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Jefferson Lake and Washington Lake read the same on nutrients and algae. Both are in Le Sueur County, Minnesota.

Reviewed by LakeQuality Editorial Team · Updated

Jefferson Lake and Washington Lake are both in Minnesota — a same-state head-to-head where the comparison comes down to lake-specific differences in depth, watershed, and monitoring history rather than the broader state-level water-quality regime. The readings are close: Jefferson Lake and Washington Lake sit within a narrow band of each other on phosphorus, chlorophyll-a and clarity. The per-parameter table below shows where the small differences actually live.

With readings this close, the choice between the two lakes turns on non-water-quality factors: depth, fish species, public access, distance from home. The per-lake pages below cover all of those.

Jefferson Lake

Le Sueur County, Minnesota

Very murky, less than 2 ft of visibility.

Washington Lake

Le Sueur County, Minnesota

Murky, only visible to about 4.5 ft.

Side-by-Side Metrics

MetricJefferson LakeWashington Lake
Water Clarity2 ft4.5 ft Better
Phosphorus86.5 µg/L Better122 µg/L
Chlorophyll-a (Algae)72 µg/L51.3 µg/L Better
Maximum Depth-51 ft
Surface Area700 acres1,516 acres
Public AccessYesYes
Fish Species018 Better
Trophic Stateeutrophiceutrophic

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

Both lakes earn the same Grade F. The tiebreakers come down to clarity (Jefferson Lake: 2 ft, Washington Lake: 4.5 ft) and what you want from the lake. Jefferson Lake has fewer fish species than Washington Lake.

Source: EPA National Aquatic Resource Surveys, 2026.