City of Prescott Featured

City of Prescott Provides PFAS Results from Recent Testing of Chino Valley Potable Water Supply Wells 

Big Idea

  • The Arizona Department of Environmental Quality has returned test results in Chino wells
  • Three of the four Chino Valley wells returned barely detectable levels of PFOA
  • PFOs were not detected
  • Water will be blended to alleviate the issue
  • Read more…


ADEQ results are in

Prescott, Arizona (August 29, 2022) -- Following the discovery by the Arizona Department of Environmental Quality (ADEQ) of two PFAS chemicals, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in two City potable water supply wells in the airport area in early July, which were immediately turned off, the City requested that ADEQ test the additional City potable water supply wells located in Chino Valley.  ADEQ sampled these wells on July 20, 2022.  These results have come back, resulting in barely detectable levels of PFOA in three of four operational Chino Valley wells.  PFOS was not detected in these three wells.  Neither PFOA nor PFOS were detected in Chino Valley Well No. 4.  These results are similar to, albeit slightly higher, than test results received by the City last week, based on samples taken on July 26, 2022.  Some variability in test results is normal due to the non-homogenous nature of groundwater aquifers.  

Since PFAS were detected for the first time in 3 of 4 Chino Valley wells last week, City staff made operational changes to minimize levels of PFAS in city potable water supplies by turning off Well Nos. 3 and 5 and blending water from Well Nos. 2 and 4 before sending it to customers.  It is expected that this blending plan will result in non-detectable levels of PFAS in city potable water supplies.   


Both ADEQ and City test results are shown in the table below: 



As a reference point, one part per trillion is equal to ¾ of a teaspoon in Watson Lake, so these test results show extremely low levels of PFAS in three City potable water supply wells located in Chino Valley. 

The City will regularly test for PFAS in its potable water supply to continue to maintain adequate quantities of safe, clean drinking water. As test results are received, City staff will immediately inform the public and quickly make operational changes to minimize the introduction of PFAS into City potable water supplies. 

Following last week’s release of results from City-sponsored PFAS testing at all City water production wells, there were some citizen inquiries and questions which suggested that the City clarify several points. 

The laboratory used for the testing, Legend Technical Services, Inc., is fully certified to perform the drinking water analysis for PFAS chemicals.  For reference, their website https://legend-group.com/accreditations lists these certifications. 

Samples of all city potable water production wells for PFAS testing were taken by Water Operator Matt O’Brien of the City’s Utilities Department.  Mr. O’Brien is well-versed in the sampling protocol for PFAS and has an Arizona Department of Environmental Quality (ADEQ) Grade 4 (the highest level) Certification in Water Production and Water Distribution.  He takes most potable water samples for testing in the city.  A link to ADEQ’s website showing his certifications is shown here: https://legacy.azdeq.gov/databases/opcertsearch_drupal.html.   

Mayor Phil Goode offered this perspective for citizens concerned about PFAS: 

“I want our citizens to be assured that the quality of our drinking water is of the utmost importance to everyone here at the City of Prescott.  The Public Works team has been working closely with our City Manager, elected leadership, and ADEQ to make sure that we address this situation appropriately.  I have full faith in our team members.”  

PFAS have been extensively produced and used since the 1940s.  Some firefighting foams used to extinguish oil and gas fires contain PFAS.  These chemicals have also been used in a number of industrial processes and to make carpets, cosmetics, clothing, fabrics for furniture, paper packaging for food, cookware, etc., that are resistant to water, grease and stains. Because these chemicals have been used in many consumer products, most people have been exposed to them. While consumer products and food are the largest source of exposure to these chemicals for most people, drinking water can be an additional source of exposure in communities where these chemicals have contaminated water supplies. This is an emerging issue that is affecting nearly 3,000 sites in 50 states and 2 US territories as of June 2022. As we learn more, the City of Prescott is committed to be at the forefront of efforts to protect our citizens. 

Currently, the US Environmental Protection Agency (EPA) is developing guidance referred to as Health Advisory Levels (HALs).  As the EPA continues to research the chemicals, they have continued to lower the minimum level in their guidelines. While Prescott’s wells were far below the previous HAL of 70 parts per trillion (ppt), in June 2022, the EPA announced a lower HAL of 0.02 ppt for PFOS and 0.004 ppt for PFOA. Please note that HALs are only recommendations; they are not yet regulatory requirements.  Therefore, the City of Prescott remains in compliance with all applicable potable water quality regulations established by the EPA and ADEQ. 

If you are concerned about PFOA/PFAS, you can get more information from the EPA. PFAS Explained | US EPA. If you have young children and/or members of a sensitive subgroup, you should speak to your doctor. For older children and adults (not in a sensitive subgroup), the HAL is applicable to a lifetime of consuming contaminated water.  For these groups, shorter duration exposures present less risk.  However, if you are concerned about your exposure while steps are being taken to assess and lower the PFAS concentration in the drinking water, use of PFAS-free bottled water could reduce your exposure. 

Use of home water treatment systems that are certified to remove PFAS by an independent testing group such as NSF, UL, or the Water Quality Association may be effective in treating the water.  These may include point of entry systems, which treat all the water entering a home, or point of use devices, which treat water where it is used, such as at a faucet. 

Please direct questions or concerns to the City’s Utilities Division at 928-777-1118.  This press release and related documents will be posted on the City’s website at https://www.prescott-az.gov/water-sewer/pfas-and-pfos-resource-center/ or go to the home page and select the PFAS Resource Center tile. 


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Last modified on Tuesday, 30 August 2022 22:22
Published in Prescott.news
John Heiney

Community Outreach Manager

Communications, Economic Development and Tourism

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