- PWSID
- CA0910002
- State
- California
- System type
- community water system (CWS)
- Population served
- 30,089
- City
- South Lake Tahoe
- Counties
- El Dorado County
- Primary source water
- groundwater
- UCMR 5 sampling
- 2023-07-12 to 2025-02-13 · 14 entry point(s) · water types: GW
- Service-area boundary
- authoritative
PFOA 1–3 × its limit highest single result
PFOA 1–3 × its limit worst entry-point average
Open on the California map · All California systems · All results
These are monitoring results collected under EPA's Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) at entry points, where treated water enters the distribution system; they are not tap-water samples. They are not compliance determinations: compliance with EPA's 2024 PFAS limits is judged on running annual averages of compliance monitoring, required from 2029, so a single UCMR 5 result at or above a limit is not a violation. “< MRL” means the compound was not quantified at EPA's minimum reporting level; it does not mean zero.
Compared with EPA's 2024 values
| Highest single result | Worst entry-point average* | Limit | |
|---|---|---|---|
| PFOA (ppt) | 6.1 | 5.6 | 4 |
| PFOS (ppt) | 5.2 | 4.95 | 4 |
| Hazard Index | 0.582 | 0.572 | 1.0† |
“<MRL” = every result for the compound was below its reporting limit. * Mean of all samples at each entry point with non-detects = 0 (EPA compliance convention; the Hazard Index also uses non-detects = 0); a screening comparison, not a formal running annual average. † Rescission proposed May 2026. PFOA/PFOS MCL 4 ppt (2024 NPDWR, in effect). PFHxS, PFNA, HFPO-DA (10 ppt each) and the Hazard Index (1.0) are 2024 NPDWR values; EPA proposed rescinding them on 18 May 2026 (comment period closed 20 Jul 2026).
Compared with California guidance levels
| Highest single result | Worst entry-point average* | California | |
|---|---|---|---|
| PFHxS (ppt) | 5.8 | 5.7 | 3 (guidance) |
| PFOA (ppt) | 6.1 | 5.6 | 4 (guidance) |
| PFOS (ppt) | 5.2 | 4.95 | 4 (guidance) |
| PFBS (ppt) | 3.7 | 3.4 | 500 (guidance) |
| PFHxA (ppt) | 16.3 | 14.1 | 1,000 (guidance) |
Sum standards add the listed compounds within each sample (non-detects = 0). State compliance is normally judged on averages over time; these are screening comparisons.
Sampling history
Sampled 2023-07-12 to 2025-02-13 · 14 entry point(s) · water types: GW · 35 sampling visits. PFAS in ppt (ng/L).
| Date | Entry point | Event | PFOA | PFOS | HI | Other detections |
|---|---|---|---|---|---|---|
| 2023-07-12 | Arrowhead Well 3 (GW) | SE1 | <4 | <4 | 0 | none |
| 2023-07-12 | Bayview Well (GW) | SE1 | <4 | <4 | 0 | none |
| 2023-07-12 | Elks Club Well 2 (GW) | SE1 | <4 | <4 | 0 | none |
| 2023-08-09 | Al Tahoe Well 2 (GW) | SE1 | <4 | <4 | 0 | none |
| 2023-08-09 | South Upper Truckee Well #3 (GW) | SE1 | <4 | <4 | 0 | lithium 19.1 µg/L |
| 2023-08-09 | Sunset Well (GW) | SE1 | <4 | <4 | 0 | none |
