Public water system record
Tud - Upper Basin Water System
Serves an area of Tuolumne County, CA that includes Twain Harte, Mi-Wuk Village and Mono Vista · 13,280 people served
Federal records show no health-based violations and 1 monitoring/reporting issue for Tud - Upper Basin Water System in the last ten years.
System profile
- Health-based violations, last 10 years
- 0
- Resolved
- 0
- Unresolved
- 0
- Any acute record
- No
- Monitoring issues, last 10 years
- 1
Key facts
- Tud - Upper Basin Water System draws water from 4 wells and 3 surface water intakes (1 of them for emergency, seasonal or other part-time use).
- Record on file since 1996, with 1 health-based violation before October 19, 2016.
- Lead pipe inventory: 0 lead and 0 unknown out of 4,119 service lines.
Check whether Tud - Upper Basin Water System 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.
None since October 2016.
Monitoring and reporting issues
Since October 2016Missed tests or reports, not contaminants found above a limit.
| Issue | Start date | Status |
|---|---|---|
|
Revised Total Coliform Rule
Monitoring violation
|
Apr 1, 2025 | Resolved |
Full record since 1996
EPA's records for Tud - Upper Basin Water System go back to 1996. Before October 19, 2016 they list 1 health-based violation (1 resolved) and no monitoring or reporting violations.
| Violations that began in | Health-based | Monitoring and reporting |
|---|---|---|
| 1990s | 1 | 0 |
| 2020s | 0 | 1 |
Most recent health-based violation before October 19, 2016: Surface Water Treatment Rule, began December 1996, Resolved.
Show the health-based violation before October 19, 2016
| Contaminant | Start date | Status |
|---|---|---|
|
Surface Water Treatment Rule
Treatment technique failure
|
Dec 1, 1996 | Resolved |
Where the water comes from
Tud - Upper Basin Water System draws water from 4 wells and 3 surface water intakes (1 of them for emergency, seasonal or other part-time use). It also buys water from Mi Wuk Village Mut Wtr Co. 1 other community water system buys water from Tud - Upper Basin Water System. 1 other public water system has an emergency connection to Tud - Upper Basin Water System.
Buys water from
- Mi Wuk Village Mut Wtr Co Mi Wuk Village, CA
Community systems that buy water from it
- Sonora Meadows Mutual Wtr Co Sonora, CA
Annual water quality report
Tud - Upper Basin 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.
Systems serving 10,000 or more people must mail or deliver the report to every customer, and from 2027 they must send it twice a year.
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