01The verdict: is Lower Lake water safe?
Lower Lake's drinking water has significant quality concerns based on EPA testing data. With a grade of B+ (83.8/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 4 water systems serve approximately 1,579 residents using groundwater (wells).
9 unresolved violations on record
EPA records show open compliance items for this system. Most are administrative, but unresolved items are worth watching.
See what was cited ↓Top half in California
Lower Lake ranks #297 of 690 graded California cities.
See the comparison ↓2 violations in the last five years
Recent compliance history is the best predictor of future problems — the year-by-year record is below.
See the record ↓Lower Lake's drinking water received a grade of B+ (83.8 out of 100), indicating good water quality. The city's 4 water systems serve approximately 1,579 residents using groundwater.
Lead levels were measured at 8.0 ppb (90th percentile), which is within EPA limits but above recommended levels. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 61 violations on record, including 3 health-based violations. 9 remain unresolved.
Lower Lake ranks #297 out of 690 cities in California for water quality, placing it mid-range in the state. Lower 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. While lead levels are within EPA limits, they are above the recommended 5 ppb threshold that health organizations consider ideal. A point-of-use filter adds an extra layer of protection. As a small community water system, Lower Lake may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in Lower Lake's water
Every contaminant flagged in Lower Lake, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
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. | 8.0 | 15 | ppb | Inorganic | Safe |
Cities ranked by 90th-percentile lead PF PFAS in California
Cities ranked by compounds detected Cu Copper in California
Cities ranked by 90th-percentile copper
03Lower Lake's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 61 violations on record, including 3 health-based violations. 9 remain unresolved.
5 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▼ Down 36 ppb since 1994. Latest reading: 0 ppb (2025) — 0% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Lower Lake's water comes from
Lower Lake's drinking water is drawn from underground aquifers through wells.
Groundwater
Underground aquifers reached by wells — naturally filtered, but can carry minerals like arsenic and nitrate.
Local treatment
Groundwater generally needs less treatment — typically disinfection and, where needed, mineral removal.
4 systems
4 water systems, operated under local government ownership.
1,579 people
Residents served across Lower Lake's service area.
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 1,579 people through 4 water systems.
| System name | PWSID | Population | Source |
|---|---|---|---|
| LOWER LAKE COUNTY WATER DISTRICT | CA1710010 | 1,326 | Groundwater |
| CDF-KONOCTI CONSERVATION CAMP NO. 27 | CA1710800 | 100 | Groundwater |
| SUNRISE SHORE MUTUAL WATER COMPANY | CA1700536 | 83 | Groundwater |
| BAYCLIFF WATER | CA1700606 | 70 | Groundwater |
Water bodies near Lower Lake
These water bodies shape the regional watershed and can indirectly affect groundwater quality.
05Pressure on Lower Lake's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
8 federal disaster declarations on record for Lake County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Superfund proximity
1 National Priorities List site within 10 miles. Proximity does not necessarily indicate tap-water contamination — the connection depends on hydrology and treatment.
06How Lower Lake compares
Scores for nearby California cities on one line, with the average marked.
dashed line = California average (57/100)
Lower Lake scores 83.8/100 — above the California average of 57/100. It outscores 8 of 10 nearby cities. Full California rankings →
42.8 / 100FSan Jose, CA
28 / 100BOakland, CA
77.9 / 100FSan Diego, CA
39.7 / 100FSacramento, CA
31.2 / 100ABurlingame, CA
89.2 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Lower Lake's water — not generic advice.
Filter drinking & cooking water
NSF-certified water filter. Lead detected at 8.0 ppb
Compare tested filters →Flush taps & check your service line
Lead leaches from pipes as water sits. Run cold water 30 seconds before drinking (especially mornings), and ask the utility whether your address still has a lead service line.
Lead risks explained →Watch for Lower Lake alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Lower Lake, CA tap water safe to drink?
Lower Lake's water quality earned a grade of B+ (83.8/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #297 out of 690 cities tested in California.
What contaminants are in Lower Lake's water?
Lead was measured at 8.0 ppb (90th percentile). 61 violations are on record.
How is Lower 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 Lower Lake?
While lead levels are within EPA limits, a filter adds extra protection. Based on current data, basic filtration should suffice for additional peace of mind.
Where does Lower Lake's water come from?
Lower Lake's water is sourced from Groundwater. The city has 4 water systems serving approximately 1,579 residents.
What health violations has Lower Lake's water system had?
Lower Lake has 3 health-based violations on record. The most recent violation was recorded in October 2024. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 9 violations remain unresolved.
Is Lower Lake's groundwater at risk of contamination?
Lower 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 61 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 Lower Lake's water compare to other cities?
Lower Lake ranks #297 out of 690 cities in California (better than 57% of state cities) and #6223 out of 15382 cities nationally (60th percentile). The grade of B+ reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.