Model Toxics Control Act: Liability, Defenses, and Cleanup

The Model Toxics Control Act is Washington’s law for cleaning up contaminated property, and it holds owners, former owners, operators, waste generators, transporters, and even some product sellers financially responsible for pollution tied to a site. Codified in Chapter 70A.305 RCW, it gives the Department of Ecology authority to name responsible parties, oversee the cleanup, place liens on contaminated real estate, and recover the state’s costs. If you own, operate, or are thinking about buying property in Washington where hazardous substances may have been released, MTCA almost certainly applies to you.

Who Pays Under MTCA

Liability under MTCA is strict, joint, and several. That means Ecology does not have to prove you were negligent, and any single responsible party can be forced to pay the entire cleanup bill no matter how small their share of the contamination.¹ If five companies polluted a site and only one is still solvent, that company can be stuck with the whole cost and left to chase the others for reimbursement.

The statute defines five categories of potentially liable persons:

Current owners or operators of the contaminated facility.
Past owners or operators who owned or ran the facility at the time hazardous substances were released.
Generators or arrangers who owned a hazardous substance and arranged for its disposal or treatment at the facility.
Transporters who accepted hazardous substances and selected the facility for disposal, unless the facility was legally authorized to receive the material at the time.
Sellers who provided use instructions for a hazardous substance, if the substance was used as directed and that use caused a release requiring cleanup.

That last category catches people off guard. A chemical manufacturer that sold a product with application instructions can be liable for contamination caused by following those instructions, even though it never set foot on the property.¹

How Ecology Names You a PLP

The process starts with a written preliminary notice from Ecology explaining the basis for the proposed liability finding. You then have 30 calendar days to accept PLP status, challenge it in writing, or do nothing. Ignoring the notice does not make it go away. After the window closes, Ecology issues a final determination letter.²

Defenses and Exemptions

MTCA provides a narrow set of ways out, and each requires real evidence. The statute recognizes three complete defenses where the release was caused solely by an act of God, an act of war, or the act of an unrelated third party such as a trespasser. The third-party defense works only if the person claiming it had no contractual relationship with the party who caused the release and exercised the utmost care with respect to the hazardous substance.³

Innocent Landowner Defense

A current or past owner can avoid liability by proving that, at the time of acquisition, they had no knowledge or reason to know that hazardous substances had been released on the property. This is not passive. To show “no reason to know,” the owner must have conducted all appropriate inquiry into the property’s history and prior uses, consistent with good commercial practice, before buying. Courts weigh the buyer’s expertise, the purchase price relative to the uncontaminated value, publicly available information, and how obvious the contamination was or should have been.³

The defense disappears if the owner learned about contamination while holding the property and then sold without disclosing it. It also fails if the owner contributed to the release in any way, even inadvertently.

Household Use Exemption

A natural person who uses a hazardous substance lawfully, without negligence, and for personal or domestic purposes near their home is exempt. The exemption covers residents, unpaid helpers, and employees of the resident, so long as the use was consistent with normal household activity.³

Prospective Purchaser Consent Decrees

If you want to buy property you already know is contaminated, MTCA offers a way to avoid inheriting the cleanup liability. A prospective purchaser consent decree is a court-approved settlement between the buyer and the state. To qualify, the buyer must not already be a PLP at the site, must provide substantial new resources to facilitate the cleanup, must show a legal commitment to purchase or redevelop the property, and the deal must serve a substantial public benefit. The buyer also pays Ecology’s costs for negotiating and overseeing the agreement, starting with a deposit equal to 25 percent of the estimated total.⁴ Ecology suggests about 90 days to negotiate, though complex sites take longer.

When You Must Report a Release

Property owners and operators who discover a release of hazardous substances that could threaten human health or the environment must report it to Ecology within 90 days of discovery.⁵ Releases from regulated underground storage tanks have a much shorter clock: 24 hours.⁶

The obligation starts when you become aware of the release, not when you decide to begin cleanup. The list of reportable substances is broad: petroleum products, heavy metals, solvents, and other chemicals found in soil or groundwater. Ecology’s own guidance acknowledges that no published list is exhaustive. If a release could pose a threat, report it.⁵ Reports go through Ecology’s Environmental Report Tracking System and can be submitted verbally or in writing.⁷

How a Cleanup Proceeds

Washington cleanups generally run on one of two tracks: a formal process supervised by Ecology under a legal agreement or order, or a voluntary path where the owner conducts the work and seeks Ecology’s feedback afterward.

Formal Cleanups

Where Ecology takes an active role, the agency may enter an agreed order negotiated with the PLPs, issue an enforcement order requiring cleanup, or pursue a consent decree approved by a court.⁸ Noncompliance with an enforcement order can trigger penalties and expanded cost liability.

The technical work follows WAC 173-340-350. A remedial investigation defines the nature, extent, and distribution of contamination.⁹ A feasibility study then weighs cleanup alternatives against criteria including protectiveness, permanence, cost, long-term effectiveness, and technical feasibility. Ecology prepares a draft cleanup action plan setting out the chosen remedy, cleanup standards, compliance points, schedule, and any institutional controls. Public notice and a comment period of at least 30 days must precede approval of a cleanup action plan, an agreed order, or a consent decree.¹⁰

Voluntary Cleanup Program

Owners who prefer to manage their own cleanup can work through Ecology’s Voluntary Cleanup Program. The standard track has no application fee; participants pay a portion of Ecology’s review and assistance costs. An expedited track is available for faster turnaround, but it requires paying all of Ecology’s costs plus a nonrefundable application fee, along with a thorough remedial investigation report and cleanup schedule submitted upfront.¹¹

Owners can also clean up fully independently, with no Ecology involvement, but they must report the completed work to Ecology within 90 days of finishing.¹² The risk is that Ecology may later disagree with the methods or standards used, leaving the owner without the protection of an agency-approved plan.

