- PWSID
- TX1080011
- State
- Texas
- System type
- community water system (CWS)
- Population served
- 40,033
- City
- Weslaco
- Counties
- Hidalgo County
- Primary source water
- surface water
- UCMR 5 sampling
- 2025-02-19 to 2025-11-04 · 1 entry point(s) · water types: SW
- Service-area boundary
- authoritative
PFOS 1–3 × its limit highest single result
PFOS 1–3 × its limit worst entry-point average
Open on the Texas map · All Texas systems · All results
These are monitoring results collected under EPA's Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) at entry points, where treated water enters the distribution system; they are not tap-water samples. They are not compliance determinations: compliance with EPA's 2024 PFAS limits is judged on running annual averages of compliance monitoring, required from 2029, so a single UCMR 5 result at or above a limit is not a violation. “< MRL” means the compound was not quantified at EPA's minimum reporting level; it does not mean zero.
Compared with EPA's 2024 values
| Highest single result | Worst entry-point average* | Limit | |
|---|---|---|---|
| PFOA (ppt) | <MRL | 0 | 4 |
| PFOS (ppt) | 5.9 | 5.33 | 4 |
| Hazard Index | 0.58 | 0.33 | 1.0† |
“<MRL” = every result for the compound was below its reporting limit. * Mean of all samples at each entry point with non-detects = 0 (EPA compliance convention; the Hazard Index also uses non-detects = 0); a screening comparison, not a formal running annual average. † Rescission proposed May 2026. PFOA/PFOS MCL 4 ppt (2024 NPDWR, in effect). PFHxS, PFNA, HFPO-DA (10 ppt each) and the Hazard Index (1.0) are 2024 NPDWR values; EPA proposed rescinding them on 18 May 2026 (comment period closed 20 Jul 2026).
No Texas PFAS drinking-water standard in effect or proposed as of 2026-10-17: No state PFAS drinking-water standard; TCEQ implementing federal NPDWR (BCLP state survey, Jan 2026).
Sampling history
Sampled 2025-02-19 to 2025-11-04 · 1 entry point(s) · water types: SW · 5 sampling visits. PFAS in ppt (ng/L).
| Date | Entry point | Event | PFOA | PFOS | HI | Other detections |
|---|---|---|---|---|---|---|
| 2025-02-19 | Weslaco Water Plant (SW) | SE1 | <4 | 5.9 | 0.58 | PFHpA 3.6, PFHxA 8.6, PFPeA 8.4, lithium 35.9 µg/L |
| 2025-04-28 | Weslaco Water Plant (SW) | SE1 | n/a | n/a | n/a | none |
| 2025-05-06 | Weslaco Water Plant (SW) | SE2 | <4 | 5.1 | 0.41 | PFBA 7.6, PFHxA 4.8, PFPeA 5.1, lithium 29.8 µg/L |
| 2025-09-02 | Weslaco Water Plant (SW) | SE3 | <4 | 5 | 0 | PFBA 6.3, PFHxA 6.2, PFPeA 5.9, lithium 36.1 µg/L |
| 2025-11-04 | Weslaco Water Plant (SW) | SE4 | n/a | n/a | n/a | lithium 33.9 µg/L |
“<4” = not detected at the reporting limit shown; “n/a” = not analyzed in that sample. Highlighted = at or above the 4 ppt MCL. HI computed per sample with non-detects as 0. Other detections lists every other quantified compound (lithium in µg/L).
All results by entry point
95 results. Each column is one sampling visit (date and UCMR 5 sample event). A number is a measured concentration; “< 4” = below the minimum reporting level shown; “–” = not analyzed in that visit. PFAS in ppt (ng/L); lithium in µg/L.
