Tox of the Town
The December 31, 2025, Deadline to Remove Single-Walled Underground Storage Tanks in California Has Passed. Are You Facing Civil Penalties?
by Kaylinn Charnley and Sedina L. Banks
If you own or operate a facility in California with single-walled underground storage tanks ("USTs"), the deadline to comply with the state's mandatory removal requirement has come and gone. Owners and operators who were unable to meet the December 31, 2025, deadline are now facing potential enforcement actions and significant civil penalties.
What Is the Single-Walled UST Removal Mandate?
Pursuant to Senate Bill 445, passed by the California Legislature in 2014, and its related regulations, all single-walled USTs in California were required to be "Permanently Closed" (meaning either physically removed or closed in place under the supervision of a Unified Program Agency) by December 31, 2025.
The cost, logistics, and complexity of UST removal meant that not every facility was able to come into compliance before the deadline. For those businesses, the consequences are now arriving.
Why Does This Matter?
Owners and operators of single-walled USTs who did not meet the December 31, 2025, deadline are facing civil penalties from $500 to $5,000 per UST, per day, per violation.
We have already seen enforcement actions brought against owners and operators for failing to timely remove or close their single-walled USTs.
How Is the Mandate Enforced?
UST-related violations are typically enforced by local agencies called Unified Program Agencies ("UPAs"), which work under the supervision and authority of the California State Water Resources Control Board. UPAs are responsible for issuing Notices of Violation and imposing civil penalties for UST violations.
UPAs have been enforcing UST violations with a heavy hand. If your single-walled USTs have not yet been removed or closed in place, you may have already received, or may soon receive, a Notice of Violation from your local UPA.
Typically, UPAs wait until after the single-walled USTs at a facility are removed or closed in place before calculating proposed civil penalties and issuing a notice regarding a pending administrative enforcement action. Emptying a single-walled UST is not enough to avoid enforcement; the penalties continue accruing each day that the tanks remain, even if they are empty.
What Should You Do If You Missed the Deadline?
If you were unable to comply with the single-walled UST removal mandate, there are steps you can take now to protect yourself.
First, take action on removal or closure in place as quickly as possible. The longer the tanks remain, the greater the exposure.
Second, understand that receiving a Notice of Violation is not the end of the road. There is a process for responding to enforcement actions and negotiating with your local Unified Program Agency, and that process matters enormously in determining the final penalty you may pay.
Third, seek experienced legal counsel. Navigating the administrative enforcement process and negotiating with a UPA requires knowledge of environmental law, the regulatory framework under SB 445, and the practical norms of how these agencies operate.
