year, providing a statewide perspective over a 5-year cycle.

More about Emerging Contaminants

For more information on Emerging Contaminants, visit the PFAS webpage.


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