Underground Storage Tank Owners and Operators in the state of California will be faced with a difficult decision come December 31st, 2025. Senate Bill #445 requires single-walled tank owners and operators to permanently close or replace Underground Storage Tanks containing hazardous substances. Operators that refuse to make the changes needed to comply may be red-tagged by the Unified Program Agency (UPA) or the State Water Resource Board, preventing fuel deliveries and dispensing.