Washington state has joined the growing list of states addressing the presence of per- and polyfluoroalkyl substances (PFAS), commonly known as "forever chemicals," in biosolids that are widely used in farming. With Governor Bob Ferguson's signature on SSB 5033, the Washington measure mandates a testing process to determine the extent of PFAS in biosolids, a step well short of an outright ban on the use of biosolids that some states have adopted or setting a standard for acceptable PFAS levels in biosolids that other states have established.
PFAS compounds have been raised as a health concern because they are used in a wide range of consumer products and do not degrade over time. The U.S. Environmental Protection Agency's (EPA) focus has been on manufacturers and drinking water supplies, while the states, including Washington, have been addressing PFAS on several fronts. One of the areas of the states' focus is on biosolids, which are produced by wastewater treatment facilities and may contain PFAS. More than half of the biosolids produced are used as a soil conditioner or fertilizer on farms, gardens, landscaping, and golf courses in lieu of disposal at a landfill or incineration.
Washington's new law directs the Washington Department of Ecology (Ecology) to establish sampling or testing guidance for PFAS in biosolids by July 1, 2026, and requires municipal wastewater facilities that generate biosolids to begin quarterly sampling for PFAS between July 1, 2027, and June 30, 2028. All test results are to be submitted to Ecology by September 20, 2028, and a report submitted to the legislature and public by July 1, 2029, summarizing the test results and making recommendations for next steps. However, before Ecology prepares the report it must convene and consult with an advisory committee comprising of representatives from the farming community, toxicologists, utilities that produce soil amendments, local governments, experts, interested parties, and other similar stakeholders to ensure that Ecology has sufficient input on the requirements and standards for sampling or testing biosolids for PFAS.
Meanwhile, King County, Washington's largest county by population, is not waiting for the state measure and just released a report on a year-long study of PFAS chemicals at the county's three wastewater treatment plants. The report concluded that PFAS levels are generally at or below those in San Francisco Bay wastewater, but one treatment plant, located in West Seattle, had noticeably higher PFAS concentrations biosolids than those in the Bay Area wastewater biosolids. The report recommends further work to determine upstream sources. The study also found that PFOS, a specific type of PFAS compound found in King County biosolids, was well below the Michigan standard for industrially impacted PFOS and, in two of the three plants, below what Michigan considers "elevated." The report suggests that further study is needed to determine the causes of the elevated PFOS.
Among the other states that are addressing PFAS in biosolids, Maine was the first, in 2022, to enact a ban on land application and sale of biosolids. Connecticut followed with a similar ban effective October 2024. Other states have imposed testing requirements. For example, starting in September 2025, all biosolids intended for land application in Minnesota must be tested for PFAS before use. Depending on the levels of one of two PFAS compounds—perfluorooctanic acid (PFOA) and perfluorooctane sulfate (PFOS)—land application may be barred, reduced, or require reporting of the rate of application. Similarly, Wisconsin has set a threshold for barring land application if PFOA and PFOS exceed certain concentrations and reducing land applications of biosolids for lesser values.
Massachusetts requires quarterly sampling while New Hampshire requires annual PFAS sampling. Colorado also has adopted testing requirements that include a trigger for source investigation when a sample has a detection equal to or greater than 50 micrograms per kilogram PFOS.
Oregon is considering a measure that would fund a study of selected sites by Oregon State University of the effects of PFAS on soil, water, and crops from land applications of biosolids. Earlier wastewater and biosolids data collected in Oregon found average concentrations significantly below national averages cited in a 2022 national study and median concentrations below threshold screening values set in Michigan and Minnesota. This suggests that Oregon may not have the same type of PFAS-generating industries or highly concerning levels of PFAS that have led to restrictions in other states. Nevertheless, the bill has strong support from wastewater service providers and cities each expressing a desire to know more about how even low levels of PFAS in biosolids may affect farm soils, crops, and water quality.
Whatever Washington and Oregon decide to do about PFAS in biosolids, other states are likely to have collected a significant amount of data and may be moving toward more restrictive measures depending on the outcomes of their data collection. None of this, however, addresses the follow-on issue of what alternatives are available for safe disposal if the states determine land application is not appropriate.
Attorneys in our Environment and Natural Resources Group are closely monitoring new developments and are available for counsel. Explore Ballard Spahr's PFAS Legislation Tracker tool to stay informed about PFAS-related developments, assisting businesses in navigating the increasing regulation of the chemicals.
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