Mud Lake
Mud Lake in Martin County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 1.6 ft visibility. Phosphorus: 125.5 µg/L. Chlorophyll-a (algae): 53.4 µg/L. Maximum depth: 19 ft. Surface area: 182.09 acres.
- Clarity
- 1.6 ft
- Typical in August
- 67°F
- Max depth
- 19 ft
- Area
- 182 acres
- Type
- Hypereutrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Mar 25
- Open water
- 251 days
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Mud Lake →
Next lake in Martin County
Mud Lake is a 182-acre highly nutrient-loaded hypereutrophic lake in Martin County, Minnesota with a maximum depth of 19 feet (11-foot average). Water quality is graded F based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 17 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available. Compared to the 11 other monitored lakes in Martin County, Mud Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-30. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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 1.6 ft of visibility. Phosphorus level: 125.5 µg/L. Chlorophyll-a: 53.4 µg/L. Trophic State Index: 71.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | Not graded |
| Phosphorus | 125.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 53.4 µg/L | Poor |
| Trophic State Index (TSI) | 71 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Mud Lake
Compare lakeside cabins, hotels, and vacation rentals near Mud Lake in Martin 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 Mud Lake are listed below.
Top-rated places to stay near Mud Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Mud Lake typically sits around 67°F at the surface in August. Summer average is about 75°F. Usually warmest in Jun (about 80°F) and coldest in Aug (about 67°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 9 field readings (2025–2025) via the EPA Water Quality Portal.
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 19 ft |
| Average Depth | 11 ft |
| Surface Area | 182 acres |
| Shoreline Length | 2.2 mi |
| Littoral Zone | 59% |
| Public Access | Yes |
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 Mud Lake
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.127 m/yr | 6 |
| Phosphorus | ↑ Improving | -9.13 µg/L/yr | 6 |
| Chlorophyll-a | → Stable | +0.29 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (27 observations).
Estimated open water season: 251 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-02-29 (2024) | 2018-04-29 (2018) |
| Ice-In | 2018-11-13 (2018) | 2017-12-14 (2017) |
Most recent ice-out: 2026-03-10
EPA Impairment Status
Mud Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN46-0034-00 · Official waterbody report · Matched by proximity (1.9 km)
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Mud Lake under Clean Water Act (NPDES) discharge permits.
- Fairmont Puc-LincolnFairmont · 0.7 mi away · NPDES MN0045691
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
County Ranking
Ranked #1 of 12 lakes in Martin County
Nearby Lakes in Martin County
Frequently asked questions about Mud Lake
What is the water quality grade for Mud Lake?
- Mud Lake in Martin County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 1.6 ft visibility. Phosphorus: 125.5 µg/L. Chlorophyll-a (algae): 53.4 µg/L. Maximum depth: 19 ft. Surface area: 182.09 acres.
Is Mud 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. Mud Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 53.4 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Mud Lake?
- Mud Lake typically sits around 67°F at the surface in August, from 9 EPA Water Quality Portal field readings (2025–2025). That is a typical value for the month, not a live reading.
How deep is Mud Lake?
- Mud Lake has a maximum depth of 19 feet and an average depth of 11 feet. The lake covers 182.09 acres.
What fish are in Mud Lake?
- Fish species found in Mud Lake include bigmouth buffalo, black bullhead, black crappie, bluegill, channel catfish, common carp, freshwater drum, green sunfish, largemouth bass, orangespotted sunfish, quillback, walleye, white crappie, white sucker, yellow bass, yellow bullhead, yellow perch. Mud Lake is located in Martin County, Minnesota.
When does Mud Lake thaw?
- Mud Lake typically has ice-out around Mar 25. Ice typically forms around Dec 1. The open water season is approximately 251 days.
Explore Mud Lake across LakeGrade
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Where this data comes from
18 measurements from 1 monitoring station, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA18 samples · 2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H 3 ~ Chlorophyll a-b-c Determination by fluorometer
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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate