PlainWater
Counties → Washington

Mason County, Washington

Water Systems
241
Population Served
78,167
Total Violations
10,829
780 health-based
PFAS Detected
1
of 4 tested

Violation Analysis

97.1%
Systems with Violations
44.9
Avg Violations per System
7.2%
Health-Based Violations

Water Source Types

GW
50 systems (21%)

PFAS Contamination

4
Systems Tested
1
PFAS Detected
25.0%
Detection Rate

PFAS (per- and polyfluoroalkyl substances) are persistent chemicals found in drinking water. The EPA has set enforceable limits for several PFAS compounds under UCMR5 monitoring.

Compliance Snapshot

Mason Washington water systems by violation status, EPA SDWIS records.

No violations on record (1) One or more violations (49)

Violation history is cumulative, many flagged systems have already returned to compliance. Detail pages show per-system context.

Water Systems

System Name Population Violations PFAS
Shelton City Of 17,575 108 Clean
Belfair Water District 1 4,432 151 -
Lake Cushman System 5 3,675 58 Detected
Twanoh State Park 3,173 32 -
Belfair State Park 2,411 32 -
Timberlake Community Club Inc 2,337 29 -
Washington Corrections Center 2,223 73 -
Alderbrook Water Co 2,154 14 -
Lake Limerick Water 2,148 422 -
Lakeland Village Water 2,120 21 -
Hoodsport 1,853 51 -
Shorecrest Estates Water Co 1,321 71 -
North Mason High School 1,300 368 -
Beards Cove 1,100 18 -
Potlatch State Park 1,055 13 -
Fawn Lake Maintenance Comm 1,044 138 -
Lake Cushman System 3 917 23 -
Pioneer School District 903 39 -
Lynch Cove 721 21 -
Jarrell Cove State Park 715 21 -
Union 700 25 -
Oak Park 695 61 -
Sand Hill Elementary 650 239 -
Twanoh Falls Beach Club 481 116 -
Schafer State Park 465 25 -
Hartstene Pointe 460 20 -
Allyn Shopping Center 414 3 -
Paradise Estates 403 45 -
Ridge Motorsports Park 403 0 -
Port of Allyn 397 14 -
Hood Canal 368 50 -
Tahuya River Valley Water District 367 281 -
Hiapark 360 10 -
Lake Arrowhead 343 10 -
Emerald Lake 331 16 Clean
Port of Shelton Johns Prairie 328 25 -
Rustlewood 322 33 -
Collins Lake Community Club 321 40 -
Treasure Island Country Club 321 24 -
Taylor Station 314 21 -
Maggie Lake Water District 287 120 -
Colony Surf Water Supply 285 37 -
Port of Shelton Sanderson Field 283 23 -
View Ridge Heights 271 23 -
Mary M Knight School 270 35 -
Southside Elementary School 260 181 -
Grapeview School 257 38 -
Union Food Mart 255 13 -
Island Lake Manor 233 32 -
Sunset Beach 224 262 -

Other Counties in Washington

King County
217 systems · 3,193,095 served · 20,636 violations
Pierce County
359 systems · 1,138,508 served · 14,826 violations
Snohomish County
170 systems · 947,238 served · 8,193 violations
Spokane County
164 systems · 621,798 served · 9,829 violations
Clark County
72 systems · 615,931 served · 9,864 violations
Thurston County
322 systems · 395,780 served · 24,330 violations

Drinking Water Guides

Frequently Asked Questions

How many water violations are in Mason County? ▼
Mason County has 10,829 total drinking water violations across 241 water systems, of which 780 are health-based violations. 97.1% of systems have at least one violation.
How many people get water from Mason County systems? ▼
Water systems in Mason County serve approximately 78,167 people through 241 public water systems.
Has PFAS been detected in Mason County water? ▼
Of 4 water systems tested for PFAS in Mason County, 1 had PFAS detected (25.0% detection rate).
What types of water sources supply Mason County? ▼
Water systems in Mason County use GW (50 systems) as their primary water sources.
Are health-based violations serious? ▼
Health-based violations indicate that drinking water exceeded Maximum Contaminant Levels (MCLs) set by the EPA or failed treatment technique requirements. 7.2% of Mason County's violations are health-based. Not all violations indicate immediate health risk, but they require corrective action.
Data Sources & Methodology

Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.

Violations are categorized as health-based (Maximum Contaminant Level exceedances, treatment technique failures) or monitoring/reporting violations. Not all violations indicate an immediate health risk.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.