TTHM (Total Trihalomethanes) violations in Washington
212 active public water systems in Washington had a TTHM (Total Trihalomethanes) violation in the past three years, 22 of them in the latest quarter of EPA's data. What TTHM (Total Trihalomethanes) is and why it matters.
Systems with a TTHM (Total Trihalomethanes) violation
Latest quarter first, then largest first| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Kalispel Usk · County |
330 | 7 | 0 | |
|
Kens Korner Island County |
300 | 2 | 0 | |
|
Mariners Cove Beach Club INC Island County |
300 | 2 | 0 | |
|
Driftwood Heights Association Island County |
298 | 1 | 0 | |
|
Camano Hills Water Company INC Island County |
286 | 1 | 0 | |
|
Whidbey Shores Water System Island County |
262 | 2 | 0 | |
|
Percie Road Water Association Whatcom County |
250 | 3 | 0 | |
|
Washtucna Water Department Adams County |
250 | 4 | 0 | |
|
Holden Village Chelan County |
228 | 3 | 0 | |
|
Wsu Iarec Prosser Benton County |
224 | 1 | 0 | |
|
Juniper Beach Water District Island County |
213 | 2 | 0 | |
|
Steptoe Water/sewer District Whitman County |
210 | 2 | 0 | |
|
Country Place Mobile Home Park Island County |
200 | 2 | 0 | |
|
Polnell Shores Comm Org INC Island County |
200 | 1 | 0 | |
|
Harris Custer Estates Water Assn Island County |
194 | 2 | 0 | |
|
Sun Harbor Water District #3 Walla Walla County |
187 | 2 | 0 | |
|
Parkshore Estates Mason County |
183 | 1 | 0 | |
|
Ranch Pierce County |
183 | 1 | 0 | |
|
Long Point Water Company INC Island County |
182 | 2 | 0 | |
|
Pine Terrace Water Association Island County |
181 | 1 | 0 | |
|
Fieldstone Memory Care Bainbridge Kitsap County |
175 | 3 | 0 | |
|
Meadow Ridge Snohomish County |
175 | 2 | 0 | |
|
Cape San Juan Water District San Juan County |
164 | 2 | 0 | |
|
Fobes Water District Snohomish County |
156 | 3 | 0 | |
|
Shadowood Mason County |
154 | 1 | 0 | |
|
Alps Mobile Home Park Yakima County |
150 | 2 | 0 | |
|
Rutsatz Road Deming · County |
150 | 5 | 0 | |
|
Sulwhanon Sverson · County |
150 | 5 | 0 | |
|
Sunlight Shores Country Club Island County |
150 | 1 | 0 | |
|
Wagon Wheel Island County |
150 | 1 | 0 | |
|
Martell Mobile Manor Kitsap County |
143 | 2 | 0 | |
|
Valley High Park Island County |
141 | 1 | 0 | |
|
Lakeview Terrace Island County |
140 | 3 | 0 | |
|
Lake Grove Water Association Island County |
134 | 2 | 0 | |
|
Campo Hacienda Island County |
123 | 4 | 0 | |
|
Hoh Tribe Forks · County |
120 | 9 | 1 | |
|
Elgerwood Maintenance Association Island County |
112 | 2 | 0 | |
|
Bush Point Trac Park Island County |
111 | 2 | 0 | |
|
Idlewood Community Island County |
111 | 2 | 0 | |
|
Holmes Harbor Water CO Island County |
110 | 1 | 0 | |
|
Roza Heights Water Assn Benton County |
110 | 1 | 0 | |
|
Woodland Estates Island County |
106 | 1 | 0 | |
|
Ski Hill Domestic Water Association Chelan County |
102 | 3 | 0 | |
|
Shore Hill Mason County |
101 | 3 | 0 | |
|
Fairway Estates INC Island County |
100 | 2 | 0 | |
|
Warner Flats Domestic Water CO INC Chelan County |
100 | 2 | 0 | |
|
MT ST Helens National Volcanic Monu Clark County |
95 | 4 | 0 | |
|
Pheasant Farm Acres Island County |
95 | 3 | 0 | |
|
Blackmans Lake Water District Snohomish County |
93 | 2 | 0 | |
|
Beachwood Water Company Island County |
90 | 3 | 1 |
About this data
A system is counted once if any of its violations in the past three years involved TTHM (Total Trihalomethanes), including monitoring and reporting lapses. Rules violated and status in the table are for the whole system, not TTHM (Total Trihalomethanes) alone.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The Washington records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet.