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Lake County, CA Water Quality

Water quality data for 15 public water systems serving Lake County, California — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 15 water systems · 15 cities
✅
Generally Safe — Most Systems Performing Well

The majority of water systems have no active violations and lead levels well below the federal action level.

B

Lake County Earns a B

Lake County: 15 communities across 15 water systems. 86.7% have no open violations.

  • Median lead where detected: 4.90 ppb
  • 2 communities with a lead detection, 13 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 1 with significant inspection deficiencies
  • 86.7% of communities have no open violations
4.9 ppb
Median Lead Level
County-wide, 90th percentile
15
Water Systems
Active CWS & NTNCWS
86%
Violation-Free
No active violations on record
How we grade counties: MyWaterIQ uses EPA SDWIS enforcement data — actual MCL violations and lead test results — not the aspirational MCLG targets used by some sites. A grade reflects real compliance history, not theoretical risk. Learn more →

Cities by Water Quality

⭐ Best Performing
  • Hidden Valley Lake
    Not detected
    No federal limits exceeded on record
    A
  • North Lakeport
    Not detected
    No federal limits exceeded on record
    B
  • Lucerne
    Not detected
    No federal limits exceeded on record
    A
  • Upper Lake
    Not detected
    No federal limits exceeded on record
    B
  • Nice
    Not detected
    1 health-based violation since 2015
    B
⚠ Needs Attention
  • Cobb
    Not detected
    Copper above the 1,300 ppb action level
    D
  • Middletown
    Not detected
    1 violation currently open
    C
  • Clearlake Oaks
    Not detected
    Copper above the 1,300 ppb action level
    B
  • Lower Lake
    Not detected
    1 significant inspection deficiency
    B
  • Clearlake
    4.60 ppb
    5 health-based violations since 2015
    B
County Lead Level — Median 4.9 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 4.9 ppb — 32.7% of the federal action level
Systems by Lead Level
Under 5 ppb
1
5 – 10 ppb
1
No Data
13

All Cities in Lake County

Clearlake 4.60 ppb B
Hidden Valley Lake Not detected A
Lakeport Not detected A
North Lakeport Not detected B
Kelseyville 5.20 ppb A
Clearlake Riviera Not detected B
Lucerne Not detected A
Nice Not detected B
Clearlake Oaks Not detected B
Soda Bay Not detected B
Cobb Not detected D
Lower Lake Not detected B
Spring Valley Not detected B
Upper Lake Not detected B
Middletown Not detected C
Showing 15 cities
No active violations Active violations

About Lake County Drinking Water

Lake County is served by 15 water systems covering 15 communities. 87% have no open violations.

Of the communities reporting lead results, 2 recorded a detection, with a median of 4.90 ppb — 33% of the federal action level. 13 reported none detected, which means below the laboratory limit rather than an absence of lead.

No community here has PFAS above the federal limit on record. State inspectors recorded significant deficiencies at 1 of them.

Frequently Asked Questions

Is Lake County tap water safe to drink?▼
87% of communities have no open violation. No community has PFAS above the federal limit on record.
What is the lead level in Lake County?▼
Among communities with a detection the median is 4.90 ppb, 33% of the 15 ppb action level. 13 reported none detected and 0 reported no result.
How many water systems serve Lake County?▼
15 community water systems serve 15 communities here.
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