Data & Methodology — Blue Earth County

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

Contaminant Data — All Analytes

575 well testing events on record, covering 20 analytes. Data spans 1960 to 2025.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. MN Avg
Manganese 193 1970–2025 97%
8500% of limit ↑ 2137% above
Iron 277 1970–2025 64%
600% of limit ~ typical
PFOS municipal 23 2023–2025 48%
149% of limit —
PFOA municipal 20 2023–2025 40%
117% of limit ↑ 3010% above
Arsenic 265 1980–2025 72%
27% of limit ↓ 67% below
Nitrate 354 1974–2014 74%
10% of limit ↓ 50% below
Sulfate 281 1970–2025 99%
56% of limit ↑ 136% above
Lead 265 1980–2025 42%
1% of limit ↓ 98% below
Nitrite 328 1974–2014 35%
4% of limit ↑ 34% above
Chloride 293 1970–2025 99%
3% of limit ↓ 79% below
Fluoride 177 1970–2025 98%
6% of limit ↓ 34% below
HFPO-DA (GenX) municipal 12 2023–2025 0%
— —
PFHxS municipal 13 2023–2024 23%
30% of limit —
PFNA municipal 13 2023–2025 8%
14% of limit —
Radon 1 2014 100%
41% of limit ↓ 48% below
Uranium 88 2012–2014 94%
2% of limit ↓ 35% below
Sodium 275 1970–2025 100%
— ↓ 54% below
pH 161 1970–2014 100%
— ~ typical
PFBS municipal 14 2023–2024 29%
— —
Hardness 20 1970–2014 100%
— ↑ 47% 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 MN.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 193 samples
  • Iron 277 samples
  • PFOS 23 samples
  • PFOA 20 samples
  • Arsenic 265 samples
  • Nitrate 354 samples
  • Sulfate 281 samples
  • Lead 265 samples
  • Nitrite 328 samples
  • Chloride 293 samples
  • Fluoride 177 samples
  • Uranium 88 samples
  • Sodium 275 samples
  • pH 161 samples
  • Hardness 20 samples

Limited data (<15 samples) — interpret with caution

  • HFPO-DA (GenX) 12 samples
  • PFHxS 13 samples
  • PFNA 13 samples
  • Radon 1 sample
  • PFBS 14 samples

Public vs. Private Water in Blue Earth County

64 Active public water systems
59,656 Residents on public water

Public water systems in Blue Earth 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 Blue Earth 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 Blue Earth County Prevalence MN Average Source Year
Arsenic Cancer prevalence 5.9% 7.0% 2020
Arsenic Kidney disease rate 2.6% 2.9% 2020
Lead Heart disease rate 5.6% 6.6% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Blue Earth 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 →