What was found in Clearlake'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 | 800 µg/L 8% of the EPA limit 10000 µg/L Highest in the city: WINDFLOWER POINT MUTUAL WATER COMPANY · 25 people · 2019 | 2/3 | SYR4 |
| Fluoride | 200 µg/L 5% of the EPA limit 4000 µg/L Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019
Highest in the city: 278 µg/L — WINDFLOWER POINT MUTUAL WATER COMPANY · 25 people · 2017 | 3/3 | SYR4 |
| Barium | 110 µg/L 5.5% of the EPA limit 2000 µg/L Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019
Highest in the city: 140 µg/L — KONOCTI COUNTY WATER DISTRICT · 5,928 people · 2019 | 2/3 | SYR4 |
| TTHM | 87.423 µg/L 109% of the EPA limit, at the 95th percentile of samples — 80 µg/L Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019 | 3/3 | SYR4 |
| Chloroform | 70.409 µg/L No EPA limit set Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019 | 2/3 | SYR4 |
| Total Haloacetic Acids (HAA5) | 68.36 µg/L 114% of the EPA limit, at the 95th percentile of samples — 60 µg/L Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019 | 2/3 | SYR4 |
| Dichloroacetic Acid | 43.9 µg/L No EPA limit set Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019 | 2/3 | SYR4 |
| Bromate | 10.79 µg/L 108% of the EPA limit, at the 95th percentile of samples — 10 µg/L Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019
Highest in the city: 36.2 µg/L — KONOCTI COUNTY WATER DISTRICT · 5,928 people · 2019 | 2/3 | SYR4 |
| Lithium | 25 µg/L No EPA limit set Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2024 | 2/3 | UCMR-5 |
| Bromodichloromethane | 17.96 µg/L No EPA limit set Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019 | 3/3 | SYR4 |
| Trichloroacetic Acid | 17.26 µg/L No EPA limit set Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019 | 2/3 | SYR4 |
| Monochloroacetic Acid | 8.05 µg/L No EPA limit set Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019 | 2/3 | SYR4 |
| Dibromochloromethane | 4.6475 µg/L No EPA limit set Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019
Highest in the city: 6.315 µg/L — KONOCTI COUNTY WATER DISTRICT · 5,928 people · 2019 | 3/3 | SYR4 |
| Arsenic | 2.57 µg/L 26% of the EPA limit 10 µg/L Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019
Highest in the city: 6.045 µg/L — KONOCTI COUNTY WATER DISTRICT · 5,928 people · 2019 | 2/3 | SYR4 |
| Bromoform | 1.7775 µg/L No EPA limit set Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019
Highest in the city: 3.14 µg/L — WINDFLOWER POINT MUTUAL WATER COMPANY · 25 people · 2018 | 3/3 | SYR4 |
| Dibromoacetic Acid | 2.34 µg/L No EPA limit set Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019
Highest in the city: 2.665 µg/L — KONOCTI COUNTY WATER DISTRICT · 5,928 people · 2019 | 2/3 | SYR4 |
| Monobromoacetic Acid | 1.3 µg/L No EPA limit set Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2019 | 1/3 | SYR4 |
| Pfba | 0.0082 µg/L No EPA limit set Highest in the city: KONOCTI COUNTY WATER DISTRICT · 5,928 people · 2023 | 1/3 | UCMR-5 |
| Lead | 0.0046 mg/L 31% of the EPA limit 0.0150 mg/L Main supplier: HIGHLANDS MUTUAL WATER COMPANY · 7,772 people · 2023 | 3/3 | LCR |
| Pfpea | 0.0039 µg/L No EPA limit set Highest in the city: KONOCTI COUNTY WATER DISTRICT · 5,928 people · 2023 | 1/3 | UCMR-5 |
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 Clearlake
| Supplier | Population served |
|---|---|
| HIGHLANDS MUTUAL WATER COMPANY | 7,772 |
| KONOCTI COUNTY WATER DISTRICT | 5,928 |
| WINDFLOWER POINT MUTUAL WATER COMPANY | 25 |
Frequently asked questions about Clearlake tap water
Is Clearlake tap water safe to drink?
EPA testing detected 20 contaminants in the water serving Clearlake. 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 Clearlake?
3 public water suppliers report drinking-water monitoring for Clearlake, California to the EPA. Each is listed above with its population served.
What contaminants are in Clearlake's water?
The contaminants EPA monitoring detected in Clearlake include Nitrate, Fluoride, Barium, TTHM, Chloroform. 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.