Poestenkill Assessment Area

Protecting Poestenkill's Drinking Water & Investigating Sources of PFOAs

Latest News:

DEC is holding a community availability session on Thursday, May 18, 2023 from 5 to 8 p.m. at the Algonquin Middle School Cafeteria to update the community on the ongoing efforts to protect drinking water supplies and investigate potential sources of contamination. At the availability session, DEC, DOH, and Rensselaer County experts will staff individual stations on the various aspects of the investigation and agency response, providing opportunities for local residents to ask questions of experts one on one.

The Poestenkill Assessment Area Final Report, which includes detailed results and findings of DEC's investigations, can be found below.

Most Recent Fact Sheet: Community Update #5 - April 2023 (PDF, 550 KB)

The DEC and DOH, working with the Rensselaer County Department of Health (RCDOH), are providing this web site to share progress on the agencies' efforts to ensure the protection of drinking water in Poestenkill, and ongoing efforts to identify a potential source of contamination. These efforts began immediately after public water supply sampling at the Algonquin Middle School detected the emerging contaminants per- and polyfluoroalkyl substances (PFAS), specifically perfluorooctanoic acid (PFOA), at levels slightly above New York State's maximum contaminant level (MCL) standards for public drinking water of 10 parts per trillion (ppt). New York's MCLs were developed for public water supplies but are also used as guidance when evaluating private well data.

Algonquin Middle School: Discovery of PFAS and Prevention of Exposure

Algonquin Middle School, located near the intersection of Routes 66 and 351 in the Town of Poestenkill, is served by two water supply wells (Well #1 and Well #2) located on the property. As required by the State's new public water supply drinking water regulations, initial sampling for PFAS in the school's water supply wells was conducted on Jan. 7, 2021. Results showed levels of 13 ppt of PFOA in both wells on school grounds, exceeding the MCL of 10 ppt. Out of an abundance of caution, after reviewing results with RCDOH, the Averill Park School District shut off drinking water fountains at the school and began providing bottled water to ensure students and staff were not exposed to contamination while confirmation samples were being collected.

The public water supply wells were retested on February 1, 2021, and results indicated that PFOA was detected in both wells at 12 ppt. Perfluorooctane sulfonic acid (PFOS), another PFAS, was also detected but below its MCL of 10 ppt. The school is currently working with RCDOH to install a granular activated carbon (GAC) system to treat the drinking water. Updates on the school's treatment system (link leaves DEC website).

Protecting Poestenkill's Drinking Water

DEC and DOH are dedicated to ensuring that all area residents have access to clean drinking water and are coordinating with the RCDOH to oversee sampling private wells in the area and providing an alternate water supply if levels are detected above public drinking water standards.

RCDOH began coordinating with DOH and DEC in February 2021 to gather information on private wells and potential sources of PFAS in the area and to develop a private well sampling plan to assess and take action to address any potential exposure to contamination. Letters requesting permission to begin sampling nearby private wells were sent to property owners in June 2021, and, with property owners' consent, RCDOH began sampling at nearby private wells in August 2021. As of February 2022, RCDOH has sampled 89 private wells near the Algonquin Middle School. PFOA or PFOS was detected in 14 of the sampled private wells, slightly above the State's public drinking water standards. The remaining 64 private wells did not show PFAS detections above the MCLs.

RCDOH and DEC initially provided bottled water to the 14 residences whose results were above the MCL and have subsequently installed Point-of-Entry-Treatment systems (or POETs) in these locations to filter out PFAS and provide clean drinking water on a longer-term basis. DEC will maintain these systems for as long as necessary to prevent potential exposure to contamination. POET System Homeowner's Guide (PDF, 88 KB).

Additional information about private wells, including information about PFAS in private wells and steps people can take if they are concerned about PFAS or other contaminants in drinking water, can be found here:

DEC Source Investigations

DEC is working closely with DOH, Rensselaer County, and the Town of Poestenkill to conduct a comprehensive investigation of potential sources for the low-level PFAS contamination found in the groundwater at and around Algonquin Middle School.

There are several commercial properties near the Algonquin Middle School that were evaluated for potential use or disposal of PFAS-containing material. Other manufacturing facilities further from the school but with potential connections to PFAS use were also evaluated for potential impacts to the Algonquin area.

