Data & Methodology — Santa Barbara County

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

Contaminant Data — All Analytes

10131 well testing events on record, covering 25 analytes. Data spans 1927 to 2025.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. CA Avg
Radon 21 2011 100%
253% of limit ↑ 178% above
Manganese 3143 1943–2023 87%
260% of limit ~ typical
Sulfate 6690 1924–2023 100%
104% of limit ↑ 414% above
Iron 4141 1924–2023 80%
30% of limit ↓ 76% below
Chloride 9860 1924–2023 100%
43% of limit ↑ 43% above
Nitrate 4628 1927–2023 80%
14% of limit ↓ 43% below
Arsenic 459 1958–2021 83%
8% of limit ↓ 80% below
Lead 272 1954–2021 33%
7% of limit ↓ 28% below
Uranium 125 2008–2021 93%
7% of limit ↑ 22% above
Fluoride 5921 1941–2023 97%
8% of limit ~ typical
Boron 9 2008–2021 100%
15% of limit ~ typical
Chromium (total) 9 2008–2021 22%
1% of limit ↓ 67% below
1,2,3-Trichloropropane 10 2008–2021 0%
— —
PFOA municipal 161 2021–2025 1%
30% of limit ↓ 82% below
HFPO-DA (GenX) municipal 161 2021–2025 0%
— —
Nitrite 2025 1980–2023 28%
0% of limit ↓ 59% below
PFOS municipal 161 2021–2025 1%
38% of limit ↓ 82% below
Perchlorate 10 2008–2021 90%
14% of limit ↑ 102% above
PFHxS municipal 161 2021–2025 1%
55% of limit ~ typical
PFNA municipal 161 2021–2025 0%
— —
Tds 9 2008–2021 100%
— ↑ 235% above
Hardness 7517 1924–2023 100%
— ↑ 130% above
Sodium 6706 1924–2023 100%
— ↑ 27% above
pH 7850 1930–2023 100%
— ~ typical
PFBS municipal 161 2021–2025 2%
— ~ typical

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 Santa Barbara County

Of the 459 arsenic tests on record for Santa Barbara County (1958–2021), 17% found none, and half were below 0.52 µg/L.

Of the 9860 chloride tests on record for Santa Barbara County (1924–2023), 0% found none, and half were below 107 mg/L.

Of the 5921 fluoride tests on record for Santa Barbara County (1941–2023), 3% found none, and half were below 300 µg/L.

Of the 4141 iron tests on record for Santa Barbara County (1924–2023), 20% found none, and half were below 40 µg/L.

Of the 272 lead tests on record for Santa Barbara County (1954–2021), 67% found none.

Of the 3143 manganese tests on record for Santa Barbara County (1943–2023), 13% found none, and half were below 73.5 µg/L.

Of the 4628 nitrate tests on record for Santa Barbara County (1927–2023), 20% found none, and half were below 678 µg/L.

Of the 6690 sulfate tests on record for Santa Barbara County (1924–2023), 0% found none, and half were below 259 mg/L.

Of the 125 uranium tests on record for Santa Barbara County (2008–2021), 7% found none, and half were below 1.56 µg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Radon 21 samples
  • Manganese 3143 samples
  • Sulfate 6690 samples
  • Iron 4141 samples
  • Chloride 9860 samples
  • Nitrate 4628 samples
  • Arsenic 459 samples
  • Lead 272 samples
  • Uranium 125 samples
  • Fluoride 5921 samples
  • PFOA 161 samples
  • HFPO-DA (GenX) 161 samples
  • Nitrite 2025 samples
  • PFOS 161 samples
  • PFHxS 161 samples
  • PFNA 161 samples
  • Hardness 7517 samples
  • Sodium 6706 samples
  • pH 7850 samples
  • PFBS 161 samples

Limited data (<15 samples) — interpret with caution

  • Boron 9 samples
  • Chromium (total) 9 samples
  • 1,2,3-Trichloropropane 10 samples
  • Perchlorate 10 samples
  • Tds 9 samples

Public vs. Private Water in Santa Barbara County

150 Active public water systems
488,317 Residents on public water
2% Households on private wells

Public water systems in Santa Barbara 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 Santa Barbara 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 Santa Barbara County Prevalence CA Average Source Year
Arsenic Cancer prevalence 5.9% 6.2% 2020
Arsenic Kidney disease rate 2.9% 3.0% 2020
Lead Heart disease rate 5.6% 6.3% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Santa Barbara 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 →