| 2023-08-16 | Airport Well (GW) | SE1 | <4 | <4 | 0 | none |
| 2023-08-21 | Blackrock Well 2 (GW) | SE1 | <4 | <4 | 0 | none |
| 2023-09-05 | Arrowhead Well 3 (GW) | SE1 | n/a | n/a | n/a | none |
| 2023-09-05 | Bayview Well (GW) | SE1 | n/a | n/a | n/a | none |
| 2023-09-06 | Clement Ave. Well (GW) | SE1 | n/a | n/a | n/a | none |
| 2023-09-06 | Helen Ave. Well 2 (GW) | SE1 | n/a | n/a | n/a | none |
| 2023-09-06 | Valhalla Well (GW) | SE1 | n/a | n/a | n/a | none |
| 2023-09-07 | Bakersfield Well (GW) | SE1 | n/a | n/a | n/a | none |
| 2023-09-07 | Elks Club Well 2 (GW) | SE1 | n/a | n/a | n/a | none |
| 2023-09-27 | Glenwood Well 5 (GW) | SE1 | <4 | <4 | 0 | PFHxA 11.3, PFPeA 12 |
| 2023-11-20 | Clement Ave. Well (GW) | SE1 | 5.1 | 4.7 | 0.561 | PFHpA 4.5, PFHxA 11.9, PFPeA 15.9 |
| 2023-11-20 | Valhalla Well (GW) | SE1 | <4 | <4 | 0 | none |
| 2024-01-03 | Arrowhead Well 3 (GW) | SE2 | <4 | <4 | 0 | none |
| 2024-01-03 | Bakersfield Well (GW) | SE2 | <4 | <4 | 0 | none |
| 2024-01-09 | Glenwood Well 5 (GW) | SE2 | <4 | <4 | 0 | PFHxA 12.3, PFPeA 13.9 |
| 2024-01-09 | Helen Ave. Well 2 (GW) | SE1 | 4 | <4 | 0 | none |
| 2024-01-17 | Bayview Well (GW) | SE2 | <4 | <4 | 0 | none |
| 2024-01-17 | Elks Club Well 2 (GW) | SE2 | <4 | <4 | 0 | none |
| 2024-02-06 | Airport Well (GW) | SE2 | <4 | <4 | 0 | none |
| 2024-02-06 | Al Tahoe Well 2 (GW) | SE2 | <4 | <4 | 0 | PFHpA 4, PFHxA 9.3, PFPeA 14 |
| 2024-02-06 | Blackrock Well 2 (GW) | SE2 | <4 | <4 | 0 | none |
| 2024-02-06 | Sunset Well (GW) | SE2 | <4 | <4 | 0 | none |
| 2024-02-29 | Paloma Well (GW) | SE1 | <4 | <4 | 0 | none |
| 2024-03-12 | Clement Ave. Well (GW) | SE2 | 6.1 | 5.2 | 0.582 | PFBA 5.3, PFHpA 6.5, PFHxA 16.3, PFPeA 22.4 |
| 2024-03-13 | Helen Ave. Well 2 (GW) | SE2 | n/a | n/a | n/a | none |
| 2024-03-13 | Valhalla Well (GW) | SE2 | <4 | <4 | 0 | none |
| 2024-09-17 | Paloma Well (GW) | SE2 | <4 | <4 | 0 | none |
| 2025-02-13 | Helen Ave. Well 2 (GW) | SE2 | <4 | <4 | 0 | none |
| 2025-02-13 | South Upper Truckee Well #3 (GW) | SE2 | <4 | <4 | 0 | lithium 26.3 µg/L |
“<4” = not detected at the reporting limit shown; “n/a” = not analyzed in that sample. Highlighted = at or above the 4 ppt MCL. HI computed per sample with non-detects as 0. Other detections lists every other quantified compound (lithium in µg/L).
All results by entry point
804 results. Each column is one sampling visit (date and UCMR 5 sample event). A number is a measured concentration; “< 4” = below the minimum reporting level shown; “–” = not analyzed in that visit. PFAS in ppt (ng/L); lithium in µg/L.
Airport Well facility 91823 · sample point 0910002823 · groundwater
| Compound | MRL | 2023-08-16 SE1 | 2024-02-06 SE2 |
|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | < 5 | < 5 |
| 4:2 FTS | 3 ppt | < 3 | < 3 |
| 6:2 FTS | 5 ppt | < 5 | < 5 |
| 8:2 FTS | 5 ppt | < 5 | < 5 |
| 9Cl-PF3ONS | 2 ppt | < 2 | < 2 |
| ADONA | 3 ppt | < 3 | < 3 |
