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State file — WA

Underground storage tanks in Washington

16,732 registered facilities · 8,601 tanks in service · 2,983 leak records · 2,730 open cleanup cases (EPA UST Finder snapshot, 2018–2021 state data).

16,732UST facilities
8,601tanks in service
39,919closed tanks
2,983leak records
2,730open cases
5%cases closed / NFA

Washington runs 11.8 tanks in service per 10,000 residents (population 7,311,450). 139 of its 2,983 reported releases have reached No Further Action. The regulator of record is the WA Ecology UST Program, which holds the live registration and case files.

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By county

CountyFacilitiesTanks in serviceLeak recordsOpen cases
Adams County191711110
Asotin County661933
Benton County3782213333
Chelan County3261391313
Clallam County2841484539
Clark County6414447873
Columbia County431411
Cowlitz County3562065855
Douglas County924344
Ferry County561392
Franklin County311143109
Garfield County35811
Grant County4721881818
Grays Harbor County3581457368
Island County115651818
Jefferson County124582525
King County3,9322,1181,0881,041
Kitsap County4522649385
Kittitas County189984038
Klickitat County108431916
Lewis County3651958886
Lincoln County1881597
Mason County1791063227
Okanogan County193922010
Pacific County93442525
Pend Oreille County602544
Pierce County1,606859306280
San Juan County534999
Skagit County3922028483
Skamania County551533
Snohomish County1,163805251236
Spokane County1,1895039055
Stevens County160572016
Thurston County5313437164
Wahkiakum County16711
Walla Walla County2761021616
Whatcom County551334125118
Whitman County307562828
Yakima County826344161110

Frequently asked questions

How many underground storage tanks are in Washington?

The EPA UST Finder snapshot lists 16,732 registered UST facilities in Washington, with 8,601 tanks in service and 39,919 closed or removed tanks across 39 countys.

How many tank leaks have been reported in Washington?

2,983 releases are on record statewide. 139 (5%) were closed with No Further Action; 2,730 cleanup cases remained open in the snapshot.

Which Washington county has the most underground storage tanks?

By facility count: King (3,932), Pierce (1,606), Spokane (1,189), Snohomish (1,163), Yakima (826). Use the county pages for tank and leak detail, or screen any specific address free at https://tankcheckusa.site/.