No Further Action Determination

When a site meets all MTCA requirements, Ecology issues a No Further Action opinion. The site is removed from the Contaminated Sites List and added to the No Further Action Sites List.¹³ More than 240 contaminated sites across Washington have reached this status using model remedies.¹⁴ An NFA letter is the clearest signal to future buyers and lenders that a property has been properly addressed.

Residual Contamination and Deed Restrictions

Not every cleanup removes all contamination. When hazardous substances remain above applicable cleanup levels after remediation, WAC 173-340-440 requires institutional controls to protect human health and prevent interference with the cleanup action.¹⁵ Controls can include physical barriers like fences, restrictions on property use, maintenance requirements for engineered systems like caps or groundwater barriers, and public education measures such as posted notices.

The main legal mechanism is a restrictive covenant recorded with the county where the property sits. The covenant runs with the land and binds all future owners. It must prohibit activities that could interfere with the cleanup, prevent releases of contained hazardous substances, and require the owner to notify Ecology before conveying any interest in the site. Any sale, lease, or easement must include notice of the covenant, and the owner must ensure that leases are consistent with the restrictions.¹⁵

If you are buying property with residual contamination, these covenants will directly affect what you can do with it. A site cleaned to industrial standards may carry a covenant that prohibits residential use entirely. Checking for recorded environmental covenants before closing is essential.

State Liens and Cost Recovery

When the state spends money cleaning up a site, Ecology can get it back. Under RCW 70A.305.060, if the state incurs unreimbursed remedial action costs on real property, Ecology can file a lien against the property. The lien takes priority over nearly all other claims, including most mortgages and security interests. Only local property tax assessments and mortgages recorded before the lien or notice of intent to conduct remedial action outrank it. The lien amount is capped at the costs the state actually incurred.³

Because liability is joint and several, a PLP that pays more than its fair share can pursue contribution against other PLPs. Much of the real litigation under MTCA happens here, among responsible parties fighting over percentages, and the outcome depends on evidence of each party’s relative share of the contamination.

How MTCA Fits with Federal Superfund

MTCA runs alongside the federal Comprehensive Environmental Response, Compensation, and Liability Act, commonly called Superfund. For the most serious sites, EPA may lead under CERCLA. For lower-risk sites, EPA generally defers to Washington. CERCLA Section 128(b) contains an enforcement bar that limits EPA action at eligible response sites being addressed under a qualifying state program like MTCA.¹⁶ For sites not on the National Priorities List, a state-supervised MTCA cleanup generally satisfies federal expectations and reduces the chance of a second round of federal enforcement.

How Cleanups Are Funded

MTCA’s cleanup programs are primarily funded by Washington’s Hazardous Substance Tax, the largest single source of environmental cleanup funding in the state. The tax applies to the first person or business to take possession of a hazardous substance in Washington.¹⁷ For non-liquid petroleum products and other hazardous substances, the rate is 0.7 percent of the wholesale value. For liquid petroleum products measured by the barrel, the rate is $1.49 per barrel for the period from July 1, 2026, through June 30, 2027.¹⁸

Revenue flows into three Model Toxics Control accounts. For liquid petroleum, 60 percent goes to the Operating Account, 25 percent to the Capital Account, and 15 percent to the Stormwater Account. Revenue from other hazardous substances goes into the Capital Account.¹⁷ Those accounts fund Ecology’s direct cleanup work and support grants to local governments addressing legacy contamination, including both oversight remedial action grants for ongoing projects¹⁹ and independent remedial action grants for sites that have already reached NFA status through the voluntary program.²⁰ These grants carry much of the brownfield redevelopment work, where former industrial properties would otherwise sit idle.

1
Washington State Legislature. RCW 70A.305.040 – Liability of Persons
2
Washington State Department of Ecology. Toxics Cleanup Program Procedure 500A – Identification of Potentially Liable Persons
3
Washington State Legislature. Chapter 70A.305 RCW – Hazardous Waste Cleanup, Model Toxics Control Act
4
Washington State Department of Ecology. Toxics Cleanup Program Policy 520B
5
Washington State Department of Ecology. Policy 300 Site Discovery – Reporting Releases
6
Washington State Office of Regulatory Innovation and Assistance. Reporting Requirements for Contaminated Sites and Releases Under MTCA
7
Washington State Department of Ecology. Statewide Environmental Reports Tracking System
8
Washington State Department of Ecology. Cleanup Process
9
Washington State Legislature. WAC 173-340-350 – Remedial Investigation and Feasibility Study
10
Washington State Legislature. WAC 173-340-600 – Public Notice and Participation
11
Washington State Department of Ecology. Voluntary Cleanup Program
12
Governor’s Office for Regulatory Innovation and Assistance. Cleaning Up a Contaminated Site Under the Model Toxics Control Act
13
Washington State Department of Ecology. Before You Apply
14
Washington State Department of Ecology. No Further Actions
15
Washington State Legislature. WAC 173-340-440
16
US EPA. State Response Programs
17
Washington State Department of Ecology. Hazardous Substance Tax
18
Washington Department of Revenue. Hazardous Substance Tax
19
Washington State Department of Ecology. Oversight Remedial Action Grants and Loans
20
Washington State Department of Ecology. Independent Remedial Action Grants