| HFPO-DA | 5 ppt | < 5 | < 5 |
| NEtFOSAA | 5 ppt | – | < 5 |
| NFDHA | 20 ppt | < 20 | < 20 |
| NMeFOSAA | 6 ppt | – | < 6 |
| PFBA | 5 ppt | < 5 | < 5 |
| PFBS | 3 ppt | < 3 | < 3 |
| PFDA | 3 ppt | < 3 | < 3 |
| PFDoA | 3 ppt | < 3 | < 3 |
| PFEESA | 3 ppt | < 3 | < 3 |
| PFHpA | 3 ppt | < 3 | < 3 |
| PFHpS | 3 ppt | < 3 | < 3 |
| PFHxA | 3 ppt | < 3 | < 3 |
| PFHxS | 3 ppt | < 3 | < 3 |
| PFMBA | 3 ppt | < 3 | < 3 |
| PFMPA | 4 ppt | < 4 | < 4 |
| PFNA | 4 ppt | < 4 | < 4 |
| PFOA | 4 ppt | < 4 | < 4 |
| PFOS | 4 ppt | < 4 | < 4 |
| PFPeA | 3 ppt | < 3 | < 3 |
| PFPeS | 4 ppt | < 4 | < 4 |
| PFTA | 8 ppt | – | < 8 |
| PFTrDA | 7 ppt | – | < 7 |
| PFUnA | 2 ppt | < 2 | < 2 |
| lithium | 9 µg/L | – | < 9 |
Al Tahoe Well 2 facility 91809 · sample point 0910002809 · groundwater
| Compound | MRL | 2023-08-09 SE1 | 2024-02-06 SE2 |
|---|---|---|---|
| PFHpA | 3 ppt | < 3 | 4 |
| PFHxA | 3 ppt | < 3 | 9.3 |
| PFPeA | 3 ppt | < 3 | 14 |
| 11Cl-PF3OUdS | 5 ppt | < 5 | < 5 |
| 4:2 FTS | 3 ppt | < 3 | < 3 |
| 6:2 FTS | 5 ppt | < 5 | < 5 |
| 8:2 FTS | 5 ppt | < 5 | < 5 |
| 9Cl-PF3ONS | 2 ppt | < 2 | < 2 |
| ADONA | 3 ppt | < 3 | < 3 |
| HFPO-DA | 5 ppt | < 5 | < 5 |
| NEtFOSAA | 5 ppt | < 5 | < 5 |
| NFDHA | 20 ppt | < 20 | < 20 |
| NMeFOSAA | 6 ppt | < 6 | < 6 |
| PFBA | 5 ppt | < 5 | < 5 |
| PFBS | 3 ppt | < 3 | < 3 |
| PFDA | 3 ppt | < 3 | < 3 |
| PFDoA | 3 ppt | < 3 | < 3 |
| PFEESA | 3 ppt | < 3 | < 3 |
| PFHpS | 3 ppt | < 3 | < 3 |
| PFHxS | 3 ppt | < 3 | < 3 |
| PFMBA | 3 ppt | < 3 | < 3 |
| PFMPA | 4 ppt | < 4 | < 4 |
| PFNA | 4 ppt | < 4 | < 4 |
| PFOA | 4 ppt | < 4 | < 4 |
| PFOS | 4 ppt | < 4 | < 4 |
| PFPeS | 4 ppt | < 4 | < 4 |
| PFTA | 8 ppt | < 8 | < 8 |
| PFTrDA | 7 ppt | < 7 | < 7 |
| PFUnA | 2 ppt | < 2 | < 2 |
| lithium | 9 µg/L | < 9 | < 9 |
Arrowhead Well 3 facility 91805 · sample point 0910002805 · groundwater
| Compound | MRL | 2023-07-12 SE1 | 2023-09-05 SE1 | 2024-01-03 SE2 |
|---|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | < 5 | – | < 5 |
| 4:2 FTS | 3 ppt | < 3 | – | < 3 |
| 6:2 FTS | 5 ppt | < 5 | – | < 5 |
| 8:2 FTS | 5 ppt | < 5 | – | < 5 |
| 9Cl-PF3ONS | 2 ppt | < 2 | – | < 2 |
| ADONA | 3 ppt | < 3 | – | < 3 |
| HFPO-DA | 5 ppt | < 5 | – | < 5 |
| NEtFOSAA | 5 ppt | – | < 5 | < 5 |
| NFDHA | 20 ppt | < 20 | – | < 20 |
| NMeFOSAA | 6 ppt | – | < 6 | < 6 |
| PFBA | 5 ppt | < 5 | – | < 5 |
| PFBS | 3 ppt | < 3 | – | < 3 |
| PFDA | 3 ppt | < 3 | – | < 3 |
| PFDoA | 3 ppt | < 3 | – | < 3 |
| PFEESA | 3 ppt | < 3 | – | < 3 |
| PFHpA | 3 ppt | < 3 | – | < 3 |
| PFHpS | 3 ppt | < 3 | – | < 3 |
| PFHxA | 3 ppt | < 3 | – | < 3 |
| PFHxS | 3 ppt | < 3 | – | < 3 |
| PFMBA | 3 ppt | < 3 | – | < 3 |
| PFMPA | 4 ppt | < 4 | – | < 4 |
| PFNA | 4 ppt | < 4 | – | < 4 |
| PFOA | 4 ppt | < 4 | – | < 4 |
| PFOS | 4 ppt | < 4 | – | < 4 |
| PFPeA | 3 ppt | < 3 | – | < 3 |
| PFPeS | 4 ppt | < 4 | – | < 4 |
| PFTA | 8 ppt | – | < 8 | < 8 |
| PFTrDA | 7 ppt | – | < 7 | < 7 |
