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LakeQuality
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Rock River Lake

Rock County, WisconsinLimited DataOligotrophic

Rock River Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

A TSI value of 16 puts Rock River Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Rock River Lake ranks 1 of 4 in Rock County, putting it in the upper tier of locally monitored lakes.

No invasive species are currently listed at Rock River Lake — the lake remains off the Wisconsin infested-waters roster. The state fisheries records do not list documented species for Rock River Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2021-07-06. Grade methodology: LakeGrade methodology.

Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

Crystal clear, you can see 68.9 ft down. Trophic State Index: 16.

MetricValueGrade
Water Clarity (Secchi Depth)68.9 ftA
PhosphorusNo data
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)16Oligotrophic

Low nutrients, clear water, excellent for swimming

Location

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County Ranking

Ranked #1 of 4 lakes in Rock County

Nearby Lakes in Rock County

State Parks Near Rock River Lake

DNR Reports & Resources

Wisconsin DNR Fisheries scientists publish multi-year survey reports for Rock River Lake covering fish populations, stocking, water quality, and management. 1 report on file.

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Fish and recreation data from Wisconsin DNR Lakes

Most recent sample: 2021-07-06

Monitoring stations: 1