Mason County, WA
The federal environmental record for Mason County (population 68,389): what is on file, where it is, and what remains open. Sources and retrieval dates are on the methodology page.
0
Superfund NPL sites
0
federal cleanup sites
1
PFAS-detecting water systems
1
TRI facilities
27
open tank releases
Drinking water: PFAS testing
Public water systems serving Mason with at least one PFAS detection under UCMR5. The federal limit for PFOA and PFOS is 4 ng/L; EPA proposed in May 2026 to rescind the limits for the other compounds, which are shown for information.
| System | Highest results | Reading |
|---|---|---|
| LAKE CUSHMAN SYSTEM 5 WA5303529 | PFPeA: 6.3 ng/L PFHxA: 4.6 ng/L | detected |
On a system with detections? Testing and treatment options
Facilities reporting toxic releases (2024)
1 facilities in Mason filed TRI reports for 2024, totalling 0 lb released.
| Facility | City | Top chemicals | Total released |
|---|---|---|---|
| SIERRA PACIFIC INDUSTRIES - SHELTON | SHELTON | Dioxin and dioxin-like compounds | 0 lb |
Underground fuel tanks
EPA's UST Finder records 179 tank facilities in Mason: 106 tanks in service and 397 closed. 32 fuel releases are on record, of which 27 remain open. Open releases are cleanups that have not reached "no further action".
Radon
EPA maps Mason as Zone 3, the lowest predicted indoor radon (under 2 pCi/L average). Radon and air quality are covered in depth on lung.com.
The record for one specific address
County figures blur what matters: distance. The Address Environmental Report runs these same federal datasets against one address and reports every site, tank, polluter and water result around it, with distances, in about a minute.
Get the report - $39