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LakeQuality

St. Croix 0.3 Mi. Downstream of I Lake vs St. Croix 3.5 Mi. Downstream of E Chestnut St Lake

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

St. Croix 0.3 Mi. Downstream of I Lake and St. Croix 3.5 Mi. Downstream of E Chestnut St Lake both received the same overall water quality grade of C (Fair). Both are in Washington County, Minnesota.

St. Croix 0.3 Mi. Downstream of I Lake and St. Croix 3.5 Mi. Downstream of E Chestnut St 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 grades are close: St. Croix 0.3 Mi. Downstream of I Lake (C) and St. Croix 3.5 Mi. Downstream of E Chestnut St Lake (C) 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.

C

St. Croix 0.3 Mi. Downstream of I Lake

Washington County, Minnesota

Murky, only visible to about 6.1 ft.

Murky, only visible to about 5.9 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.

MetricSt. Croix 0.3 Mi. Downstream of I LakeSt. Croix 3.5 Mi. Downstream of E Chestnut St Lake
Overall GradeC (Fair)C (Fair)
Water Clarity6.1 ft5.9 ft
Phosphorus34 µg/L38 µg/L
Chlorophyll-a (Algae)No dataNo data
Maximum Depth78 ft78 ft
Surface Area8.4K acres8.4K acres
Public AccessNoNo
Fish Species11
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 (St. Croix 0.3 Mi. Downstream of I Lake: 6.1 ft, St. Croix 3.5 Mi. Downstream of E Chestnut St Lake: 5.9 ft) and what you want from the lake. St. Croix 0.3 Mi. Downstream of I Lake matches its peer on species count.