Data & Methodology — Mifflin County

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

Contaminant Data — All Analytes

82 well testing events on record, covering 22 analytes. Data spans 1926 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. PA Avg
Manganese 42 1965–2023 69%
100% of limit ↓ 84% below
Iron 51 1934–2023 80%
57% of limit ↓ 79% below
Radon 11 1994–2023 100%
29% of limit ↓ 84% below
Nitrate 54 1934–2018 96%
18% of limit ↑ 114% above
Sulfate 49 1934–2023 100%
12% of limit ↓ 70% below
Arsenic 14 1977–2023 29%
2% of limit ↓ 96% below
Chloride 50 1934–2023 100%
3% of limit ↓ 81% below
Fluoride 46 1965–2023 78%
3% of limit ↓ 24% below
HFPO-DA (GenX) municipal 24 2024–2025 0%
— —
Lead 11 1977–2023 9%
0% of limit ↓ 99% below
Nitrite 45 1980–2018 13%
2% of limit ↑ 80% above
PFHxS municipal 4 2024 0%
— —
PFNA municipal 4 2024 0%
— —
PFOA municipal 25 2024–2025 0%
— —
PFOS municipal 25 2024–2025 8%
51% of limit ↑ 156% above
Uranium 7 1994–2023 71%
1% of limit ↓ 50% below
E. coli 2 1994–2023 27%
— —
Hardness 51 1934–2023 100%
— ↑ 145% above
PFBS municipal 24 2024–2025 0%
— —
pH 57 1965–2023 100%
— ~ typical
Sodium 46 1934–2023 100%
— ↓ 84% below
Total Coliform 2 1994–2023 73%
— —

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 PA.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 42 samples
  • Iron 51 samples
  • Nitrate 54 samples
  • Sulfate 49 samples
  • Chloride 50 samples
  • Fluoride 46 samples
  • HFPO-DA (GenX) 24 samples
  • Nitrite 45 samples
  • PFOA 25 samples
  • PFOS 25 samples
  • Hardness 51 samples
  • PFBS 24 samples
  • pH 57 samples
  • Sodium 46 samples

Limited data (<15 samples) — interpret with caution

  • Radon 11 samples
  • Arsenic 14 samples
  • Lead 11 samples
  • Uranium 7 samples
  • E. coli 2 samples
  • Total Coliform 2 samples

Public vs. Private Water in Mifflin County

28 Active public water systems
32,820 Residents on public water
29% Households on private wells

Public water systems in Mifflin 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 Mifflin 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 Mifflin County Prevalence PA Average Source Year
Nitrate Cancer prevalence 6.1% 7.0% 2020
Lead Heart disease rate 9.4% 7.2% 2020

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

Last updated: 2026-07-15

Full methodology →