Methoxychlor in drinking water
1,232 active public water systems in 40 states had a Methoxychlor violation in the past three years, and 62 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 Methoxychlor and lists the water systems whose records include a related violation. It does not show measured levels.
Is Methoxychlor 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
Methoxychlor was a broad-spectrum organochlorine insecticide used as a lower-toxicity alternative to DDT on livestock, pets, vegetables, and crops. Its EPA registration was voluntarily canceled in 2003. Though less persistent than DDT, it can leach into groundwater from historically treated agricultural soils.
Health effects
Chronic exposure to methoxychlor is associated with reproductive and endocrine disruption — it acts as an estrogen mimic and can interfere with hormone signaling. Liver and kidney effects have been observed in animal studies. Developing fetuses, infants, and individuals with hormonal conditions may be most susceptible.
The standard and what a violation means
EPA limit: 0.04 mg/L (40 ppb).
Water systems with a Methoxychlor 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 | 199 | 3% | 7 |
| New York | 120 | 1% | 1 |
| Texas | 115 | 2% | 0 |
| Oklahoma | 98 | 8% | 0 |
| Oregon | 73 | 3% | 3 |
| Illinois | 59 | 1% | 12 |
| Washington | 44 | 1% | 8 |
| Colorado | 38 | 2% | 4 |
| Montana | 37 | 2% | 1 |
| Idaho | 36 | 2% | 3 |
| West Virginia | 32 | 4% | 4 |
| Connecticut | 31 | 1% | 1 |
| Utah | 29 | 3% | 1 |
| Michigan | 28 | 0% | 1 |
| Indiana | 27 | 1% | 2 |
| California | 26 | 0% | 1 |
| Alaska | 25 | 2% | 0 |
| Alabama | 25 | 4% | 0 |
| Wyoming | 24 | 3% | 1 |
| Vermont | 22 | 2% | 3 |
| Wisconsin | 18 | 0% | 0 |
| Missouri | 16 | 1% | 1 |
| North Carolina | 16 | 0% | 1 |
| Nevada | 16 | 3% | 0 |
| Arizona | 13 | 1% | 1 |
| Massachusetts | 12 | 1% | 1 |
| Maine | 11 | 1% | 0 |
| Rhode Island | 9 | 2% | 0 |
| Minnesota | 8 | 0% | 2 |
| New Jersey | 7 | 0% | 2 |
| Maryland | 3 | 0% | 1 |
| South Dakota | 3 | 0% | 0 |
| Virginia | 3 | 0% | 0 |
| North Dakota | 2 | 1% | 0 |
| New Mexico | 2 | 0% | 0 |
| Kentucky | 1 | 0% | 0 |
| Nebraska | 1 | 0% | 0 |
| New Hampshire | 1 | 0% | 0 |
| Ohio | 1 | 0% | 0 |
| Tennessee | 1 | 0% | 0 |
Largest water systems with a Methoxychlor 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 | |
|
Tucson City of Tucson · Pima County |
732,906 | 3 | 0 | |
|
Pittsburgh Water & Sewer Auth Allegheny County |
520,000 | 3 | 0 | |
|
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 Methoxychlor, including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Methoxychlor 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.