Weslaco Water Plant facility 54178 · sample point EP001MC · surface water
| Compound | MRL | 2025-02-19 SE1 | 2025-04-28 SE1 | 2025-05-06 SE2 | 2025-09-02 SE3 | 2025-11-04 SE4 |
|---|---|---|---|---|---|---|
| PFBA | 5 ppt | < 5 | – | 7.6 | 6.3 | – |
| PFHpA | 3 ppt | 3.6 | – | < 3 | < 3 | – |
| PFHxA | 3 ppt | 8.6 | – | 4.8 | 6.2 | – |
| PFHxS | 3 ppt | 5.8 | – | 4.1 | < 3 | – |
| PFOS | 4 ppt | 5.9 | – | 5.1 | 5 | – |
| PFPeA | 3 ppt | 8.4 | – | 5.1 | 5.9 | – |
| 11Cl-PF3OUdS | 5 ppt | < 5 | – | < 5 | < 5 | – |
| 4:2 FTS | 3 ppt | < 3 | – | < 3 | < 3 | – |
| 6:2 FTS | 5 ppt | < 5 | – | < 5 | < 5 | – |
| 8:2 FTS | 5 ppt | < 5 | – | < 5 | < 5 | – |
| 9Cl-PF3ONS | 2 ppt | < 2 | – | < 2 | < 2 | – |
| ADONA | 3 ppt | < 3 | – | < 3 | < 3 | – |
| HFPO-DA | 5 ppt | < 5 | – | < 5 | < 5 | – |
| NEtFOSAA | 5 ppt | – | < 5 | < 5 | < 5 | < 5 |
| NFDHA | 20 ppt | < 20 | – | < 20 | < 20 | – |
| NMeFOSAA | 6 ppt | – | < 6 | < 6 | < 6 | < 6 |
| PFBS | 3 ppt | < 3 | – | < 3 | < 3 | – |
| PFDA | 3 ppt | < 3 | – | < 3 | < 3 | – |
| PFDoA | 3 ppt | < 3 | – | < 3 | < 3 | – |
| PFEESA | 3 ppt | < 3 | – | < 3 | < 3 | – |
| PFHpS | 3 ppt | < 3 | – | < 3 | < 3 | – |
| PFMBA | 3 ppt | < 3 | – | < 3 | < 3 | – |
| PFMPA | 4 ppt | < 4 | – | < 4 | < 4 | – |
| PFNA | 4 ppt | < 4 | – | < 4 | < 4 | – |
| PFOA | 4 ppt | < 4 | – | < 4 | < 4 | – |
| PFPeS | 4 ppt | < 4 | – | < 4 | < 4 | – |
| PFTA | 8 ppt | – | < 8 | < 8 | < 8 | < 8 |
| PFTrDA | 7 ppt | – | < 7 | < 7 | < 7 | < 7 |
| PFUnA | 2 ppt | < 2 | – | < 2 | < 2 | – |
| lithium | 9 µg/L | 35.9 | – | 29.8 | 36.1 | 33.9 |
Statistics by compound
| Compound | Results | Detected | Highest (date) | Mean bounds | KM median | P75 | P90 | P95 |
|---|---|---|---|---|---|---|---|---|
| lithium | 4 | 100% | 36.1 2025-09-02 | 33.92–33.92 | 33.9 | 35.9 | 36.1 | 36.1 |
| PFHxA | 3 | 100% | 8.6 2025-02-19 | 6.53–6.53 | fewer than 4 results: raw values only | |||
| PFOS | 3 | 100% | 5.9 2025-02-19 | 5.33–5.33 | fewer than 4 results: raw values only | |||
| PFPeA | 3 | 100% | 8.4 2025-02-19 | 6.47–6.47 | fewer than 4 results: raw values only | |||
| PFBA | 3 | 67% | 7.6 2025-05-06 | 4.63–6.3 | fewer than 4 results: raw values only | |||
| PFHxS | 3 | 67% | 5.8 2025-02-19 | 3.3–4.3 | fewer than 4 results: raw values only | |||
| PFHpA | 3 | 33% | 3.6 2025-02-19 | 1.2–3.2 | fewer than 4 results: raw values only | |||
Never detected (23): 11Cl-PF3OUdS, 4:2 FTS, 6:2 FTS, 8:2 FTS, 9Cl-PF3ONS, ADONA, HFPO-DA, NEtFOSAA, NFDHA, NMeFOSAA, PFBS, PFDA, PFDoA, PFEESA, PFHpS, PFMBA, PFMPA, PFNA, PFOA, PFPeS, PFTA, PFTrDA, PFUnA.
Left-censored Kaplan–Meier statistics (Helsel 2005; Helsel & Lee 2006, NADA for R). Units: ppt; lithium µg/L. Each compound has one reporting limit, so the Kaplan–Meier mean equals the upper mean bound (non-detects at the MRL); the lower bound sets non-detects to 0. “<MRL” = the percentile falls below the reporting limit and cannot be estimated. These describe this system's UCMR 5 samples, not population estimates.
Sources
- EPA UCMR 5 occurrence data text files (UCMR5_All.txt; samples 2023-01-09 to 2026-06-16; data summary dated Jul 2026)
- EPA SDWIS via ECHO SDWA downloads, quarter 2026Q3
- EPA Public Water System Service Areas v3 (Mar 2026)
- US Census Bureau cartographic boundary counties 1:500k, 2024
- EPA/USGS NHDPlus V2 (medium resolution) flowlines, Strahler order 2+
Data build a6f3d99247ed · 2026-10-18T04:13Z · UCMR 5 release Jul2026 · SDWIS 2026Q3. Data and methods.