UST Check → counties → Washington → Mason
Underground storage tanks & leak sites in Mason County, WA
Every figure below is from EPA UST Finder — the EPA-compiled national registry of state-reported underground storage tanks — county aggregates as published by EPA.
179registered tank facilities
106open tanks
397closed tanks
32leak incidents on record
27cleanups still open
27 leak cleanups in
Mason County are still open — the state has not closed the case.
An open cleanup near a property you're buying or lending on is a findable, checkable fact: it appears in a
per-address screen with distance and the registry record.
Largest registered facilities
By open-tank count, from the facility-level registry. Every fact is attributed to the EPA record (linked ID); something wrong — use the correction path in the footer and we'll fix or remove it promptly.
| Facility | City | Open / closed tanks | Status | EPA record |
|---|---|---|---|---|
| SHELTON BULK PLANT | Shelton | 5 / 0 | Open UST(s) | WA69261716 |
| JAMES FOOD MART | Shelton | 4 / 0 | Open UST(s) | WA71359371 |
| AM/PM GAS STATION | Shelton | 4 / 0 | Open UST(s) | WA64487875 |
| ALDERBROOK COUNTRY STORE | Union | 4 / 0 | Open UST(s) | WA35386124 |
| SHELTON TEXACO | Shelton | 4 / 0 | Open UST(s) | WA61696173 |
| AIRPORT GROCERY | Shelton | 4 / 0 | Open UST(s) | WA72961678 |
| BELFAIR GROCERY | Belfair | 4 / 0 | Open UST(s) | WA19915125 |
| SANDY'S DELI | Belfair | 4 / 0 | Open UST(s) | WA16929485 |
Open leak cleanups — most recently reported
| Site | City | Reported | Substance | EPA record |
|---|---|---|---|---|
| MASON COUNTY TRANSPORTATION COOP | SHELTON | not reported | Petroleum-Other | WA5731 |
| BURLINGTON NORTHERN RR | SHELTON | not reported | Petroleum-Other | WA8382 |
| SHELTON SHELL | SHELTON | not reported | Non-Halogenated Solvents | WA7062 |
| MASON COUNTY FIRE DISTRICT 5 STATION 5 | SHELTON | not reported | Base/Neutral/Acid Organics | WA3072 |
| TWANOH STATE PARK | UNION | not reported | Petroleum-Diesel | WA7957 |
| Jackpot 467 | SHELTON | not reported | Benzene | WA8480 |
What this means if you're buying or lending here
- "Closed" ≠ clean. A closed tank was taken out of service per the registry — many were closed without soil testing, especially before the late 1990s.
- The registry is incomplete by design. Tanks removed before 1986 and most residential heating-oil tanks were never registered. A county with 179 registered facilities has an unknown number of unregistered ones.
- Open cleanups are the headline. 27 cases in this county are still open; contamination may still be under investigation or remediation — distance from a specific parcel is what matters, and that's a per-address question.
Screen a specific property
This page covers the county. A purchase or loan decision needs the registry around one address: registered tanks at the parcel, every facility within 500 and 1,500 ft, leak cleanups with status and distance — each line cited to the official record.
Screen an address — $49 How it worksThis is a screen of EPA-registered tank and leak records, not an environmental site assessment. State registries are incomplete by design: tanks removed before 1986 and most residential heating-oil tanks were never registered, so a clean screen cannot prove the absence of a tank. "Closed" means a tank was taken out of service per the registry — it does not certify that no contamination remains.
source: EPA UST Finder EPA data vintage 2024-12-04 computed 2026-06-12