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Geneva Lake reads lower on nutrients and algae than Smith Lake. Both are in Douglas County, Minnesota.

Reviewed by LakeQuality Editorial Team · Updated

Both Geneva Lake and Smith Lake sit in Minnesota. A same-state comparison strips out the state-level water-quality regime as a variable: any differences in the readings here are about the lakes themselves, not the agencies sampling them. The readings are meaningfully apart: Geneva Lake carries clearly lower phosphorus and chlorophyll-a readings than Smith Lake. A spread that wide reflects real underlying differences, in watershed inputs, depth profiles, or monitoring rigor.

For a recreational visitor, the wider gap in the readings is decisive: Geneva Lake has the lower nutrient and algae numbers. For a researcher, the gap is the interesting part: what is different about the two watersheds, and which of those differences is mutable?

Geneva Lake

Douglas County, Minnesota

Good clarity, visible to about 14.1 ft.

Smith Lake

Douglas County, Minnesota

Murky, only visible to about 3.6 ft.

Side-by-Side Metrics

MetricGeneva LakeSmith Lake
Water Clarity14.1 ft Better3.6 ft
Phosphorus21.5 µg/L Better58 µg/L
Chlorophyll-a (Algae)4.9 µg/L Better36 µg/L
Maximum Depth63 ft Better30 ft
Surface Area640 acres666 acres
Public AccessYesYes
Fish Species17 Better15
Trophic Statemesotrophiceutrophic

A green ✓ marks the better value for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better). Surface area and trophic state carry no tick — a bigger lake is not a better lake.

Verdict

Geneva Lake reads lower on nutrients and algae than Smith Lake. Water clarity: 14.1 ft vs 3.6 ft. For fishing diversity, Geneva Lake also leads with 17 species.

Source: EPA National Aquatic Resource Surveys, 2026.