Community Water System · PWS CA4010017
Golden State Water Company - los Osos
Operator location Hawthorne, California - larger served population (> 3,309) at 5,924 people served; 0 SDWIS violations on record from groundwater sources.
- 5,924
- People served (this PWS)
- 0
- EPA violations (this PWS)
- 0
- Health-based (this PWS)
- 4 PFAS
- UCMR5 (this PWS)
Golden State Water Company - los Osos standing, low SDWIS violation third
5,924 people served (SDWIS) - larger served population (> 3,309). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). UCMR5: middle-third PFAS panel (≤ 4 compounds). Population rank #6,901 of 29,740 among systems serving 500+.
The verdict
Golden State Water Company - los Osos is in the lower third by violation count (0; lower-third violation load (≤ 21 violations)). A low count does not mean the system is unmonitored - monitoring and reporting violations still appear in SDWIS. Population served is large (5,924; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. No violations are on record in this extract. UCMR5 detected 4 PFAS compounds (middle-third PFAS panel (≤ 4 compounds)).
- #6,901 of 29,740
- Population · /systems
- #604 of 1,701
- Population · CA
- 0
- Total EPA violations on record
- 0%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
4 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.
System Details
- System Type
- Community
- Owner Type
- Private
- Connections
- 2,673
- County
- San Luis Obispo
- School/Daycare
- No
- MCL Violations
- 0
- Monitoring Violations
- 0
- Treatment Tech Violations
- 0
Violation Count vs. the National Corpus
Golden State Water Company - los Osos has 0 recorded EPA violations, 0% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 96% carry more. 0% of this system's own violations are health-based (0 of 0), and it ranks #6,901 of 29,740 by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
0 Among the lowest violation counts fewer violations than 96% of 29,740 water systems
the national water-system corpus, bucketed by value
Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS · 2026-05-15
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 8 of 232 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFHxA | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 8/9/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 8/9/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFUnA | 8/9/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHxS | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NMeFOSAA | 8/9/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 8/9/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTrDA | 8/9/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFNA | 8/9/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFTA | 8/9/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| NEtFOSAA | 8/9/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMBA | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 8/9/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHpA | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 8/9/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFEESA | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpS | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeA | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMPA | 8/9/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 8/9/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 8/9/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 8/9/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| HFPO-DA | 8/9/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| ADONA | 8/9/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NFDHA | 8/9/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| NMeFOSAA | 8/9/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| NEtFOSAA | 8/9/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTA | 8/9/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFTrDA | 8/9/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFTA | 8/9/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| NEtFOSAA | 8/9/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| NMeFOSAA | 8/9/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFTrDA | 8/9/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| NFDHA | 4/30/2024 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFMPA | 4/30/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 4/30/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 4/30/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFEESA | 4/30/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 4/30/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHpS | 4/30/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 4/30/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFUnA | 4/30/2024 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFDoA | 4/30/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 4/30/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 4/30/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxS | 4/30/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
Population served record for Golden State Water Company - los Osos
EPA SDWIS lists 5,924 people served and 2,673 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS · California State Water Resources Control Board, Division of Drinking Water
Nationwide peers
0 violations · 5,924 served: nearest cross-state SDWIS matches.
Cross-state systems with similar served population
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Golden State Water Company - los Osos
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in California compares on the same EPA violation measures. California systems
- Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
- Find and compare another public water system by name or PWSID. Search systems
EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.