Data & Methodology — Redwood County

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

Contaminant Data — All Analytes

306 well testing events on record, covering 18 analytes. Data spans 1953 to 2025.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. MN Avg
Manganese 213 1953–2025 95%
270% of limit ↓ 45% below
Iron 221 1964–2025 81%
677% of limit ~ typical
Sulfate 248 1953–2025 100%
137% of limit ↑ 626% above
Arsenic 142 1980–2025 69%
58% of limit ↓ 33% below
Chloride 271 1953–2025 97%
6% of limit ↓ 25% below
Nitrate 140 1953–2012 78%
4% of limit ↓ 84% below
Lead 142 1980–2025 20%
1% of limit ↓ 98% below
Fluoride 206 1953–2025 98%
8% of limit ~ typical
HFPO-DA (GenX) municipal 7 2024–2025 0%
— —
Nitrite 88 1989–2012 41%
1% of limit ~ typical
PFHxS municipal 4 2024–2025 0%
— —
PFNA municipal 7 2024–2025 0%
— —
PFOA municipal 7 2024–2025 0%
— —
PFOS municipal 7 2024–2025 29%
10% of limit ↓ 95% below
Hardness 79 1953–2012 100%
— ↑ 58% above
PFBS municipal 4 2024–2025 0%
— —
pH 104 1953–2012 100%
— ~ typical
Sodium 221 1953–2025 100%
— ↑ 42% 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.

Compare your result with Redwood County

Of the 142 arsenic tests on record for Redwood County (1980–2025), 31% found none, and half were below 1 µg/L.

Of the 271 chloride tests on record for Redwood County (1953–2025), 3% found none, and half were below 13.9 mg/L.

Of the 206 fluoride tests on record for Redwood County (1953–2025), 2% found none, and half were below 320 µg/L.

Of the 221 iron tests on record for Redwood County (1964–2025), 19% found none, and half were below 1.2 mg/L.

Of the 142 lead tests on record for Redwood County (1980–2025), 80% found none.

Of the 213 manganese tests on record for Redwood County (1953–2025), 5% found none, and half were below 125 µg/L.

Of the 140 nitrate tests on record for Redwood County (1953–2012), 22% found none, and half were below 135 µg/L.

Of the 248 sulfate tests on record for Redwood County (1953–2025), 0% found none, and half were below 343 mg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 213 samples
  • Iron 221 samples
  • Sulfate 248 samples
  • Arsenic 142 samples
  • Chloride 271 samples
  • Nitrate 140 samples
  • Lead 142 samples
  • Fluoride 206 samples
  • Nitrite 88 samples
  • Hardness 79 samples
  • pH 104 samples
  • Sodium 221 samples

Limited data (<15 samples) — interpret with caution

  • HFPO-DA (GenX) 7 samples
  • PFNA 7 samples
  • PFOA 7 samples
  • PFOS 7 samples

Public vs. Private Water in Redwood County

30 Active public water systems
11,372 Residents on public water
32% Households on private wells

Public water systems in Redwood 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 Redwood 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 Redwood County Prevalence MN Average Source Year
Arsenic Cancer prevalence 6.0% 7.0% 2020
Arsenic Kidney disease rate 2.6% 2.9% 2020
Lead Heart disease rate 8.2% 6.6% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Redwood 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: 2026-08-04

Full methodology →