Mason, WA
Transparent derived index from EPA TRI / SDWIS / Superfund extracts: not an official EPA rating. Fixed caps: facilities ≤25 pts (50+ = max), log10 releases ≤25 pts, Superfund ≤25 pts (5/site), health-violation systems ≤15 pts (3/system), high-chemical facilities ≤10 pts. Bands: High ≥60, Moderate ≥30. See methodology.
Environmental data for Mason in Washington · Population: 66,968
TRI sites such as Sierra Pacific Industries - Shelton; SDWIS systems such as SHELTON CITY OF; BELFAIR WATER DISTRICT 1; LAKE CUSHMAN SYSTEM 5 anchor Mason, WA's EPA extract. Derived burden score 16/100 (Low Risk) uses fixed national caps on density, log release volume, Superfund count, and health-flagged systems - not an official EPA rating.
Health-flagged SDWIS rows in Mason include SQUAXIN CONSOLIDATED; HARTSTENE POINTE; LAKEWOOD HEIGHTS, while Sierra Pacific Industries - Shelton leads reported TRI pounds among local Form R filers. AQS median AQI 21 / peak 73 in 2024.
Burden score 16/100 (Low Risk) is the only weighted composite on this page. The tables below list every TRI facility, SDWIS system, and Superfund site EPA has on record for Mason -- not just the names called out above -- reproducing the disclosure history as filed, not a current-safety verdict. Extract current as of 2026-08-25.
Air Quality History (2020–2024)
EPA Air Quality Index (AQI) data showing how many days per year fall into each air quality category.
| Year | Good | Moderate | Unhealthy (SG) | Max AQI |
|---|---|---|---|---|
| 2024 | 341 (93%) | 25 | 0 | 73 |
| 2023 | 313 (86%) | 49 | 1 | 106 |
| 2022 | 302 (83%) | 60 | 3 | 125 |
| 2021 | 339 (94%) | 22 | 0 | 70 |
| 2020 | 312 (87%) | 36 | 2 | 397 |
Source: EPA Air Quality System (AQS) Annual AQI by County AQI categories: Good (0-50), Moderate (51-100), Unhealthy for Sensitive Groups (101-150), Unhealthy (151-200), Very Unhealthy (201-300), Hazardous (301+)
For real-time air quality readings and pollutant breakdowns in Washington, see the EPA's AirNow.gov.
Water Systems (103)
| System | System pop (SDWIS) | Violations |
|---|---|---|
| SHELTON CITY OF | 15,089 | 0 |
| BELFAIR WATER DISTRICT 1 | 4,432 | 0 |
| LAKE CUSHMAN SYSTEM 5 | 3,675 | 0 |
| TIMBERLAKE COMMUNITY CLUB INC | 2,337 | 0 |
| WASHINGTON CORRECTIONS CENTER | 2,223 | 0 |
| ALDERBROOK WATER CO | 2,154 | 0 |
| LAKE LIMERICK WATER | 2,148 | 0 |
| LAKELAND VILLAGE WATER | 2,120 | 0 |
| SUNNYSLOPE | 2,112 | 0 |
| HOODSPORT | 1,853 | 0 |
| SQUAXIN CONSOLIDATED | 1,500 | 4 |
| Shorecrest Estates Water Co | 1,321 | 0 |
| SKOKOMISH | 1,150 | 0 |
| BEARDS COVE | 1,100 | 0 |
| FAWN LAKE MAINTENANCE COMM | 1,044 | 0 |
| CAPE GEORGE COLONY CLUB INC | 1,022 | 0 |
| LAKE CUSHMAN SYSTEM 3 | 917 | 0 |
| UNION | 700 | 0 |
| OAK PARK | 695 | 0 |
| TWANOH FALLS BEACH CLUB | 481 | 0 |
| HARTSTENE POINTE | 460 | 4 |
| PORT OF ALLYN | 397 | 0 |
| DELPHI | 381 | 0 |
| HOOD CANAL | 368 | 0 |
| Tahuya River Valley Water District | 367 | 0 |
| LAKE LUCINDA COMMUNITY CLUB | 360 | 0 |
| LAKE ARROWHEAD | 343 | 0 |
| EMERALD LAKE | 331 | 0 |
| RUSTLEWOOD | 322 | 0 |
| COLONY SURF WATER SUPPLY | 297 | 0 |
| MAGGIE LAKE WATER DISTRICT | 287 | 0 |
| VIEW RIDGE HEIGHTS | 271 | 0 |
| ISLAND LAKE MANOR | 233 | 0 |
| COUGAR RIDGE | 216 | 0 |
| RIVERHILL HOMEOWNERS ASSN | 215 | 0 |
| TRAILS END WATER DISTRICT | 211 | 0 |
| WOODLAND MANOR | 192 | 0 |
| VUECREST | 191 | 0 |
