Endothall in drinking water
793 active public water systems in 28 states had a Endothall violation in the past three years, and 41 have one that is still unresolved.
You are on Tapcensus, an independent guide to the EPA compliance records of every public water system in the United States. This page explains Endothall and lists the water systems whose records include a related violation. It does not show measured levels.
Is Endothall in the records for your water system?
Enter a ZIP code, town, or street address to see the water systems that serve your area, their status, and which rules and contaminants appear in their violations.
Enter a ZIP code, town, or street address.
What it is and where it comes from
Endothall is an aquatic and terrestrial herbicide used to control algae, weeds, and grass in irrigation canals, ponds, and lakes. It is still in use in the United States and is applied directly to water bodies for aquatic vegetation management. It degrades relatively quickly in aquatic environments but can appear in source water shortly after application.
Health effects
Short-term exposure above the MCL can cause gastrointestinal irritation and stomach cramps. Chronic exposure is associated with liver, kidney, and gastrointestinal damage in animal studies. EPA has not classified endothall as a human carcinogen. The general population is at risk from water system violations.
The standard and what a violation means
EPA limit: 0.1 mg/L (100 ppb).
Water systems with a Endothall violation, by state
Active public water systems that reported at least one related violation to EPA in the past three years. Each state links to the list of its affected systems.
| State | Systems with violations, 3 yr | Share of active systems | Unresolved |
|---|---|---|---|
| Pennsylvania | 196 | 3% | 8 |
| Oklahoma | 101 | 8% | 0 |
| Oregon | 76 | 3% | 3 |
| Maine | 60 | 3% | 0 |
| Illinois | 49 | 1% | 12 |
| Idaho | 40 | 2% | 3 |
| Colorado | 38 | 2% | 4 |
| California | 28 | 0% | 1 |
| Indiana | 27 | 1% | 2 |
| Alaska | 25 | 2% | 0 |
| Alabama | 25 | 4% | 0 |
| Wyoming | 24 | 3% | 1 |
| Wisconsin | 20 | 0% | 0 |
| Nevada | 16 | 3% | 0 |
| Arizona | 13 | 1% | 1 |
| Massachusetts | 12 | 1% | 1 |
| Montana | 9 | 0% | 0 |
| Washington | 8 | 0% | 1 |
| New Jersey | 6 | 0% | 2 |
| Minnesota | 5 | 0% | 2 |
| New Mexico | 4 | 0% | 0 |
| South Dakota | 3 | 0% | 0 |
| Michigan | 2 | 0% | 0 |
| North Dakota | 2 | 1% | 0 |
| Kansas | 1 | 0% | 0 |
| Kentucky | 1 | 0% | 0 |
| Ohio | 1 | 0% | 0 |
| Tennessee | 1 | 0% | 0 |
Largest water systems with a Endothall violation
The ten biggest systems, by people served, whose records include a related violation in the past three years.
| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Denver Water Board Denver County |
1,287,000 | 3 | 0 | |
|
Pittsburgh Water & Sewer Auth Allegheny County |
520,000 | 3 | 0 | |
|
Gilbert, Town of Gilbert · Maricopa County |
247,600 | 9 | 1 | |
|
Corona, City of Corona · Riverside County |
169,380 | 6 | 0 | |
|
City of Sunnyvale Sunnyvale · Santa Clara County |
157,566 | 5 | 0 | |
|
Epcor Agua Fria Surprise · Maricopa County |
128,040 | 5 | 0 | |
|
Inima USA / Aquaria LLC Dighton · Bristol County |
105,643 | 1 | 0 | |
|
GW Santa Cruz Water CO Maricopa · Pinal County |
84,000 | 7 | 0 | |
|
Flagstaff City of Flagstaff · Coconino County |
79,796 | 5 | 0 | |
|
Foley, Utilities Board of the City of Foley · Baldwin County |
50,919 | 1 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved Endothall, including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Endothall alone. Counts cover active systems in all 50 states and the District of Columbia.
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 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.