Shoalwater Bay Lake
Klamath County, OregonView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- #13 of 17 in the county
Shoalwater Bay Lake in Klamath County, Oregon has a water quality grade of F (Algae-prone). Phosphorus: 215 µg/L. Chlorophyll-a (algae): 143.5 µg/L.
- Type
- Hypereutrophic
- Phosphorus
- 215 µg/L
- Chlorophyll-a
- 143.5 µg/L
- Trend
- ↑ Improving
Stays via Stay22
Stays near Shoalwater Bay Lake
Compare lakeside cabins, hotels, and vacation rentals near Shoalwater Bay 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 Shoalwater Bay Lake are listed below.
Top-rated places to stay near Shoalwater Bay Lake
Prices for Sep 11–13, 4 adults. Change dates on the map below.
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Watch Shoalwater Bay Lake’s letter
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Shoalwater Bay 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 improving over recent sampling years. Compared to the 16 other monitored lakes in Klamath County, Shoalwater Bay Lake ranks #13 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 215 µg/L. Chlorophyll-a 143.5 µg/L. TSI 80. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 215 µg/L | Poor |
| Chlorophyll-a (Algae) | 143.5 µg/L | Poor |
| Trophic State Index (TSI) | 80 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Fishing Shoalwater Bay 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 |
County Ranking
Ranked #13 of 17 lakes in Klamath County
Nearby Lakes in Klamath County
Frequently asked questions about Shoalwater Bay Lake
Where is Shoalwater Bay Lake?
- Shoalwater Bay 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 Shoalwater Bay Lake?
- Shoalwater Bay Lake in Klamath County, Oregon has a water quality grade of F (Algae-prone). Phosphorus: 215 µg/L. Chlorophyll-a (algae): 143.5 µg/L.
Is Shoalwater Bay Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Shoalwater Bay 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?
Shoalwater Bay 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
Where this data comes from
81 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-OR81 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.