Full contaminant data, sample history, and sourcing for Matagorda County. For readers who want to go beyond the summary.
Contaminant Data — All Analytes
935 well testing events on record, covering
20 analytes.
Data spans 1943 to 2021.
Contaminant
Samples
Years
Detection Rate
Distribution LowModHigh
vs. Limit
vs. TX Avg
Radon
1
2013
100%
163% of limit
↑ 354% above
Manganese
483
1938–2021
66%
134% of limit
↑ 109% above
Chloride
252
1943–2013
100%
42% of limit
~ typical
Iron
438
1938–2021
79%
43% of limit
↓ 72% below
Arsenic
191
1977–2021
38%
30% of limit
~ typical
Nitrate
247
1943–2013
93%
4% of limit
↓ 82% below
Lead
185
1977–2021
6%
13% of limit
↓ 21% below
Fluoride
845
1938–2021
100%
12% of limit
↓ 48% below
HFPO-DA (GenX)
municipal
13
2023–2025
0%
—
—
Nitrite
1
2013
100%
0% of limit
↓ 81% below
PFHxS
municipal
13
2023–2025
0%
—
—
PFNA
municipal
13
2023–2025
0%
—
—
PFOA
municipal
13
2023–2025
0%
—
—
PFOS
municipal
13
2023–2025
0%
—
—
Sulfate
248
1943–2013
100%
6% of limit
↓ 78% below
Uranium
84
2005–2021
31%
12% of limit
↓ 25% below
Sodium
250
1943–2013
100%
—
~ typical
pH
241
1949–2013
100%
—
~ typical
PFBS
municipal
13
2023–2025
0%
—
—
Hardness
248
1943–2013
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 Matagorda County
Of the 191 arsenic tests on record for Matagorda County (1977–2021),
62% found none.
Of the 252 chloride tests on record for Matagorda County (1943–2013),
0% found none, and half were below 104 mg/L.
Of the 845 fluoride tests on record for Matagorda County (1938–2021),
0% found none, and half were below 500 µg/L.
Of the 438 iron tests on record for Matagorda County (1938–2021),
21% found none, and half were below 100 µg/L.
Of the 185 lead tests on record for Matagorda County (1977–2021),
94% found none.
Of the 483 manganese tests on record for Matagorda County (1938–2021),
34% found none, and half were below 24.3 µg/L.
Of the 247 nitrate tests on record for Matagorda County (1943–2013),
7% found none, and half were below 400 µg/L.
Of the 248 sulfate tests on record for Matagorda County (1943–2013),
0% found none, and half were below 16 mg/L.
Of the 84 uranium tests on record for Matagorda County (2005–2021),
69% found none.
Data Coverage & Gaps
Well-sampled analytes (15+ samples)
Manganese 483 samples
Chloride 252 samples
Iron 438 samples
Arsenic 191 samples
Nitrate 247 samples
Lead 185 samples
Fluoride 845 samples
Sulfate 248 samples
Uranium 84 samples
Sodium 250 samples
pH 241 samples
Hardness 248 samples
Limited data (<15 samples) — interpret with caution
Radon 1 sample
Nitrite 1 sample
No private-well PFAS data for Matagorda County
We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Matagorda 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 →
Public vs. Private Water in Matagorda County
45Active public water systems
39,939Residents on public water
10%Households on private wells
Public water systems in Matagorda 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 Matagorda 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 Matagorda 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 Matagorda County. Census data explorer →
USGS Aquifer Atlas — principal aquifer type underlying Matagorda 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 Matagorda County, used in contamination risk scoring. TRI Explorer →
EPA Superfund NPL — National Priorities List sites in or near Matagorda 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.