Upper Klamath Lake is a highly nutrient-loaded hypereutrophic lake in Klamath County, Oregon. Water quality is graded F based on 2 sampling years through 2025. Compared to the 19 other monitored lakes in Klamath County, Upper Klamath Lake ranks #17 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DNR, last sampled 2025-10-01. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
No clarity data. Phosphorus level: 195 µg/L. Chlorophyll-a: 117 µg/L. Trophic State Index: 79.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 195 µg/L | F |
| Chlorophyll-a (Algae) | 117 µg/L | F |
| Trophic State Index (TSI) | 79 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Upper Klamath Lake
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Fishing Upper Klamath Lake
Location
County Ranking
Ranked #17 of 20 lakes in Klamath County
Nearby Lakes in Klamath County
Explore Upper Klamath Lake across LakeGrade
More Oregon Lake Rankings
Other Grade F Lakes in Oregon
Hypereutrophic 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: 2025-10-01
Monitoring stations: 3