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LakeQuality
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Hidden Valley Lake 1

Lafayette County, WisconsinLimited DataOligotrophic

On the LakeGrade rubric, Hidden Valley Lake 1 pulls an A: clarity at 20.5 ft and phosphorus readings still being added put it in the top bracket for Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

The lake's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. 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. Hidden Valley Lake 1 ranks 1 of 3 in Lafayette County — solidly in the upper half of the local distribution.

Hidden Valley Lake 1 has no invasive species recorded in Wisconsin state databases as of 2021, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Hidden Valley Lake 1, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2021-07-21. 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 20.5 ft down. Trophic State Index: 34.

MetricValueGrade
Water Clarity (Secchi Depth)20.5 ftA
PhosphorusNo data
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)34Oligotrophic

Low nutrients, clear water, excellent for swimming

Water Quality Trend: Declining

Based on 7 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.357 m/yr7
Phosphorus Declining+9.41 µg/L/yr6
See year-by-year chart →

Location

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County Ranking

Ranked #1 of 3 lakes in Lafayette County

Nearby Lakes in Lafayette County

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2021-07-21

Monitoring stations: 1