Data & Methodology — Benton County

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

Contaminant Data — All Analytes

163 well testing events on record, covering 19 analytes. Data spans 1953 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. MN Avg
PFHxS municipal 6 2023–2024 67%
240% of limit —
PFOS municipal 9 2023–2024 78%
137% of limit —
Manganese 30 1969–2010 60%
789% of limit ↑ 108% above
PFOA municipal 9 2006–2024 67%
129% of limit ↑ 3333% above
Iron 134 1969–2011 98%
24% of limit ↓ 96% below
Nitrate 125 1969–2011 91%
1% of limit ↓ 97% below
Arsenic 94 1994–2010 87%
12% of limit ↓ 85% below
Uranium 79 2010 100%
2% of limit ↓ 59% below
Lead 94 1994–2010 83%
0% of limit ↓ 99% below
Chloride 148 1969–2025 100%
4% of limit ↓ 71% below
Fluoride 118 1969–2011 98%
6% of limit ↓ 30% below
HFPO-DA (GenX) municipal 6 2023–2024 0%
— —
Nitrite 105 1977–2011 22%
1% of limit ↓ 67% below
PFNA municipal 7 2006–2024 0%
— —
Sulfate 128 1969–2014 100%
6% of limit ↓ 73% below
Sodium 123 1969–2011 100%
— ↓ 71% below
pH 18 1969–2015 100%
— ~ typical
PFBS municipal 6 2023–2024 83%
— —
Hardness 9 1969–1978 100%
— ↓ 47% below

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 MN.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 30 samples
  • Iron 134 samples
  • Nitrate 125 samples
  • Arsenic 94 samples
  • Uranium 79 samples
  • Lead 94 samples
  • Chloride 148 samples
  • Fluoride 118 samples
  • Nitrite 105 samples
  • Sulfate 128 samples
  • Sodium 123 samples
  • pH 18 samples

Limited data (<15 samples) — interpret with caution

  • PFOS 9 samples
  • PFOA 9 samples
  • PFNA 7 samples
  • Hardness 9 samples

Public vs. Private Water in Benton County

68 Active public water systems
28,730 Residents on public water

Public water systems in Benton 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 Benton 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 Benton County Prevalence MN Average Source Year
Arsenic Cancer prevalence 6.7% 7.0% 2020
Arsenic Kidney disease rate 2.7% 2.9% 2020
Lead Heart disease rate 6.1% 6.6% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Benton 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 MN with at least one sample for that analyte.

Last updated: 2026-07-15

Full methodology →