Compliance record
Formal violations the EPA has on file for this supplier. A health-based violation means a contaminant limit or a required treatment was breached; the rest are monitoring or reporting failures — still violations, but not a measured health risk.
4
health-based violations
7
violations on file
0
still open
| Violation | Type | Status | Period |
|---|---|---|---|
| MCL | Health-based | Resolved | 1996-04-10 → 1996-06-10 |
| MCL | Health-based | Resolved | 1996-04-10 → 1996-06-10 |
| MCL | Health-based | Resolved | 1996-04-01 → 1996-06-30 |
| MCL | Health-based | Resolved | 1996-04-01 → 1996-06-30 |
| MR | Monitoring | Resolved | 2005-01-01 → 2005-12-31 |
| MR | Monitoring | Resolved | 2005-01-01 → 2005-12-31 |
| MR | Monitoring | Resolved | 1993-07-01 → 2000-04-04 |
Other contaminants detected
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of this
system's samples — over 100% is worth reading, but is not by itself a
violation. Where a single sample came in higher than that percentile, it
is noted under the bar. Formal violations are listed separately.
| Contaminant | Level vs EPA limit | Detection rate | Source | Period |
|---|---|---|---|---|
| Nitrate | 6620.45 µg/L 66% of the EPA limit 10000 µg/L
worst single sample: 6767 µg/L | 78/78 | SYR4 | 2012–2019 |
| 1,1-Dichloroethylene | 2.1 µg/L 30% of the EPA limit 7 µg/L
worst single sample: 2.41 µg/L | 44/68 | SYR4 | 2012–2019 |
| Trichloroethylene | 1.364 µg/L 27% of the EPA limit 5 µg/L
worst single sample: 1.46 µg/L | 44/68 | SYR4 | 2012–2019 |
| Chromium | 19.3881 µg/L 19% of the EPA limit 100 µg/L
worst single sample: 20.058 µg/L | 39/47 | SYR4 | 2012–2019 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L | 27/27 | LCR | 2025 |
| Tetrachloroethylene | 1.001 µg/L 20% of the EPA limit 5 µg/L
worst single sample: 1.18 µg/L | 27/68 | SYR4 | 2012–2019 |
| cis-1,2-Dichloroethylene | 1.195 µg/L 1.7% of the EPA limit 70 µg/L
worst single sample: 1.3 µg/L | 26/68 | SYR4 | 2012–2019 |
| Bromoform | 4.92 µg/L No EPA limit set
worst single sample: 5.17 µg/L | 11/56 | SYR4 | 2012–2019 |
| Dibromochloromethane | 3.14 µg/L No EPA limit set
worst single sample: 3.3 µg/L | 11/56 | SYR4 | 2012–2019 |
| Fluoride | 200 µg/L 5% of the EPA limit 4000 µg/L | 11/11 | SYR4 | 2012–2019 |
| TTHM | 9.15 µg/L 11% of the EPA limit 80 µg/L
worst single sample: 9.2 µg/L | 11/55 | SYR4 | 2012–2019 |
| Dibromoacetic Acid | 2.68 µg/L No EPA limit set
worst single sample: 2.8 µg/L | 9/11 | SYR4 | 2014–2019 |
| Combined Uranium | 2.7646 µg/L 9.2% of the EPA limit 30 µg/L
worst single sample: 2.8 µg/L | 7/14 | SYR4 | 2012–2017 |
| Nitrate-Nitrite | 739000 µg/L 7390% of the EPA limit, at the 95th percentile of samples — 10000 µg/L
worst single sample: 820000 µg/L | 7/7 | SYR4 | 2012–2019 |
| Bromodichloromethane | 0.9975 µg/L No EPA limit set
worst single sample: 1.02 µg/L | 6/56 | SYR4 | 2012–2019 |
| Arsenic | 2.3136 µg/L 23% of the EPA limit 10 µg/L
worst single sample: 2.317 µg/L | 5/16 | SYR4 | 2012–2019 |
| Total Haloacetic Acids (HAA5) | 5.2 µg/L 8.7% of the EPA limit 60 µg/L
worst single sample: 5.5 µg/L | 4/11 | SYR4 | 2014–2019 |
| Lithium | 28.7 µg/L No EPA limit set | 4/4 | UCMR-5 | 2023 |
| Copper | 72.2612 µg/L 5.6% of the EPA limit 1300 µg/L
worst single sample: 76 µg/L | 2/16 | SYR4 | 2012–2019 |
| Monobromoacetic Acid | 1.2 µg/L No EPA limit set | 2/11 | SYR4 | 2014–2019 |
| Antimony, Total | 0.0310 µg/L 0.5% of the EPA limit 6 µg/L | 1/16 | SYR4 | 2012–2019 |
| Barium | 86.879 µg/L 4.3% of the EPA limit 2000 µg/L | 1/13 | SYR4 | 2012–2019 |
| Cadmium | 0.0010 µg/L 0% of the EPA limit 5 µg/L | 1/15 | SYR4 | 2012–2019 |
| Dichloroacetic Acid | 1.8 µg/L No EPA limit set | 1/11 | SYR4 | 2014–2019 |
| Lead | 0.0240 µg/L 0.2% of the EPA limit 15 µg/L | 1/16 | SYR4 | 2012–2019 |
| Selenium | 0.4520 µg/L 0.9% of the EPA limit 50 µg/L | 1/16 | SYR4 | 2012–2019 |
| Thallium, Total | 0.0040 µg/L 0.2% of the EPA limit 2 µg/L | 1/16 | SYR4 | 2012–2019 |
| Trichloroacetic Acid | 1 µg/L No EPA limit set | 1/11 | SYR4 | 2014–2019 |
84 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,3,7,8-TCDD2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAsbestosAtrazineBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCyanideCarbofuranCarbon TetrachlorideChlordaneChloroformDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateGross Beta Particle ActivityHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorMonochloroacetic AcidNetfosaaNfdhaNmefosaaNitriteOxamylPfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPFHXSPfmbaPfmpaPFNAPFOAPFOSPfpeaPfpesPftaPftrdaPfunaPentachlorophenolPicloramSimazineStyreneTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneVinyl ChlorideXylenes, TotalO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene
Utility contact
Frequently asked questions about Cwsc Oak Hills
Is Cwsc Oak Hills tap water safe to drink?
EPA monitoring detected 28 contaminants in Cwsc Oak Hills's water. A detection isn't the same as a violation — most levels are within federal limits. See each level and source above, and the utility's annual Consumer Confidence Report for its official compliance status.
What contaminants were detected in Cwsc Oak Hills's water?
EPA monitoring detected Nitrate, 1,1-Dichloroethylene, Trichloroethylene, Chromium, Lead, and others. The full list with the level and data source for each is above.
How many people does Cwsc Oak Hills serve?
Cwsc Oak Hills reports serving 3,161 people in California, per its EPA record.
Has Cwsc Oak Hills had any water quality violations?
The EPA has 7 violations on file for Cwsc Oak Hills, of which 4 are health-based (a contaminant limit or required treatment was breached) and 0 remain open. The rest are monitoring or reporting failures.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.