Williamson River Outlet Lake
Klamath County, OregonView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- #10 of 17 in the county
Williamson River Outlet Lake in Klamath County, Oregon has a water quality grade of F (Algae-prone). Phosphorus: 165 µg/L. Chlorophyll-a (algae): 67.9 µg/L.
- Type
- Hypereutrophic
- Phosphorus
- 165 µg/L
- Chlorophyll-a
- 67.9 µg/L
- Trend
- ↓ Declining
Stays via Stay22
Stays near Williamson River Outlet Lake
Compare lakeside cabins, hotels, and vacation rentals near Williamson River Outlet 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Williamson River Outlet Lake are listed below.
Top-rated places to stay near Williamson River Outlet Lake
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Watch Williamson River Outlet Lake’s letter
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Williamson River Outlet Lake is a highly nutrient-loaded hypereutrophic lake in Klamath County, Oregon. Water quality is graded F based on 2 sampling years through 2023. Overall water quality is declining over recent sampling years. Compared to the 16 other monitored lakes in Klamath County, Williamson River Outlet Lake ranks #10 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, last sampled 2023-09-25. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyAlgae risk
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
No clarity data. Phosphorus 165 µg/L. Chlorophyll-a 67.9 µg/L. TSI 75. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 165 µg/L | Poor |
| Chlorophyll-a (Algae) | 67.9 µg/L | Poor |
| Trophic State Index (TSI) | 75 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Fishing Williamson River Outlet Lake
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↓ Declining | +12 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +7.49 µg/L/yr | 4 |
County Ranking
Ranked #10 of 17 lakes in Klamath County
Nearby Lakes in Klamath County
Frequently asked questions about Williamson River Outlet Lake
Where is Williamson River Outlet Lake?
- Williamson River Outlet Lake is a lake in Klamath County, Oregon. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Williamson River Outlet Lake?
- Williamson River Outlet Lake in Klamath County, Oregon has a water quality grade of F (Algae-prone). Phosphorus: 165 µg/L. Chlorophyll-a (algae): 67.9 µg/L.
Is Williamson River Outlet Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Williamson River Outlet Lake across LakeQuality
1.7 mi away · recorded at 95°F
Species activity outlook by water temperature and season
Where to stay at Oregon's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
Oregon's cleanest and most-polluted lakes, ranked
Planning a trip around Crater Lake?
Williamson River Outlet Lake is about 35 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
Where this data comes from
83 measurements from 1 monitoring station, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Oregon Water Science Center
USGS-OR83 samples · 2020–2023
Analytical methods
- Nutrients, wu, WCA,persulfate,CF
- Chlorophyll a, phytoplankton
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.