Mud Lake
Mud Lake in Polk County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 2 ft visibility. Phosphorus: 93 µg/L. Maximum depth: 7 ft. Surface area: 96 acres.
Wisconsin DNR lists Musky as present on Mud Lake. DNR survey details →
- Clarity
- 2 ft
- Max depth
- 7 ft
- Area
- 96 acres
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Mud Lake →
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Mud Lake is a 96-acre productive, nutrient-rich eutrophic lake in Polk County, Wisconsin with a maximum depth of 7 feet. Water quality is graded D based on 1 sampling years through 2020. Overall water quality is improving over recent sampling years. The lake supports 4 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available. Compared to the 54 other monitored lakes in Polk County, Mud Lake ranks #43 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2020-09-14. Grade methodology: LakeQuality 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.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 2 ft of visibility. Phosphorus level: 93 µg/L. Trophic State Index: 68.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | Not graded |
| Phosphorus | 93 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 68 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Mud Lake
Compare lakeside cabins, hotels, and vacation rentals near Mud Lake in Polk 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. 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 Wisconsin’s top lakes →
Wisconsin DNR lists Musky as present on Mud Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Mud Lake D from EPA Water Quality Portal chemistry, and the water-quality trend over 6 years of monitoring is improving. 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. 2 stations on file (most recent sample 2020).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 7 ft |
| Surface Area | 96 acres |
| 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
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.043 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.65 µg/L/yr | 6 |
EPA Impairment Status
Mud Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5R).
Causes of impairment
Source: EPA ATTAINS assessment unit WI10004943 · Official waterbody report
County Ranking
Ranked #43 of 55 lakes in Polk County
Nearby Lakes With Higher Grades
Mud Lake holds Grade D. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Polk County
Frequently asked questions about Mud Lake
Where is Mud Lake?
- Mud Lake is a lake in Polk County, Wisconsin. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Mud Lake?
- Mud Lake in Polk County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 2 ft visibility. Phosphorus: 93 µg/L. Maximum depth: 7 ft. Surface area: 96 acres.
Is Mud Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Mud Lake has a water quality grade of D (Nutrient-rich). Always check local health department advisories before swimming.
How deep is Mud Lake?
- Mud Lake has a maximum depth of 7 feet. The lake covers 96 acres.
What fish are in Mud Lake?
- Fish species found in Mud Lake include Musky, Panfish, Largemouth Bass, Northern Pike. Mud Lake is located in Polk County, Wisconsin.
What did the DNR fisheries survey find at Mud Lake?
- Wisconsin DNR lists Musky as present on Mud Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Mud Lake D from EPA Water Quality Portal chemistry, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Explore Mud Lake across LakeQuality
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High nutrients, frequent algae, reduced clarity
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Where this data comes from
6 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX6 samples · 2020
Analytical methods
- Phosphorus by Colorimetry
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes