Model Toxics Control Act

Updating the MTCA Cleanup Regulations

We’ve updated the MTCA Cleanup Regulations. The amended rule was adopted Aug. 23, 2023. It will go into effect on Jan. 1, 2024.

The Model Toxics Control Act (MTCA) is Washington’s environmental cleanup law. MTCA funds and directs the investigation, cleanup, and prevention of sites that are contaminated by hazardous substances. It works to protect people’s health and the environment, and to preserve natural resources for the future.

There are about 14,000 known or suspected contaminated sites in Washington — and the list keeps growing. Thanks to cleanup efforts funded by MTCA, more than 7,700 of these sites are already cleaned up or require no further action.

The Hazardous Substance Tax helps pay for this cleanup work. Voters approved a tax on hazardous substances (such as petroleum products, pesticides, and other chemicals) to pay for cleanups. Under MTCA, we might also recover penalties or require polluters to pay for cleanups and our oversight.

Rules and policies put MTCA into action. We’ve developed rules and policies that set cleanup standards and other requirements. These make sure cleanups protect your health and the environment.

The Toxics Cleanup Program is one of several Ecology programs that receive funds from MTCA. The Toxics Cleanup Program has primary responsibility for implementing and enforcing MTCA. They develop MTCA’s rules, policies, and guidance, and oversee or manage most of the cleanups in Washington. They also manage a grant program that helps local governments clean up contaminated sites in their communities so they can put abandoned properties back into use.

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MTCA is Washington's cleanup law

The Model Toxics Control Act (MTCA) is one of several environmental laws in Washington. Known as the state’s cleanup law, MTCA governs the cleanup and prevention of contaminated sites that can threaten people’s health and the environment.

MTCA’s main purpose is “to raise sufficient funds to clean up all hazardous waste sites and to prevent the creation of future hazards due to improper disposal of toxic wastes into the state’s lands and waters.” (RCW 70A.305.010).

MTCA evolved from citizens’ Initiative 97 in 1988 and became law in 1989. It's been substantially amended more than 20 times (most recently in 2019) but its key principles remain in place today:

Polluter pays
Cleanups should be as permanent as possible
Public participation is crucial
Processes should demonstrate a bias toward action, permanence, and innovation

Taxes. Voters authorized a tax on hazardous substances to help pay for cleanups.
Cost-recovery. We recover cleanup costs from potentially liable persons.
Penalties. We collect or recover penalties under the MTCA law.
Other sources. The state Legislature may transfer other funding for cleanup work.

Revenues from these sources are deposited into three accounts: MTCA Operating Account, MTCA Capital Account, and MTCA Stormwater Account. Collectively, these are called the MTCA accounts. Learn how we’re using these funds in our reports to the Legislature.

More than 7,700 contaminated sites in Washington have been cleaned up with MTCA funds and collection authority since it became law in 1989. That’s more than half of the state's 14,000-plus cleanup sites. MTCA’s role is becoming even more essential because between 200 to 300 new sites are reported each year.

MTCA powers our work to investigate, clean up, and prevent hazardous waste. Cleanups protect people’s health by removing toxic chemicals from the environment, like arsenic from playground soil or methane gas from a solid waste landfill. Cleanups preserve wildlife habitat for future generations, spur new economic developments, and put abandoned properties back into use.

MTCA — and every person involved in a cleanup — make these transformations possible.

We developed regulations (called “rules”) to implement the Model Toxics Control Act. They set standards and requirements for contaminated site cleanups. Rules ensure that cleanups are protecting people’s health and environment. If you’re cleaning up a contaminated site in Washington, you’ll need to meet the requirements of:

Model Toxics Control Act (MTCA) - Chapter 70A.305 RCW (MTCA law)
MTCA Cleanup Regulations - Chapter 173-340 WAC (MTCA rule, also known as the MTCA Cleanup Rule)
Sediment Management Standards - Chapter 173-204-WAC (SMS rule, also known as the Sediment Cleanup Rule)
Remedial Action Grants and Loans – Chapter 173-322A WAC (RAG rule)

Dangerous waste cleanups and management also need to comply with Washington's hazardous waste management law and dangerous waste regulations.

We have policies and guidance to help you meet these requirements.

What's the difference between the MTCA and SMS rules?

MTCA Rule (Cleanup Rule)
SMS Rule

MTCA Cleanup Regulations (also called the MTCA Cleanup Rule) applies to all cleanups, whether they're upland cleanups on land or in groundwater, or sediment cleanups in freshwater or marine environments. We published the first MTCA Cleanup Rule in 1991. We are updating this rule in a series of rulemakings that will take several years to complete. In 2023 we completed the first rulemaking, which focuses on procedures for conducting cleanups. Learn more at Chapter 173-340 WAC rulemaking and updating the cleanup rule.

Sediment Management Standards apply only to cleanups in freshwater and marine environments. We published the first SMS rule in 1991 and most recently amended it in 2013. Learn more about our sediment cleanups.

Which programs and agencies have MTCA regulatory oversight?

Toxics Cleanup Program has primary responsibility for implementing and enforcing the Model Toxics Control Act. The program develops rules and guidelines that govern cleanups. It manages the Remedial Action Grant program that funds cleanups by local governments. It also oversees or manages most cleanups in Washington.

Hazardous Waste and Toxics Reduction Program oversees cleanups of releases from hazardous waste treatment, storage, and disposal facilities that are regulated under the Hazardous Waste Management Act (Chapter 70A.300 RCW). They also manage dangerous waste permits.

Solid Waste Management Program oversees cleanups of releases from permitted landfills and large industrial facilities — such as pulp and paper mills, aluminum smelters, and petroleum refining — and distribution systems.

Nuclear Waste Program ensures that cleanup of contaminated sites on the Hanford Nuclear Reservation is consistent with state law.

Pollution Liability Insurance Agency provides technical assistance to people who independently clean up sites contaminated by petroleum from leaking heating oil tanks. This includes written opinions on sufficiency of cleanups based on MTCA standards. In 2017, the legislature authorized PLIA to expand its existing technical assistance program to include other petroleum storage tank sites we identify. (House Bill 1266).

Find cleanup policies, guidance, and sites

TCP’s policies and guidance interpret the MTCA rule and provide best management practices for conducting successful cleanups.

MTCA legislative reports: Biennial Reports describe how we spent MTCA funds over the past two years. Ten-Year Financing Reports describe cleanup financing needs in the next ten years. Cleanup Settlement Account Reports describe how we’re using money from legal settlements and court orders for specific sites and restorations.

How the cleanup process works summarizes MTCA’s cleanup steps. The fact sheet Process for cleanup of hazardous waste sites provides more details.

Private right of action gives steps for persons intending to recover cleanup costs from other liable persons under MTCA.

The Site Register provides updates on MTCA policies and cleanup activities. Subscribe or download back issues.

How we developed MTCA standards and selected cleanup actions

Focus on: Washington's envrionmental cleanup law (rev. 2018)
Developing ground water cleanup standards (2005)
Developing surface water cleanup standards (2005)
Developing soil cleanup standards (2005)
Developing air cleanup standards (2005)

Contact information

Toxics Cleanup Program
Policy & Technical Support Unit
360-407-7170