Paulsen Lake
Polk County, WisconsinOligotrophic
Paulsen Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Polk County. 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 32 puts Paulsen 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. Paulsen Lake ranks 24 of 77 in Polk County — solidly in the upper half of the local distribution.
No invasive species are currently listed at Paulsen Lake — the lake remains off the Wisconsin infested-waters roster. The state fisheries records do not list documented species for Paulsen Lake, 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 2025-09-08. 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 39.4 ft down. Phosphorus level: 12.7 µg/L. Trophic State Index: 32.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 39.4 ft | A |
| Phosphorus | 12.7 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 32 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.086 m/yr | 6 |
| Phosphorus | ↑ Improving | -1.1 µg/L/yr | 2 |
Location
County Ranking
Ranked #24 of 77 lakes in Polk County
Nearby Lakes in Polk County
More Wisconsin Lake Rankings
State Parks Near Paulsen Lake
Other Grade A Lakes in Wisconsin
Waukesha County · Clarity: 14.6 ft
Waukesha County · Clarity: 13.8 ft
Walworth County · Clarity: 19 ft
Washington County · Clarity: 12 ft
Kenosha County · Clarity: 10.1 ft
Washington County · Clarity: 12.5 ft
Oligotrophic Lakes in Wisconsin
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-09-08
Monitoring stations: 2