Public water system · LA1101006
ActiveCity of Patterson Water System
At a glance
City of Patterson Water System (PWSID LA1101006) is an active community water system in St. Mary Parish County, Louisiana. It reports serving 8,456 people through 2,591 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 9 are health-based, and the most recent began in January 2026.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
8,456
Service connections
2,591
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does City of Patterson Water System compare with other water systems in St. Mary Parish County?
By EPA's size categories, City of Patterson Water System is a medium system (3,301 to 10,000 people). St. Mary Parish County has 16 active public water systems, and City of Patterson Water System is the 3rd-largest of them by population served. Its population served is about twice the county average of 3,945 people per system, and accounts for 13% of the 63,113 people reported by systems filed under the county. Across Louisiana, the 1,121 active systems average 4,685 people each. Nationally, the average active community water system reports serving 6,703 people, so City of Patterson Water System is about 26% above that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Louisiana has 815 active community water systems, 73% of the state's 1,121 active systems. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 53 Louisiana systems (4.7%) list surface water as their primary source.
Who owns and regulates City of Patterson Water System?
EPA lists City of Patterson Water System as owned by a local government. The LA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 12 of the 16 active systems in St. Mary Parish County (75%) are also owned by a local government.
Does City of Patterson Water System have drinking water violations?
Of the 12 most recent violations in EPA's records, 9 are health-based, and the most recent began in January 2026. The violations listed here began between September 2000 and January 2026. By type: 9 contaminant level above the legal limit and 3 public notice, recordkeeping or other. The contaminant or rule involved most often is Total trihalomethanes (TTHM) (6 of them). EPA lists 7 as archived and 5 as resolved. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2026-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2025-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2025-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2025-04-29 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2025-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2025-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2024-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Archived |
| 2010-02-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2010-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2008-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2004-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2000-09-15 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
The 12 most recent violations in EPA's records, newest first. Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
City of Patterson Water System: frequently asked questions
Who runs City of Patterson Water System?
City of Patterson Water System (PWSID LA1101006) is a community water system owned by a local government. It is regulated by the LA state drinking water program.
How many people does City of Patterson Water System serve?
City of Patterson Water System reports serving 8,456 people through 2,591 service connections in St. Mary Parish County, Louisiana.
Where does City of Patterson Water System get its water?
EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.
Does City of Patterson Water System have any drinking water violations?
Of the 12 most recent violations in EPA's records, 9 are health-based, and the most recent began in January 2026. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is City of Patterson Water System's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. Of the 12 most recent violations in EPA's records, 9 are health-based, and the most recent began in January 2026. For current results, consult the system's annual water quality report, EPA ECHO, or the LA state drinking water program.
Where can I find City of Patterson Water System's water quality report?
As a community water system, City of Patterson Water System must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in St. Mary Parish County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| City of Morgan City Water System | St. Mary Parish | 12,703 | Community | Surface water |
| Water & Sewer Commission 4 of St Mary | St. Mary Parish | 9,709 | Community | Surface water |
| City of Franklin Water Supply | St. Mary Parish | 8,325 | Community | Surface water |
| St Mary Water & Sewer Comm #3 | St. Mary Parish | 7,828 | Community | Surface water |
| St Mary Parish W&S #2 Bayou Vista | St. Mary Parish | 5,379 | Community | Purchased surface water |
| City of Berwick | St. Mary Parish | 5,024 | Community | Purchased surface water |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “City of Patterson Water System, PWSID LA1101006, Louisiana”, https://aquacensus.com/water-systems/louisiana/city-of-patterson-water-system-la1101006 (data as of October 1, 2026).