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LakeQuality

Mariposa Lake vs Rock Creek Beach Lake

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

Mariposa Lake has a higher water quality grade (C, Fair) than Rock Creek Beach Lake (F, Very Poor). Both are in Jasper County, Wisconsin.

Both Mariposa Lake and Rock Creek Beach Lake sit in Iowa. 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. Mariposa Lake (C) is materially cleaner than Rock Creek Beach Lake (F). A gap that wide is unlikely to close in a single year of remediation work; it reflects multi-decade differences in the lakes themselves.

For a recreational visitor, the wider grade gap is decisive — Mariposa Lake is the better water-quality choice. For a researcher, the gap is the interesting part: what is different about the two watersheds, and which of those differences is mutable?

C

Mariposa Lake

Jasper County, Wisconsin

Murky, only visible to about 5.1 ft.

F

Rock Creek Beach 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.

MetricMariposa LakeRock Creek Beach Lake
Overall GradeC (Fair)F (Very Poor)
Water Clarity5.1 ft1.1 ft
PhosphorusNo dataNo data
Chlorophyll-a (Algae)8.9 µg/LNo data
Maximum Depth--
Surface Area18.7 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

Mariposa Lake wins on overall water quality with a Grade C versus Rock Creek Beach Lake's Grade F. Water clarity: 5.1 ft vs 1.1 ft. For fishing diversity, Mariposa Lake also leads with 0 species.