Full contaminant data, sample history, and sourcing for Inyo County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
420 well testing events on record, covering
25 analytes.
Data spans 1910 to 2021.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. CA Avg
Chloride
379
1910–2023
100%
268% of limit
↑ 794% above
Sulfate
376
1910–2023
100%
154% of limit
↑ 661% above
Manganese
268
1961–2023
68%
80% of limit
↓ 74% below
Radon
17
1990–2013
100%
13% of limit
↓ 86% below
Arsenic
137
1945–2023
92%
22% of limit
↓ 44% below
Iron
337
1910–2023
74%
20% of limit
↓ 84% below
Fluoride
386
1946–2023
97%
28% of limit
↑ 295% above
Uranium
91
1986–2023
100%
6% of limit
~ typical
Nitrate
140
1910–2021
90%
2% of limit
↓ 90% below
Lead
103
1945–2023
27%
5% of limit
↓ 42% below
PFNA
municipal
4
2023
0%
—
—
PFOS
municipal
4
2023
0%
—
—
Boron
5
2006
100%
4% of limit
↓ 73% below
Chromium (total)
5
2006
0%
—
—
1,2,3-Trichloropropane
5
2006
0%
—
—
HFPO-DA (GenX)
municipal
4
2023
0%
—
—
Nitrite
96
1968–2021
11%
0% of limit
↓ 84% below
PFHxS
municipal
4
2023
0%
—
—
Perchlorate
5
2006
0%
—
—
PFOA
municipal
4
2023
0%
—
—
Tds
5
2006
100%
—
↓ 64% below
Hardness
379
1910–2023
100%
—
↑ 47% above
PFBS
municipal
4
2023
0%
—
—
pH
405
1946–2023
100%
—
~ typical
Sodium
377
1910–2023
100%
—
↑ 794% above
Distribution shows the share of samples in each concentration band relative to the EPA Maximum Contaminant Level (MCL): Low = below half the MCL, Moderate = between half and the MCL, High = above the MCL. Analytes without an MCL (e.g. sodium, pH) show — in the limit columns. State average is based on county median values across CA.
Compare your result with Inyo County
Of the 137 arsenic tests on record for Inyo County (1945–2023),
8% found none, and half were below 1.9 µg/L.
Of the 379 chloride tests on record for Inyo County (1910–2023),
0% found none, and half were below 670 mg/L.
Of the 386 fluoride tests on record for Inyo County (1946–2023),
3% found none, and half were below 1.1 mg/L.
Of the 337 iron tests on record for Inyo County (1910–2023),
26% found none, and half were below 40 µg/L.
Of the 103 lead tests on record for Inyo County (1945–2023),
73% found none.
Of the 268 manganese tests on record for Inyo County (1961–2023),
32% found none, and half were below 14.2 µg/L.
Of the 140 nitrate tests on record for Inyo County (1910–2021),
10% found none, and half were below 180 µg/L.
Of the 376 sulfate tests on record for Inyo County (1910–2023),
0% found none, and half were below 385 mg/L.
Of the 91 uranium tests on record for Inyo County (1986–2023),
0% found none, and half were below 1.8 µg/L.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Chloride 379 samples
Sulfate 376 samples
Manganese 268 samples
Radon 17 samples
Arsenic 137 samples
Iron 337 samples
Fluoride 386 samples
Uranium 91 samples
Nitrate 140 samples
Lead 103 samples
Nitrite 96 samples
Hardness 379 samples
pH 405 samples
Sodium 377 samples
Limited data (<15 samples) — interpret with caution
Boron 5 samples
Chromium (total) 5 samples
1,2,3-Trichloropropane 5 samples
Perchlorate 5 samples
Tds 5 samples
No private-well PFAS data for Inyo County
We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Inyo County.
PFAS testing for private wells requires a dedicated lab panel (~$300–$500). If you are near a military base, airport, or industrial site, consider testing proactively. Learn more about PFAS →
Public vs. Private Water in Inyo County
113Active public water systems
49,551Residents on public water
3%Households on private wells
Public water systems in Inyo County are regulated by the EPA and must test and report contaminant levels. Private well owners are responsible for their own testing — there is no routine monitoring of private wells by any government agency.
CDC Health Outcome Correlations
Where contaminants detected in Inyo County have established associations with specific health outcomes, we cross-reference CDC PLACES county-level prevalence data. This is a contextual signal, not a causal claim.
This report aggregates data from the following public databases:
Water Quality Portal (WQP) — groundwater sample results for Inyo County from EPA, USGS, and state agencies. Browse WQP data →
EPA Safe Drinking Water Information System (SDWIS) — public water system inventory used to estimate the share of residents on private wells. Browse SDWIS →
Census ACS 5-Year Estimates — well and cistern household counts (variable DP04_0074E) used to calculate the private-well percentage for Inyo County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Inyo County, which informs which contaminants are geologically likely. USGS Aquifer Atlas →
EPA UCMR 5 (2023–2025) — PFAS occurrence data from public water systems, used as a proxy indicator for aquifer PFAS exposure. Rows marked "municipal" in the table above come from this source. About UCMR 5 →
EPA Toxics Release Inventory (TRI) — industrial facility chemical releases near Inyo County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Inyo County, used in contamination risk scoring. Superfund site search →
CDC PLACES — county-level health outcome prevalence (kidney disease, cancer, heart disease) correlated with detected contaminants. About CDC PLACES →
Methodology
Raw records are downloaded from the Water Quality Portal and normalized to µg/L (ppb). Records are deduplicated by sample ID and date, and certified outliers are excluded. Analyte names are mapped to EPA canonical forms. Detection rates, distribution bands, and MCL comparisons are computed from the normalized dataset.
Distribution bands use the EPA Maximum Contaminant Level as the threshold: concentrations below 50% of the MCL are classed as Low, between 50% and 100% as Moderate, and above 100% as High. For analytes without an MCL (sodium, hardness, pH), distribution is not computed.
State comparison uses the median of county median values across all counties in CA with at least one sample for that analyte.