Public water system record
Nacimiento Water Company
Serves Oak Shores, San Luis Obispo County, CA · 2,181 people served
Federal records show 21 health-based violations and 13 monitoring/reporting issues for Nacimiento Water Company in the last ten years. The most serious issue in this window was a Haloacetic Acids (HAA5) violation that EPA lists as archived, not resolved.
System profile
Source water
Surface water
ZIP
93426
EPA system ID
CA4010027
- Health-based violations, last 10 years
- 21
- Resolved
- 20
- Unresolved
- 0
- Archived by EPA
- 1
- Any acute record
- No
- Monitoring issues, last 10 years
- 13
Key facts
- Nacimiento Water Company draws water from 1 surface water intake.
- Highest measured level in the last 10 years: Haloacetic Acids (HAA5), 0.66 mg/L, federal limit 0.06 mg/L (11 times the limit), 2024.
- Most recent formal enforcement: compliance order (no penalty) by California, January 2025.
- Record on file since 1992, with 13 health-based violations before October 19, 2016.
- Lead pipe inventory: 0 lead and 0 unknown out of 671 service lines.
Check whether Nacimiento Water Company 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 |
|---|---|---|---|---|
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.66 mg/L, federal limit 0.06 mg/L (11 times the limit)
|
220 | Oct 1, 2024 |
Archived
Violation period ended. EPA no longer counts it toward current compliance, but no fix was formally recorded.
|
No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.102 mg/L, federal limit 0.06 mg/L (1.7 times the limit)
|
220 | Apr 1, 2023 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.1 mg/L, federal limit 0.08 mg/L (1.3 times the limit)
|
220 | Apr 1, 2023 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.102 mg/L, federal limit 0.06 mg/L (1.7 times the limit)
|
220 | Jan 1, 2023 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.105 mg/L, federal limit 0.08 mg/L (1.3 times the limit)
|
220 | Jan 1, 2023 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.083 mg/L, federal limit 0.06 mg/L (1.4 times the limit)
|
220 | Oct 1, 2022 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.083 mg/L, federal limit 0.08 mg/L (at or just above the limit)
|
220 | Oct 1, 2022 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.072 mg/L, federal limit 0.06 mg/L (1.2 times the limit)
|
220 | Jul 1, 2022 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.091 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Jul 1, 2022 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.07 mg/L, federal limit 0.06 mg/L (1.2 times the limit)
|
220 | Jul 1, 2020 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.079 mg/L, federal limit 0.06 mg/L (1.3 times the limit)
|
220 | Apr 1, 2019 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.08 mg/L, federal limit 0.06 mg/L (1.3 times the limit)
|
220 | Apr 1, 2019 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.086 mg/L, federal limit 0.06 mg/L (1.4 times the limit)
|
220 | Jan 1, 2019 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.085 mg/L, federal limit 0.06 mg/L (1.4 times the limit)
|
220 | Jan 1, 2019 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.084 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Jan 1, 2019 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.081 mg/L, federal limit 0.08 mg/L (at or just above the limit)
|
220 | Jan 1, 2019 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.083 mg/L, federal limit 0.06 mg/L (1.4 times the limit)
|
220 | Oct 1, 2018 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.063 mg/L, federal limit 0.06 mg/L (1.1 times the limit)
|
220 | Oct 1, 2018 | Resolved | No |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.107 mg/L, federal limit 0.06 mg/L (1.8 times the limit)
|
220 | Jul 1, 2018 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.087 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
220 | Jan 1, 2017 | Resolved | No |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.092 mg/L, federal limit 0.08 mg/L (1.2 times the limit)
|
220 | Oct 1, 2016 | Resolved | No |
Monitoring and reporting issues
Since October 2016Missed tests or reports, not contaminants found above a limit.
| Issue | Start date | Status |
|---|---|---|
|
Consumer Confidence Rule
OTHER
|
Jul 1, 2024 |
Active
Enforcement action in place
|
|
Lead and Copper Rule
Monitoring and reporting
|
Oct 1, 2023 | Resolved |
|
Haloacetic Acids (HAA5)
Monitoring and reporting
|
Apr 1, 2023 | Resolved |
|
Total Trihalomethanes (TTHMs)
Monitoring and reporting
|
Apr 1, 2023 | Resolved |
|
Lead and Copper Rule
Monitoring and reporting
|
Jan 1, 2023 |
Active
Enforcement action in place
|
|
Bromate
Monitoring and reporting
|
Jul 1, 2020 | Resolved |
|
Bromate
Monitoring and reporting
|
Jan 1, 2019 | Resolved |
|
Haloacetic Acids (HAA5)
Monitoring and reporting
|
Jan 1, 2019 | Resolved |
|
Total Trihalomethanes (TTHMs)
Monitoring and reporting
|
Jan 1, 2019 | Resolved |
|
Bromate
Monitoring and reporting
|
Oct 1, 2018 | Resolved |
|
Bromate
Monitoring and reporting
|
Apr 1, 2018 | Resolved |
|
Haloacetic Acids (HAA5)
Monitoring and reporting
|
Apr 1, 2018 | Resolved |
|
Total Trihalomethanes (TTHMs)
Monitoring and reporting
|
Apr 1, 2018 | Resolved |
Full record since 1992
EPA's records for Nacimiento Water Company go back to 1992. Before October 19, 2016 they list 13 health-based violations (13 resolved) and 5 monitoring or reporting violations.
| Violations that began in | Health-based | Monitoring and reporting |
|---|---|---|
| 1990s | 5 | 3 |
| 2000s | 0 | 1 |
| 2010 to October 18, 2016 | 8 | 1 |
| October 19, 2016 to 2019 | 10 | 7 |
| 2020s | 10 | 6 |
Most recent health-based violation before October 19, 2016: Total Trihalomethanes (TTHMs), began October 2016, Resolved.
