Sevier County Lake Quality
Utah, 13 lakes, average grade C (Fair)
Sevier County has 13 graded lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. Sevier County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.
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 Nla Lake (A); the most-stressed is Nla Lake (F).
Quick Answers for Sevier County
Planning a trip? Check special fishing regulations for Nla Lake — or check the official Utah fishing regulations.
All Lakes in Sevier County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Nla Lake | A | 33.1 ft | - |
| 2 | Nla Lake | A | 10.7 ft | - |
| 3 | Forsyth Reservoir | A | 13.8 ft | - |
| 4 | Nla Lake | C | 6.5 ft | - |
| 5 | Redmond Lake | D | 0.7 ft | - |
| 6 | Koosharem Reservoir | D | 7.2 ft | - |
| 7 | Nla Lake | D | 4.6 ft | - |
| 8 | Johnson Reservoir | D | 2 ft | - |
| 9 | Nla Lake | F | 0.5 ft | - |
Other Counties in Utah
See how Sevier 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 Sevier County
Top-rated places to stay near Sevier County
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Sevier County?
Get lake water-quality report cards plus the best cabin & lodging deals near Sevier County — straight to your inbox. No spam, unsubscribe anytime.
Source: EPA National Aquatic Resource Surveys, 2026.