Klamath County, Oregon · 42.41°N · Water Quality Report Card
Upper Klamath Lake
Upper Klamath Lake in Klamath County, Oregon has a water quality grade of F (Very Poor). Chlorophyll-a (algae): 71.6 µg/L.
- Mean depth
- ~8 ft est.
- Type
- Hypereutrophic
- Trend
- ↑ Improving
Upper Klamath Lake is a highly nutrient-loaded hypereutrophic lake in Klamath County, Oregon with an estimated average depth of about 8 feet. Water quality is graded F based on 1 sampling years through 2025. Overall water quality is improving over recent sampling years. Compared to the 16 other monitored lakes in Klamath County, Upper Klamath Lake ranks #17 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, 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. Chlorophyll-a: 71.6 µg/L. Trophic State Index: 72.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 71.6 µg/L | Poor |
| Trophic State Index (TSI) | 72 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~8 ft est. |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Oregon has not published bathymetry for Upper Klamath Lake.
Where to stay near Upper Klamath Lake
Compare lakeside cabins, hotels, and vacation rentals near Upper Klamath Lake in Klamath County, Oregon — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
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Fishing Upper Klamath Lake
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↑ Improving | -45 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -16.83 µg/L/yr | 5 |
Location
County Ranking
Ranked #17 of 17 lakes in Klamath County
Nearby Lakes in Klamath County
Explore Upper Klamath Lake across LakeGrade
Planning a trip around Crater Lake?
Upper Klamath Lake is about 38 miles from Crater Lake National Park. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Crater Lake →More Oregon Lake Rankings
Other Grade F Lakes in Oregon
Hypereutrophic Lakes in Oregon
More records, surveys & data sources
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Where this data comes from
4 measurements from 1 monitoring station, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Department of Environmental Quality - State of Oregon
OREGONDEQ4 samples · 2025
Analytical methods
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
Grade thresholds come from the U.S. EPA National Lakes Assessment 2022 Technical Support Document (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated.
Data Sources
Water quality data from the EPA Water Quality Portal
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2025-10-01
Monitoring stations: 1