Howell Mountain Mutual Water Company
PWSID: CA2810001
This system has no unresolved violations. The most recent violation on record was 2023-01-01.
This system has more violations on record than 97% of water systems in California.
Violation trend: 1.2 per year over the last 5 years, down from 2.0 per year in the previous 5.
System Details
| Population Served | 1,240 |
| Service Connections | 379 |
| Water Source | Surface Water |
| System Type | Community Water System |
| Owner | Private |
| Status | Active |
| City | Angwin |
| EPA ZIP on File | 94508 |
Lead & Copper Testing
| Contaminant | Level | EPA Action Level | Status |
|---|---|---|---|
| Lead (90th percentile) | 0.0000 mg/L | 0.015 mg/L | Below Action Level |
| Lead (90th percentile) | 0.0000 mg/L | 0.015 mg/L | Below Action Level |
| Lead (90th percentile) | 0.0000 mg/L | 0.015 mg/L | Below Action Level |
Violation History (78 total)
| Contaminant | Violation | Date | Health-Based | Status |
|---|---|---|---|---|
| 2950 | MCL Measured: 82.00 UG/L (limit: 80.00 UG/L) | 2023-01-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 82.00 UG/L (limit: 80.00 UG/L) | 2023-01-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 82.00 UG/L (limit: 80.00 UG/L) | 2023-01-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 82.00 UG/L (limit: 80.00 UG/L) | 2023-01-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 88.00 UG/L (limit: 80.00 UG/L) | 2022-10-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 84.70 UG/L (limit: 80.00 UG/L) | 2022-07-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0830 MG/L (limit: 0.0800 MG/L) | 2021-04-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0830 MG/L (limit: 0.0800 MG/L) | 2021-04-01 | Yes | Acknowledged |
| 2950 | MCL Measured: 0.0830 MG/L (limit: 0.0800 MG/L) | 2021-04-01 | Yes | Returned to Compliance |
| 5000 | MR | 2020-10-01 | Returned to Compliance | |
| 5000 | MR | 2020-10-01 | Returned to Compliance | |
| 5000 | MR | 2020-10-01 | Returned to Compliance | |
| 2950 | MCL Measured: 0.0865 MG/L (limit: 0.0800 MG/L) | 2016-10-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0865 MG/L (limit: 0.0800 MG/L) | 2016-10-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 81.75 UG/L (limit: 80.00 UG/L) | 2016-07-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 81.75 UG/L (limit: 80.00 UG/L) | 2016-07-01 | Yes | Returned to Compliance |
| 1040 | MR | 2015-01-01 | Major | Returned to Compliance |
| 1040 | MR | 2015-01-01 | Major | Returned to Compliance |
| 2950 | MCL Measured: 0.0860 MG/L (limit: 0.0800 MG/L) | 2013-07-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0860 MG/L (limit: 0.0800 MG/L) | 2013-07-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0860 MG/L (limit: 0.0800 MG/L) | 2013-07-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0890 MG/L (limit: 0.0800 MG/L) | 2013-04-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0890 MG/L (limit: 0.0800 MG/L) | 2013-04-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0890 MG/L (limit: 0.0800 MG/L) | 2013-04-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0616 MG/L (limit: 0.0600 MG/L) | 2011-04-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0616 MG/L (limit: 0.0600 MG/L) | 2011-04-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0907 MG/L (limit: 0.0800 MG/L) | 2011-01-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0907 MG/L (limit: 0.0800 MG/L) | 2011-01-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0693 MG/L (limit: 0.0600 MG/L) | 2011-01-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0693 MG/L (limit: 0.0600 MG/L) | 2011-01-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0994 MG/L (limit: 0.0800 MG/L) | 2010-10-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0994 MG/L (limit: 0.0800 MG/L) | 2010-10-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0731 MG/L (limit: 0.0600 MG/L) | 2010-10-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0731 MG/L (limit: 0.0600 MG/L) | 2010-10-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.1044 MG/L (limit: 0.0800 MG/L) | 2010-07-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.1044 MG/L (limit: 0.0800 MG/L) | 2010-07-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0755 MG/L (limit: 0.0600 MG/L) | 2010-07-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0755 MG/L (limit: 0.0600 MG/L) | 2010-07-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0990 MG/L (limit: 0.0800 MG/L) | 2010-04-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0990 MG/L (limit: 0.0800 MG/L) | 2010-04-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0650 MG/L (limit: 0.0600 MG/L) | 2010-04-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0650 MG/L (limit: 0.0600 MG/L) | 2010-04-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.1070 MG/L (limit: 0.0800 MG/L) | 2010-01-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.1070 MG/L (limit: 0.0800 MG/L) | 2010-01-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0816 MG/L (limit: 0.0600 MG/L) | 2010-01-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0816 MG/L (limit: 0.0600 MG/L) | 2010-01-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0706 MG/L (limit: 0.0600 MG/L) | 2009-10-01 | Yes | Returned to Compliance |
| 2456 | MCL Measured: 0.0706 MG/L (limit: 0.0600 MG/L) | 2009-10-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0930 MG/L (limit: 0.0800 MG/L) | 2009-10-01 | Yes | Returned to Compliance |
| 2950 | MCL Measured: 0.0930 MG/L (limit: 0.0800 MG/L) | 2009-10-01 | Yes | Returned to Compliance |
Showing 50 of 78 historical violations.
Understanding This Water System's Record
Howell Mountain Mutual Water Company is a community water system water system that draws from surface water sources and serves a population of 1,240 in Angwin, California. This page shows its complete compliance history as reported to the EPA's Safe Drinking Water Information System (SDWIS), the federal database that tracks every public water system in the United States.
What Do These Violations Mean?
Health-based violations mean the system exceeded an EPA maximum contaminant level (MCL) or failed to provide required treatment. These indicate potential health risks from contaminants like lead, arsenic, bacteria, nitrates, or disinfection byproducts. Non-health-based violations involve monitoring, reporting, or procedural requirements — the system missed a testing deadline or failed to notify customers, but contaminant levels were not necessarily unsafe.
What Should You Do?
Your water utility is required to publish an annual Consumer Confidence Report (CCR) that details test results and any violations. If your system has active health-based violations, consider a certified water filter rated for the specific contaminants involved. The contaminant guides on this site explain health risks and filter options for common pollutants. For the most current results, contact your water utility directly — EPA data can lag weeks or months behind real-time testing.