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EPA SDWIS ยท Lake County, California ยท 291 providers profiled

Lake County, CA Water Quality Report

Lake County is served by 291 major public water systems on file with the EPA.

Data current as of July 2026
๐Ÿ”Straight from EPA
๐ŸงชReal Lab Results
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Results for Lake County, CA

291 water providers on file for this county, sorted by population served.

Quick answer: Lake County has 291 water providers profiled, sorted by population served.

Violations on file

Coliform (TCR)
Older/archived health-based violation
Found at 7 of 291 providers
Barium
Older/archived health-based violation
Found at 1 of 291 providers
Selenium
Older/archived health-based violation
Found at 1 of 291 providers
Lead And Copper Rule Revisions
Currently open health violation
Found at 10 of 291 providers
TTHM
Older/archived health-based violation
Found at 1 of 291 providers
A group of disinfection byproducts formed when chlorine reacts with organic matter. Long-term exposure above the legal limit has been linked to increased cancer risk in some studies.
Total Haloacetic Acids (HAA5)
Older/archived health-based violation
Found at 3 of 291 providers
Nitrite
Older/archived health-based violation
Found at 1 of 291 providers

Contaminants found

Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.041 mg/L (ppm)
Found at 66 providers
Copper Summary
Detected: 4.65 mg/L (ppm)
Found at 18 providers
Copper, Free
Detected: 540 UG/L (ppb)
Found at 16 providers
Manganese
Detected: 450 UG/L (ppb)
Found at 23 providers
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Zinc
Detected: 270 UG/L (ppb)
Found at 4 providers
Lead
Detected: 15 UG/L (ppb)
Found at 4 providers
A metal that can leach from old pipes, solder, and fixtures. Current medical guidance holds there is no truly safe level of lead exposure, especially for children and pregnant women.
Iron
Detected: 2000 UG/L (ppb)
Found at 18 providers
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Nickel
Detected: 2.1 UG/L (ppb)
Found at 2 providers
Arsenic
Detected: 6.9 UG/L (ppb)
Found at 6 providers
Occurs naturally in some groundwater. Long-term exposure above the legal limit (10 ppb) has been linked to increased cancer risk and cardiovascular disease.
Aluminum
Detected: 620 UG/L (ppb)
Found at 13 providers
Combined Uranium
Detected: 1.2 PCI/L
7/30/2025
A naturally occurring radioactive metal. Long-term exposure above the legal limit is associated with kidney effects and increased cancer risk.
Lithium, Total
Detected: 16 UG/L (ppb)
5/5/2025
Strontium
Detected: 220 UG/L (ppb)
5/5/2025
Barium
Detected: 340 UG/L (ppb)
Found at 7 providers
Vanadium, Total
Detected: 11 UG/L (ppb)
Found at 3 providers
Chromium
Detected: 13 UG/L (ppb)
Found at 3 providers
Occurs in two forms โ€” trivalent (an essential nutrient in trace amounts) and hexavalent (linked to increased cancer risk).
Chromium, Hex
Detected: 13.4 UG/L (ppb)
Found at 7 providers
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 64.9 UG/L (ppb)
Found at 20 providers
TTHM
Detected: 120 UG/L (ppb)
Found at 23 providers
A group of disinfection byproducts formed when chlorine reacts with organic matter. Long-term exposure above the legal limit has been linked to increased cancer risk in some studies.
Chloroform
Detected: 100 UG/L (ppb)
Found at 22 providers
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 14 UG/L (ppb)
Found at 20 providers
Dibromochloromethane
Detected: 11.93 UG/L (ppb)
Found at 21 providers
Bromoform
Detected: 3.27 UG/L (ppb)
Found at 4 providers
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Nitrate
Detected: 13 MG/L (ppm)
Found at 18 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Nitrate-Nitrite
Detected: 0.64 MG/L (ppm)
10/9/2025
Fluoride
Detected: 0.48 MG/L (ppm)
Found at 17 providers
Often added deliberately for dental health; can also occur naturally.
Sulfate
Detected: 22 MG/L (ppm)
Found at 24 providers
Chloride
Detected: 50 MG/L (ppm)
Found at 24 providers
Boron, Total
Detected: 3400 UG/L (ppb)
Found at 13 providers
Nitrite
Detected: 0.26 MG/L (ppm)
Found at 2 providers
Minerals
Everyday minerals that mainly affect taste and water hardness
Magnesium
Detected: 39 MG/L (ppm)
Found at 23 providers
Calcium
Detected: 87 MG/L (ppm)
Found at 24 providers
Potassium
Detected: 2.6 MG/L (ppm)
Found at 3 providers
Sodium
Detected: 37 MG/L (ppm)
Found at 23 providers
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Hardness, Total (ASCACO3)
Detected: 328 MG/L (ppm)
Found at 23 providers
pH
Detected: 8.25 PH
Found at 24 providers
A measure of how acidic or basic the water is (7 is neutral). Affects taste and plumbing, not a direct health measure.
Langelier Index (pH(s))
