Umatilla County Lake Quality
Oregon, 4 lakes, average grade D (Poor)
Umatilla 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. On average, Umatilla County lakes grade D, with phosphorus loading and reduced clarity showing up across most of the dataset.
Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Mckay Reservoir (C) is the cleanest in the county.
Quick Answers for Umatilla County
Planning a trip? Check special fishing regulations for Mckay Reservoir — or check the official Oregon fishing regulations.
All Lakes in Umatilla County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Mckay Reservoir | C | - | - |
| 2 | Mckay Lake | F | 3.3 ft | 121.5 µg/L |
| 3 | Cold Springs Reservoir | F | - | - |
Other Counties in Oregon
See how Umatilla County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 27 states.
Where to stay near Umatilla County
Top-rated places to stay near Umatilla County
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Source: EPA National Aquatic Resource Surveys, 2026.