Simazine in drinking water
1,261 active public water systems in 41 states had a Simazine violation in the past three years, and 60 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 Simazine and lists the water systems whose records include a related violation. It does not show measured levels.
Is Simazine 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.
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What it is and where it comes from
Simazine is a triazine herbicide used to control broadleaf weeds and grasses in orchards, vineyards, turf, and some crops. It remains in use in the United States and is chemically related to atrazine. Simazine is mobile in soil and readily leaches into groundwater, particularly in sandy soils.
Health effects
Chronic exposure to simazine is associated with potential cancer risk; EPA classifies it as a possible human carcinogen (Group C) based on animal studies. Blood and nervous system effects have also been observed in animal studies. Long-term exposure at levels above the MCL is the primary concern for public water system violations.
The standard and what a violation means
EPA limit: 0.004 mg/L (4 ppb).
Water systems with a Simazine 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 | 195 | 3% | 7 |
| New York | 119 | 1% | 1 |
| Texas | 115 | 2% | 0 |
| Oklahoma | 101 | 8% | 0 |
| Oregon | 72 | 3% | 3 |
| Illinois | 68 | 1% | 10 |
| Washington | 44 | 1% | 8 |
| Colorado | 38 | 2% | 4 |
| Montana | 37 | 2% | 1 |
| Idaho | 36 | 2% | 3 |
| Connecticut | 33 | 1% | 1 |
| Indiana | 32 | 1% | 2 |
| West Virginia | 32 | 4% | 4 |
| Utah | 29 | 3% | 1 |
| Michigan | 28 | 0% | 1 |
| California | 27 | 0% | 1 |
| Alaska | 25 | 2% | 0 |
| Alabama | 25 | 4% | 0 |
| Wyoming | 24 | 3% | 1 |
| Vermont | 22 | 2% | 3 |
| Missouri | 20 | 1% | 1 |
| Wisconsin | 18 | 0% | 0 |
| Nevada | 16 | 3% | 0 |
| Arizona | 15 | 1% | 1 |
| Iowa | 15 | 1% | 0 |
| Massachusetts | 12 | 1% | 1 |
| Maine | 11 | 1% | 0 |
| North Carolina | 11 | 0% | 1 |
| Rhode Island | 9 | 2% | 0 |
| Minnesota | 8 | 0% | 2 |
| New Jersey | 6 | 0% | 2 |
| Maryland | 3 | 0% | 1 |
| South Dakota | 3 | 0% | 0 |
| Virginia | 3 | 0% | 0 |
| North Dakota | 2 | 1% | 0 |
| Ohio | 2 | 0% | 0 |
| Kentucky | 1 | 0% | 0 |
| Nebraska | 1 | 0% | 0 |
| New Hampshire | 1 | 0% | 0 |
| New Mexico | 1 | 0% | 0 |
| Tennessee | 1 | 0% | 0 |
Largest water systems with a Simazine 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 | |
|
Naperville Naperville · DuPage County |
156,406 | 1 | 0 | |
|
Epcor Agua Fria Surprise · Maricopa County |
128,040 | 5 | 0 | |
|
Pasco Water Department Franklin County |
115,102 | 2 | 0 | |
|
Inima USA / Aquaria LLC Dighton · Bristol County |
105,643 | 1 | 0 | |
|
Lehi City Utah County |
93,446 | 2 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved Simazine, including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Simazine 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.