Full contaminant data, sample history, and sourcing for Columbia County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
177 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
Iron
88
1931–2023
94%
77% of limit
↓ 87% below
Manganese
86
1970–2023
73%
120% of limit
↓ 76% below
PFOA
municipal
114
2023–2025
25%
180% of limit
↑ 93% above
Arsenic
22
1981–2023
95%
20% of limit
↓ 32% below
PFOS
municipal
115
2023–2025
29%
92% of limit
↓ 27% below
Sulfate
91
1930–2023
100%
7% of limit
↓ 62% below
Chloride
92
1930–2023
100%
3% of limit
↓ 72% below
Fluoride
83
1968–2023
41%
2% of limit
↓ 44% below
HFPO-DA (GenX)
municipal
109
2023–2025
0%
—
—
Lead
21
1981–2023
5%
0% of limit
↓ 96% below
Nitrate
12
1930–2023
92%
10% of limit
↓ 44% below
Nitrite
4
1998–2023
0%
—
—
PFHxS
municipal
14
2023–2024
0%
—
—
PFNA
municipal
14
2023–2024
0%
—
—
Radon
1
2023
100%
2% of limit
↓ 99% below
Uranium
2
1999–2023
50%
1% of limit
↓ 71% below
Total Coliform
1
1998–2023
67%
—
~ typical
Sodium
84
1970–2023
100%
—
↓ 72% below
pH
88
1968–2023
100%
—
~ typical
PFBS
municipal
109
2023–2025
19%
—
~ typical
Hardness
91
1930–2023
100%
—
↓ 50% below
E. coli
1
1998–2023
33%
—
~ 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 PA.
Compare your result with Columbia County
Of the 22 arsenic tests on record for Columbia County (1981–2023),
5% found none, and half were below 1.5 µg/L.
Of the 92 chloride tests on record for Columbia County (1930–2023),
0% found none, and half were below 7.4 mg/L.
Of the 83 fluoride tests on record for Columbia County (1968–2023),
59% found none.
Of the 88 iron tests on record for Columbia County (1931–2023),
6% found none, and half were below 195 µg/L.
Of the 21 lead tests on record for Columbia County (1981–2023),
95% found none.
Of the 86 manganese tests on record for Columbia County (1970–2023),
27% found none, and half were below 25 µg/L.
Of the 100 pfoa tests on record for Columbia County (2025),
73% found none.
Of the 101 pfos tests on record for Columbia County (2025),
68% found none.
Of the 91 sulfate tests on record for Columbia County (1930–2023),
0% found none, and half were below 16.4 mg/L.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Iron 88 samples
Manganese 86 samples
PFOA 114 samples
Arsenic 22 samples
PFOS 115 samples
Sulfate 91 samples
Chloride 92 samples
Fluoride 83 samples
HFPO-DA (GenX) 109 samples
Lead 21 samples
Sodium 84 samples
pH 88 samples
PFBS 109 samples
Hardness 91 samples
Limited data (<15 samples) — interpret with caution
Nitrate 12 samples
Nitrite 4 samples
Radon 1 sample
Uranium 2 samples
Total Coliform 1 sample
E. coli 1 sample
Public vs. Private Water in Columbia County
94Active public water systems
65,107Residents on public water
51%Households on private wells
Public water systems in Columbia 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 Columbia 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.
This report aggregates data from the following public databases:
Water Quality Portal (WQP) — groundwater sample results for Columbia County from EPA, USGS, and state agencies. Browse WQP data →
EPA Safe Drinking Water Information System (SDWIS) — public water system inventory used to estimate the share of residents on private wells. Browse SDWIS →
Census ACS 5-Year Estimates — well and cistern household counts (variable DP04_0074E) used to calculate the private-well percentage for Columbia County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Columbia County, which informs which contaminants are geologically likely. USGS Aquifer Atlas →
EPA UCMR 5 (2023–2025) — PFAS occurrence data from public water systems, used as a proxy indicator for aquifer PFAS exposure. Rows marked "municipal" in the table above come from this source. About UCMR 5 →
EPA Toxics Release Inventory (TRI) — industrial facility chemical releases near Columbia County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Columbia County, used in contamination risk scoring. Superfund site search →
CDC PLACES — county-level health outcome prevalence (kidney disease, cancer, heart disease) correlated with detected contaminants. About CDC PLACES →
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.