Los Osos Community Services District
Published drinking-water records and contacts for Los Osos Community Services District. System CA4010016. Review sources and dates; not a real-time water assessment.
- System ID
- CA4010016
- State or territory
- CA
- Published population served
- 7086
- System type (source code)
- CWS
Published records and dates
- PFAS / lithium (EPA UCMR 5): 420 — 2024-01-08 – 2024-07-08
- Lead and copper monitoring summaries: 59 — 1992-01-01 – 2026-12-31
- California DDW laboratory results: 942 — 2026-01-05 – 2026-06-29
Missing records here do not mean the provider did not test. Published records are not a real-time assessment of your tap water.
Published testing results
Selected recent records are shown below. Different sampling locations and dates are not interchangeable. These excerpts are not a complete testing history.
“<” means below the stated reporting limit, not zero. A reported measurement alone is not a safety verdict. Read an example
| Substance | Published result | Reporting limit | Sample date | Sampling location |
|---|---|---|---|---|
| 11Cl-PF3OUdS | < 0.005 µg/L | 0.005 µg/L | 2024-07-08 | 3rd Street Well / EP009 |
| 4:2 FTS | < 0.003 µg/L | 0.003 µg/L | 2024-07-08 | South Bay Upper Aquifer Treated / EP021 |
| 6:2 FTS | < 0.005 µg/L | 0.005 µg/L | 2024-07-08 | 8th Street Well Treated / EP015 |
| 8:2 FTS | < 0.005 µg/L | 0.005 µg/L | 2024-07-08 | 8th Street Upper Well Treated / EP022 |
| 9Cl-PF3ONS | < 0.002 µg/L | 0.002 µg/L | 2024-07-08 | 10th Street Well / EP008 |
| ADONA | < 0.003 µg/L | 0.003 µg/L | 2024-07-08 | Pallisades Well / EP005 |
| HFPO-DA | < 0.005 µg/L | 0.005 µg/L | 2024-07-08 | 10th Street Well / EP008 |
| NEtFOSAA | < 0.005 µg/L | 0.005 µg/L | 2024-07-08 | 8th Street Well Treated / EP015 |
| NFDHA | < 0.02 µg/L | 0.02 µg/L | 2024-07-08 | Pallisades Well / EP005 |
| NMeFOSAA | < 0.006 µg/L | 0.006 µg/L | 2024-07-08 | 10th Street Well / EP008 |
| PFBA | 0.0060 µg/L | 0.005 µg/L | 2024-07-08 | South Bay Upper Aquifer Treated / EP021 |
| PFBS | < 0.003 µg/L | 0.003 µg/L | 2024-07-08 | Pallisades Well / EP005 |
| PFDA | < 0.003 µg/L | 0.003 µg/L | 2024-07-08 | 8th Street Upper Well Treated / EP022 |
| PFDoA | < 0.003 µg/L | 0.003 µg/L | 2024-07-08 | South Bay Upper Aquifer Treated / EP021 |
| PFEESA | < 0.003 µg/L | 0.003 µg/L | 2024-07-08 | 10th Street Well / EP008 |
| PFHpA | 0.0054 µg/L | 0.003 µg/L | 2024-07-08 | South Bay Upper Aquifer Treated / EP021 |
| PFHpS | < 0.003 µg/L | 0.003 µg/L | 2024-07-08 | South Bay Upper Aquifer Treated / EP021 |
| PFHxA | 0.0166 µg/L | 0.003 µg/L | 2024-07-08 | South Bay Upper Aquifer Treated / EP021 |
| PFHxS | < 0.003 µg/L | 0.003 µg/L | 2024-07-08 | Pallisades Well / EP005 |
| PFMBA | < 0.003 µg/L | 0.003 µg/L | 2024-07-08 | 3rd Street Well / EP009 |
| PFMPA | < 0.004 µg/L | 0.004 µg/L | 2024-07-08 | 3rd Street Well / EP009 |
| PFNA | < 0.004 µg/L | 0.004 µg/L | 2024-07-08 | 10th Street Well / EP008 |
| PFOA | < 0.004 µg/L | 0.004 µg/L | 2024-07-08 | 3rd Street Well / EP009 |
| PFOS | < 0.004 µg/L | 0.004 µg/L | 2024-07-08 | 3rd Street Well / EP009 |
| PFPeA | < 0.003 µg/L | 0.003 µg/L | 2024-07-08 | South Bay Lower Aquifer Treated / EP019 |
| PFPeS | < 0.004 µg/L | 0.004 µg/L | 2024-07-08 | Pallisades Well / EP005 |
| PFTA | < 0.008 µg/L | 0.008 µg/L | 2024-07-08 | 8th Street Upper Well Treated / EP022 |
| PFTrDA | < 0.007 µg/L | 0.007 µg/L | 2024-07-08 | South Bay Lower Aquifer Treated / EP019 |
| PFUnA | < 0.002 µg/L | 0.002 µg/L | 2024-07-08 | 3rd Street Well / EP009 |
| lithium | < 9 µg/L | 9 µg/L | 2024-07-08 | 8th Street Upper Well Treated / EP022 |
