Is Upper Lake, CA Tap Water Safe to Drink?
Graded B, with 9 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
79/100
waterverge.com Upper Lake, CA — Water Quality Report
Upper Lake's drinking water received a grade of B (79 out of 100), indicating good water quality. The city's 4 water systems serve approximately 1,237 residents using groundwater.
Lead levels were measured at 5.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 107 violations on record, including 4 health-based violations. 9 remain unresolved.
What to know about Upper Lake's water
Upper Lake ranks #387 out of 694 cities in California for water quality, placing it below average in the state.
Upper Lake relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
As a small community water system, Upper Lake may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Upper Lake, CA water safe to drink?
Upper Lake's drinking water has significant quality concerns based on EPA testing data. With a grade of B (79/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 4 water systems serve approximately 1,237 residents using groundwater (wells).
Recent water quality updates for Upper Lake
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Upper Lake's water quality assessment. Grade: B (79/100).
Contaminants: LEAD AND COPPER RULE REVISIONS.
1 health-based. Contaminants: LEAD AND COPPER RULE REVISIONS.
Federal disaster declaration (FEMA DR-3592). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-3591). Flood event — may have impacted local water infrastructure.
Contaminants: Chlorine.
Key contaminant findings
Based on the most recent EPA sampling data for Upper Lake's water supply.
Well within EPA limits.
Violation history
Upper Lake's water system has 107 total violations on record, including 4 health-based violations. 9 remain unresolved. 4 violations were issued in the last 5 years.
Flood & environmental risk
Lake County has experienced 8 federally declared disasters since 1964. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Sf Scotts C Nr Lakeport, Scotts C Bl Sf Scotts C Nr Lakeport, Clover C Bypass A Elk Mtn Rd Nr Upper Lake, Scotts C Ab State Route 29 A Upper Lake, Clear Lk A Lakeport.
Where does Upper Lake's water come from?
Upper Lake's drinking water comes from groundwater (wells), supplied by 4 water systems serving approximately 1,237 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Sf Scotts C Nr Lakeport (river), Scotts C Bl Sf Scotts C Nr Lakeport (river), Clover C Bypass A Elk Mtn Rd Nr Upper Lake (river), Scotts C Ab State Route 29 A Upper Lake (river), Clear Lk A Lakeport (lake).
What Upper Lake residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Upper Lake's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Run cold water for 30 seconds before drinking, especially in the morning. Lead and copper leach from household plumbing when water sits in pipes.
Upper Lake's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Flood & disaster history
Lake County has experienced 8 federally declared disasters since 1964. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 5.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Upper Lake compares by contaminant
Explore where Upper Lake ranks among all California cities for specific contaminants.
Water source & infrastructure
Where Upper Lake's water comes from
Upper Lake's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by local government ownership and serves approximately 1,237 people through 4 water systems.
Water bodies near Upper Lake
Upper Lake is located near 5 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Upper Lake
| System Name | PWSID | Population | Source |
|---|---|---|---|
| UPPER LAKE COUNTY WATER DISTRICT | CA1710009 | 989 | GW |
| Upper Lake Hardisty System | 090605025 | 98 | GW |
| BLUE LAKES IMPROVEMENT CLUB | CA1700561 | 90 | GW |
| VILLA BLUE ESTATES WATER DISTRICT | CA1700579 | 60 | GW |
How Upper Lake compares
Full California rankings →Upper Lake's score of 79/100 is above the average of 57/100 among major California cities. It outscores 8 of 10 nearby cities.
Nearby cities
View California rankings →ZIP codes served by Upper Lake
The water systems serving Upper Lake cover 1 ZIP code. Select any ZIP to see which water systems serve that area.
About Upper Lake, CA
Wikipedia →Upper Lake is a census-designated place (CDP) in Lake County, California, United States. Upper Lake is located 8 miles (13 km) north of Lakeport, at an elevation of 1,345 feet (410 m). The population was 1,095 at the 2020 census, up from 1,052 at the 2010 census. The Habematolel Pomo of Upper Lake are headquartered here.
Learn more about your water
Guides and resources related to Upper Lake's water quality findings.
Explore water quality across Lake
Frequently asked questions
Is Upper Lake, CA tap water safe to drink?
Upper Lake's water quality earned a grade of B (79/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #387 out of 694 cities tested in California.
What contaminants are in Upper Lake's water?
Lead was measured at 5.0 ppb (90th percentile). 107 violations are on record.
How is Upper Lake's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Upper Lake?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Upper Lake's water come from?
Upper Lake's water is sourced from Groundwater. The city has 4 water systems serving approximately 1,237 residents.
What health violations has Upper Lake's water system had?
Upper Lake has 4 health-based violations on record. The most recent violation was recorded in July 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 9 violations remain unresolved.
Is Upper Lake's groundwater at risk of contamination?
Upper Lake uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 107 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Upper Lake's water compare to other cities?
Upper Lake ranks #387 out of 694 cities in California (better than 44% of state cities) and #8441 out of 15744 cities nationally (46th percentile). The grade of B reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.