Martha Lake
Iron County, Wisconsin · WBIC 2314300
Size
152 acres
Max depth
51 ft
DNR lake type
Complex, Warm, clear water color
Water clarity
7 ft
Moderate, measured Sep 2025
A warm-water lake type: the DNR groups it with lakes that warm up through summer. This describes the lake type in general, not this lake in particular.
Outline
Drawn from the DNR's 24K hydrography (surveyed 1981), so the shape is approximate and a landing can sit a little off the shore. Open the DNR lake map.
Water clarity
7 ft Secchi depthModerate
Last measured Sep 26, 2025. 71 readings on record, 2012 to 2025.
Typical summer clarity (June to September): 7.1 ft, moderate, from 54 readings (2012 to 2025).
Secchi depth is how far down a white disk stays visible. A bigger number means clearer water. Clear means a Secchi depth of 10 feet or more, moderate 5 to 10 feet, low under 5 feet.
Wisconsin DNR water monitoring (volunteer and staff), via the Water Quality Portal; station Martha Lake - Deep Hole. Checked Oct 23, 2026.
Water temperature
A typical year Modeled estimate
- Ice goes outabout Apr 21 (Apr 15 to Apr 26)
- Surface reaches 48°Fabout May 8 (Apr 28 to May 13)
- Surface reaches 64°Fabout May 24 (May 18 to May 27)
- June surface70°F, usually 69 to 72°F
- July surface76°F, usually 74 to 77°F
- August surface72°F, usually 71 to 74°F
Forms a warm top layer around May 5, lasting about 188 days.
A computer model of this lake's typical weather and water, built from 15 years, 2005 to 2019. Ranges show the middle half of years. The model was not calibrated against measured temperatures for this lake. It is an estimate, not a measurement.
Modeled: U.S. Geological Survey lake temperature data release (doi:10.5066/P9CA6XP8).
Today at the lake
Forecast: National Weather Service (no endorsement implied). Sunrise, sunset and moon phase are calculated. The moon phase can be a day off.
Stocking history
- Walleyelast stocked 2018 (large fingerling); stocked in 2 years since 2010
Stocking shows what was added to the lake, not what is in it now.
Wisconsin DNR annual fish stocking summary. Checked Oct 23, 2026.
More lakes in Iron County
- Grand Portage Lake0.8 miles away
- Little Martha Lake1.1 miles away
- San Domingo Lake1.1 miles away
- Brush Lake1.2 miles away
- Echo Lake1.4 miles away
- Payment Lake1.6 miles away
Where this comes from
- Size, depth and lake typeWisconsin DNR lake classifications, checked Oct 23, 2026
- OutlineWisconsin DNR 24K hydrography, checked Oct 23, 2026
- Stocking historyWisconsin DNR annual fish stocking summary, checked Oct 23, 2026
- Regulations linkWisconsin DNR fishing regulations (linked, not restated), checked Oct 23, 2026
- Water clarityWisconsin DNR water monitoring, via the Water Quality Portal, checked Oct 23, 2026
- Typical-year temperatureU.S. Geological Survey lake temperature model (modeled estimate), checked Oct 23, 2026
- VHS statusWisconsin DNR VHS status by watershed, checked Oct 24, 2026
- Depth map linkWisconsin DNR lake maps list, checked Oct 24, 2026
See data sources for what each source covers, and about for how the numbers are matched to lakes.
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