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LakeQuality

Shallow Lake vs Third River Flowage Lake

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

Shallow Lake has a higher water quality grade (A, Excellent) than Third River Flowage Lake (B, Good). Both are in Itasca County, Minnesota.

Both Shallow Lake and Third River Flowage Lake sit in Minnesota. 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. The grades are close: Shallow Lake (A) and Third River Flowage Lake (B) are within one letter of each other on the LakeGrade rubric. The per-parameter sub-grades below will show where the small differences actually live.

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.

A

Shallow Lake

Itasca County, Minnesota

Crystal clear, you can see 16.4 ft down.

B

Third River Flowage Lake

Itasca County, Minnesota

Moderate clarity, visible to about 6.9 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.

MetricShallow LakeThird River Flowage Lake
Overall GradeA (Excellent)B (Good)
Water Clarity16.4 ft6.9 ft
Phosphorus9 µg/LNo data
Chlorophyll-a (Algae)No data5.5 µg/L
Maximum Depth85 ft69.8 ft
Surface Area538.95 acres56.5K acres
Public AccessYesYes
Fish Species11
Trophic Stateoligotrophicmesotrophic

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

Verdict

Shallow Lake wins on overall water quality with a Grade A versus Third River Flowage Lake's Grade B. Water clarity: 16.4 ft vs 6.9 ft. For fishing diversity, Shallow Lake also leads with 1 species.