Public water system record
Ponderosa Basin Mutual Wtr Co
Serves an area of Mariposa County, CA · 798 people served
Federal records show no health-based violations and 1 monitoring/reporting issue for Ponderosa Basin Mutual Wtr Co in the last ten years. At least one of these issues remains unresolved.
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
- Ponderosa Basin Mutual Wtr Co draws water from 6 wells.
- Most recent formal enforcement: compliance order (no penalty) by California, July 2025.
- Record on file since 1992, with 8 health-based violations before October 19, 2016.
- Lead pipe inventory: 0 lead and 0 unknown out of 314 service lines.
Check whether Ponderosa Basin Mutual Wtr Co 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 |
|---|---|---|
|
Lead and Copper Rule
Monitoring and reporting
|
Oct 1, 2024 |
Active
Enforcement action in place
|
Full record since 1992
EPA's records for Ponderosa Basin Mutual Wtr Co go back to 1992. Before October 19, 2016 they list 8 health-based violations (8 resolved) and 6 monitoring or reporting violations.
| Violations that began in | Health-based | Monitoring and reporting |
|---|---|---|
| 1990s | 3 | 1 |
| 2000s | 4 | 4 |
| 2010 to October 18, 2016 | 1 | 1 |
| 2020s | 0 | 1 |
Most recent health-based violation before October 19, 2016: Total Coliform, began July 2013, Resolved.
Show all 8 health-based violations before October 19, 2016
| Contaminant | Start date | Status |
|---|---|---|
|
Total Coliform
Contaminant limit exceeded
|
Jul 1, 2013 | Resolved |
|
Total Coliform (acute)
Contaminant limit exceeded
|
Aug 1, 2007 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Feb 1, 2007 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Jun 1, 2006 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Oct 1, 2004 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Jul 1, 1998 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Jan 1, 1993 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Oct 1, 1992 | Resolved |
Enforcement actions
California regulators took 7 formal enforcement actions against Ponderosa Basin Mutual Wtr Co between 1998 and 2025. The most recent was a compliance order (no penalty) in July 2025.
| Date | By | Action | Violations covered |
|---|---|---|---|
| Jul 17, 2025 | California | Compliance order (no penalty) | 1 violation: Lead and Copper Rule |
| Aug 31, 2013 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Coliform |
| Sep 12, 2007 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Coliform |
| Apr 9, 2007 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Coliform |
| Aug 17, 2006 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Coliform |
| Nov 17, 2004 | California | Compliance order (no penalty) | 2 violations (1 health-based): Total Coliform |
| Sep 1, 1998 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Coliform |
Where the water comes from
Ponderosa Basin Mutual Wtr Co draws water from 6 wells.
Annual water quality report
Ponderosa Basin Mutual Wtr Co 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 California.
Certified drinking water labs by state EPA guidance for private wells