Martha Lake
Martha Lake in Wright County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 3 ft visibility. Phosphorus: 77.5 µg/L. Chlorophyll-a (algae): 68.1 µg/L. Maximum depth: 22 ft. Surface area: 102.45 acres.
- Clarity
- 3 ft
- Typical in August
- 76°F
- Max depth
- 22 ft
- Area
- 102 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 9
- Open water
- 235 days
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Martha Lake →
Next lake in Wright County
Martha Lake is a 102-acre productive, nutrient-rich eutrophic lake in Wright County, Minnesota with a maximum depth of 22 feet (8-foot average). Water quality is graded F based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 9 documented fish species including black crappie, bluegill, and brown bullhead. Public access is available with 1 public boat landing. Compared to the 50 other monitored lakes in Wright County, Martha Lake ranks #38 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-29. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyAlgae risk
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom
Water Quality Grade: F (Algae-prone)
Very murky, less than 3 ft of visibility. Phosphorus level: 77.5 µg/L. Chlorophyll-a: 68.1 µg/L. Trophic State Index: 67.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 77.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 68.1 µg/L | Poor |
| Trophic State Index (TSI) | 67 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Martha Lake
Compare lakeside cabins, hotels, and vacation rentals near Martha Lake in Wright County, Minnesota — 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Martha Lake are listed below.
Top-rated places to stay near Martha Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Martha Lake typically sits around 76°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 76°F) and coldest in May (about 61°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 188 field readings (2011–2025) via the EPA Water Quality Portal. See the full Martha Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 22 ft |
| Average Depth | 7.9 ft |
| Surface Area | 102 acres |
| Shoreline Length | 1.9 mi |
| Littoral Zone | 70% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Lake MarthaPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Martha Lake
DNR Fisheries Survey Summary
6 surveys on file from MN DNR Fisheries. Most recent: 2022-06-13 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 184.85 | 0.41 lb |
| Bluegill | 34.85 | 0.18 lb |
| Black Crappie | 32.36 | 0.19 lb |
| Largemouth Bass | 29.15 | 0.92 lb |
| Pumpkinseed | 22.74 | 0.13 lb |
| Hybrid Sunfish | 14.30 | 0.21 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Black Bullhead
Bluegill
Black Crappie
Largemouth Bass
From the 2022-06-13 survey
Lake Martha is a small 97-acre lake located two miles southwest of Hanover in Wright County. Martha has a maximum depth of 25 feet and an average water clarity of six feet. A state-owned public access is located along the south shore and offers parking for two to three vehicle/trailer combos. A standard survey was…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Martha Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — MarthaFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Martha (2024)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — MarthaPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.533 m/yr | 6 |
| Phosphorus | ↓ Declining | +7.19 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +4.52 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (14 observations).
Estimated open water season: 235 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2016-03-13 (2016) | 2008-04-21 (2008) |
| Ice-In | 1991-11-04 (1991) | 1998-12-20 (1998) |
Most recent ice-out: 2016-03-13
EPA Impairment Status
Martha Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MN86-0011-00 · Official waterbody report · Matched by proximity (1.15 km)
County Ranking
Ranked #38 of 51 lakes in Wright County
Nearby Lakes With Higher Grades
Martha Lake holds Grade F. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Wright County
Frequently asked questions about Martha Lake
What is the water quality grade for Martha Lake?
- Martha Lake in Wright County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 3 ft visibility. Phosphorus: 77.5 µg/L. Chlorophyll-a (algae): 68.1 µg/L. Maximum depth: 22 ft. Surface area: 102.45 acres.
Is Martha Lake safe to swim in?
- Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. Martha Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 68.1 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Martha Lake?
- Martha Lake typically sits around 76°F at the surface in August, from 188 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Martha Lake?
- Martha Lake has a maximum depth of 22 feet and an average depth of 7.9 feet. The lake covers 102.45 acres.
What fish are in Martha Lake?
- Fish species found in Martha Lake include black crappie, bluegill, brown bullhead, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, yellow bullhead. Martha Lake is located in Wright County, Minnesota.
When does Martha Lake thaw?
- Martha Lake typically has ice-out around Apr 9. Ice typically forms around Nov 30. The open water season is approximately 235 days.
Are there boat ramps on Martha Lake?
- Martha Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lake Martha. Public access is listed as yes.
Explore Martha Lake across LakeGrade
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Where this data comes from
187 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA187 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (2)
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate