EPA SDWIS ยท Trinity County, California ยท 231 providers profiled
Trinity County, CA Water Quality Report
Trinity County is served by 231 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 Trinity County, CA
231 water providers on file for this county, sorted by population served.
Quick answer: Trinity County has 231 water providers profiled, sorted by population served.
Lead Summary
Copper Summary
TTHM
Chloroform
Bromodichloromethane
Magnesium
Sodium
Calcium
Alkalinity, Total
Alkalinity, Bicarbonate
Hardness, Total (ASCACO3)
TDS
Chloride
Sulfate
Fluoride
Nitrate
Perfluorobutanesulfonicacid (PFBS)
pH
Manganese
Chromium, Hex
Barium
Copper, Free
Conductivity (at 25ยฐC)
Arsenic
Iron
Totalhaloaceticacids (HAA5)
Dichloroaceticacid
Trichloroaceticacid
Lead
Dibromochloromethane
Monochloroaceticacid
PFHXS
PFOS
Potassium
Boron, Total
Nickel
Chlorite
Gross Alpha Particle Activity
Violations on file
Surface Water Treatment Rule
Currently open health violation
Found at 5 of 231 providers
Nitrate
Older/archived health-based violation
Found at 4 of 231 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Cadmium
Older/archived health-based violation
Found at 1 of 231 providers
Coliform (TCR)
Older/archived health-based violation
Found at 2 of 231 providers
Lead And Copper Rule Revisions
Currently open health violation
Found at 7 of 231 providers
Interim Enhanced Surface Water Treatment Rule
Older/archived health-based violation
Found at 2 of 231 providers
Long Term 2 Enhanced Surface Water Treatment Rule
Currently open health violation
Found at 1 of 231 providers
Contaminants found
Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.0441 mg/L (ppm)
Found at 30 providers
Copper Summary
Detected: 2.10658 mg/L (ppm)
Found at 5 providers
Manganese
Detected: 8000 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.
Chromium, Hex
Detected: 6.9 UG/L (ppb)
Found at 14 providers
Barium
Detected: 9 UG/L (ppb)
5/29/2025
Copper, Free
Detected: 260 UG/L (ppb)
Found at 7 providers
Arsenic
Detected: 3.66 UG/L (ppb)
8/26/2025
Occurs naturally in some groundwater. Long-term exposure above the legal limit (10 ppb) has been linked to increased cancer risk and cardiovascular disease.
Iron
Detected: 1570 UG/L (ppb)
Found at 2 providers
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Lead
Detected: 3.77 UG/L (ppb)
Found at 3 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.
Nickel
Detected: 2.25 UG/L (ppb)
6/26/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
TTHM
Detected: 49 UG/L (ppb)
Found at 9 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: 49 UG/L (ppb)
Found at 10 providers
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 6.2 UG/L (ppb)
Found at 9 providers
Totalhaloaceticacids (HAA5)
Detected: 33 UG/L (ppb)
Found at 9 providers
Dibromochloromethane
Detected: 2.8 UG/L (ppb)
Found at 2 providers
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Chloride
Detected: 2.06 MG/L (ppm)
5/29/2025
Sulfate
Detected: 5.89 MG/L (ppm)
5/29/2025
Fluoride
Detected: 0.26 MG/L (ppm)
Found at 2 providers
Often added deliberately for dental health; can also occur naturally.
Nitrate
Detected: 0.74 MG/L (ppm)
Found at 3 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Boron, Total
Detected: 10.6 UG/L (ppb)
6/26/2025
Minerals
Everyday minerals that mainly affect taste and water hardness
Magnesium
Detected: 11.5 MG/L (ppm)
Found at 3 providers
Sodium
Detected: 11.7 MG/L (ppm)
Found at 3 providers
Calcium
Detected: 31.8 MG/L (ppm)
Found at 3 providers
Potassium
Detected: 1 MG/L (ppm)
6/26/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Hardness, Total (ASCACO3)
Detected: 140 MG/L (ppm)
Found at 2 providers
pH
Detected: 7.7 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: 3.26 PCI/L
6/30/2025
PFAS & Emerging Contaminants
Human-made "forever chemicals" and other substances not yet fully regulated
PFHXS
Detected: 0.0056 ยตg/L (ppb)
5/31/2023
PFOS
Detected: 0.0055 ยตg/L (ppb)
9/11/2024
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 134 MG/L (ppm)
Found at 2 providers
Other
Additional substances tested that don't fit neatly into the categories above
Alkalinity, Total
Detected: 134 MG/L (ppm)
Found at 2 providers
TDS
Detected: 199 MG/L (ppm)
5/29/2025
Perfluorobutanesulfonicacid (PFBS)
Detected: 1.7 NG/L (ppt)
8/5/2025
Conductivity (at 25ยฐC)
Detected: 324 UMHO/CM
Found at 2 providers
Dichloroaceticacid
Detected: 16 UG/L (ppb)
Found at 9 providers
Trichloroaceticacid
Detected: 17 UG/L (ppb)
Found at 7 providers
Monochloroaceticacid
Detected: 3.4 UG/L (ppb)
8/27/2025
Chlorite
Detected: 0.14 MG/L (ppm)
6/30/2025
Filtration considerations: General system types, not a specific product recommendation.