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LakeQuality

Lake Kegonsa vs Lake Mendota

Water quality, depth, fish species, and recreation comparison.

Lake Kegonsa and Lake Mendota both received the same overall water quality grade of C (Fair). Both are in Dane County, Wisconsin.

Both Lake Kegonsa and Lake Mendota sit in Wisconsin. A same-state comparison strips out the state-level water-quality regime as a variable: any grade differences here are about the lakes themselves, not the agencies grading them. These two are within a letter of each other on the rubric — Lake Kegonsa (C) versus Lake Mendota (C). The deciding factors for a recreational visitor are likely physical (depth, access, fish species) rather than water-quality differences.

With grades 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.

C

Lake Kegonsa

Dane County, Wisconsin

Murky, only visible to about 3.7 ft.

C

Lake Mendota

Dane County, Wisconsin

Murky, only visible to about 5 ft.

Side-by-Side Metrics

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

MetricLake KegonsaLake Mendota
Overall GradeC (Fair)C (Fair)
Water Clarity3.7 ft5 ft
Phosphorus59.5 µg/L50.2 µg/L
Chlorophyll-a (Algae)No dataNo data
Maximum Depth32 ft83 ft
Surface Area3.2K acres9.8K acres
Public AccessUnknownUnknown
Fish Species00
Trophic Stateeutrophiceutrophic

Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).

Verdict

Both lakes earn the same Grade C. The tiebreakers come down to clarity (Lake Kegonsa: 3.7 ft, Lake Mendota: 5 ft) and what you want from the lake. Lake Kegonsa matches its peer on species count.