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LakeQuality
B

Marion County Lake Quality

Oregon, 1 lakes, average grade B (Good)

Only 1 lakes in Marion County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. The county-wide average lands at B — solid water quality with most lakes carrying clear summer transparency and low-to-moderate phosphorus.

The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Detroit Lake (B); the most-stressed is Detroit Lake (B).

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All Lakes in Marion County

RankLakeGradeClarityPhosphorus
1Detroit LakeB-20 µg/L

See how Marion County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 27 states.

Where to stay near Marion County

Top-rated places to stay near Marion County

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Source: EPA National Aquatic Resource Surveys, 2026.