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EPA SDWIS ยท Madera County, California ยท 311 providers profiled

Madera County, CA Water Quality Report

Madera County is served by 311 major public water systems on file with the EPA.

Data current as of July 2026
๐Ÿ”Straight from EPA
๐ŸงชReal Lab Results
๐Ÿ“…Updated Quarterly
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Results for Madera County, CA

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

Quick answer: Madera County has 311 water providers profiled, sorted by population served.

Violations on file

Coliform (TCR)
Older/archived health-based violation
Found at 16 of 311 providers
Nitrate
Older/archived health-based violation
Found at 4 of 311 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Lead And Copper Rule Revisions
Currently open health violation
Found at 17 of 311 providers
Arsenic
Older/archived health-based violation
Found at 12 of 311 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.
Total Haloacetic Acids (HAA5)
Older/archived health-based violation
Found at 2 of 311 providers
TTHM
Older/archived health-based violation
Found at 2 of 311 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.
Surface Water Treatment Rule
Older/archived health-based violation
Found at 1 of 311 providers
Combined Uranium
Older/archived health-based violation
Found at 7 of 311 providers
A naturally occurring radioactive metal. Long-term exposure above the legal limit is associated with kidney effects and increased cancer risk.
1, 2-Dibromo-3-Chloropropane
Older/archived health-based violation
Found at 2 of 311 providers

