| Cleanest/Best Watersheds |
National Average |
Dirtiest/Worst Watersheds |
| Percentage of Surface Waters with Impaired or Threatened Uses (state + EPA data): |
    |
| |
| Number of Impaired Waterbodies (as reported by the state): |
     |
| |
NOTE: Data limitations affect the accuracy of these rankings.
Rank watersheds by assessed use impairments
Rank counties by assessed use impairments.
Rank states by assessed use impairments, impairments due to specific causes, or impairments due to specific sources