Public water system record
Twain Harte Valley MWC
Serves Twain Harte, Tuolumne County, CA · 202 people served
Federal records show 1 health-based violation and 3 monitoring/reporting issues for Twain Harte Valley MWC in the last ten years, including an unresolved LEAD AND COPPER RULE REVISIONS violation.
System profile
- Health-based violations, last 10 years
- 1
- Resolved
- 0
- Unresolved
- 1
- Any acute record
- No
- Monitoring issues, last 10 years
- 3
Key facts
- Twain Harte Valley MWC draws water from 1 surface water intake.
- Record on file since 1980, with 0 health-based violations before October 19, 2016.
- Lead pipe inventory: 0 lead and 38 unknown out of 106 service lines.
Check whether Twain Harte Valley MWC serves your address
Health-based violations
Since October 2016Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.
| Contaminant | Rule family | Start date | Status | Acute |
|---|---|---|---|---|
|
LEAD AND COPPER RULE REVISIONS
Treatment technique failure
|
350 | Oct 17, 2024 | Active | No |
Monitoring and reporting issues
Since October 2016Missed tests or reports, not contaminants found above a limit.
| Issue | Start date | Status |
|---|---|---|
|
LEAD AND COPPER RULE REVISIONS
RPT
|
Jul 2, 2025 | Active |
|
Revised Total Coliform Rule
Monitoring violation
|
Apr 1, 2025 | Resolved |
|
LEAD AND COPPER RULE REVISIONS
RPT
|
Oct 17, 2024 | Active |
Full record since 1980
EPA's records for Twain Harte Valley MWC go back to 1980. Before October 19, 2016 they list no health-based violations and 26 monitoring or reporting violations.
| Violations that began in | Health-based | Monitoring and reporting |
|---|---|---|
| 1980s | 0 | 26 |
| 2020s | 1 | 3 |
What the violations mean
LEAD AND COPPER RULE REVISIONS
1 incidentThe system did not complete a treatment step or action that the LEAD AND COPPER RULE REVISIONS requires (a treatment technique violation).
The utility had to notify customers about this violation.
Where the water comes from
Twain Harte Valley MWC draws water from 1 surface water intake.
Annual water quality report
Twain Harte Valley MWC 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.
Systems serving 500 or fewer people may meet the rule by telling customers the report is available on request, so you may need to ask Twain Harte Valley MWC for a copy.
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 California.
Certified drinking water labs by state EPA guidance for private wells