| PFUnA | 2 ppt | < 2 | – | < 2 |
| lithium | 9 µg/L | < 9 | – | < 9 |
Bakersfield Well facility 91803 · sample point 0910002803 · groundwater
| Compound | MRL | 2023-09-07 SE1 | 2024-01-03 SE2 |
|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | – | < 5 |
| 4:2 FTS | 3 ppt | – | < 3 |
| 6:2 FTS | 5 ppt | – | < 5 |
| 8:2 FTS | 5 ppt | – | < 5 |
| 9Cl-PF3ONS | 2 ppt | – | < 2 |
| ADONA | 3 ppt | – | < 3 |
| HFPO-DA | 5 ppt | – | < 5 |
| NEtFOSAA | 5 ppt | < 5 | < 5 |
| NFDHA | 20 ppt | – | < 20 |
| NMeFOSAA | 6 ppt | < 6 | < 6 |
| PFBA | 5 ppt | – | < 5 |
| PFBS | 3 ppt | – | < 3 |
| PFDA | 3 ppt | – | < 3 |
| PFDoA | 3 ppt | – | < 3 |
| PFEESA | 3 ppt | – | < 3 |
| PFHpA | 3 ppt | – | < 3 |
| PFHpS | 3 ppt | – | < 3 |
| PFHxA | 3 ppt | – | < 3 |
| PFHxS | 3 ppt | – | < 3 |
| PFMBA | 3 ppt | – | < 3 |
| PFMPA | 4 ppt | – | < 4 |
| PFNA | 4 ppt | – | < 4 |
| PFOA | 4 ppt | – | < 4 |
| PFOS | 4 ppt | – | < 4 |
| PFPeA | 3 ppt | – | < 3 |
| PFPeS | 4 ppt | – | < 4 |
| PFTA | 8 ppt | < 8 | < 8 |
| PFTrDA | 7 ppt | < 7 | < 7 |
| PFUnA | 2 ppt | – | < 2 |
| lithium | 9 µg/L | – | < 9 |
Bayview Well facility 91060 · sample point 0910002824 · groundwater
| Compound | MRL | 2023-07-12 SE1 | 2023-09-05 SE1 | 2024-01-17 SE2 |
|---|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | < 5 | – | < 5 |
| 4:2 FTS | 3 ppt | < 3 | – | < 3 |
| 6:2 FTS | 5 ppt | < 5 | – | < 5 |
| 8:2 FTS | 5 ppt | < 5 | – | < 5 |
| 9Cl-PF3ONS | 2 ppt | < 2 | – | < 2 |
| ADONA | 3 ppt | < 3 | – | < 3 |
| HFPO-DA | 5 ppt | < 5 | – | < 5 |
| NEtFOSAA | 5 ppt | – | < 5 | < 5 |
| NFDHA | 20 ppt | < 20 | – | < 20 |
| NMeFOSAA | 6 ppt | – | < 6 | < 6 |
| PFBA | 5 ppt | < 5 | – | < 5 |
| PFBS | 3 ppt | < 3 | – | < 3 |
| PFDA | 3 ppt | < 3 | – | < 3 |
| PFDoA | 3 ppt | < 3 | – | < 3 |
| PFEESA | 3 ppt | < 3 | – | < 3 |
| PFHpA | 3 ppt | < 3 | – | < 3 |
| PFHpS | 3 ppt | < 3 | – | < 3 |
| PFHxA | 3 ppt | < 3 | – | < 3 |
| PFHxS | 3 ppt | < 3 | – | < 3 |
| PFMBA | 3 ppt | < 3 | – | < 3 |
| PFMPA | 4 ppt | < 4 | – | < 4 |
| PFNA | 4 ppt | < 4 | – | < 4 |
| PFOA | 4 ppt | < 4 | – | < 4 |
| PFOS | 4 ppt | < 4 | – | < 4 |
| PFPeA | 3 ppt | < 3 | – | < 3 |
| PFPeS | 4 ppt | < 4 | – | < 4 |
| PFTA | 8 ppt | – | < 8 | < 8 |
| PFTrDA | 7 ppt | – | < 7 | < 7 |
| PFUnA | 2 ppt | < 2 | – | < 2 |
| lithium | 9 µg/L | < 9 | – | < 9 |
Blackrock Well 2 facility 91822 · sample point 0910002822 · groundwater
| Compound | MRL | 2023-08-21 SE1 | 2024-02-06 SE2 |
|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | < 5 | < 5 |
| 4:2 FTS | 3 ppt | < 3 | < 3 |
| 6:2 FTS | 5 ppt | < 5 | < 5 |
| 8:2 FTS | 5 ppt | < 5 | < 5 |
| 9Cl-PF3ONS | 2 ppt | < 2 | < 2 |
| ADONA | 3 ppt | < 3 | < 3 |
| HFPO-DA | 5 ppt | < 5 | < 5 |
| NEtFOSAA | 5 ppt | < 5 | < 5 |
| NFDHA | 20 ppt | < 20 | < 20 |
| NMeFOSAA | 6 ppt | < 6 | < 6 |
| PFBA | 5 ppt | < 5 | < 5 |
| PFBS | 3 ppt | < 3 | < 3 |
| PFDA | 3 ppt | < 3 | < 3 |
| PFDoA | 3 ppt | < 3 | < 3 |
