EPA SDWIS ยท Siskiyou County, California ยท 277 providers profiled
Siskiyou County, CA Water Quality Report
Siskiyou County is served by 277 major public water systems on file with the EPA.
Data current as of July 2026
๐Straight from EPA
๐งชReal Lab Results
๐ Updated Quarterly
๐ Local Expertise
Results for Siskiyou County, CA
277 water providers on file for this county, sorted by population served.
Quick answer: Siskiyou County has 277 water providers profiled, sorted by population served.
Lead Summary
Nitrate
Copper Summary
Lead
Copper, Free
Chromium, Hex
Perfluorobutanesulfonicacid (PFBS)
Perfluoroctanoicacid (PFOA)
Perfluorohexanoicacid (PFHXA)
TTHM
Totalhaloaceticacids (HAA5)
Chloroform
Bromodichloromethane
Dichloroaceticacid
Trichloroaceticacid
Magnesium
Sodium
Calcium
Hardness, Total (ASCACO3)
Dibromochloromethane
Alkalinity, Total
Alkalinity, Bicarbonate
Alkalinity, Carbonate
TDS
Sulfate
pH
Barium
Conductivity (at 25ยฐC)
Aggressive Index
Chloride
Fluoride
Turbidity
Manganese
Arsenic
Zinc
Perchlorate
Iron
Perfluorobutanoicacid (PFBA)
Perfluoropentanoicacid (PFPEA)
Bromoform
Dibromoaceticacid
Perfluoroctanesulfonicacid (PFOS)
Carbon, Total
Aluminum
Nickel
Radium-228
Gross Alpha Particle Activity
Monochloroaceticacid
Violations on file
Coliform (TCR)
Older/archived health-based violation
Found at 9 of 277 providers
Surface Water Treatment Rule
Older/archived health-based violation
Found at 2 of 277 providers
Nitrate
Older/archived health-based violation
Found at 2 of 277 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 277 providers
Arsenic
Older/archived health-based violation
Found at 1 of 277 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.
Contaminants found
Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.088 mg/L (ppm)
Found at 52 providers
Copper Summary
Detected: 2.315 mg/L (ppm)
Found at 10 providers
Lead
Detected: 7.42 UG/L (ppb)
Found at 9 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: 1800 UG/L (ppb)
Found at 12 providers
Chromium, Hex
Detected: 5.6 UG/L (ppb)
Found at 17 providers
Barium
Detected: 77.4 UG/L (ppb)
Found at 5 providers
Manganese
Detected: 480 UG/L (ppb)
Found at 3 providers
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Arsenic
Detected: 23 UG/L (ppb)
Found at 2 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.
Zinc
Detected: 5.9 UG/L (ppb)
4/22/2025
Iron
Detected: 6180 UG/L (ppb)
Found at 2 providers
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Aluminum
Detected: 91.8 UG/L (ppb)
Found at 3 providers
Nickel
Detected: 1.68 UG/L (ppb)
1/28/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
TTHM
Detected: 120 UG/L (ppb)
Found at 5 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.
Totalhaloaceticacids (HAA5)
Detected: 53 UG/L (ppb)
Found at 6 providers
Chloroform
Detected: 100 UG/L (ppb)
Found at 5 providers
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 6.6 UG/L (ppb)
Found at 6 providers
Dibromochloromethane
Detected: 1.6 UG/L (ppb)
Found at 2 providers
Bromoform
Detected: 1.1 UG/L (ppb)
8/7/2025
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Nitrate
Detected: 16 MG/L (ppm)
Found at 30 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Sulfate
Detected: 3.57 MG/L (ppm)
Found at 3 providers
Chloride
Detected: 8.95 MG/L (ppm)
Found at 2 providers
Fluoride
Detected: 0.3 MG/L (ppm)
4/22/2025
Often added deliberately for dental health; can also occur naturally.
Minerals
Everyday minerals that mainly affect taste and water hardness
Magnesium
Detected: 6.2 MG/L (ppm)
Found at 4 providers
Sodium
Detected: 19 MG/L (ppm)
Found at 4 providers
Calcium
Detected: 15.3 MG/L (ppm)
Found at 5 providers
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Hardness, Total (ASCACO3)
Detected: 57 MG/L (ppm)
Found at 5 providers
pH
Detected: 7.54 PH
Found at 2 providers
A measure of how acidic or basic the water is (7 is neutral). Affects taste and plumbing, not a direct health measure.
Gross Alpha Particle Activity
Detected: 2.27 PCI/L
5/7/2025
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 178 MG/L (ppm)
Found at 4 providers
Alkalinity, Carbonate
Detected: 11 MG/L (ppm)
10/2/2025
Other
Additional substances tested that don't fit neatly into the categories above
Perfluorobutanesulfonicacid (PFBS)
Detected: 4 NG/L (ppt)
Found at 4 providers
Perfluoroctanoicacid (PFOA)
Detected: 3.3 NG/L (ppt)
Found at 3 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluorohexanoicacid (PFHXA)
Detected: 3.1 NG/L (ppt)
Found at 3 providers
Dichloroaceticacid
Detected: 20 UG/L (ppb)
Found at 5 providers
Trichloroaceticacid
Detected: 35 UG/L (ppb)
Found at 5 providers
Alkalinity, Total
Detected: 189 MG/L (ppm)
Found at 4 providers
TDS
Detected: 137 MG/L (ppm)
Found at 3 providers
Conductivity (at 25ยฐC)
Detected: 169 UMHO/CM
Found at 3 providers
Aggressive Index
Detected: 10.7 AGGR
4/22/2025
Turbidity
Detected: 1.3 NTU
4/22/2025
A measure of water cloudiness from suspended particles.
Perchlorate
Detected: 20 UG/L (ppb)
2/6/2025
Can occur naturally or from industrial/military sources; may interfere with thyroid function at elevated levels.
Perfluorobutanoicacid (PFBA)
Detected: 1.8 NG/L (ppt)
6/18/2025
Perfluoropentanoicacid (PFPEA)
Detected: 2.4 NG/L (ppt)
Found at 2 providers
Dibromoaceticacid
Detected: 4 UG/L (ppb)
8/7/2025
Perfluoroctanesulfonicacid (PFOS)
Detected: 3.3 NG/L (ppt)
6/19/2025
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Carbon, Total
Detected: 2.2 MG/L (ppm)
2/27/2025
Radium-228
Detected: 0.964 PCI/L
Found at 2 providers
Monochloroaceticacid
Detected: 2.1 UG/L (ppb)
8/7/2025
Filtration considerations: General system types, not a specific product recommendation.