Download all EPA UCMR 5 records (CSV)
Lead and copper: 90th-percentile summaries
These describe a monitoring period across sampled locations, not the result at your home. How to read the 90th percentile
| Substance | Published 90th percentile | Monitoring period | Source quarter |
|---|---|---|---|
| Lead (PB90) | 0.0011 mg/L | 2024-01-01 – 2026-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2021-01-01 – 2023-12-31 | 2026Q3 |
| Lead (PB90) | 0.0051 mg/L | 2020-01-01 – 2022-12-31 | 2026Q3 |
| Lead (PB90) | 0.0025 mg/L | 2014-01-01 – 2016-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2011-01-01 – 2013-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2008-01-01 – 2010-12-31 | 2026Q3 |
| Lead (PB90) | 0 mg/L | 2005-01-01 – 2007-12-31 | 2026Q3 |
| Lead (PB90) | 0.007 mg/L | 2004-01-01 – 2004-12-31 | 2026Q3 |
| Substance | Published result | Sample date | Location / source |
|---|---|---|---|
| ALKALINITY, TOTAL | 238 MG/L | 2026-06-29 | 8TH ST WELL 02 (EL MORO WELL)- 1986 / California DDW laboratory results |
| CONDUCTIVITY @ 25 C UMHOS/CM | 580 UMHO/CM | 2026-06-29 | BAY OAKS WELL / California DDW laboratory results |
| CALCIUM | 43 MG/L | 2026-06-29 | BAY OAKS WELL / California DDW laboratory results |
| ALKALINITY, TOTAL | 133 MG/L | 2026-06-29 | SOUTH BAY LOWER AQUIFER WELL / California DDW laboratory results |
| ALKALINITY, TOTAL | 225 MG/L | 2026-06-29 | BAY OAKS WELL / California DDW laboratory results |
| CONDUCTIVITY @ 25 C UMHOS/CM | 440 UMHO/CM | 2026-06-29 | SOUTH BAY LOWER AQUIFER WELL / California DDW laboratory results |
| PH | 7.23 PH | 2026-06-29 | THIRD ST (BAYSIDE) WELL / California DDW laboratory results |
| ALKALINITY, TOTAL | 40 MG/L | 2026-06-29 | 8TH STREET UPPER AQUIFER WELL / California DDW laboratory results |
| CONDUCTIVITY @ 25 C UMHOS/CM | 320 UMHO/CM | 2026-06-29 | PALISADES WELL 01 (PALISADES WELL / California DDW laboratory results |
| ALKALINITY, TOTAL | 50 MG/L | 2026-06-29 | PALISADES WELL 01 (PALISADES WELL / California DDW laboratory results |
| ALKALINITY, TOTAL | 60 MG/L | 2026-06-29 | THIRD ST (BAYSIDE) WELL / California DDW laboratory results |
| CALCIUM | 50 MG/L | 2026-06-29 | 8TH ST WELL 02 (EL MORO WELL)- 1986 / California DDW laboratory results |
State sampling points can include untreated water. Publisher qualifiers and units are retained; consult the full source notes before interpreting a record.
Download state records with source notes (CSV)
Published compliance history
1 imported records. Status is as recorded in the source; historical records are not current advisories. Missing records do not establish that no violations occurred.
| Rule / record | Period | Recorded status | Health-based (EPA classification) | Source quarter |
|---|---|---|---|---|
| Lead and Copper Rule / Follow-up Or Routine LCR Tap M/R | 2019-10-01 – — | Resolved | No | 2026Q3 |
Source dates and refresh checks
A refresh check is not a sample date. Publication periods, sample dates and checks are shown separately.
- EPA SDWIS lead/copper summaries and service areas — source period: — – —; last checked: 2026-10-17
- EPA SDWIS contacts and compliance records — source period: — – —; last checked: 2026-10-17
- EPA UCMR 5 sample results — source period: 2023-01-03 – 2026-06-17; last checked: 2026-10-17
- California DDW laboratory results — last successful check: 2026-10-18
Administrative contact (EPA filing)
Riddiough, Eric: 805-528-9376
An administrative filing contact may not be a customer-service line. Confirm current contact details with the provider.