| PFEESA | 3 ppt | < 3 | < 3 |
| PFHpA | 3 ppt | < 3 | < 3 |
| PFHpS | 3 ppt | < 3 | < 3 |
| PFHxA | 3 ppt | < 3 | < 3 |
| PFHxS | 3 ppt | < 3 | < 3 |
| PFMBA | 3 ppt | < 3 | < 3 |
| PFMPA | 4 ppt | < 4 | < 4 |
| PFNA | 4 ppt | < 4 | < 4 |
| PFOA | 4 ppt | < 4 | < 4 |
| PFOS | 4 ppt | < 4 | < 4 |
| PFPeA | 3 ppt | < 3 | < 3 |
| PFPeS | 4 ppt | < 4 | < 4 |
| PFTA | 8 ppt | < 8 | < 8 |
| PFTrDA | 7 ppt | < 7 | < 7 |
| PFUnA | 2 ppt | < 2 | < 2 |
| lithium | 9 µg/L | < 9 | < 9 |
Clement Ave. Well facility 91818 · sample point 0910002818 · groundwater
| Compound | MRL | 2023-09-06 SE1 | 2023-11-20 SE1 | 2024-03-12 SE2 |
|---|---|---|---|---|
| PFBA | 5 ppt | – | < 5 | 5.3 |
| PFBS | 3 ppt | – | 3.1 | 3.7 |
| PFHpA | 3 ppt | – | 4.5 | 6.5 |
| PFHxA | 3 ppt | – | 11.9 | 16.3 |
| PFHxS | 3 ppt | – | 5.6 | 5.8 |
| PFOA | 4 ppt | – | 5.1 | 6.1 |
| PFOS | 4 ppt | – | 4.7 | 5.2 |
| PFPeA | 3 ppt | – | 15.9 | 22.4 |
| 11Cl-PF3OUdS | 5 ppt | – | < 5 | < 5 |
| 4:2 FTS | 3 ppt | – | < 3 | < 3 |
| 6:2 FTS | 5 ppt | – | < 5 | < 5 |
| 8:2 FTS | 5 ppt | – | < 5 | < 5 |
| 9Cl-PF3ONS | 2 ppt | – | < 2 | < 2 |
| ADONA | 3 ppt | – | < 3 | < 3 |
| HFPO-DA | 5 ppt | – | < 5 | < 5 |
| NEtFOSAA | 5 ppt | < 5 | – | < 5 |
| NFDHA | 20 ppt | – | < 20 | < 20 |
| NMeFOSAA | 6 ppt | < 6 | – | < 6 |
| PFDA | 3 ppt | – | < 3 | < 3 |
| PFDoA | 3 ppt | – | < 3 | < 3 |
| PFEESA | 3 ppt | – | < 3 | < 3 |
| PFHpS | 3 ppt | – | < 3 | < 3 |
| PFMBA | 3 ppt | – | < 3 | < 3 |
| PFMPA | 4 ppt | – | < 4 | < 4 |
| PFNA | 4 ppt | – | < 4 | < 4 |
| PFPeS | 4 ppt | – | < 4 | < 4 |
| PFTA | 8 ppt | < 8 | – | < 8 |
| PFTrDA | 7 ppt | < 7 | – | < 7 |
| PFUnA | 2 ppt | – | < 2 | < 2 |
| lithium | 9 µg/L | < 9 | – | < 9 |
Elks Club Well 2 facility 91807 · sample point 0910002807 · groundwater
| Compound | MRL | 2023-07-12 SE1 | 2023-09-07 SE1 | 2024-01-17 SE2 |
|---|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | < 5 | – | < 5 |
| 4:2 FTS | 3 ppt | < 3 | – | < 3 |
| 6:2 FTS | 5 ppt | < 5 | – | < 5 |
| 8:2 FTS | 5 ppt | < 5 | – | < 5 |
| 9Cl-PF3ONS | 2 ppt | < 2 | – | < 2 |
| ADONA | 3 ppt | < 3 | – | < 3 |
| HFPO-DA | 5 ppt | < 5 | – | < 5 |
| NEtFOSAA | 5 ppt | – | < 5 | < 5 |
| NFDHA | 20 ppt | < 20 | – | < 20 |
| NMeFOSAA | 6 ppt | – | < 6 | < 6 |
| PFBA | 5 ppt | < 5 | – | < 5 |
| PFBS | 3 ppt | < 3 | – | < 3 |
| PFDA | 3 ppt | < 3 | – | < 3 |
| PFDoA | 3 ppt | < 3 | – | < 3 |
| PFEESA | 3 ppt | < 3 | – | < 3 |
| PFHpA | 3 ppt | < 3 | – | < 3 |
| PFHpS | 3 ppt | < 3 | – | < 3 |
| PFHxA | 3 ppt | < 3 | – | < 3 |
| PFHxS | 3 ppt | < 3 | – | < 3 |
| PFMBA | 3 ppt | < 3 | – | < 3 |
| PFMPA | 4 ppt | < 4 | – | < 4 |
| PFNA | 4 ppt | < 4 | – | < 4 |
| PFOA | 4 ppt | < 4 | – | < 4 |
| PFOS | 4 ppt | < 4 | – | < 4 |
| PFPeA | 3 ppt | < 3 | – | < 3 |
| PFPeS | 4 ppt | < 4 | – | < 4 |
| PFTA | 8 ppt | – | < 8 | < 8 |
| PFTrDA | 7 ppt | – | < 7 | < 7 |
| PFUnA | 2 ppt | < 2 | – | < 2 |
| lithium | 9 µg/L | < 9 | – | < 9 |
