Full contaminant data, sample history, and sourcing for Scott County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
115 well testing events on record, covering
22 analytes.
Data spans 1960 to 2025.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. MN Avg
Manganese
62
1960–2025
68%
220% of limit
↓ 55% below
Iron
81
1960–2025
81%
197% of limit
↓ 72% below
PFOS
municipal
58
2023–2025
38%
600% of limit
↑ 199% above
PFOA
municipal
53
2022–2025
32%
625% of limit
↑ 45% above
PFHxS
municipal
48
2023–2025
25%
630% of limit
↑ 688% above
Arsenic
44
1980–2025
48%
27% of limit
↓ 69% below
Lead
44
1980–2025
20%
1% of limit
↓ 97% below
Nitrate
66
1960–2023
70%
12% of limit
↓ 49% below
Chloride
93
1960–2025
96%
10% of limit
↑ 31% above
Fluoride
51
1960–2025
80%
6% of limit
~ typical
HFPO-DA (GenX)
municipal
38
2022–2025
0%
—
—
Nitrite
18
1974–2023
17%
0% of limit
↓ 67% below
PFNA
municipal
43
2022–2025
12%
11% of limit
↓ 32% below
Radon
5
1996–2014
100%
9% of limit
↓ 82% below
Sulfate
63
1960–2025
100%
8% of limit
↓ 58% below
Uranium
10
1980–2018
90%
4% of limit
~ typical
E. coli
3
2000–2023
6%
—
~ typical
Hardness
28
1960–2018
100%
—
~ typical
PFBS
municipal
45
2023–2025
29%
—
↑ 100% above
pH
34
1960–2018
100%
—
~ typical
Sodium
62
1960–2025
100%
—
↓ 60% below
Total Coliform
2
2000–2018
12%
—
~ 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 MN.
Compare your result with Scott County
Of the 44 arsenic tests on record for Scott County (1980–2025),
52% found none.
Of the 93 chloride tests on record for Scott County (1960–2025),
4% found none, and half were below 23.5 mg/L.
Of the 51 fluoride tests on record for Scott County (1960–2025),
20% found none, and half were below 200 µg/L.
Of the 81 iron tests on record for Scott County (1960–2025),
19% found none, and half were below 80 µg/L.
Of the 44 lead tests on record for Scott County (1980–2025),
80% found none.
Of the 62 manganese tests on record for Scott County (1960–2025),
32% found none, and half were below 47.6 µg/L.
Of the 66 nitrate tests on record for Scott County (1960–2023),
30% found none, and half were below 80 µg/L.
Of the 22 pfos tests on record for Scott County (2024),
0% found none, and half were below 24 ng/L.
Of the 63 sulfate tests on record for Scott County (1960–2025),
0% found none, and half were below 19.9 mg/L.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Manganese 62 samples
Iron 81 samples
PFOS 58 samples
PFOA 53 samples
PFHxS 48 samples
Arsenic 44 samples
Lead 44 samples
Nitrate 66 samples
Chloride 93 samples
Fluoride 51 samples
HFPO-DA (GenX) 38 samples
Nitrite 18 samples
PFNA 43 samples
Sulfate 63 samples
Hardness 28 samples
PFBS 45 samples
pH 34 samples
Sodium 62 samples
Limited data (<15 samples) — interpret with caution
Radon 5 samples
Uranium 10 samples
E. coli 3 samples
Total Coliform 2 samples
Public vs. Private Water in Scott County
115Active public water systems
133,319Residents on public water
19%Households on private wells
Public water systems in Scott 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 Scott 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 Scott 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 Scott County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Scott 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 Scott County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Scott 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 MN with at least one sample for that analyte.