Shallow Lake vs Third River Flowage Lake
Water quality, depth, fish species, and recreation comparison.
Shallow Lake reads lower on nutrients and algae than Third River Flowage Lake. 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 differences in the readings here are about the lakes themselves, not the agencies sampling them. The readings are meaningfully apart: Shallow Lake carries clearly lower phosphorus and chlorophyll-a readings than Third River Flowage 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: Shallow 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?
Shallow Lake
Crystal clear, you can see 16.4 ft down.
Third River Flowage Lake
Moderate clarity, visible to about 6.9 ft.
Side-by-Side Metrics
| Metric | Shallow Lake | Third River Flowage Lake |
|---|---|---|
| Water Clarity | 16.4 ft Better | 6.9 ft |
| Phosphorus | 9 µg/L Better | 28.5 µg/L |
| Chlorophyll-a (Algae) | 3.2 µg/L Better | 5.5 µg/L |
| Maximum Depth | 85 ft Better | 69.8 ft |
| Surface Area | 539 acres | 56,471 acres |
| Public Access | Yes | Yes |
| Fish Species | 12 | 20 Better |
| Trophic State | oligotrophic | mesotrophic |
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.
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Compare Shallow Lake or Third River Flowage Lake against a different lake.
Verdict
Shallow Lake reads lower on nutrients and algae than Third River Flowage Lake. Water clarity: 16.4 ft vs 6.9 ft. For more fish-species variety, Third River Flowage Lake edges ahead with 20 documented species.
Source: EPA National Aquatic Resource Surveys, 2026.