Clearest Lakes in Wisconsin 2026: Top 25 Ranked by Secchi Clarity, LakeQuality

The single clearest lake in Wisconsin is Adams Lake in Vilas County, with a Secchi depth of 100 feet — meaning a Secchi disk lowered from the surface disappears at that depth. Adams Lake holds an overall water quality grade of A. The 25 clearest lakes in Wisconsin are ranked below by 2026 measurements.

How clear are Wisconsin's clearest lakes?

Across the 1,285 Wisconsin lakes with Secchi clarity readings in our 2026 dataset, the 25 clearest range from 22 to 100 feet of visibility. Adams Lake sits at the top, 62.5 ft clearer than the next lake on the list, well above the 24.1-foot median of this leading group — a spread that shows how quickly clarity falls off once you move past a state's handful of truly pristine waters.

The clearest water is not spread evenly. Vilas County alone accounts for 7 of the 25 top-ranked lakes, with the rest drawn from 13 other counties. That clustering follows the terrain: deep, glacially carved basins ringed by forest take in little sediment or fertilizer runoff, so phosphorus stays low and the water stays transparent.

Clarity and overall health usually align here: 25 of these 25 lakes also earn an A- or B-range overall grade, and they average 83 feet of maximum depth — deeper water resists the wind-driven mixing that keeps sediment suspended in shallow lakes. Where the two diverge — a clear lake carrying a weaker grade — the cause is typically elevated phosphorus that transparency alone can't reveal, which is why our grade combines phosphorus and chlorophyll-a with Secchi depth rather than relying on clarity by itself.

Rank	Lake	County	Secchi Depth	Grade	Max Depth	Area
1	Adams Lake	Vilas	100 ft	A	-	9 acres
2	Clear Lake	Rock	37.5 ft	A	-	-
3	Wazee Lake	Jackson	30 ft	A	350 ft	146 acres
4	Black Oak Lake	Vilas	28.5 ft	A	85 ft	564 acres
5	Wheeler Lake	Oconto	27 ft	A	35 ft	281 acres
6	Bardon Lake	Douglas	27 ft	A	102 ft	848 acres
7	Saxon Fall Flowage Lake	Iron	26.2 ft	B	-	68 acres
8	Sealion Lake	Florence	25.6 ft	A	-	-
9	Whitefish Lake	Douglas	25.3 ft	A	102 ft	848 acres
10	Pine Lake	Waukesha	25 ft	A	85 ft	711 acres
11	Lake Owen	Bayfield	24.6 ft	A	95 ft	1,250 acres
12	Whitefish Lake	Douglas	24.5 ft	A	102 ft	848 acres
13	Geneva Lake Site B	Walworth	24.1 ft	A	135 ft	5,401 acres
14	Carlin Lake	Vilas	24 ft	A	36 ft	155 acres
15	Roach Lake	Vilas	24 ft	A	48 ft	48 acres
16	Big Hurst Lake	Vilas	24 ft	A	44 ft	47 acres
17	Clara Lake-Deep Hole	Lincoln	23.8 ft	A	50 ft	21 acres
18	Stone Lake	Washburn	23 ft	A	49 ft	490 acres
19	Millicent Lake	Bayfield	23 ft	A	-	-
20	Blue Lake	Oneida	23 ft	A	49 ft	441 acres
21	Forest Lake	Vilas	23 ft	A	60 ft	468 acres
22	Maiden Lake	Oconto	22.7 ft	A	52 ft	269 acres
23	Lee Lake	Oneida	22.5 ft	A	44 ft	65 acres
24	Forest Lake	Vilas	22.2 ft	A	60 ft	468 acres
25	Lake Metonga	Forest	22 ft	A	79 ft	2,038 acres

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 →

Frequently Asked Questions

What is the clearest lake in Wisconsin?

Adams Lake is the clearest lake in Wisconsin by Secchi depth, with water transparency of 100 feet. Secchi depth is measured by lowering a black-and-white disk until it disappears from view — deeper readings mean clearer water. Located in Vilas County, Adams Lake holds an overall water quality grade of A.

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.

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 glacial lakes with rocky basins and forested watersheds — common in northern Wisconsin — tend to be clearest because they have little soil runoff and limited nutrient input. Shallow agricultural-watershed lakes are typically less clear because they receive more sediment and fertilizer runoff.

Is the clearest lake the cleanest?

Not always. Clarity (Secchi depth) is one of three indicators we use; the others are total phosphorus and chlorophyll-a. A lake can be very clear but still have elevated phosphorus that just hasn't bloomed yet, or chlorophyll-a from a recent bloom that's still settling. The most reliable measure of overall lake health is the combined grade, which weights all three signals. See our companion cleanest-lakes ranking for Wisconsin for the combined-score list.

How does Wisconsin compare to other states?

Wisconsin's clearest waters compete with the most pristine lakes in our 36-state dataset, where top-tier lakes typically register Secchi depths of 15–25 feet. Nationally, the gold standard is Crater Lake in Oregon (~100 ft) and Lake Tahoe (~65 ft).

Source: EPA National Aquatic Resource Surveys + state DNR Secchi sampling, 2026.