Contaminant Data — All Analytes
113 well testing events on record, covering
23 analytes.
Data spans 1956 to 2023.
| Contaminant |
Samples |
Years |
Detection Rate |
Distribution LowModHigh |
vs. Limit |
vs. NY Avg |
|
Radon
|
20 |
2007–2022
|
100% |
|
182% of limit
|
↑ 64% above
|
|
Manganese
|
96 |
1964–2022
|
83% |
|
40% of limit
|
↓ 87% below
|
|
Iron
|
96 |
1964–2022
|
86% |
|
15% of limit
|
↓ 92% below
|
|
Chloride
|
96 |
1964–2022
|
99% |
|
2% of limit
|
↓ 92% below
|
|
Arsenic
|
38 |
1971–2022
|
66% |
|
8% of limit
|
↓ 54% below
|
|
Fluoride
|
96 |
1964–2022
|
74% |
|
2% of limit
|
↓ 55% below
|
|
HFPO-DA (GenX)
municipal
|
16 |
2023–2025
|
0% |
|
— |
— |
|
Lead
|
38 |
1971–2022
|
61% |
|
2% of limit
|
↓ 51% below
|
|
Nitrate
|
34 |
1964–2022
|
79% |
|
2% of limit
|
↓ 81% below
|
|
Nitrite
|
31 |
1971–2022
|
26% |
|
0% of limit
|
↓ 63% below
|
|
PFHxS
municipal
|
16 |
2023–2025
|
0% |
|
— |
— |
|
PFNA
municipal
|
16 |
2023–2025
|
0% |
|
— |
— |
|
PFOA
municipal
|
16 |
2023–2025
|
0% |
|
— |
— |
|
PFOS
municipal
|
16 |
2023–2025
|
0% |
|
— |
— |
|
Sulfate
|
96 |
1964–2022
|
98% |
|
6% of limit
|
↓ 59% below
|
|
Uranium
|
29 |
2007–2022
|
83% |
|
1% of limit
|
↓ 71% below
|
|
E. coli
|
6 |
2007–2022
|
0% |
|
— |
— |
|
Fecal Coliform
|
7 |
2007–2022
|
10% |
|
— |
~ typical
|
|
Hardness
|
99 |
1964–2022
|
99% |
|
— |
↓ 32% below
|
|
PFBS
municipal
|
16 |
2023–2025
|
0% |
|
— |
— |
|
pH
|
99 |
1964–2022
|
100% |
|
— |
~ typical
|
|
Sodium
|
96 |
1964–2022
|
99% |
|
— |
↓ 89% below
|
|
Total Coliform
|
7 |
2007–2022
|
15% |
|
— |
~ 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 NY.
Compare your result with Oswego County
Of the 38 arsenic tests on record for Oswego County (1971–2022),
34% found none, and half were below 0.315 µg/L.
Of the 96 chloride tests on record for Oswego County (1964–2022),
1% found none, and half were below 5.75 mg/L.
Of the 96 fluoride tests on record for Oswego County (1964–2022),
26% found none, and half were below 100 µg/L.
Of the 96 iron tests on record for Oswego County (1964–2022),
14% found none, and half were below 18 µg/L.
Of the 38 lead tests on record for Oswego County (1971–2022),
39% found none, and half were below 75 ng/L.
Of the 96 manganese tests on record for Oswego County (1964–2022),
17% found none, and half were below 12 µg/L.
Of the 34 nitrate tests on record for Oswego County (1964–2022),
21% found none, and half were below 200 µg/L.
Of the 96 sulfate tests on record for Oswego County (1964–2022),
2% found none, and half were below 14 mg/L.
Of the 29 uranium tests on record for Oswego County (2007–2022),
17% found none, and half were below 0.108 µg/L.
Data Sources
This report aggregates data from the following public databases:
- Water Quality Portal (WQP) — groundwater sample results for Oswego 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 Oswego County. Census data explorer →
- USGS Aquifer Atlas — principal aquifer type underlying Oswego 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 Oswego County, used in contamination risk scoring. TRI Explorer →
- EPA Superfund NPL — National Priorities List sites in or near Oswego 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 NY with at least one sample for that analyte.
Last updated: 2026-08-04
Full methodology →