Full contaminant data, sample history, and sourcing for Bastrop County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
750 well testing events on record, covering
20 analytes.
Data spans 1941 to 2018.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. TX Avg
Iron
561
1940–2019
91%
120% of limit
↓ 22% below
Manganese
248
1940–2019
71%
80% of limit
↑ 24% above
Sulfate
220
1941–2015
100%
34% of limit
↑ 21% above
Chloride
226
1941–2015
100%
24% of limit
↓ 33% below
Nitrate
214
1941–2015
93%
0% of limit
↓ 98% below
Lead
124
1976–2019
7%
1% of limit
↓ 95% below
Arsenic
144
1976–2019
24%
0% of limit
↓ 100% below
Fluoride
530
1940–2019
92%
5% of limit
↓ 79% below
HFPO-DA (GenX)
municipal
39
2023–2025
0%
—
—
Nitrite
16
1980–2015
69%
0% of limit
↓ 100% below
PFHxS
municipal
39
2023–2025
0%
—
—
PFNA
municipal
39
2023–2025
0%
—
—
PFOA
municipal
39
2023–2025
0%
—
—
PFOS
municipal
39
2023–2025
0%
—
—
Radon
5
2008–2015
100%
7% of limit
↓ 81% below
Uranium
40
2008–2019
12%
0% of limit
↓ 99% below
Sodium
194
1941–2015
100%
—
↓ 40% below
pH
186
1941–2015
100%
—
~ typical
PFBS
municipal
39
2023–2025
0%
—
—
Hardness
224
1941–2015
100%
—
~ 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 TX.
Compare your result with Bastrop County
Of the 144 arsenic tests on record for Bastrop County (1976–2019),
76% found none.
Of the 226 chloride tests on record for Bastrop County (1941–2015),
0% found none, and half were below 60 mg/L.
Of the 530 fluoride tests on record for Bastrop County (1940–2019),
8% found none, and half were below 200 µg/L.
Of the 561 iron tests on record for Bastrop County (1940–2019),
9% found none, and half were below 270 µg/L.
Of the 124 lead tests on record for Bastrop County (1976–2019),
93% found none.
Of the 248 manganese tests on record for Bastrop County (1940–2019),
29% found none, and half were below 18.1 µg/L.
Of the 214 nitrate tests on record for Bastrop County (1941–2015),
7% found none, and half were below 50 µg/L.
Of the 220 sulfate tests on record for Bastrop County (1941–2015),
0% found none, and half were below 86 mg/L.
Of the 40 uranium tests on record for Bastrop County (2008–2019),
88% found none.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Iron 561 samples
Manganese 248 samples
Sulfate 220 samples
Chloride 226 samples
Nitrate 214 samples
Lead 124 samples
Arsenic 144 samples
Fluoride 530 samples
Nitrite 16 samples
Uranium 40 samples
Sodium 194 samples
pH 186 samples
Hardness 224 samples
Limited data (<15 samples) — interpret with caution
Radon 5 samples
No private-well PFAS data for Bastrop County
We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Bastrop County.
PFAS testing for private wells requires a dedicated lab panel (~$300–$500). If you are near a military base, airport, or industrial site, consider testing proactively. Learn more about PFAS →
CDC Health Outcome Correlations
Where contaminants detected in Bastrop 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 Bastrop 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 Bastrop County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Bastrop 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 Bastrop County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Bastrop 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 TX with at least one sample for that analyte.