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Moose Lake

Waukesha County, WisconsinLimited DataOligotrophic

Moose Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI value of 37 puts Moose 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. Moose Lake ranks 3 of 45 in Waukesha County, putting it in the upper tier of locally monitored lakes.

Moose Lake has no invasive species recorded in Wisconsin state databases as of 2025, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Moose 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 2025-09-01. Grade methodology: LakeGrade methodology.

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Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

Crystal clear, you can see 16 ft down. Trophic State Index: 37.

MetricValueGrade
Water Clarity (Secchi Depth)16 ftA
PhosphorusNo data
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)37Oligotrophic

Low nutrients, clear water, excellent for swimming

Water Quality Trend: Improving

Based on 6 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.621 m/yr6
Phosphorus Improving-0.55 µg/L/yr3
See year-by-year chart →

Recreation & Access

1
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #3 of 45 lakes in Waukesha County

Nearby Lakes in Waukesha County

State Parks Near Moose Lake

EPA Impairment Status

Moose Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5R).

Causes of impairment

Nutrients (phosphorus, nitrogen)

Source: EPA ATTAINS assessment unit WI10009840 · Official waterbody report · Matched by proximity (2.36 km)

Data Sources

Water quality data from the EPA Water Quality Portal

Impairment status from EPA ATTAINS 303(d) database

Grading methodology based on Metropolitan Council standards

Public boat-access points from the USGS National Boat Ramps inventory

Most recent sample: 2025-09-01

Monitoring stations: 2

Where to stay near Moose Lake

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