Glenwood Well 5 facility 91819 · sample point 0910002819 · groundwater
| Compound | MRL | 2023-09-27 SE1 | 2024-01-09 SE2 |
|---|---|---|---|
| PFHxA | 3 ppt | 11.3 | 12.3 |
| PFPeA | 3 ppt | 12 | 13.9 |
| 11Cl-PF3OUdS | 5 ppt | < 5 | < 5 |
| 4:2 FTS | 3 ppt | < 3 | < 3 |
| 6:2 FTS | 5 ppt | < 5 | < 5 |
| 8:2 FTS | 5 ppt | < 5 | < 5 |
| 9Cl-PF3ONS | 2 ppt | < 2 | < 2 |
| ADONA | 3 ppt | < 3 | < 3 |
| HFPO-DA | 5 ppt | < 5 | < 5 |
| NEtFOSAA | 5 ppt | – | < 5 |
| NFDHA | 20 ppt | < 20 | < 20 |
| NMeFOSAA | 6 ppt | – | < 6 |
| PFBA | 5 ppt | < 5 | < 5 |
| PFBS | 3 ppt | < 3 | < 3 |
| PFDA | 3 ppt | < 3 | < 3 |
| PFDoA | 3 ppt | < 3 | < 3 |
| PFEESA | 3 ppt | < 3 | < 3 |
| PFHpA | 3 ppt | < 3 | < 3 |
| PFHpS | 3 ppt | < 3 | < 3 |
| PFHxS | 3 ppt | < 3 | < 3 |
| PFMBA | 3 ppt | < 3 | < 3 |
| PFMPA | 4 ppt | < 4 | < 4 |
| PFNA | 4 ppt | < 4 | < 4 |
| PFOA | 4 ppt | < 4 | < 4 |
| PFOS | 4 ppt | < 4 | < 4 |
| PFPeS | 4 ppt | < 4 | < 4 |
| PFTA | 8 ppt | – | < 8 |
| PFTrDA | 7 ppt | – | < 7 |
| PFUnA | 2 ppt | < 2 | < 2 |
| lithium | 9 µg/L | – | < 9 |
Helen Ave. Well 2 facility 91817 · sample point 0910002817 · groundwater
| Compound | MRL | 2023-09-06 SE1 | 2024-01-09 SE1 | 2024-03-13 SE2 | 2025-02-13 SE2 |
|---|---|---|---|---|---|
| PFOA | 4 ppt | – | 4 | – | < 4 |
| 11Cl-PF3OUdS | 5 ppt | – | < 5 | – | < 5 |
| 4:2 FTS | 3 ppt | – | < 3 | – | < 3 |
| 6:2 FTS | 5 ppt | – | < 5 | – | < 5 |
| 8:2 FTS | 5 ppt | – | < 5 | – | < 5 |
| 9Cl-PF3ONS | 2 ppt | – | < 2 | – | < 2 |
| ADONA | 3 ppt | – | < 3 | – | < 3 |
| HFPO-DA | 5 ppt | – | < 5 | – | < 5 |
| NEtFOSAA | 5 ppt | < 5 | – | < 5 | – |
| NFDHA | 20 ppt | – | < 20 | – | < 20 |
| NMeFOSAA | 6 ppt | < 6 | – | < 6 | – |
| PFBA | 5 ppt | – | < 5 | – | < 5 |
| PFBS | 3 ppt | – | < 3 | – | < 3 |
| PFDA | 3 ppt | – | < 3 | – | < 3 |
| PFDoA | 3 ppt | – | < 3 | – | < 3 |
| PFEESA | 3 ppt | – | < 3 | – | < 3 |
| PFHpA | 3 ppt | – | < 3 | – | < 3 |
| PFHpS | 3 ppt | – | < 3 | – | < 3 |
| PFHxA | 3 ppt | – | < 3 | – | < 3 |
| PFHxS | 3 ppt | – | < 3 | – | < 3 |
| PFMBA | 3 ppt | – | < 3 | – | < 3 |
| PFMPA | 4 ppt | – | < 4 | – | < 4 |
| PFNA | 4 ppt | – | < 4 | – | < 4 |
| PFOS | 4 ppt | – | < 4 | – | < 4 |
| PFPeA | 3 ppt | – | < 3 | – | < 3 |
| PFPeS | 4 ppt | – | < 4 | – | < 4 |
| PFTA | 8 ppt | < 8 | – | < 8 | – |
| PFTrDA | 7 ppt | < 7 | – | < 7 | – |
| PFUnA | 2 ppt | – | < 2 | – | < 2 |
| lithium | 9 µg/L | < 9 | – | < 9 | – |
Paloma Well facility 91802 · sample point 0910002802 · groundwater
| Compound | MRL | 2024-02-29 SE1 | 2024-09-17 SE2 |
|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | < 5 | < 5 |
| 4:2 FTS | 3 ppt | < 3 | < 3 |
| 6:2 FTS | 5 ppt | < 5 | < 5 |
| 8:2 FTS | 5 ppt | < 5 | < 5 |
| 9Cl-PF3ONS | 2 ppt | < 2 | < 2 |
| ADONA | 3 ppt | < 3 | < 3 |
| HFPO-DA | 5 ppt | < 5 | < 5 |
| NEtFOSAA | 5 ppt | < 5 | < 5 |
| NFDHA | 20 ppt | < 20 | < 20 |
| NMeFOSAA | 6 ppt | < 6 | < 6 |
| PFBA | 5 ppt | < 5 | < 5 |
| PFBS | 3 ppt | < 3 | < 3 |
| PFDA | 3 ppt | < 3 | < 3 |
| PFDoA | 3 ppt | < 3 | < 3 |
| PFEESA | 3 ppt | < 3 | < 3 |
| PFHpA | 3 ppt | < 3 | < 3 |
| PFHpS | 3 ppt | < 3 | < 3 |
| PFHxA | 3 ppt | < 3 | < 3 |
| PFHxS | 3 ppt | < 3 | < 3 |
| PFMBA | 3 ppt | < 3 | < 3 |
| PFMPA | 4 ppt | < 4 | < 4 |
| PFNA | 4 ppt | < 4 | < 4 |
| PFOA | 4 ppt | < 4 | < 4 |
| PFOS | 4 ppt | < 4 | < 4 |
| PFPeA | 3 ppt | < 3 | < 3 |
| PFPeS | 4 ppt | < 4 | < 4 |
| PFTA | 8 ppt | < 8 | < 8 |
| PFTrDA | 7 ppt | < 7 | < 7 |
| PFUnA | 2 ppt | < 2 | < 2 |
| lithium | 9 µg/L | < 9 | < 9 |
South Upper Truckee Well #3 facility 91826 · sample point 0910002826 · groundwater
| Compound | MRL | 2023-08-09 SE1 | 2025-02-13 SE2 |
|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | < 5 | < 5 |
| 4:2 FTS | 3 ppt | < 3 | < 3 |
| 6:2 FTS | 5 ppt | < 5 | < 5 |
| 8:2 FTS | 5 ppt | < 5 | < 5 |
| 9Cl-PF3ONS | 2 ppt | < 2 | < 2 |
| ADONA | 3 ppt | < 3 | < 3 |
| HFPO-DA | 5 ppt | < 5 | < 5 |
| NEtFOSAA | 5 ppt | < 5 | < 5 |
| NFDHA | 20 ppt | < 20 | < 20 |
| NMeFOSAA | 6 ppt | < 6 | < 6 |
| PFBA | 5 ppt | < 5 | < 5 |
| PFBS | 3 ppt | < 3 | < 3 |
| PFDA | 3 ppt | < 3 | < 3 |
| PFDoA | 3 ppt | < 3 | < 3 |
| PFEESA | 3 ppt | < 3 | < 3 |
| PFHpA | 3 ppt | < 3 | < 3 |
| PFHpS | 3 ppt | < 3 | < 3 |
| PFHxA | 3 ppt | < 3 | < 3 |
| PFHxS | 3 ppt | < 3 | < 3 |
| PFMBA | 3 ppt | < 3 | < 3 |
| PFMPA | 4 ppt | < 4 | < 4 |
| PFNA | 4 ppt | < 4 | < 4 |
| PFOA | 4 ppt | < 4 | < 4 |
| PFOS | 4 ppt | < 4 | < 4 |
| PFPeA | 3 ppt | < 3 | < 3 |
| PFPeS | 4 ppt | < 4 | < 4 |
| PFTA | 8 ppt | < 8 | < 8 |
| PFTrDA | 7 ppt | < 7 | < 7 |
| PFUnA | 2 ppt | < 2 | < 2 |
| lithium | 9 µg/L | 19.1 | 26.3 |
Sunset Well facility 91814 · sample point 0910002814 · groundwater
| Compound | MRL | 2023-08-09 SE1 | 2024-02-06 SE2 |
|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | < 5 | < 5 |
| 4:2 FTS | 3 ppt | < 3 | < 3 |
| 6:2 FTS | 5 ppt | < 5 | < 5 |
| 8:2 FTS | 5 ppt | < 5 | < 5 |
| 9Cl-PF3ONS | 2 ppt | < 2 | < 2 |
| ADONA | 3 ppt | < 3 | < 3 |
| HFPO-DA | 5 ppt | < 5 | < 5 |
| NEtFOSAA | 5 ppt | < 5 | < 5 |
| NFDHA | 20 ppt | < 20 | < 20 |
| NMeFOSAA | 6 ppt | < 6 | < 6 |
| PFBA | 5 ppt | < 5 | < 5 |
| PFBS | 3 ppt | < 3 | < 3 |
| PFDA | 3 ppt | < 3 | < 3 |
| PFDoA | 3 ppt | < 3 | < 3 |
| PFEESA | 3 ppt | < 3 | < 3 |
| PFHpA | 3 ppt | < 3 | < 3 |
| PFHpS | 3 ppt | < 3 | < 3 |
| PFHxA | 3 ppt | < 3 | < 3 |
| PFHxS | 3 ppt | < 3 | < 3 |
| PFMBA | 3 ppt | < 3 | < 3 |
| PFMPA | 4 ppt | < 4 | < 4 |
| PFNA | 4 ppt | < 4 | < 4 |
| PFOA | 4 ppt | < 4 | < 4 |
| PFOS | 4 ppt | < 4 | < 4 |
| PFPeA | 3 ppt | < 3 | < 3 |
| PFPeS | 4 ppt | < 4 | < 4 |
| PFTA | 8 ppt | < 8 | < 8 |
| PFTrDA | 7 ppt | < 7 | < 7 |
| PFUnA | 2 ppt | < 2 | < 2 |
| lithium | 9 µg/L | < 9 | < 9 |
Valhalla Well facility 91808 · sample point 0910002808 · groundwater
| Compound | MRL | 2023-09-06 SE1 | 2023-11-20 SE1 | 2024-03-13 SE2 |
|---|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | – | < 5 | < 5 |
