Tap WaterIndex

← California

Tap water quality report

Upper Lake, CA

EPA monitoring detected 11 contaminants across the 4 water suppliers serving Upper Lake. A detection doesn't automatically mean the water is unsafe — see the level at the main supplier for each below, with its EPA source and period.

4
water suppliers
1,237
people served
11
contaminants found
California rankings Lead in California PFAS in California

What was found in Upper Lake'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.

ContaminantLevel vs EPA limitSuppliersSource
Nitrate
520 µg/L 5.2%
of the EPA limit 10000 µg/L
Main supplier: UPPER LAKE COUNTY WATER DISTRICT · 989 people · 2018
Highest in the city: 2100 µg/L — Upper Lake Hardisty System · 98 people · 2019
3/4 SYR4
Barium
129.5 µg/L 6.5%
of the EPA limit 2000 µg/L
Main supplier: UPPER LAKE COUNTY WATER DISTRICT · 989 people · 2017
Highest in the city: 199 µg/L — VILLA BLUE ESTATES WATER DISTRICT · 60 people · 2019
3/4 SYR4
Fluoride
158.5 µg/L 4%
of the EPA limit 4000 µg/L
Highest in the city: BLUE LAKES IMPROVEMENT CLUB · 90 people · 2018
2/4 SYR4
TTHM
3.56 µg/L 4.5%
of the EPA limit 80 µg/L
Main supplier: UPPER LAKE COUNTY WATER DISTRICT · 989 people · 2019
Highest in the city: 8.017 µg/L — BLUE LAKES IMPROVEMENT CLUB · 90 people · 2018
4/4 SYR4
Chloroform
7.618 µg/L
No EPA limit set
Highest in the city: BLUE LAKES IMPROVEMENT CLUB · 90 people · 2018
2/4 SYR4
Total Haloacetic Acids (HAA5)
3.295 µg/L 5.5%
of the EPA limit 60 µg/L
Highest in the city: Upper Lake Hardisty System · 98 people · 2019
2/4 SYR4
Bromodichloromethane
1.13 µg/L
No EPA limit set
Main supplier: UPPER LAKE COUNTY WATER DISTRICT · 989 people · 2019
Highest in the city: 2.66 µg/L — BLUE LAKES IMPROVEMENT CLUB · 90 people · 2018
2/4 SYR4
Dichloroacetic Acid
2.39 µg/L
No EPA limit set
Highest in the city: BLUE LAKES IMPROVEMENT CLUB · 90 people · 2018
1/4 SYR4
Dibromochloromethane
1.4 µg/L
No EPA limit set
Main supplier: UPPER LAKE COUNTY WATER DISTRICT · 989 people · 2019
1/4 SYR4
Bromoform
1.03 µg/L
No EPA limit set
Main supplier: UPPER LAKE COUNTY WATER DISTRICT · 989 people · 2019
1/4 SYR4
Lead
0.0 mg/L 0%
of the EPA limit 0.0150 mg/L
Main supplier: UPPER LAKE COUNTY WATER DISTRICT · 989 people · 2025
Highest in the city: 0.0100 mg/L — VILLA BLUE ESTATES WATER DISTRICT · 60 people · 2024
4/4 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 Upper Lake

SupplierPopulation served
UPPER LAKE COUNTY WATER DISTRICT 989
Upper Lake Hardisty System 98
BLUE LAKES IMPROVEMENT CLUB 90
VILLA BLUE ESTATES WATER DISTRICT 60

Frequently asked questions about Upper Lake tap water

Is Upper Lake tap water safe to drink?

EPA testing detected 11 contaminants in the water serving Upper Lake. 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 Upper Lake?

4 public water suppliers report drinking-water monitoring for Upper Lake, California to the EPA. Each is listed above with its population served.

What contaminants are in Upper Lake's water?

The contaminants EPA monitoring detected in Upper Lake include Nitrate, Barium, Fluoride, 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.