Washington County Lake Quality
Utah, 15 lakes, average grade B (Good)
Washington 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-wide average lands at B — solid water quality with most lakes carrying clear summer transparency and low-to-moderate phosphorus.
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 Quail Creek Reservoir (A); the most-stressed is Baker Dam Reservoir (D).
Quick Answers for Washington County
Planning a trip? Check special fishing regulations for Quail Creek Reservoir — or check the official Utah fishing regulations.
All Lakes in Washington County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Quail Creek Reservoir | A | 14.6 ft | - |
| 2 | Kolob Reservoir | A | 10.5 ft | - |
| 3 | Nla Lake | B | 7.9 ft | - |
| 4 | Kolob Reservoir Midway | B | 9.5 ft | - |
| 5 | Upper Enterprise Reservoir | B | 5.2 ft | - |
| 6 | Gunlock Reservoir | B | 4.6 ft | - |
| 7 | Gunlock Reservoir Midway | B | 4.6 ft | - |
| 8 | Baker Dam Reservoir | D | 3.6 ft | - |
Other Counties in Utah
See how Washington County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 34 states.
Where to stay near Washington County
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Source: EPA National Aquatic Resource Surveys, 2026.