Sweetwater County Lake Quality
Wyoming, 15 lakes, average grade C (Fair)
Sweetwater County's 15 graded lakes fall in the moderate-density bracket for {{stateName}}. The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. The county average is C — the middle of the rubric, with one or two lakes pulling the average up or down depending on year.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Flaming Gorge Reservoir (A); the most-stressed is Green River Inflow Lake (F).
Quick Answers for Sweetwater County
Planning a trip? Check special fishing regulations for Flaming Gorge Reservoir — or check the official Wyoming fishing regulations.
All Lakes in Sweetwater County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Flaming Gorge Reservoir | A | 22 ft | 11 µg/L |
| 2 | Flaming Gorge-Green River Lake | A | 18.4 ft | - |
| 3 | Flaming Gorge Lake | A | 17.4 ft | - |
| 4 | Flaming Gorge Res Bl Buckboard Replicate of Lake | A | 12.6 ft | 7 µg/L |
| 5 | Flaming Gorge Reservoir | B | 11.8 ft | - |
| 6 | Jim Bridger Pond | B | 4.9 ft | 13 µg/L |
| 7 | Flaming Gorge-Green River Off Firehole Canyon Campground Lake | B | 4.4 ft | - |
| 8 | Blacks Fork Lake | C | 8.5 ft | - |
| 9 | A And M Reservoir | C | - | 30 µg/L |
| 10 | Blacks Fork Inflow Lake | D | 5.2 ft | - |
| 11 | Big Sandy Reservoir | D | 0.7 ft | 45 µg/L |
| 12 | Green River Inflow Lake | F | 1.6 ft | - |
| 13 | Scotty Lake | F | - | 900 µg/L |
Other Counties in Wyoming
See how Sweetwater County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 34 states.
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Source: EPA National Aquatic Resource Surveys, 2026.