Martha Lake
Martha Lake in Iron County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 9 ft visibility. Maximum depth: 55 ft. Surface area: 146 acres.
- Clarity
- 9 ft
- Max depth
- 55 ft
- Area
- 146 acres
- Trend
- ↓ Declining
Next lake in Iron County
Why Martha Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Martha Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by WI DNR and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
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. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Martha Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Moderate clarity, visible to about 9 ft. Trophic State Index: 45.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Martha Lake
Compare lakeside cabins, hotels, and vacation rentals near Martha Lake in Iron County, Wisconsin — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Martha Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 55 ft |
| Surface Area | 146 acres |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Martha Lake
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)
Water Quality Trend: ↓ Declining
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.343 m/yr | 6 |
| Phosphorus | → Stable | +0.2 µg/L/yr | 3 |
Graded lakes near Martha Lake
Martha Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Iron County
Frequently asked questions about Martha Lake
What is the water quality grade for Martha Lake?
- Martha Lake in Iron County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 9 ft visibility. Maximum depth: 55 ft. Surface area: 146 acres.
Is Martha Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Martha Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
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.
Explore Martha Lake across LakeGrade
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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)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes