PFAS in Drinking Water

PFAS Update December 14, 2022

Sammamish Plateau Water and Sewer District (The District) strives for transparency regarding the water quality provided to our customers. This site provides the most up to date information regarding PFAS and all other water quality information.

Here are some of the ways the District provides water quality data:

  • The District is subject to State and Federal drinking water regulations. 
  • Two wells, Wells 7 and 8, were removed from production after tests found elevated PFAS levels.
  • All PFAS levels and arsenic levels for active wells are below regulatory limits.
  • The District presents information about PFAS and Arsenic in the Consumer Confidence Report which is sent out annually.
  • The District website has a section regarding PFAS which includes information and ongoing District efforts. 
  • The District has a sample plan for PFAS. Monthly sampling is done for all wells that have detects of PFAS. All other sources of the District water supply are tested twice a year.
  • The District interacts with customers and shares data as requested on a regular basis.

What are PFAS?

Per- and Poly-Fluoroalkyl Substances (PFAS) are a family of man-made chemicals that are not found naturally in the environment. PFAS are found in many common consumer products such as food packaging, non-stick cookware, stain resistant carpet treatments, water resistant clothing, cleaning products, paints, firefighting foam, and some cosmetics. PFAS are also used in many industrial processes and for other applications such as firefighting. There is evidence that exposure to PFAS can lead to adverse health outcomes in humans.

How are drinking water regulations established?

The U.S. Environmental Protection Agency sets standards and regulations to control the level of contaminants in the nation’s drinking water. Once a contaminant such as PFAS has been identified and scientifically shown as potentially having negative public health consequences, a federal rule making process takes place to establish drinking water regulations. As a public water system, the District is required to meet these federal regulations. Under the EPA’s Safe Drinking Water Act, individual states also have the opportunity to set and enforce their own more stringent drinking water standards, which the District must also meet.

What are Washington State PFAS State Action Levels?

The WA State Board of Health approved updates to the Drinking Water Regulations for Group A Water Systems (Chapter 246-290 WAC). This revision establishes PFAS State Action Levels (SALs) that require water systems to test for PFAS compounds and report to the state and their customers if PFAS levels exceed the SALs. PFAS levels in active District wells are below the adopted SALs. As stewards of your water supply, staff members continue to regularly monitor State and Federal regulatory activities in order to stay on top of the latest developments related to PFAS and drinking water.

Where and why is this happening?PFAS Map

District wells that have been affected by PFAS are Wells 1, 2, and 10 in the Plateau Aquifer, and Wells 7, 8 and 9 in the Lower Issaquah Valley Aquifer. The PFAS detected in the Lower Issaquah Valley Aquifer was attributed to the use of firefighting foam in fire training exercises originating within the City of Issaquah. This led to an environmental study by the City of Issaquah, Eastside Fire and Rescue, and the Washington State Department of Ecology in coordination with a third party consultant.

How we're proactively protecting your water.

When PFAS was first detected in the three wells in the Lower Issaquah Valley Aquifer, the District proactively conducted extensive research and worked with expert consultants to develop a three-dimensional groundwater model to assess how PFAS travels through the aquifer. Based on what we learned from the groundwater model, District Wells 7 and 8 were taken out of production and we changed our point of withdrawal to Well 9, which is farthest from the potential plume migration. Since then, the District has been following our interim Monitoring and Response Plan for Perfluorinated Compounds, which has included maintaining a vigorous water testing and analysis protocol that exceeds state and federal requirements.

When PFAS was detected in Wells 1, 2 and 10 in the Plateau Aquifer as part of an internal investigative process, the District worked with consultants to develop testing and monitoring plans for those wells and will continue to assess these new findings moving forward. The PFAS levels are below the existing Washington State Actions Levels (SALs).

Evaluating options for PFAS treatment.

The District worked with consultants on an in-depth PFAS removal treatment plant analysis. The analysis included evaluating PFAS treatment options, site-specific treatment feasibility, and costs associated with treatment versus the long-term purchase of regional water. After evaluating treatment options and completing a cost-benefit analysis, the Board of Commissioners approved a process for completing the design of a treatment plant which if constructed would remove PFAS from Wells 7, 8 and 9. Taking proactive measures to design this treatment plant puts the District in a better position should treatment be required in the future to continue meeting state or federal drinking water regulations.

The Board is still evaluating when and whether to proceed with construction of the treatment plant based upon further evaluation of emerging state and federal water quality requirements, costs, available state and federal grants, rate impacts to customers, and customer input. This Board should complete their evaluation and provide direction sometime in 2023.

How is the District funding this project?

The District received a tentative federal appropriation of $1.585 million to help finance construction of the PFAS water treatment plant to remove PFAS from Wells 7, 8, and 9. The District would like to express its thanks to U.S. Representative Kim Schrier and her staff for taking specific interest in our situation. Representative Schrier has advocated on behalf of our community’s needs by including the treatment plant as part of her Community Project Funding priorities. If built, the treatment plant is estimated to cost $18 million. In addition to this tentative federal appropriation, the District is actively pursuing other grants and funding assistance to offset the financial impact to ratepayers.

District files lawsuit against PFAS manufacturers.

The District has engaged with a group of law firms and initiated a lawsuit against 3M Company, E.I. DuPont de Nemours, Inc., and other primary PFAS manufacturers for their involvement in the manufacture, promotion, and sale of the chemical. As the manufacturers and sellers of PFAS containing products, 3M, DuPont, and other defendants knew or had reason to know that these products would pollute groundwater, yet failed to take reasonable and available steps to avoid the use of PFAS in products and failed to provide warnings that using these products as directed could result in groundwater contamination. We are seeking to hold the defendants liable for the damages to our water supply.


Additional PFAS information and resources

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