Detected: -0.4 LANG
5/5/2025
pH, Field
Detected: 8.1 PH
10/7/2025
Gross Alpha Particle Activity
Detected: 3.21 PCI/L
Found at 6 providers
PFAS & Emerging Contaminants
Human-made "forever chemicals" and other substances not yet fully regulated
Lithium
Detected: 26 ยตg/L (ppb)
Found at 7 providers
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
PFBA
Detected: 0.0082 ยตg/L (ppb)
4/5/2023
PFPEA
Detected: 0.0039 ยตg/L (ppb)
4/5/2023
VOCs (Volatile Organic Compounds)
Industrial solvents and fuel-related chemicals that evaporate easily
1, 2, 3-Trichloropropane
Detected: 0.0057 UG/L (ppb)
5/14/2025
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 320 MG/L (ppm)
Found at 29 providers
Alkalinity, Carbonate
Detected: 52 MG/L (ppm)
Found at 8 providers
Other
Additional substances tested that don't fit neatly into the categories above
Bromate
Detected: 14 UG/L (ppb)
Found at 2 providers
Dichloroaceticacid
Detected: 40.4 UG/L (ppb)
Found at 20 providers
Trichloroaceticacid
Detected: 32 UG/L (ppb)
Found at 21 providers
Dibromoaceticacid
Detected: 4.2 UG/L (ppb)
Found at 12 providers
Carbon, Total
Detected: 5.6 MG/L (ppm)
Found at 11 providers
Alkalinity, Total
Detected: 320 MG/L (ppm)
Found at 29 providers
Radium-228
Detected: 0.798 PCI/L
Found at 5 providers
TDS
Detected: 430 MG/L (ppm)
Found at 23 providers
Turbidity
Detected: 9.4 NTU
Found at 22 providers
A measure of water cloudiness from suspended particles.
Conductivity (at 25ยฐC)
Detected: 710 UMHO/CM
Found at 26 providers
Color
Detected: 36 UNITS
Found at 24 providers
Monochloroaceticacid
Detected: 3.8 UG/L (ppb)
Found at 4 providers
Aggressive Index
Detected: 12.24 AGGR
Found at 18 providers
Odor
Detected: 28 TON
Found at 17 providers
Combined Radium (-226 & -228)
Detected: 0.797 PCI/L
Found at 2 providers
A naturally occurring radioactive element found in some groundwater.
Gross Beta Particle Activity
Detected: 5.94 PCI/L
Found at 5 providers
4-Methyl-2-Pentanone
Detected: 0.8 UG/L (ppb)
3/11/2025
Methyltert-Butylether
Detected: 4.1 UG/L (ppb)
9/9/2025
Filtration considerations: General system types, not a specific product recommendation.
Contaminant Whole-House Carbon Under-Sink RO Under-Sink Carbon
Total Trihalomethanes (TTHM)YesYesYes
Haloacetic Acids (HAA5)YesYesYes
ChloroformYesYesYes
Chlorine / TasteYesYesYes
Sediment / TurbidityYesYesYes
TrichloroethyleneYesYesYes
TetrachloroethyleneYesYesYes
cis-1,2-DichloroethyleneYesYesYes
1,1-DichloroethyleneYesYesYes
BromoformYesYesYes
BromodichloromethaneYesYesYes
DibromochloromethaneYesYesYes
1,1,2-TrichloroethaneYesYesYes
Vinyl ChlorideYesYesYes
Carbon TetrachlorideYesYesYes
BenzeneYesYesYes
TolueneYesYesYes
XyleneYesYesYes
Totalhaloaceticacids (HAA5)YesYesYes
1, 2, 3-TrichloropropaneYesYesYes
LeadPartialYesPartial
ArsenicPartialYesPartial
Chromium-6 (Hexavalent)PartialYesPartial
CopperPartialYesPartial
Combined UraniumPartialYesPartial
PFOAPartialYes*Partial
PFOSPartialYes*Partial
NitratePartialYesPartial
Combined RadiumPartialYesPartial
BromatePartialYesPartial
Nitrate-NitritePartialYesPartial
DichloroaceticacidPartialYesPartial
TrichloroaceticacidPartialYesPartial
DibromoaceticacidPartialYesPartial
Copper, FreePartialYesPartial
Carbon, TotalPartialYesPartial
Alkalinity, TotalPartialYesPartial
FluoridePartialYesPartial
LithiumPartialYes*Partial
TDSPartialYesPartial
SulfatePartialYesPartial
ChloridePartialYesPartial
ManganesePartialYesPartial
ZincPartialYesPartial
Conductivity (at 25ยฐC)PartialYesPartial
ColorPartialYesPartial
MonochloroaceticacidPartialYesPartial
IronPartialYesPartial
NickelPartialYesPartial
AluminumPartialYesPartial
Combined UraniumPartialYesPartial
Aggressive IndexPartialYesPartial
OdorPartialYesPartial
Boron, TotalPartialYesPartial
Combined Radium (-226 & -228)PartialYesPartial
Gross Beta Particle ActivityPartialYesPartial
Lithium, TotalPartialYesPartial
StrontiumPartialYesPartial
4-Methyl-2-PentanonePartialYesPartial
BariumPartialYesPartial
PFBAPartialYes*Partial
PFPEAPartialYes*Partial
Vanadium, TotalPartialYesPartial
ChromiumPartialYesPartial
Chromium, HexPartialYesPartial
Methyltert-ButyletherPartialYesPartial
NitritePartialYesPartial
Coliform Bacteria (indicator)NoYesNo
Alkalinity, BicarbonateNoNoNo
Alkalinity, CarbonateNoNoNo
MagnesiumNoPartialNo
CalciumNoPartialNo
Hardness, Total (ASCACO3)NoNoNo
PotassiumNoPartialNo
SodiumNoPartialNo
pHNoNoNo
Langelier Index (pH(s))NoNoNo
pH, FieldNoNoNo
Gross Alpha Particle ActivityNoNoNo

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What is TTHM? Understanding EPA Violation Status Is Chromium-6 Dangerous? Whole-House vs. Under-Sink Filtration Lead and Copper in Drinking Water What is PFAS? Arsenic and Uranium Explained Nitrate and Fluoride Explained Water Hardness, pH, and Turbidity What is Coliform Bacteria?