Alachlor (Lasso) in drinking water
1,265 active public water systems in 42 states had a Alachlor (Lasso) violation in the past three years, and 63 had one in the latest quarter of EPA's data.
You are on Tapcensus, an independent guide to the EPA compliance records of every public water system in the United States. This page explains Alachlor (Lasso) and lists the water systems whose records include a related violation. It does not show measured levels.
Is Alachlor (Lasso) 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
Alachlor is a chloroacetanilide herbicide sold under the trade name Lasso, used primarily on corn and soybeans. It remains in limited use in the United States. Alachlor is moderately mobile in soil and can leach into groundwater and enter surface water through agricultural runoff, particularly in the Midwest.
Health effects
Chronic exposure to alachlor is associated with eye, liver, kidney, and spleen damage. EPA classifies it as a probable human carcinogen (Group B2) based on animal studies showing nasal tumors. Long-term exposure above the MCL is the primary concern; children may be more susceptible to carcinogenic effects.
The standard and what a violation means
EPA limit: 0.002 mg/L (2 ppb).
Water systems with a Alachlor (Lasso) 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 | In violation, latest quarter |
|---|---|---|---|
| Pennsylvania | 213 | 3% | 8 |
| New York | 119 | 1% | 1 |
| Texas | 115 | 2% | 0 |
| Oklahoma | 94 | 7% | 0 |
| Oregon | 73 | 3% | 3 |
| Illinois | 60 | 1% | 12 |
| Washington | 44 | 1% | 8 |
| Colorado | 38 | 2% | 4 |
| Montana | 37 | 2% | 1 |
| Idaho | 36 | 2% | 3 |
| Indiana | 32 | 1% | 2 |
| West Virginia | 32 | 4% | 4 |
| Connecticut | 31 | 1% | 1 |
| Utah | 29 | 3% | 1 |
| Michigan | 28 | 0% | 1 |
| Alabama | 26 | 5% | 0 |
| California | 26 | 0% | 1 |
| Alaska | 25 | 2% | 0 |
| Wyoming | 24 | 3% | 1 |
| Vermont | 22 | 2% | 3 |
| Missouri | 20 | 1% | 1 |
| Wisconsin | 18 | 0% | 0 |
| Nevada | 16 | 3% | 0 |
| Iowa | 15 | 1% | 0 |
| Arizona | 13 | 1% | 1 |
| Massachusetts | 12 | 1% | 1 |
| Maine | 11 | 1% | 0 |
| North Carolina | 11 | 0% | 1 |
| 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 |
| Ohio | 2 | 0% | 0 |
| Tennessee | 2 | 0% | 0 |
| Florida | 1 | 0% | 0 |
| Kentucky | 1 | 0% | 0 |
| Nebraska | 1 | 0% | 0 |
| New Hampshire | 1 | 0% | 0 |
Largest water systems with a Alachlor (Lasso) 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 Alachlor (Lasso), including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Alachlor (Lasso) 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.