Yakima County Lake Quality
Washington, 4 lakes, average grade B (Good)
Yakima County has 4 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. 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 Rimrock Reservoir (A); the most-stressed is Nla Lake (C).
Quick Answers for Yakima County
Planning a trip? Check special fishing regulations for Rimrock Reservoir — or check the official Washington fishing regulations.
All Lakes in Yakima County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Rimrock Reservoir | A | - | 15 µg/L |
| 2 | Nla Lake | C | 9.4 ft | 34.8 µg/L |
Other Counties in Washington
See how Yakima 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 Yakima County
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Source: EPA National Aquatic Resource Surveys, 2026.