Tap Truth EPA drinking water records, in plain English

Public water system record

Patterson Water System

Serves an area of St. Mary Parish, LA that includes Patterson · 8,456 people served

Federal records show 5 health-based violations and 1 monitoring/reporting issue for Patterson Water System in the last ten years. The most serious issue in this window was a Total Trihalomethanes (TTHMs) violation that EPA lists as archived, not resolved.

  • LA1101006
  • PATTERSON
  • LA
  • 8,456 served

System profile

Source water Surface water
ZIP 70392
EPA system ID LA1101006

Verify this system on EPA ECHO →

Health-based violations, last 10 years
5
Resolved
0
Unresolved
0
Archived by EPA
5
Any acute record
No
Monitoring issues, last 10 years
1

Key facts

  • Patterson Water System draws water from 1 surface water intake.
  • Highest measured level in the last 10 years: Total Trihalomethanes (TTHMs), 0.091 mg/L, federal limit 0.08 mg/L (1.1 times the limit), 2025.
  • Most recent formal enforcement: compliance order (no penalty) by Louisiana, January 1995.
  • Record on file since 1992, with 8 health-based violations before October 19, 2016.
  • Lead pipe inventory: 0 lead and 0 unknown out of 2,567 service lines.

Check whether Patterson Water System serves your address

Address suggestions by Mapbox

Health-based violations

Since October 2016

Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.

Contaminant Rule family Start date Status Acute
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.091 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
 220 Oct 1, 2025 Archived
Violation period ended. EPA no longer counts it toward current compliance, but no fix was formally recorded.
 No
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.083 mg/L, federal limit 0.08 mg/L (at or just above the limit)
 220 Jul 1, 2025 Archived
Violation period ended. EPA no longer counts it toward current compliance, but no fix was formally recorded.
 No
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.082 mg/L, federal limit 0.08 mg/L (at or just above the limit)
 220 Apr 1, 2025 Archived
Violation period ended. EPA no longer counts it toward current compliance, but no fix was formally recorded.
 No
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.082 mg/L, federal limit 0.08 mg/L (at or just above the limit)
 220 Jan 1, 2025 Archived
Violation period ended. EPA no longer counts it toward current compliance, but no fix was formally recorded.
 No
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.081 mg/L, federal limit 0.08 mg/L (at or just above the limit)
 220 Oct 1, 2024 Archived
Violation period ended. EPA no longer counts it toward current compliance, but no fix was formally recorded.
 No

Monitoring and reporting issues

Since October 2016

Missed tests or reports, not contaminants found above a limit.

Issue Start date Status
Public Notice
OTHER
 Apr 29, 2025 Resolved

Full record since 1992

EPA's records for Patterson Water System go back to 1992. Before October 19, 2016 they list 8 health-based violations (3 resolved, 5 archived by EPA without a recorded fix) and 3 monitoring or reporting violations.

Violations that began in Health-based Monitoring and reporting
1990s 5 1
2000s 1 2
2010 to October 18, 2016 2 0
2020s 5 1

Most recent health-based violation before October 19, 2016: Total Coliform, began February 2010, Resolved.

Show all 8 health-based violations before October 19, 2016
Contaminant Start date Status
Total Coliform
Contaminant limit exceeded
 Feb 1, 2010 Resolved
Total Coliform
Contaminant limit exceeded
 Jan 1, 2010 Resolved
Total Coliform (acute)
Contaminant limit exceeded
 Sep 15, 2000 Archived
Surface Water Treatment Rule
Treatment technique failure
 Nov 1, 1994 Archived
Surface Water Treatment Rule
Treatment technique failure
 Apr 1, 1994 Archived
Surface Water Treatment Rule
Treatment technique failure
 Jan 1, 1994 Resolved
Surface Water Treatment Rule
Treatment technique failure
 Dec 1, 1993 Archived
Surface Water Treatment Rule
Treatment technique failure
 Jul 1, 1993 Archived

Enforcement actions

Louisiana regulators took 2 formal enforcement actions against Patterson Water System between 1994 and 1995. The most recent was a compliance order (no penalty) in January 1995.

Date By Action Violations covered
Jan 25, 1995 Louisiana Compliance order (no penalty) 1 violation (1 health-based): Surface Water Treatment Rule
Nov 28, 1994 Louisiana Signed compliance agreement 1 violation (1 health-based): Surface Water Treatment Rule

What the violations mean

Total Trihalomethanes (TTHMs)

5 incidents

Disinfection byproduct levels exceeded the federal limit

Long-term TTHM exposure may increase bladder cancer risk

Where the water comes from

Patterson Water System draws water from 1 surface water intake. It also has emergency connections to St Mary Water & Sewer Comm #3 and St Mary Parish W&S #2 Bayou Vista.

Emergency or part-time connections to

Annual water quality report

Patterson Water System must give its customers an annual water quality report (Consumer Confidence Report) by July 1, with the levels its tests found in the previous year.

Where the state allows it, systems serving fewer than 10,000 people may publish the report in a local newspaper or news site instead of mailing it, and must provide a copy on request.

Find a posted report with EPA's Consumer Confidence Report search

Testing your own water

To test the water at your tap, or a private well this record does not cover, use a laboratory certified for drinking water by Louisiana.

Certified drinking water labs by state EPA guidance for private wells