Mckay Reservoir is a productive, nutrient-rich eutrophic lake in Umatilla County, Oregon. Water quality is graded C based on 1 sampling years through 2025. Compared to the 3 other monitored lakes in Umatilla County, Mckay Reservoir ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DNR, last sampled 2025-10-08. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
No clarity data. Chlorophyll-a: 11.1 µg/L. Trophic State Index: 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 11.1 µg/L | C |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Mckay Reservoir
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Fishing Mckay Reservoir
Location
County Ranking
Ranked #1 of 4 lakes in Umatilla County
Nearby Lakes in Umatilla County
Explore Mckay Reservoir across LakeGrade
More Oregon Lake Rankings
Other Grade C Lakes in Oregon
Eutrophic Lakes in Oregon
More records, surveys & data sources
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-10-08
Monitoring stations: 1