Public water system record
Mammoth CWD
Serves Mammoth Lakes, Mono County, CA · 8,234 people served
Federal records show no health-based violations and 2 monitoring/reporting issues for Mammoth CWD 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
- 2
Key facts
- Mammoth CWD draws water from 10 wells and 1 surface water intake (1 of them for emergency, seasonal or other part-time use).
- Most recent formal enforcement: compliance order (no penalty) by California, July 2024.
- Record on file since 1991, with 3 health-based violations before October 19, 2016.
- Lead pipe inventory: 0 lead and 2,708 unknown out of 3,688 service lines.
Check whether Mammoth CWD 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 |
|---|---|---|
|
Total Trihalomethanes (TTHMs)
Monitoring and reporting
|
Jan 1, 2023 | Resolved |
|
Haloacetic Acids (HAA5)
Monitoring and reporting
|
Jan 1, 2023 | Resolved |
Full record since 1991
EPA's records for Mammoth CWD go back to 1991. Before October 19, 2016 they list 3 health-based violations (3 resolved) and no monitoring or reporting violations.
| Violations that began in | Health-based | Monitoring and reporting |
|---|---|---|
| 1990s | 2 | 0 |
| 2010 to October 18, 2016 | 1 | 0 |
| 2020s | 0 | 2 |
Most recent health-based violation before October 19, 2016: Surface Water Treatment Rule, began August 2016, Resolved.
Show all 3 health-based violations before October 19, 2016
| Contaminant | Start date | Status |
|---|---|---|
|
Surface Water Treatment Rule
Treatment technique failure
|
Aug 1, 2016 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Sep 1, 1992 | Resolved |
|
Surface Water Treatment Rule
Treatment technique failure
|
Jun 1, 1991 | Resolved |
Enforcement actions
California regulators took 2 formal enforcement actions against Mammoth CWD between 2016 and 2024. The most recent was a compliance order (no penalty) in July 2024.
| Date | By | Action | Violations covered |
|---|---|---|---|
| Jul 25, 2024 | California | Compliance order (no penalty) | 2 violations: Total Trihalomethanes (TTHMs), Haloacetic Acids (HAA5) |
| Oct 31, 2016 | California | Compliance order (no penalty) | 1 violation (1 health-based): Surface Water Treatment Rule |
Where the water comes from
Mammoth CWD draws water from 10 wells and 1 surface water intake (1 of them for emergency, seasonal or other part-time use).
Annual water quality report
Mammoth CWD 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