What was found in Lake Arrowhead's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate-Nitrite | 689.5 µg/L 6.9% of the EPA limit 10000 µg/L Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019
Highest in the city: 525000 µg/L — DEER LODGE WATER SYSTEM · 845 people · 2019 | 2/3 | SYR4 |
| Nitrate | 700 µg/L 7% of the EPA limit 10000 µg/L Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 2/3 | SYR4 |
| Fluoride | 220 µg/L 5.5% of the EPA limit 4000 µg/L Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 2/3 | SYR4 |
| Combined Uranium | 178.8 µg/L 596% of the EPA limit, at the 95th percentile of samples — 30 µg/L Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 2/3 | SYR4 |
| TTHM | 75.59 µg/L 94% of the EPA limit 80 µg/L Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 3/3 | SYR4 |
| Copper | 56 µg/L 4.3% of the EPA limit 1300 µg/L Highest in the city: DEER LODGE WATER SYSTEM · 845 people · 2019 | 1/3 | SYR4 |
| Chloroform | 46.07 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 3/3 | SYR4 |
| Bromoform | 27.015 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019
Highest in the city: 42.12 µg/L — LACSD - RIMFOREST · 817 people · 2019 | 3/3 | SYR4 |
| Lead | 41 µg/L 273% of the EPA limit, at the 95th percentile of samples — 15 µg/L Highest in the city: DEER LODGE WATER SYSTEM · 845 people · 2019 | 1/3 | SYR4 |
| Total Haloacetic Acids (HAA5) | 31.29 µg/L 52% of the EPA limit 60 µg/L Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 3/3 | SYR4 |
| Dibromochloromethane | 15.08 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019
Highest in the city: 22.18 µg/L — LACSD - RIMFOREST · 817 people · 2019 | 3/3 | SYR4 |
| Bromodichloromethane | 17.26 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 3/3 | SYR4 |
| Dichloroacetic Acid | 17.2 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 3/3 | SYR4 |
| Xylenes, Total | 16 µg/L 0.2% of the EPA limit 10000 µg/L Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 1/3 | SYR4 |
| Trichloroacetic Acid | 13.075 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 1/3 | SYR4 |
| Dibromoacetic Acid | 7.955 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019
Highest in the city: 10.6 µg/L — LACSD - RIMFOREST · 817 people · 2019 | 3/3 | SYR4 |
| Arsenic | 5.3 µg/L 53% of the EPA limit 10 µg/L Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 1/3 | SYR4 |
| Monochloroacetic Acid | 3.1 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 1/3 | SYR4 |
| Ethylbenzene | 2.5 µg/L 0.4% of the EPA limit 700 µg/L Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019 | 1/3 | SYR4 |
| Monobromoacetic Acid | 1.1 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2019
Highest in the city: 1.2 µg/L — LACSD - RIMFOREST · 817 people · 2019 | 2/3 | SYR4 |
| PFOA | 0.0140 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2024 | 1/3 | UCMR-5 |
| PFOS | 0.0072 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2024 | 1/3 | UCMR-5 |
| Pfhxa | 0.0067 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2024 | 1/3 | UCMR-5 |
| Pfhpa | 0.0057 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2024 | 1/3 | UCMR-5 |
| PFNA | 0.0046 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2024 | 1/3 | UCMR-5 |
| Pfpea | 0.0045 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2024 | 1/3 | UCMR-5 |
| Pfda | 0.0039 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2024 | 1/3 | UCMR-5 |
| PFHXS | 0.0033 µg/L No EPA limit set Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2024 | 1/3 | UCMR-5 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: LAKE ARROWHEAD CSD · 7,038 people · 2023 | 3/3 | LCR |
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 the
system's samples — over 100% is worth reading, but is not by itself a
violation.
Formal violations are listed separately.
These are the utilities' own EPA-reported results, not a city-wide
average. A detection means the lab measured the
substance — it isn't the same as exceeding a legal limit. Hover a source
tag to see the EPA program and years behind each figure.
Water suppliers serving Lake Arrowhead
| Supplier | Population served |
|---|---|
| LAKE ARROWHEAD CSD | 7,038 |
| DEER LODGE WATER SYSTEM | 845 |
| LACSD - RIMFOREST | 817 |
Frequently asked questions about Lake Arrowhead tap water
Is Lake Arrowhead tap water safe to drink?
EPA testing detected 29 contaminants in the water serving Lake Arrowhead. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve Lake Arrowhead?
3 public water suppliers report drinking-water monitoring for Lake Arrowhead, California to the EPA. Each is listed above with its population served.
What contaminants are in Lake Arrowhead's water?
The contaminants EPA monitoring detected in Lake Arrowhead include Nitrate-Nitrite, Nitrate, Fluoride, Combined Uranium, TTHM. The full list, with the level at the main supplier and the data source, is in the table above.
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.