CASTLE ROCK TOWN OF
PWS ID: CO0118010 · CASTLE ROCK, Colorado 80109
PFAS Detected
3 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.
Population Served
106,822
Total Violations
52
Health-Based Violations
0
Water Source
Surface Water
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 27,172
- County
- Douglas
- School/Daycare
- No
- MCL Violations
- 0
- Monitoring Violations
- 50
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Surface Water Treatment Rule | MR | 15 | 2025 |
| Nitrate | MR | 8 | 2006 |
| Gross Alpha, Excl. Radon and U | MR | 6 | 2022 |
| Combined Uranium | MR | 6 | 2022 |
| Combined Radium (-226 and -228) | MR | 6 | 2022 |
| Coliform (TCR) | MR | 6 | 2006 |
| Nitrite | MR | 3 | 2008 |
| Consumer Confidence Rule | Other | 2 | 2007 |
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 14 of 360 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| NEtFOSAA | 8/7/2024 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFTrDA | 8/7/2024 | <0.007 µg/L | 0.007 µg/L | Not Detected |
| NMeFOSAA | 8/7/2024 | <0.006 µg/L | 0.006 µg/L | Not Detected |
| PFTA | 8/7/2024 | <0.008 µg/L | 0.008 µg/L | Not Detected |
| PFTA | 8/28/2023 | <0.008 µg/L | 0.008 µg/L | Not Detected |
| PFTrDA | 8/28/2023 | <0.007 µg/L | 0.007 µg/L | Not Detected |
| NMeFOSAA | 8/28/2023 | <0.006 µg/L | 0.006 µg/L | Not Detected |
| PFMPA | 8/28/2023 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| NEtFOSAA | 8/28/2023 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| 9Cl-PF3ONS | 8/28/2023 | <0.002 µg/L | 0.002 µg/L | Not Detected |
| PFBS | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFHpA | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFEESA | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| NFDHA | 8/28/2023 | <0.02 µg/L | 0.02 µg/L | Not Detected |
| PFHxS | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFNA | 8/28/2023 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFOS | 8/28/2023 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFOA | 8/28/2023 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFDA | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFDoA | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFHxA | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFMBA | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| 11Cl-PF3OUdS | 8/28/2023 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| lithium | 8/28/2023 | 22.3000 µg/L | 9 µg/L | Detected |
| ADONA | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| HFPO-DA | 8/28/2023 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFBA | 8/28/2023 | 0.0051 µg/L | 0.005 µg/L | Detected |
| 6:2 FTS | 8/28/2023 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| 4:2 FTS | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| 8:2 FTS | 8/28/2023 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFPeA | 8/28/2023 | 0.0047 µg/L | 0.003 µg/L | Detected |
| PFPeS | 8/28/2023 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFHpS | 8/28/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFUnA | 8/28/2023 | <0.002 µg/L | 0.002 µg/L | Not Detected |
| 8:2 FTS | 7/11/2023 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFBA | 7/11/2023 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| 6:2 FTS | 7/11/2023 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| 4:2 FTS | 7/11/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFMPA | 7/11/2023 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFPeA | 7/11/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFMBA | 7/11/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFEESA | 7/11/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| NFDHA | 7/11/2023 | <0.02 µg/L | 0.02 µg/L | Not Detected |
| PFHpS | 7/11/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFPeS | 7/11/2023 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| PFOS | 7/11/2023 | <0.004 µg/L | 0.004 µg/L | Not Detected |
| HFPO-DA | 7/11/2023 | <0.005 µg/L | 0.005 µg/L | Not Detected |
| PFHxS | 7/11/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| ADONA | 7/11/2023 | <0.003 µg/L | 0.003 µg/L | Not Detected |
| PFNA | 7/11/2023 | <0.004 µg/L | 0.004 µg/L | Not Detected |
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025.
PFAS data from EPA UCMR5 monitoring program (2023-2025).
This data is provided for informational purposes only.