Underground storage tank (UST) program

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Coronavirus (COVID-19) regulatory update

Please read our letter outlining compliance assistance for UST owners/operators and service providers while under the Governor’s Stay Home – Stay Heathy order and Safe Start plan.

We want everyone to stay safe and healthy, and appreciate your understanding.

Our Underground Storage Tank (UST) program is one of the largest pollution prevention programs at Ecology. Every year, just over 3 billion gallons of fuel are stored underground. We conduct compliance inspections and provide technical assistance to help tank owners prevent leaks and spills.

Program overview

We regulate more than 9,200 tanks at more than 3,400 facilities, including gas stations, industrial and commercial properties, and government-owned properties. We make sure these tanks and their associated piping systems are installed, managed, and monitored to prevent releases into the environment.

Washington’s UST program is federally-approved. This means that state law, not federal law, applies to UST systems in this state. We are federally required to inspect tanks at least every three years.​

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Annual fees
The annual fee for each underground storage tank is:

UST News: May 2020

The underground storage tank program's newsletter is designed to help tank owners and operators keep their tank systems operating safely. 

Sources and causes of releases

View our data on the sources and causes of releases from UST systems in Washington. 

Other storage tanks

You must report any spills or leaks of petroleum or hazardous substances to Ecology, whether or not we regulate the tank. Report releases affecting water or spills of dangerous materials immediately.

Aboveground storage tanks

Ecology does not regulate most above-ground storage tanks (ASTs). These tanks typically hold petroleum products (like heating oil, propane, or diesel) or other potentially hazardous chemicals. Local fire agencies, counties, and/or cities, regulate and permit ASTs, with two exceptions:

Certain ASTs are subject to federal regulations, including:

Home heating oil tanks

We do not regulate any home heating oil tanks, underground or aboveground. For information about home heating oil tanks, contact the Pollution Liability Insurance Agency (1-800-822-3905).