| HIGHLAND PARK | 180 | 0 |
| LAKEWOOD HEIGHTS | 170 | 3 |
| PIRATES COVE COUNTRY CLUB | 168 | 0 |
| RAINBOW LAKE | 168 | 0 |
| CANAL MUTUAL WATER | 167 | 0 |
| LAUREL PARK COMMUNITY LLC | 165 | 0 |
| BELLWOOD A | 163 | 0 |
| BEACON POINT COMMUNITY CLUB | 158 | 0 |
| SHADOWOOD | 154 | 2 |
| Mission Creek Tracts | 150 | 0 |
| HIDDEN HAVEN MOBILE HOME PARK | 149 | 0 |
| DAYTON TRAILS | 148 | 0 |
| EVERGREEN MOBILE HOMEOWNERS CO-OP | 140 | 0 |
| BAYSHORE | 130 | 0 |
| HOLIDAY BEACH WATER SUPPLY | 130 | 0 |
| ENCHANTED FIRS MOBILE ESTATES | 120 | 0 |
| TWANOH HEIGHTS COMMUNITY CLUB | 118 | 0 |
| CHERRY PARK | 111 | 0 |
| ARCADIA ESTATES | 110 | 0 |
| HIGHLAND ESTATES | 110 | 0 |
| POTLATCH BEACH MUTUAL | 109 | 0 |
| SHORE HILL | 101 | 0 |
| BAY EAST | 96 | 0 |
| PENINSULA MOBILE PARK | 92 | 0 |
| SPRINGWOOD | 90 | 0 |
| HARSTENE RETREAT | 88 | 0 |
| COOPER POINT WATER CO | 85 | 0 |
| MINERVA TERRACE | 85 | 0 |
| WONDERLAND WATER COMPANY | 82 | 0 |
| LAKE LAWRENCE MOBILE HOME PARK | 80 | 0 |
| EDGEWATER BEACH WATER CO | 78 | 0 |
| WESTERN AIRPARK | 78 | 0 |
| TWANOH TERRACE WATER CO | 75 | 0 |
| MADRONA PARK | 73 | 0 |
| RAE LAKE | 73 | 0 |
| RHODODENDRON PLACE | 70 | 0 |
| TIGER LAKE TERRACE TRACTS | 70 | 0 |
| WOODLAND PARK UTILITY ASSN | 68 | 0 |
| HOLIDAY ACRES | 65 | 0 |
| Sylvan Terrace Condominiums | 64 | 0 |
| ORCHARD BEACH COMMUNITY | 64 | 0 |
| PEBBLE BEACH | 64 | 0 |
| HAMMA RIDGE | 63 | 0 |
| PARKWOOD APARTMENTS | 60 | 2 |
| NEW PINE ACRES | 60 | 0 |
| CEDAR PARK | 53 | 1 |
| BOLDUC COMMUNITY | 51 | 0 |
| AGATE BEACH | 48 | 0 |
| LITTLE MISSION CREEK | 47 | 0 |
| Ripplewood Tracts | 45 | 0 |
| Allyn Carey | 45 | 0 |
| CANYONWOOD BEACH WATER SUPPLY | 43 | 0 |
| LAKEWOOD MANOR ASSOCIATION | 42 | 0 |
| MOUNTAIN VIEW | 41 | 0 |
| OLYMPIC VISTA CLUB COMMUNITY WATER | 41 | 0 |
| PRINE DRIVE APARTMENTS | 40 | 0 |
| MOUNTAIN SHORES CC | 40 | 0 |
| VIEWCREST BEACH | 40 | 0 |
| KAMILCHE POINT COMMUNITY CLUB | 39 | 0 |
| RAINIER VIEW | 37 | 0 |
| SHERMAN HILL | 37 | 0 |
| BEL AIRE COVE | 32 | 0 |
| VALLEY VIEW MOBILE HOME PARK | 30 | 0 |
| ELMA EVERGREEN VILLAGE | 29 | 0 |
| Queen Anne Water Works LLC | 28 | 0 |
TRI Facilities (1)
| # | Facility | Total Releases |
|---|---|---|
| 1 | Sierra Pacific Industries - Shelton | 0 lbs |
Cities in Mason (9)
Frequently Asked Questions
What is the environmental risk level in Mason, Washington? ▼
Are there Superfund sites in Mason? ▼
How many toxic release facilities are in Mason? ▼
What is the air quality in Mason? ▼
Is the drinking water safe in Mason? ▼
What environmental agencies cover Mason? ▼
What does this county environmental profile show?
This county environmental profile rolls up EPA Toxics Release Inventory facility reports, Safe Drinking Water Information System public-water-system filings, and Superfund National Priorities List sites for the county boundary defined by the U.S. Census Bureau. Facility counts reflect facilities with a reporting address inside the county, not where downstream environmental effects may be observed. Population figures are from the most recent Census ACS 5-year estimate. The county detail page is updated whenever the upstream EPA programs publish revised data; see the methodology page for the documented ingest cadence and the editorial choices governing how aggregations are computed.
Read our methodology - how this data is sourced, computed, and verified.