EPA UCMR 5 PFAS Monitoring Data
PFAS in Colorado Drinking Water
Detection data from EPA UCMR 5 monitoring (2023–2025)
Last updated: May 28, 2026Monitoring results are not compliance determinations. Detection levels reflect a specific sample point and date. Utilities may have taken corrective action after sampling. Methodology
Under the EPA's Fifth Unregulated Contaminant Monitoring Rule (UCMR 5), public water systems are required to test for 29 PFAS compounds between 2023 and 2025. This page summarizes the monitoring results reported for 154 water utilities in Colorado, drawn directly from EPA's published occurrence data. 13 utilities reported one or more samples above an EPA Maximum Contaminant Level for PFOA, PFOS, PFNA, PFHxS, or HFPO-DA.
Highest PFOA / PFOS detections reported
| Utility | Analyte | Value (ng/L) |
|---|---|---|
| Snake River Wd CO0159105 | PFOS | 22.00Above MCL |
| Widefield Wsd CO0121900 | PFOS | 15.80Above MCL |
| City of Brighton CO0101025 | PFOS | 10.60Above MCL |
| Widefield Wsd CO0121900 | PFOA | 10.50Above MCL |
| Town of Mountain Village CO0157400 | PFOS | 7.50Above MCL |
| City of Thornton CO0101150 | PFOA | 7.10Above MCL |
| Todd Creek Village Md CO0101157 | PFOS | 6.80Above MCL |
| Cherokee Md CO0121125 | PFOA | 6.10Above MCL |
| Snake River Wd CO0159105 | PFOA | 5.80Above MCL |
| Stonegate Md CO0118076 | PFOA | 5.60Above MCL |
Source: EPA UCMR 5 occurrence data. Detection levels reflect a single sample at a specific point in the system on the date shown. The EPA's Maximum Contaminant Level for PFOA and PFOS is 4 ng/L (finalized April 2024, compliance required by 2029). EPA UCMR 5
PFAS analytes — detection breakdown
Detections / total records per analyte. All 29 UCMR 5 analytes shown where records exist for Colorado.
All CO utilities with PFAS records
154 systems| Water System | |
|---|---|
Denver Water Board Denver | View |
City of Aurora | View |
Colorado Springs Utilities Colorado Springs | View |
City of Thornton Thornton Above MCL | View |
City of Westminster Westminster | View |
City of Ft Collins | View |
City of Arvada Arvada | View |
City of Boulder Boulder | View |
City of Greeley Greeley | View |
Pueblo Board of Ww Pueblo | View |
How this data was collected
Source dataset
All records on this page are drawn from the EPA's Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) occurrence dataset, published by the U.S. Environmental Protection Agency. UCMR 5 required large public water systems (serving more than 3,300 people) to sample for 29 PFAS compounds between 2023 and 2025. EPA UCMR 5 occurrence data
Sampling methodology
Samples were collected at entry points to the distribution system (EPTDS) as required by UCMR 5 regulations. Each utility collected at least four quarterly samples during the monitoring period. Results represent concentrations at the specified sample point on the sample date — not a continuous measure of system-wide levels.
Unit normalization
Source data may express concentrations in micrograms per liter (µg/L, also written ug/L or ppb) or nanograms per liter (ng/L, also called ppt). All values on this page are normalized to ng/L (ppt) for consistent comparison with EPA Maximum Contaminant Levels (MCLs). Conversion: 1 µg/L = 1,000 ng/L. Records with unrecognized units are excluded from numeric aggregates and flagged in the raw export.
What "detection" means
A result is counted as a detection when the EPA reports it as "Detected above MRL" — meaning the analyte was measured at or above the minimum reporting limit (MRL) for that analyte. Non-detect results (below MRL) are included in total record counts but not in detection counts. Detection is a monitoring outcome, not a compliance determination.
Validation and exclusion criteria
Records are included only where validated = true and suppressed = false. Records flagged during ingestion for format errors, duplicate source hashes, or missing required fields are excluded.
Update cadence
Pages are regenerated every 24 hours via Next.js ISR. The underlying dataset is updated when EPA publishes new UCMR 5 occurrence data. The source retrieval date shown on each record reflects the date the EPA file was last downloaded to our system.
Cite this page
Water Utility Report. (2026). PFAS in Colorado drinking water: EPA UCMR 5 monitoring records (2025). Retrieved May 28, 2026, from https://waterutilityreport.com/data/pfas/colorado
Nearby states
Detection levels represent results from EPA-required compliance monitoring at the time of sampling. They are not a real-time indicator of current water quality. Utilities may have taken corrective action or installed treatment after sampling. For current information about your water, contact your utility or consult your annual Consumer Confidence Report.
At a Glance
Utilities tested
Total PFAS records
With detections
of 154
Above PFOA MCL (4 ng/L)
of 154
Above PFOS MCL (4 ng/L)
of 154
Above any individual MCL
PFOA, PFOS, PFNA, PFHxS, or HFPO-DA