Contaminants found

Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.05 mg/L (ppm)
Found at 119 providers
Lead
Detected: 16 UG/L (ppb)
Found at 29 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.
Copper, Free
Detected: 460 UG/L (ppb)
Found at 40 providers
Iron
Detected: 4100 UG/L (ppb)
Found at 32 providers
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Manganese
Detected: 234 UG/L (ppb)
Found at 34 providers
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Chromium, Hex
Detected: 3.8 UG/L (ppb)
Found at 51 providers
Barium
Detected: 340 UG/L (ppb)
Found at 25 providers
Aluminum
Detected: 6000 UG/L (ppb)
Found at 14 providers
Molybdenum, Total
Detected: 1.2 UG/L (ppb)
5/19/2025
Nickel
Detected: 2.7 UG/L (ppb)
Found at 7 providers
Chromium
Detected: 3.3 UG/L (ppb)
Found at 8 providers
Occurs in two forms โ€” trivalent (an essential nutrient in trace amounts) and hexavalent (linked to increased cancer risk).
Selenium
Detected: 2.7 UG/L (ppb)
Found at 3 providers
Zinc
Detected: 1200 UG/L (ppb)
Found at 8 providers
Arsenic
Detected: 27 UG/L (ppb)
Found at 45 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.
Combined Uranium
Detected: 310 PCI/L
Found at 24 providers
A naturally occurring radioactive metal. Long-term exposure above the legal limit is associated with kidney effects and increased cancer risk.
Copper Summary
Detected: 3.4 mg/L (ppm)
Found at 3 providers
Mercury
Detected: 0.57 UG/L (ppb)
Found at 4 providers
Antimony, Total
Detected: 2.2 UG/L (ppb)
8/18/2025
Strontium
Detected: 44 UG/L (ppb)
6/17/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
TTHM
Detected: 120 UG/L (ppb)
Found at 19 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: 120 UG/L (ppb)
Found at 12 providers
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 18 UG/L (ppb)
Found at 15 providers
Dibromochloromethane
Detected: 11 UG/L (ppb)
Found at 12 providers
Bromoform
Detected: 7.1 UG/L (ppb)
Found at 9 providers
Totalhaloaceticacids (HAA5)
Detected: 130 UG/L (ppb)
Found at 10 providers
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Nitrate
Detected: 8.5 MG/L (ppm)
Found at 110 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Fluoride
Detected: 0.82 MG/L (ppm)
Found at 27 providers
Often added deliberately for dental health; can also occur naturally.
Nitrate-Nitrite
Detected: 11 MG/L (ppm)
Found at 23 providers
Chloride
Detected: 130 MG/L (ppm)
Found at 20 providers
Sulfate
Detected: 41 MG/L (ppm)
Found at 19 providers
Nitrite
Detected: 0.57 MG/L (ppm)
Found at 2 providers
Minerals
Everyday minerals that mainly affect taste and water hardness
Magnesium
Detected: 21 MG/L (ppm)
Found at 23 providers
Potassium
Detected: 7.4 MG/L (ppm)
Found at 15 providers
Sodium
Detected: 82 MG/L (ppm)
Found at 21 providers
Calcium
Detected: 86 MG/L (ppm)
Found at 22 providers
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Gross Alpha Particle Activity
Detected: 373 PCI/L
Found at 37 providers
Langelier Index (pH(s))
Detected: -0.24 LANG
Found at 9 providers
Hardness, Total (ASCACO3)
Detected: 300 MG/L (ppm)
Found at 16 providers
pH
Detected: 8.7 PH
Found at 20 providers
A measure of how acidic or basic the water is (7 is neutral). Affects taste and plumbing, not a direct health measure.
Orthophosphate
Detected: 0.93 MG/L (ppm)
Found at 3 providers
pH, Field
Detected: 7.5 PH
Found at 2 providers
PFAS & Emerging Contaminants
Human-made "forever chemicals" and other substances not yet fully regulated
PFOA
Detected: 0.0075 ยตg/L (ppb)
Found at 2 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFBA
Detected: 0.0075 ยตg/L (ppb)
2/26/2025
Lithium
Detected: 82.4 ยตg/L (ppb)
Found at 3 providers
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
PFBS
Detected: 0.0128 ยตg/L (ppb)
10/8/2025
PFOS
Detected: 0.0079 ยตg/L (ppb)
10/8/2025
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFPEA
Detected: 0.0037 ยตg/L (ppb)
10/8/2025
PFHXA
Detected: 0.0033 ยตg/L (ppb)
3/4/2025
PFHXS
Detected: 0.0067 ยตg/L (ppb)
9/9/2025
VOCs (Volatile Organic Compounds)
Industrial solvents and fuel-related chemicals that evaporate easily
Tetrachloroethylene
Detected: 1.9 UG/L (ppb)
Found at 2 providers
Dichloromethane
Detected: 0.63 UG/L (ppb)
8/13/2025
1, 2, 3-Trichloropropane
Detected: 0.027 UG/L (ppb)
Found at 7 providers
Ethylenedibromide
Detected: 0.048 UG/L (ppb)
4/28/2025
Petroleum Compounds
Substances associated with fuel or petroleum contamination
Toluene
Detected: 28 UG/L (ppb)
3/18/2025
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 180 MG/L (ppm)
Found at 18 providers
Alkalinity, Carbonate
Detected: 5.7 MG/L (ppm)
