Mud Lake
Mud Lake in Jefferson County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 2.3 ft visibility. Phosphorus: 63.6 µg/L. Maximum depth: 22 ft. Surface area: 84 acres.
- Clarity
- 2.3 ft
- Typical in August
- 72°F
- Max depth
- 22 ft
- Area
- 84 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 →
Next lake in Jefferson County
Mud Lake is a 84-acre productive, nutrient-rich eutrophic lake in Jefferson County, Wisconsin with a maximum depth of 22 feet. Water quality is graded D based on 1 sampling years through 2026. Overall water quality is improving over recent sampling years. The lake supports 2 documented fish species including Panfish and Northern Pike. Public access is available with 1 public boat landing. Compared to the 6 other monitored lakes in Jefferson County, Mud Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-19. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyElevated nutrients
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 2.3 ft of visibility. Phosphorus level: 63.6 µg/L. Trophic State Index: 65.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.3 ft | Not graded |
| Phosphorus | 63.6 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 65 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Mud Lake
Compare lakeside cabins, hotels, and vacation rentals near Mud Lake in Jefferson 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 →
Water Temperature
Mud Lake typically sits around 72°F at the surface in August. Summer average is about 73°F. Usually warmest in Jun (about 73°F) and coldest in Mar (about 43°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 23 field readings (2024–2026) via the EPA Water Quality Portal. See the full Mud Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 22 ft |
| Surface Area | 84 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Sandhill Station State CampgroundPublic
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.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 2017. 1 station on file (most recent sample 2026).
Fish Species (DNR-rated)
Water Quality Trend: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.182 m/yr | 7 |
| Phosphorus | → Stable | -0.35 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 5).
Causes of impairment
Source: EPA ATTAINS assessment unit WI10006218 · Official waterbody report
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Mud Lake under Clean Water Act (NPDES) discharge permits.
- Unlimited Renewables LlcLake Mills, Town Of · 1.2 mi away · NPDES WI0065064
- Daybreak Foods Inc Creekwood FarmLake Mills · 1.2 mi away · NPDES WI0056308
- Deans Eggs Nature Link Farms LlcAztalan, Town Of · 2.7 mi away · NPDES WI0064416
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 #6 of 7 lakes in Jefferson 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.
See full comparison →Nearby Lakes in Jefferson County
Frequently asked questions about Mud Lake
What is the water quality grade for Mud Lake?
- Mud Lake in Jefferson County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 2.3 ft visibility. Phosphorus: 63.6 µg/L. Maximum depth: 22 ft. Surface area: 84 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.
What is the water temperature of Mud Lake?
- Mud Lake typically sits around 72°F at the surface in August, from 23 EPA Water Quality Portal field readings (2024–2026). That is a typical value for the month, not a live reading.
How deep is Mud Lake?
- Mud Lake has a maximum depth of 22 feet. The lake covers 84 acres.
What fish are in Mud Lake?
- Fish species found in Mud Lake include Panfish, Northern Pike. Mud Lake is located in Jefferson County, Wisconsin.
Are there boat ramps on Mud Lake?
- Mud Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Sandhill Station State Campground. Public access is listed as yes.
Explore Mud Lake across LakeGrade
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Where this data comes from
45 measurements from 1 monitoring station, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX45 samples · 2020–2026
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory