TTHM (Total Trihalomethanes) violations in Iowa
71 active public water systems in Iowa had a TTHM (Total Trihalomethanes) violation in the past three years, 1 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 |
|---|---|---|---|---|
|
Jefferson Water Department Jefferson · Greene County |
4,182 | 1 | 0 | |
|
Sioux City Water Supply Sioux City · Woodbury County |
85,791 | 1 | 0 | |
|
Rock Valley Water Supply Rock Valley · Sioux County |
4,059 | 1 | 0 | |
|
Xenia Rwd (woodward) Woodward · Dallas County |
3,465 | 1 | 0 | |
|
West Branch Water Works West Branch · Cedar County |
2,509 | 1 | 0 | |
|
Traer Municipal Water Plant Traer · Tama County |
1,583 | 2 | 0 | |
|
Slater Muni Water Dept Slater · Story County |
1,548 | 2 | 1 | |
|
Bedford Water Works Bedford · Taylor County |
1,533 | 2 | 0 | |
|
Lone Tree Muni Water System Lone Tree · Johnson County |
1,357 | 2 | 0 | |
|
Lake Ridge, Incorporated Iowa City · Johnson County |
1,300 | 4 | 2 | |
|
Griswold Water Supply Griswold · Cass County |
1,008 | 1 | 0 | |
|
Baxter Water Supply Baxter · Jasper County |
1,002 | 2 | 1 | |
|
Danville Water Supply Danville · Des Moines County |
923 | 2 | 0 | |
|
Armstrong Water Supply Armstrong · Emmet County |
918 | 3 | 0 | |
|
Modern Manor, INC Iowa City · Johnson County |
915 | 5 | 2 | |
|
Maxwell Water Department Maxwell · Story County |
859 | 1 | 0 | |
|
Iowa Premium LLC Tama · Tama County |
841 | 1 | 0 | |
|
Prestage Foods of Iowa Eagle Grove · Wright County |
800 | 1 | 0 | |
|
Crescent Water Supply Crescent · Pottawattamie County |
778 | 2 | 0 | |
|
Dayton Municipal Water Supply Dayton · Webster County |
772 | 1 | 0 | |
|
Western Hills (mobile) Estates Coralville · Johnson County |
760 | 3 | 1 | |
|
Stratford Muni Water Dept Stratford · Hamilton County |
707 | 1 | 0 | |
|
Woodward Resource Center Woodward · Boone County |
700 | 2 | 1 | |
|
Olin Water Supply Olin · Jones County |
651 | 1 | 0 | |
|
Fonda Water Supply Fonda · Pocahontas County |
636 | 1 | 0 | |
|
Terrace Heights Dubuque · Dubuque County |
548 | 1 | 0 | |
|
Zearing Water Department Zearing · Story County |
528 | 3 | 0 | |
|
Humeston Water Plant Humeston · Wayne County |
465 | 3 | 1 | |
|
Klemme Water Works Klemme · Hancock County |
441 | 1 | 0 | |
|
Salem Water Supply Salem · Henry County |
396 | 2 | 1 | |
|
Andrew Water Supply Andrew · Jackson County |
380 | 1 | 0 | |
|
Plymouth Water Supply Plymouth · Cerro Gordo County |
378 | 5 | 1 | |
|
Massena Water Supply Massena · Cass County |
364 | 5 | 1 | |
|
Holy Cross Water Supply Holy Cross · Dubuque County |
356 | 2 | 0 | |
|
Sunrise Village Mobile Home PK Iowa City · Johnson County |
340 | 3 | 1 | |
|
Diagonal Water Department Diagonal · Ringgold County |
338 | 5 | 2 | |
|
Mystic Water Supply Mystic · Appanoose County |
322 | 1 | 0 | |
|
Ponderosa Park MHP Davenport · Scott County |
320 | 1 | 0 | |
|
Mingo Water Department Mingo · Jasper County |
316 | 1 | 0 | |
|
Fertile Municipal Water Fertile · Worth County |
306 | 3 | 0 | |
|
Libertyville Water Works Libertyville · Jefferson County |
304 | 2 | 0 | |
|
Delta Water Supply Delta · Keokuk County |
264 | 1 | 0 | |
|
Riverton Water Works Riverton · Fremont County |
250 | 2 | 0 | |
|
Kellerton Water Supply Kellerton · Ringgold County |
247 | 1 | 0 | |
|
Chelsea Water Supply Chelsea · Tama County |
229 | 4 | 2 | |
|
Dedham Water Supply Dedham · Carroll County |
221 | 3 | 2 | |
|
Coulter Water Supply Coulter · Franklin County |
219 | 3 | 0 | |
|
Oakville Water Supply Oakville · Louisa County |
200 | 3 | 0 | |
|
Jamaica Water Supply Jamaica · Guthrie County |
195 | 3 | 0 | |
|
Moorhead Water Supply Moorhead · Monona County |
189 | 2 | 0 |
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 Iowa 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.