Foster Lake is a mesotrophic lake in Linn County, Oregon. Water quality is graded A based on 1 sampling years through 2025. Compared to the 1 other monitored lakes in Linn County, Foster Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DNR, last sampled 2025-10-16. Grade methodology: LakeGrade methodology.
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
No clarity data. Chlorophyll-a: 2.7 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 2.7 µg/L | A |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Foster Lake
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Fishing Foster Lake
Location
County Ranking
Ranked #1 of 2 lakes in Linn County
Nearby Lakes in Linn County
Explore Foster Lake across LakeGrade
More Oregon Lake Rankings
Other Grade A Lakes in Oregon
Mesotrophic 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: 2025-10-16
Monitoring stations: 1