This page summarizes EPA Fifth Unregulated Contaminant Monitoring Rule (UCMR 5, 2023–2025) drinking-water monitoring records linked to ZIP codes in Arkansas, as processed for the PFAS Estimator national dataset. Data updated: July 2026.
| Compound | Applicable threshold | ZIP codes detected | At/above threshold | Mean detected | Maximum detected |
|---|---|---|---|---|---|
| PFOS | 0.004 µg/L (MCL) | 2 (1.1% of state) | 2 (100.0%) — all detections at/above limit by construction | 0.0044 µg/L | 0.0044 µg/L |
| PFHxS | 0.01 µg/L (MCL) | 2 (1.1% of state) | 0 (0.0% of detected) | 0.0053 µg/L | 0.0053 µg/L |
| PFBS | 2.0 µg/L (HI reference) | 2 (1.1% of state) | not calculated¹ | 0.007 µg/L | 0.007 µg/L |
| Lithium | 7.36 µg/L (reference, not a regulatory limit) | 143 (82.2% of state) | 143 (100.0%) at/above reference | 30.572 µg/L | 73.6 µg/L |
| PFPeA | — (no federal limit) | 2 (1.1% of state) | — | 0.0055 µg/L | 0.0055 µg/L |
| PFBA | — (no federal limit) | 33 (19.0% of state) | — | 0.0069 µg/L | 0.012 µg/L |
| 6:2 FTS | — (no federal limit) | 4 (2.3% of state) | — | 0.0062 µg/L | 0.0062 µg/L |
174 ZIP codes with at least one recorded PFAS detection. Click a ZIP code to view its full compound-level results.
Results are based on EPA UCMR 5 monitoring data (2023–2025), linked to ZIP codes via Public Water System Identifier. Non-detections are not present in this analytic dataset. For each compound and ZIP code, the highest observed concentration across the monitoring period is retained; this characterizes the upper bound of observed drinking-water concentrations, not a long-term average or an individual exposure estimate. A single water system may serve multiple ZIP codes, so the same monitoring record can appear for more than one ZIP in this table. ZIP-code assignment reflects water-system service area geography and does not establish individual household exposure. Private wells are not represented unless served by a monitored public water system. PFOA and PFOS are reported by detection prevalence because the UCMR 5 reporting limit equals their federal MCL. A full PFBS Hazard Index is not calculated because co-located, same-event multi-compound readings are not retained in this dataset. Lithium has no federal Maximum Contaminant Level; 7.36 µg/L is an evidence-based reference concentration from a prospective cohort study, not a regulatory threshold.
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