Wyoming Water Report Card: Worst Water Systems
The most contaminated public water systems in Wyoming, ranked by PFAS levels, lead, and EPA violations from official EPA data.
Quick Answer
Riverton, City Of has the highest PFAS in Wyoming at 37 ppt (9x the EPA limit). Ynp-Old Faithful has the highest lead at 125 ppb. The tables below rank the worst systems in each category so you can see how your water compares.
Highest PFAS Levels in Wyoming
Public water systems in Wyoming with the highest peak PFAS ("forever chemical") reading in EPA UCMR5 testing (2023-2025). The EPA enforceable limit for PFOA and PFOS is 4 ppt.
| # | Water System | Location | Peak PFAS (ppt) | Compounds | vs 4 ppt limit |
|---|---|---|---|---|---|
| 1 | Riverton, City Of | Riverton · 10,330 served | 37 | 7 | 9x |
| 2 | Douglas, City Of | Douglas · 6,400 served | 10.8 | 1 | 3x |
Highest Lead Levels in Wyoming
Community water systems in Wyoming with the highest 90th-percentile lead result under the EPA Lead and Copper Rule. The EPA action level is 15 ppb; there is no safe level of lead for children.
| # | Water System | Location | Lead 90th-pctile (ppb) | vs 15 ppb |
|---|---|---|---|---|
| 1 | Ynp-Old Faithful | Yellowstone · 7,675 served | 125 | 8.3x over |
| 2 | Pine Bluffs, Town Of | Fort Collins · 1,186 served | 27 | 1.8x over |
| 3 | Ynp - Lake Village | Yellowstone · 5,925 served | 15 | within |
| 4 | Cheyenne Board Of Public Utilities | Cheyenne · 64,165 served | 15 | within |
| 5 | Buffalo, City Of | Buffalo · 4,419 served | 14 | within |
| 6 | Pinedale Municipal Ws | Pinedale · 1,900 served | 14 | within |
| 7 | Gtnp-Jackson Lake Lodge | Moose · 1,830 served | 13 | within |
| 8 | Leisure Valley Inc/ Star Valley Rv Park | Grover · 1,910 served | 12 | within |
| 9 | Alpine, Town Of | Alpine · 1,300 served | 12 | within |
| 10 | Torrington Municipal Water Dept, City Of | Torrington · 6,847 served | 11 | within |
| 11 | Mountain View, Town Of | Mountain View · 1,250 served | 10 | within |
| 12 | Burns Board Of Public Utilities | Burns · 1,024 served | 9 | within |
Most EPA Violations in Wyoming
Community water systems in Wyoming with the most health-based EPA Safe Drinking Water Act violations on record. A health-based violation means a contaminant exceeded its federal limit or required treatment was not applied.
| # | Water System | Location | Health-based violations |
|---|---|---|---|
| 1 | Little America Hotels & Resorts, Inc- Wy | Little America · 2,004 served | 17 |
| 2 | Ynp-Old Faithful | Yellowstone · 7,675 served | 11 |
| 3 | Kemmerer-Diamondville Jpb | Kemmerer · 3,348 served | 10 |
| 4 | Pine Bluffs, Town Of | Fort Collins · 1,186 served | 5 |
| 5 | Rawlins Water Supply, City Of | Rawlins · 9,006 served | 5 |
| 6 | Wheatland, Town Of | Wheatland · 3,659 served | 4 |
| 7 | Buffalo, City Of | Buffalo · 4,419 served | 4 |
| 8 | Bear River Regional Joint Powers | Bear River · 1,200 served | 4 |
| 9 | Mills, City Of | Mills · 4,050 served | 3 |
| 10 | Star Valley Ranch, Town Of | Star Valley Ranch · 2,030 served | 3 |
| 11 | Lusk, Town Of | Lusk · 1,576 served | 3 |
| 12 | Leisure Valley Inc/ Star Valley Rv Park | Grover · 1,910 served | 3 |
How This Report Card Is Built
PFAS rankings use EPA UCMR5 monitoring (2023-2025), showing each system's peak detection above the 4 ppt EPA limit. Lead rankings use the EPA Lead and Copper Rule 90th-percentile tap results. Violation counts come from the EPA Safe Drinking Water Information System (SDWIS) and count health-based violations. Lead and violation lists are limited to community water systems serving 1,000 or more people. Figures are the most severe on record and do not necessarily reflect current treated water.
Frequently Asked Questions
What is the most PFAS-contaminated water system in Wyoming?
In EPA UCMR5 testing (2023-2025), Riverton, City Of in Riverton had the highest recorded PFAS level in Wyoming at 37 ppt - about 9x the EPA's 4 ppt limit for PFOA and PFOS.
Which Wyoming water system has the highest lead levels?
Ynp-Old Faithful in Yellowstone had the highest 90th-percentile lead result in Wyoming under the EPA Lead and Copper Rule at 125 ppb - 8.3x the 15 ppb action level.
Which Wyoming water system has the most EPA violations?
Little America Hotels & Resorts, Inc- Wy in Little America has the most health-based EPA Safe Drinking Water Act violations on record in Wyoming, with 17 violations.
Where does the Wyoming water report card data come from?
PFAS figures come from EPA UCMR5 monitoring (2023-2025), lead from the EPA Lead and Copper Rule 90th-percentile tap results, and violations from EPA SDWIS health-based violation records. Figures are the most severe on record and do not necessarily reflect current treated water. Check your exact address at knowyourexposure.com.
What Wyoming Residents Should Do
- Look up your exact address at knowyourexposure.com for your system's data
- See the full Wyoming water quality overview
- If your system is listed, a certified filter (reverse osmosis for PFAS, NSF-53 for lead) reduces exposure at the tap. See the best water filters.