9/4/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dibromoaceticacid
Detected: 13 UG/L (ppb)
Found at 10 providers
Turbidity
Detected: 49 NTU
Found at 22 providers
A measure of water cloudiness from suspended particles.
1, 2-Dibromo-3-Chloropropane
Detected: 0.49 UG/L (ppb)
Found at 9 providers
Conductivity (at 25ยฐC)
Detected: 670 UMHO/CM
Found at 29 providers
Radium-228
Detected: 0.581 PCI/L
Found at 8 providers
Aggressive Index
Detected: 11.8 AGGR
Found at 9 providers
Alkalinity, Total
Detected: 180 MG/L (ppm)
Found at 21 providers
TDS
Detected: 582 MG/L (ppm)
Found at 22 providers
Color
Detected: 500 UNITS
Found at 18 providers
Odor
Detected: 4 TON
Found at 13 providers
Dichloroaceticacid
Detected: 36 UG/L (ppb)
Found at 9 providers
Trichloroaceticacid
Detected: 87 UG/L (ppb)
Found at 7 providers
Monochloroaceticacid
Detected: 5.9 UG/L (ppb)
Found at 6 providers
Carbon, Total
Detected: 2.8 MG/L (ppm)
Found at 4 providers
Radium-226
Detected: 5.28 PCI/L
Found at 4 providers
Temperature (CENTIGRADE)
Detected: 25 C
6/23/2025
Foamingagents (SURFACTANTS)
Detected: 0.18 MG/L (ppm)
Found at 5 providers
Perfluoropentanoicacid (PFPEA)
Detected: 4.5 NG/L (ppt)
Found at 4 providers
Adsorbableorganicfluorine
Detected: 6100 NG/L (ppt)
Found at 3 providers
Perfluorobutanesulfonicacid (PFBS)
Detected: 17 NG/L (ppt)
Found at 6 providers
Perfluoroctanoicacid (PFOA)
Detected: 8.1 NG/L (ppt)
Found at 4 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluorohexanesulfonicacid (PFHxS)
Detected: 2.8 NG/L (ppt)
Found at 3 providers
Perfluoroctanesulfonicacid (PFOS)
Detected: 9.5 NG/L (ppt)
Found at 2 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluorohexanoicacid (PFHXA)
Detected: 4.1 NG/L (ppt)
Found at 3 providers
Perfluorobutanoicacid (PFBA)
Detected: 4.4 NG/L (ppt)
7/17/2025
Monobromoaceticacid
Detected: 1.1 UG/L (ppb)
1/16/2025
Perfluoroheptanoicacid (PFHPA)
Detected: 2.3 NG/L (ppt)
8/18/2025
Combined Radium (-226 & -228)
Detected: 0.447 PCI/L
8/12/2025
A naturally occurring radioactive element found in some groundwater.
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
DichloromethaneYesYesYes
1, 2, 3-TrichloropropaneYesYesYes
EthylenedibromideYesYesYes
LeadPartialYesPartial
ArsenicPartialYesPartial
Chromium-6 (Hexavalent)PartialYesPartial
CopperPartialYesPartial
Combined UraniumPartialYesPartial
PFOAPartialYes*Partial
PFOSPartialYes*Partial
NitratePartialYesPartial
Combined RadiumPartialYesPartial
Copper, FreePartialYesPartial
DibromoaceticacidPartialYesPartial
IronPartialYesPartial
ManganesePartialYesPartial
Chromium, HexPartialYesPartial
FluoridePartialYesPartial
Nitrate-NitritePartialYesPartial
1, 2-Dibromo-3-ChloropropanePartialYesPartial
BariumPartialYesPartial
Conductivity (at 25ยฐC)PartialYesPartial
Aggressive IndexPartialYesPartial
Alkalinity, TotalPartialYesPartial
TDSPartialYesPartial
ChloridePartialYesPartial
SulfatePartialYesPartial
AluminumPartialYesPartial
ColorPartialYesPartial
OdorPartialYesPartial
Molybdenum, TotalPartialYesPartial
NickelPartialYesPartial
ChromiumPartialYesPartial
SeleniumPartialYesPartial
ZincPartialYesPartial
Combined UraniumPartialYesPartial
NitritePartialYesPartial
DichloroaceticacidPartialYesPartial
TrichloroaceticacidPartialYesPartial
MonochloroaceticacidPartialYesPartial
Carbon, TotalPartialYesPartial
Radium-226PartialYesPartial
Temperature (CENTIGRADE)PartialYesPartial
Foamingagents (SURFACTANTS)PartialYesPartial
Perfluoropentanoicacid (PFPEA)PartialYesPartial
PFBAPartialYes*Partial
LithiumPartialYes*Partial
AdsorbableorganicfluorinePartialYesPartial
Perfluorobutanesulfonicacid (PFBS)PartialYesPartial
MercuryPartialYesPartial
Perfluoroctanoicacid (PFOA)PartialYesPartial
PFBSPartialYes*Partial
PFPEAPartialYes*Partial
PFHXAPartialYes*Partial
PFHXSPartialYes*Partial
Perfluorohexanesulfonicacid (PFHxS)PartialYesPartial
Perfluoroctanesulfonicacid (PFOS)PartialYesPartial
Perfluorohexanoicacid (PFHXA)PartialYesPartial
Perfluorobutanoicacid (PFBA)PartialYesPartial
MonobromoaceticacidPartialYesPartial
Antimony, TotalPartialYesPartial
Perfluoroheptanoicacid (PFHPA)PartialYesPartial
Combined Radium (-226 & -228)PartialYesPartial
StrontiumPartialYesPartial
Coliform Bacteria (indicator)NoYesNo
Gross Alpha Particle ActivityNoNoNo
Langelier Index (pH(s))NoNoNo
MagnesiumNoPartialNo
PotassiumNoPartialNo
SodiumNoPartialNo
CalciumNoPartialNo
Alkalinity, BicarbonateNoNoNo
Hardness, Total (ASCACO3)NoNoNo
pHNoNoNo
Alkalinity, CarbonateNoNoNo
OrthophosphateNoNoNo
pH, FieldNoNoNo

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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?