| 4:2 FTS | 3 ppt | – | < 3 | < 3 |
| 6:2 FTS | 5 ppt | – | < 5 | < 5 |
| 8:2 FTS | 5 ppt | – | < 5 | < 5 |
| 9Cl-PF3ONS | 2 ppt | – | < 2 | < 2 |
| ADONA | 3 ppt | – | < 3 | < 3 |
| HFPO-DA | 5 ppt | – | < 5 | < 5 |
| NEtFOSAA | 5 ppt | < 5 | – | < 5 |
| NFDHA | 20 ppt | – | < 20 | < 20 |
| NMeFOSAA | 6 ppt | < 6 | – | < 6 |
| PFBA | 5 ppt | – | < 5 | < 5 |
| PFBS | 3 ppt | – | < 3 | < 3 |
| PFDA | 3 ppt | – | < 3 | < 3 |
| PFDoA | 3 ppt | – | < 3 | < 3 |
| PFEESA | 3 ppt | – | < 3 | < 3 |
| PFHpA | 3 ppt | – | < 3 | < 3 |
| PFHpS | 3 ppt | – | < 3 | < 3 |
| PFHxA | 3 ppt | – | < 3 | < 3 |
| PFHxS | 3 ppt | – | < 3 | < 3 |
| PFMBA | 3 ppt | – | < 3 | < 3 |
| PFMPA | 4 ppt | – | < 4 | < 4 |
| PFNA | 4 ppt | – | < 4 | < 4 |
| PFOA | 4 ppt | – | < 4 | < 4 |
| PFOS | 4 ppt | – | < 4 | < 4 |
| PFPeA | 3 ppt | – | < 3 | < 3 |
| PFPeS | 4 ppt | – | < 4 | < 4 |
| PFTA | 8 ppt | < 8 | – | < 8 |
| PFTrDA | 7 ppt | < 7 | – | < 7 |
| PFUnA | 2 ppt | – | < 2 | < 2 |
| lithium | 9 µg/L | < 9 | – | < 9 |
Statistics by compound
| Compound | Results | Detected | Highest (date) | Mean bounds | KM median | P75 | P90 | P95 |
|---|---|---|---|---|---|---|---|---|
| PFHxA | 27 | 18% | 16.3 2024-03-12 | 2.26–4.71 | <MRL | <MRL | 11.9 | 12.3 |
| PFPeA | 27 | 18% | 22.4 2024-03-12 | 2.9–5.34 | <MRL | <MRL | 14 | 15.9 |
| PFHpA | 27 | 11% | 6.5 2024-03-12 | 0.56–3.22 | <MRL | <MRL | 4 | 4.5 |
| PFOA | 27 | 11% | 6.1 2024-03-12 | 0.56–4.12 | <MRL | <MRL | 4 | 5.1 |
| PFBS | 27 | 7% | 3.7 2024-03-12 | 0.25–3.03 | <MRL | <MRL | <MRL | 3.1 |
| PFHxS | 27 | 7% | 5.8 2024-03-12 | 0.42–3.2 | <MRL | <MRL | <MRL | 5.6 |
| PFOS | 27 | 7% | 5.2 2024-03-12 | 0.37–4.07 | <MRL | <MRL | <MRL | 4.7 |
| lithium | 25 | 8% | 26.3 2025-02-13 | 1.82–10.1 | <MRL | <MRL | <MRL | 19.1 |
| PFBA | 27 | 4% | 5.3 2024-03-12 | 0.2–5.01 | <MRL | <MRL | <MRL | <MRL |
Never detected (21): 11Cl-PF3OUdS, 4:2 FTS, 6:2 FTS, 8:2 FTS, 9Cl-PF3ONS, ADONA, HFPO-DA, NEtFOSAA, NFDHA, NMeFOSAA, PFDA, PFDoA, PFEESA, PFHpS, PFMBA, PFMPA, PFNA, PFPeS, PFTA, PFTrDA, PFUnA.
Left-censored Kaplan–Meier statistics (Helsel 2005; Helsel & Lee 2006, NADA for R). Units: ppt; lithium µg/L. Each compound has one reporting limit, so the Kaplan–Meier mean equals the upper mean bound (non-detects at the MRL); the lower bound sets non-detects to 0. “<MRL” = the percentile falls below the reporting limit and cannot be estimated. These describe this system's UCMR 5 samples, not population estimates.
Sources
- EPA UCMR 5 occurrence data text files (UCMR5_All.txt; samples 2023-01-09 to 2026-06-17; data summary dated Jul 2026)
- EPA SDWIS via ECHO SDWA downloads, quarter 2026Q3
- EPA Public Water System Service Areas v3 (Mar 2026)
- US Census Bureau cartographic boundary counties 1:500k, 2024
- EPA/USGS NHDPlus V2 (medium resolution) flowlines, Strahler order 2+
Data build 90f0922cd84f · 2026-10-18T04:12Z · UCMR 5 release Jul2026 · SDWIS 2026Q3. Data and methods.