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Updated August 2026 · Top 25 of 1,087 lakes with a Secchi reading

Clearest Lake in Wisconsin: Top 25 by Secchi Depth

Adams Lake in Vilas County is the clearest lake in Wisconsin by Secchi depth, at 100 ft. Mapped and ranked below: the 25 clearest of 1,087 Wisconsin lakes with a Secchi reading. Secchi depth is clarity alone: phosphorus and chlorophyll-a are separate readings, so a clear lake can carry higher nutrient readings than a murkier one.

Map · 25 ranked lakesTap a pin for its lakeTap a pin for the lake's page

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Nutrient and algae readings on recordNo reading on record#1 in this rankingPins are this ranking's lakes at their surveyed locations.

How clear are Wisconsin's clearest lakes?

From 100 ft at Adams Lake to 21 ft at #25, Geneva Lake; the median of the 25 is 23 ft.

#	Lake	County	Secchi depth	Max depth	Area
1	Adams Lake	Vilas	100 ft	14 ft	9 acres
2	Wazee Lake	Jackson	30 ft	350 ft	146 acres
3	Black Oak Lake	Vilas	29 ft	85 ft	564 acres
4	Bardon Lake	Douglas	27 ft	102 ft	848 acres
5	Saxon Fall Flowage Lake	Iron	26.2 ft	12 ft	68 acres
6	Wheeler Lake	Oconto	26 ft	35 ft	281 acres
7	Sealion Lake	Florence	25.6 ft	—	—
8	Pine Lake	Waukesha	25 ft	85 ft	711 acres
9	Lake Owen	Bayfield	24.6 ft	95 ft	1,250 acres
10	Roach Lake	Vilas	24 ft	48 ft	48 acres
11	Big Hurst Lake	Vilas	24 ft	44 ft	47 acres
12	Clara Lake	Lincoln	23.8 ft	50 ft	21 acres
13	Stone Lake	Washburn	23 ft	49 ft	490 acres
14	Millicent Lake	Bayfield	23 ft	—	—
15	Blue Lake	Oneida	23 ft	49 ft	441 acres
16	Maiden Lake	Oconto	23 ft	52 ft	269 acres
17	Lee Lake	Oneida	22.5 ft	44 ft	65 acres
18	Forest Lake	Vilas	22.2 ft	60 ft	468 acres
19	Lake Metonga	Forest	22 ft	79 ft	2,038 acres
20	Buskey Bay Lake	Bayfield	21.9 ft	51 ft	88 acres
21	Long Lake	Burnett	21.5 ft	41 ft	222 acres
22	Boot Lake	Oconto	21.5 ft	38 ft	230 acres
23	Hart Lake	Bayfield	21.5 ft	54 ft	257 acres
24	Round Lake	Sawyer	21.1 ft	74 ft	3,294 acres
25	Geneva Lake	Walworth	21 ft	135 ft	5,401 acres

Sources and method

Secchi depth: Median of each lake's EPA Water Quality Portal readings, sampled April 2020 to July 2026, in feet. Every reading in this table was submitted by Wisconsin Department of Natural Resources. Portal: EPA Water Quality Portal.
Readings: clarity, phosphorus and chlorophyll-a from the agency's own sampling, shown as reported. Clarity is a separate measurement from nutrients and algae, which is why a clear lake here can carry higher phosphorus than a murkier one.
Max depth: Wisconsin DNR lake surveys. Surveyed depths only; a dash means no survey recorded one.
Area: state agency lake surveys and, for reservoirs, US Army Corps of Engineers National Inventory of Dams records, in acres at normal pool. A dash means no record carries one.
Map pins: all 25 table rows. No other lakes are plotted.

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Frequently Asked Questions

What is the clearest lake in Wisconsin?

Adams Lake in Vilas County is the clearest lake in Wisconsin by Secchi depth, at 100 ft. Secchi depth is measured by lowering a black-and-white disk until it disappears from view; a deeper reading means clearer water. Adams Lake has no nutrient or algae reading on record: no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).

How clear are Wisconsin's 25 clearest lakes?

They span 21 ft to 100 ft of Secchi depth, with a median of 23 ft. Adams Lake leads by 70 ft. Vilas County has 5 of the 25; the rest are spread across 14 other counties.

How is water clarity measured?

Water clarity is measured by Secchi depth, named after the 19th-century Italian astronomer Pietro Angelo Secchi who developed the method. A standardized black-and-white disk is lowered into the water on a rope; the depth (in feet or meters) at which the disk disappears from view is recorded. Greater Secchi depth means clearer water, usually a sign of low sediment, low phosphorus, and limited algae growth. The figure for each lake here is the median of its readings.

What makes a lake clear?

Lake clarity is driven by three factors: low suspended sediment (clay, silt), low nutrient load (especially phosphorus, which fuels algae), and low chlorophyll-a (active algae biomass). Deep lakes with rocky basins and forested watersheds tend to be clearest because they take in little soil runoff and few nutrients. Shallow lakes in farmed watersheds are typically less clear because they receive more sediment and fertilizer runoff.

Is the clearest lake the cleanest?

Not always. Clarity (Secchi depth) is measured and shown; nutrient and algae readings (total phosphorus and chlorophyll-a) are a separate measurement, compared against that lake’s EPA ecoregion classes. A lake can be very clear but still have elevated phosphorus that just hasn't bloomed yet. See our companion cleanest-lakes ranking for Wisconsin for the nutrient-and-algae list.

Where to stay near Wisconsin's clearest lakes

Planning a trip? Jump to live cabin, resort, and hotel availability near Wisconsin's clearest lakes.

Clearest lakes across all states →Cleanest lakes in Wisconsin (combined score) →All Wisconsin lakes →

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