Show all 13 health-based violations before October 19, 2016
| Contaminant | Start date | Status |
|---|---|---|
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.092 mg/L, federal limit 0.08 mg/L (1.2 times the limit)
|
Oct 1, 2016 | Resolved |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.099 mg/L, federal limit 0.08 mg/L (1.2 times the limit)
|
Jul 1, 2016 | Resolved |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.073 mg/L, federal limit 0.06 mg/L (1.2 times the limit)
|
Jul 1, 2016 | Resolved |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.088 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
Apr 1, 2016 | Resolved |
|
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.084 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
|
Jan 1, 2016 | Resolved |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.066 mg/L, federal limit 0.06 mg/L (1.1 times the limit)
|
Oct 1, 2015 | Resolved |
|
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.061 mg/L, federal limit 0.06 mg/L (at or just above the limit)
|
Apr 1, 2012 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Oct 1, 2010 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Mar 1, 1995 | Resolved |
|
Surface Water Treatment Rule
Treatment technique failure
|
Jun 1, 1994 | Resolved |
|
Surface Water Treatment Rule
Treatment technique failure
|
Jul 1, 1993 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Dec 1, 1992 | Resolved |
|
Surface Water Treatment Rule
Treatment technique failure
|
Dec 1, 1992 | Resolved |
Enforcement actions
California regulators took 25 formal enforcement actions against Nacimiento Water Company between 2002 and 2025, filed as 27 records in EPA's data. The most recent was a compliance order (no penalty) in January 2025.
| Date | By | Action | Violations covered |
|---|---|---|---|
| Jan 30, 2025 | California | Compliance order (no penalty) | 1 violation (1 health-based): Haloacetic Acids (HAA5) |
| Nov 19, 2024 | California | Compliance order (no penalty) | 1 violation: Consumer Confidence Rule |
| Dec 15, 2023 | California | Compliance order (no penalty) | 1 violation: Lead and Copper Rule |
| Aug 17, 2023 | California | Compliance order (no penalty) | 4 violations (2 health-based): Total Trihalomethanes (TTHMs), Haloacetic Acids (HAA5) |
| May 1, 2023 | California | Compliance order (no penalty) | 2 violations (2 health-based): Total Trihalomethanes (TTHMs), Haloacetic Acids (HAA5) |
| Feb 3, 2023 | California | Compliance order (no penalty) | 2 violations (2 health-based): Haloacetic Acids (HAA5), Total Trihalomethanes (TTHMs) |
| Nov 3, 2022 | California | Compliance order (no penalty) | 2 violations (2 health-based): Haloacetic Acids (HAA5), Total Trihalomethanes (TTHMs) |
| Oct 13, 2020 | California | Compliance order (no penalty) | 2 violations (1 health-based): Haloacetic Acids (HAA5), Bromate |
| Aug 20, 2019 | California | Compliance order (no penalty) | 2 violations (2 health-based): Haloacetic Acids (HAA5) |
| Jun 13, 2019 | California | Compliance order (no penalty) | 4 violations (4 health-based): Haloacetic Acids (HAA5), Total Trihalomethanes (TTHMs) |
| May 8, 2019 | California | Compliance order (no penalty) | 3 violations: Haloacetic Acids (HAA5), Bromate, Total Trihalomethanes (TTHMs) |
| Feb 22, 2019 | California | Compliance order (no penalty) | 3 violations (2 health-based): Haloacetic Acids (HAA5), Bromate |
| Nov 28, 2018 | California | Compliance order (no penalty) | 1 violation (1 health-based): Haloacetic Acids (HAA5) |
| Aug 16, 2018 | California | Compliance order (no penalty) | 3 violations: Total Trihalomethanes (TTHMs), Haloacetic Acids (HAA5), Bromate |
| Apr 6, 2017 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Trihalomethanes (TTHMs) |
| Jan 17, 2017 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Trihalomethanes (TTHMs) |
| Dec 29, 2016 | California | Compliance order (no penalty) | 2 violations (2 health-based): Haloacetic Acids (HAA5), Total Trihalomethanes (TTHMs) |
| Aug 11, 2016 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Trihalomethanes (TTHMs) |
| May 20, 2016 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Trihalomethanes (TTHMs) |
| Jan 13, 2016 | California | Compliance order (no penalty) | 1 violation (1 health-based): Haloacetic Acids (HAA5) |
| Sep 24, 2012 | California | Compliance order (no penalty) | 1 violation (1 health-based): Haloacetic Acids (HAA5) |
| Sep 21, 2012 | California | Compliance order (no penalty) | 1 violation: Bromate |
| Feb 16, 2012 | California | Compliance order (no penalty) | 1 violation: Lead and Copper Rule |
| Dec 22, 2010 | California | Compliance order (no penalty) | 1 violation (1 health-based): Total Coliform |
| Mar 29, 2002 | California | Compliance order (no penalty) | 1 violation: Lead and Copper Rule |
What the violations mean
Haloacetic Acids (HAA5)
13 incidentsHaloacetic acid byproducts exceeded the federal limit
Long-term exposure to HAAs may increase cancer risk
Total Trihalomethanes (TTHMs)
8 incidentsDisinfection byproduct levels exceeded the federal limit
Long-term TTHM exposure may increase bladder cancer risk
Where the water comes from
Nacimiento Water Company draws water from 1 surface water intake.
Annual water quality report
Nacimiento Water Company 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