Okanogan County Lake Quality
Washington, 7 lakes, average grade B (Good)
Only 7 lakes in Okanogan County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. 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 Fdr Lake (A); the most-stressed is Nla Lake (C).
Quick Answers for Okanogan County
Planning a trip? Check special fishing regulations for Fdr Lake — or check the official Washington fishing regulations.
All Lakes in Okanogan County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Fdr Lake | A | 21.5 ft | 11 µg/L |
| 2 | Nla Lake | B | 22.7 ft | 20518.3 µg/L |
| 3 | Nla Lake | B | 14.9 ft | 47515.6 µg/L |
| 4 | Nla Lake | C | 14 ft | 12516.3 µg/L |
Other Counties in Washington
See how Okanogan 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 Okanogan County
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Source: EPA National Aquatic Resource Surveys, 2026.