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LakeQuality

Diamond Lake vs Rkcrk 4 Lake

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

Diamond Lake and Rkcrk 4 Lake both received the same overall water quality grade of F (Very Poor). Both are in Wisconsin.

Diamond Lake and Rkcrk 4 Lake are both in Iowa — 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: Diamond Lake (F) and Rkcrk 4 Lake (F) 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.

F

Diamond Lake

Poweshiek County, Wisconsin

Very murky, less than 1.6 ft of visibility.

F

Rkcrk 4 Lake

Jasper County, Wisconsin

Very murky, less than 1.1 ft of visibility.

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.

MetricDiamond LakeRkcrk 4 Lake
Overall GradeF (Very Poor)F (Very Poor)
Water Clarity1.6 ft1.1 ft
PhosphorusNo dataNo data
Chlorophyll-a (Algae)44.6 µg/LNo data
Maximum Depth--
Surface Area93 acres640 acres
Public AccessUnknownUnknown
Fish Species00
Trophic Stateeutrophichypereutrophic

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

Verdict

Both lakes earn the same Grade F. The tiebreakers come down to clarity (Diamond Lake: 1.6 ft, Rkcrk 4 Lake: 1.1 ft) and what you want from the lake. Diamond Lake matches its peer on species count.