Data & Methodology — Yuba County

Full contaminant data, sample history, and sourcing for Yuba County. For readers who want to go beyond the summary.

Contaminant Data — All Analytes

394 well testing events on record, covering 27 analytes. Data spans 1958 to 2021.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. CA Avg
Manganese 191 1974–2021 50%
240% of limit ↓ 22% below
PFOS municipal 61 2020–2025 11%
182% of limit ~ typical
Iron 203 1960–2021 50%
27% of limit ↓ 78% below
Arsenic 182 1970–2021 56%
28% of limit ↓ 28% below
PFOA municipal 61 2020–2025 5%
250% of limit ↑ 50% above
Chloride 355 1958–2021 99%
4% of limit ↓ 85% below
Lead 131 1970–2021 21%
16% of limit ↑ 70% above
Nitrate 283 1958–2021 57%
9% of limit ↓ 63% below
Sulfate 299 1958–2021 99%
3% of limit ↓ 84% below
Uranium 40 2006–2021 58%
1% of limit ↓ 90% below
Boron 26 2015–2021 65%
2% of limit ↓ 87% below
Chromium (total) 134 2002–2021 24%
2% of limit ~ typical
1,2,3-Trichloropropane 134 2002–2021 0%
— —
Fluoride 225 1958–2021 72%
3% of limit ↓ 53% below
HFPO-DA (GenX) municipal 60 2020–2025 0%
— —
Nitrite 152 1996–2021 5%
0% of limit ↓ 68% below
PFHxS municipal 61 2020–2025 11%
39% of limit ↓ 30% below
Perchlorate 26 2015–2021 42%
3% of limit ↓ 49% below
Radon 5 1996–2008 100%
8% of limit ↓ 92% below
PFNA municipal 61 2020–2025 0%
— —
Tds 134 2002–2021 100%
— ↓ 43% below
E. coli 11 2006–2021 0%
— —
Hardness 355 1958–2021 100%
— ↓ 46% below
Sodium 354 1958–2021 100%
— ↓ 80% below
Total Coliform 11 2002–2021 82%
— ~ typical
pH 364 1958–2021 100%
— ~ typical
PFBS municipal 61 2020–2025 7%
— ↑ 210% 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 Yuba County

Of the 182 arsenic tests on record for Yuba County (1970–2021), 44% found none, and half were below 0.62 µg/L.

Of the 355 chloride tests on record for Yuba County (1958–2021), 1% found none, and half were below 11 mg/L.

Of the 134 chromium (total) tests on record for Yuba County (2002–2021), 76% found none.

Of the 225 fluoride tests on record for Yuba County (1958–2021), 28% found none, and half were below 100 µg/L.

Of the 203 iron tests on record for Yuba County (1960–2021), 50% found none.

Of the 131 lead tests on record for Yuba County (1970–2021), 79% found none.

Of the 191 manganese tests on record for Yuba County (1974–2021), 50% found none, and half were below 0.42 µg/L.

Of the 283 nitrate tests on record for Yuba County (1958–2021), 43% found none, and half were below 20 µg/L.

Of the 299 sulfate tests on record for Yuba County (1958–2021), 1% found none, and half were below 8.1 mg/L.

Of the 134 tds tests on record for Yuba County (2002–2021), 0% found none, and half were below 228 mg/L.

Of the 40 uranium tests on record for Yuba County (2006–2021), 42% found none, and half were below 21.3 ng/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 191 samples
  • PFOS 61 samples
  • Iron 203 samples
  • Arsenic 182 samples
  • PFOA 61 samples
  • Chloride 355 samples
  • Lead 131 samples
  • Nitrate 283 samples
  • Sulfate 299 samples
  • Uranium 40 samples
  • Boron 26 samples
  • Chromium (total) 134 samples
  • 1,2,3-Trichloropropane 134 samples
  • Fluoride 225 samples
  • HFPO-DA (GenX) 60 samples
  • Nitrite 152 samples
  • PFHxS 61 samples
  • Perchlorate 26 samples
  • PFNA 61 samples
  • Tds 134 samples
  • Hardness 355 samples
  • Sodium 354 samples
  • pH 364 samples
  • PFBS 61 samples

Limited data (<15 samples) — interpret with caution

  • Radon 5 samples
  • E. coli 11 samples
  • Total Coliform 11 samples

Public vs. Private Water in Yuba County

65 Active public water systems
113,358 Residents on public water
10% Households on private wells

Public water systems in Yuba 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 Yuba 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.

Contaminant Associated Condition Yuba County Prevalence CA Average Source Year
Arsenic Cancer prevalence 5.7% 6.2% 2020
Arsenic Kidney disease rate 2.9% 3.0% 2020
Lead Heart disease rate 6.3% 6.3% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Yuba County CDC PLACES data →

Data Sources

This report aggregates data from the following public databases:

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.

Last updated: 2026-09-10

Full methodology →