To update the community on the ongoing efforts to protect drinking water supplies and investigate potential sources of contamination, DEC is holding a community availability session on May 18, from 5 to 8 p.m. at the Algonquin Middle School. At the availability session, DEC, DOH, and Rensselaer County experts will staff individual stations on the various aspects of the investigation and agency response, providing opportunities for local residents to ask questions of experts one on one.

Algonquin Middle School and Nearby Properties

Following the PFAS detection at Algonquin Middle School and other properties adjacent to the school, DEC developed a plan using an iterative approach to determine the source of PFAS found in the school's water supply. DEC began its initial investigation at the school in November 2021 completing a total of 22 soil borings and installing six shallow temporary monitoring points along the perimeter of the property and around the septic system drain fields behind the school. Samples of soil and shallow groundwater were collected during the drilling program. DEC also collected samples of surface water and sediment from the creek which runs along the south and west of the school. All samples were tested for multiple PFAS chemicals using a certified laboratory for analyses. Select wells were also sampled for volatile organic compounds.

DEC also collected samples of surface water and sediment from the creek which runs along the south and west of the school. All samples were tested for multiple PFAS chemicals using a certified laboratory for analyses. Select wells were also sampled for volatile organic compounds.

Based on the results of the initial phase of sampling at the school, additional sampling at the school and offsite was deemed necessary. The supplemental phase of work included installation of overburden and bedrock wells at the school and on several nearby properties. In addition to sampling groundwater, the investigation incorporated the use of specialized equipment and methods to understand the depth and orientation of bedrock fractures and gauge whether contamination may be emanating from an off-site source or sources. The supplemental investigation field work was completed during the summer and fall of 2022. The overall scope of the supplemental investigation is documented in the following two work plans:

The results of the DEC's extensive investigations suggest there is no industrial source contributing to the PFAS detected in drinking water at or near the Algonquin Middle School. Results suggest that wastewater discharged from the school's septic system is the most likely source of PFAS contamination in groundwater serving as the school's drinking water supply. A brief summary of DEC's source investigation findings can be found in the April 2023 Community Update (PDF, 550 KB).

Detailed results and findings of DEC's supplemental investigations are included in the Poestenkill Assessment Area Report (April 2023), which can be accessed using the following links:

Poestenkill Landfill

DEC collected samples of groundwater from six wells at the closed landfill in late October. The samples were analyzed for a wide range of contaminants, including PFAS and 1,4-dioxane. Based on the results of groundwater sampling at the landfill, properties with private wells near the landfill that are not connected to the public water supply may be targeted for sampling to evaluate any drinking water sources affected by the landfill.

Waste Management Transfer Station

In September 2021, a sample from the water supply well located at the transfer station was collected and analyzed for PFAS compounds. No exceedances of drinking water standards were found although low levels of PFOA and PFOS were detected. At DEC's request Waste Management collected and analyzed water samples for PFAS from an underground leachate collection vault, a small pond, and two former drinking water supply wells located on the property. Based on the results of the transfer station sampling, DEC determined that further investigative actions were warranted. Those supplemental activities were completed by DEC during the summer of 2022.

Results of DEC's supplemental investigation at the transfer station and other nearby properties are included in Appendix I of the Poestenkill Assessment Area report (April 2023).

Other Potential Sources in Poestenkill

As part of DEC's statewide and ongoing efforts to assess facilities that have or may have used PFAS, groundwater sampling at two local manufacturing plants (Dynamic Systems Inc. and Saint-Gobain Performance Plastics) has been completed at the request of DEC. Groundwater samples were analyzed for PFAS and 1,4-dioxane. Final analytical results are available at the links below:

Additional Information

Contact Information

  • Alternate water supply/POET system maintenance and repair: 888-459-8667
  • Source investigation information, DEC project manager, Brittany O'Brien-Drake, 518-402-9672
  • Private well testing and health-related topics, DOH region chief, Justin Deming, 518-402-7896
  • Rensselaer County Department of Health, 518-270-2655
  • For additional health-related topics, go to the DOH website (link leaves DEC website)

Contact for this Page

Division of Environmental Remediation
625 Broadway
Albany, NY 12233

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