Martha Lake
Iron County, Wisconsin146 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Martha Lake. Here is what has been measured.
- 55 ft max depth
- Limited data
Martha Lake in Iron County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 9 ft visibility. Maximum depth: 55 ft. Surface area: 146 acres.
Wisconsin DNR lists Musky as common on Martha Lake. DNR survey details →
Martha Lake is a 146-acre lake in Iron County, Wisconsin with a maximum depth of 55 feet. Overall water quality is declining over recent sampling years. The lake supports 6 documented fish species including Musky, Panfish, and Largemouth Bass.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-09-26. Methodology: how these readings are compared.
What Martha Lake is good for
From access and monitoring records, not editorial picks.
- Fishing6 species recorded
- Deep water55 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Martha Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Martha Lake
These are the measurements Wisconsin DNR publishes for Martha Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 9 ft. TSI 45.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 45 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Martha Lake
Answers come straight from the public measurements and survey records on this page.
Wisconsin DNR lists Musky as common on Martha Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Martha Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 2012. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
55 ft
Surface area
146 acres
Lake Size & Watershed
Watershed (drainage) area
2 sq mi
HydroLAKES / HydroSHEDS
Shoreline
3 mi
HydroLAKES / HydroSHEDS
Elevation
1,585 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Martha Lake
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Top-rated places to stay near Martha Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Martha Lake
Water Quality Trend: Worsening
Based on 7 years of monitoring (2020–2026).
Water clarity
Worsening6 years
Phosphorus
Stable+0.2 µg/L/yr3 years
Nearby Lakes in Iron County
Frequently asked questions about Martha Lake
Where is Martha Lake?
- Martha Lake is a lake in Iron County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Martha Lake?
- Martha Lake in Iron County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 9 ft visibility. Maximum depth: 55 ft. Surface area: 146 acres.
Is Martha Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Martha Lake?
- Martha Lake has a maximum depth of 55 feet. The lake covers 146 acres.
What fish are in Martha Lake?
- Fish species found in Martha Lake include Musky, Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye. Martha Lake is located in Iron County, Wisconsin.
What did the DNR fisheries survey find at Martha Lake?
- Wisconsin DNR lists Musky as common on Martha Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Martha Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
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Where this data comes from
33 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX33 samples · 2020–2025
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes