Hazardous Substance Tax

In 1988, more than 85% of Washington voters said “yes” to a tax on hazardous substances to fund environmental cleanup and pollution prevention work. The Hazardous Substance Tax (HST) is the largest source of funding for environmental protection, restoration, and cleanup activity across Washington. This work is essential for protecting public health and the environment.

The Hazardous Substance Tax supports about 40% of Ecology’s base operating budget and provides over $100 million in capital funds each biennium. We pass most of the capital funds through to local governments, tribes, and other qualified entities. Other agencies also receive money from the tax.

Hazardous Substance Tax funds at work

You can find more examples of how we use this money in our reports to the legislature.

Man in protective equipment stands at the base of a steep hill of dirt and trash. There is an excavator halfway up.

Cleaning up a landfill in Washington’s newest state park

The old Eatonville landfill is on property now surrounded by Nisqually State Park. In 2025, workers removed about 30,000 cubic yards of waste and contaminated soil from the old landfill. Afterward, they replanted the steep slope down to the wetland and the Mashel River. Weyerhaeuser and the Town of Eatonville are responsible for the cleanup. Ecology grants paid for the town’s part of the cleanup costs.

Two smiling people empty new foam blocks from a large bag into a pit.

Helping small businesses move to safer products

In the past, foam blocks used in gymnastics facilities were made with flame-retardant chemicals. These chemicals can be absorbed into the skin or get into the air as toxic dust. In this 2024 pilot project, Ecology helped gyms safely dispose of their old blocks, deep clean, and buy safer alternatives. After minimal downtime, the gyms re-opened as safer places for children to play and train. The program will open to more gyms starting in 2026.

Two young people in high-vis vests and hardhats wade in a stream. One is taking notes.

Leveling the playing field

Washington Conservation Corps (WCC) provides training, hands-on experience, and mentorship to young adults and military veterans. Government agencies, Tribes, and non-profits partner with WCC crews to do environmental projects — and usually pay 75% of the cost. With HST funding, we added five crews who serve without cost-sharing, so underserved areas can access WCC help. In 2023, 77 of 97 HST funded projects were in economically distressed or rural counties. Sixty-seven were on Tribal land with Tribal partners. WCC crews installed 3,000 miles of fencing to protect waterways from livestock, removed invasive plants, and restored habitats for fish and wildlife.

Helping homeowners

The Onsite Sewage System Regional Loan Program helps low-income homeowners replace failing septic systems. The average repair costs $30,000, and there aren’t many other sources of loans. Nearly 40% of borrowers are low-income households who likely would not have had access to financing without this program. Replacing these old systems helps protect groundwater and health.

About the tax

The tax applies to more than 8,000 hazardous substances, including petroleum products. The person or business that takes “first possession” of a hazardous substance within Washington is responsible for paying the tax. As of July 1, 2025, the tax rate is:

$1.48 per barrel (42 gallons) for liquid petroleum products (such as gasoline)
0.7% of the wholesale value ($7 per $1,000) for other taxable hazardous substances

For information on how to pay the tax and a list of taxed substances, visit the Washington State Department of Revenue’s Hazardous Substance Tax webpage.

Where the money goes

The first $50 million per biennium from the tax on liquid petroleum products is deposited into the state Motor Vehicle Fund. This money can only be used for transportation stormwater projects. The rest of the revenue from liquid petroleum products goes into the Model Toxic Control Act accounts:

60% into the Model Toxics Control Operating Account
25% into the Model Toxics Control Capital Account
15% into the Model Toxics Control Stormwater Account

Hazardous Substance Tax revenue from other hazardous substances, including non-liquid petroleum products and some pesticides and chemicals, goes into the Model Toxics Control Capital Account.

More than 95% of the money deposited in the MTCA accounts comes from the Hazardous Substance Tax. The other 5% is from fees, cost recovery, fines, and other sources.

Hazardous Substance Tax