Mud Lake
Washington County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Mud Lake. Here is what has been measured.
- Hypereutrophic
- Limited data
Mud Lake in Washington County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.2 ft visibility. Phosphorus: 89 µg/L. Chlorophyll-a (algae): 87 µg/L.
Mud Lake is a highly nutrient-loaded hypereutrophic lake in Washington County, Minnesota. Overall water quality is improving over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 74 other monitored lakes in Washington County, Mud Lake ranks #64 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-07. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Mud Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Mud Lake
These are the measurements Minnesota PCA publishes for Mud Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.2 ft of visibility. Phosphorus 89 µg/L. Chlorophyll-a 87 µg/L. TSI 72.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 89µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 87µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 72 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Mud Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Mud Lake typically sits around 51°F at the surface in October. Summer average is about 70°F. Usually warmest in Jul (about 74°F) and coldest in Oct (about 51°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (51°F) to its warmest (74°F).
Typical surface water temperature by month, from 18 field readings (2010–2024) via the EPA Water Quality Portal. See the full Mud Lake water temperature breakdown →
Stays via Stay22
Stays near Mud Lake
Compare lakeside cabins, hotels, and vacation rentals near Mud Lake in Washington 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Mud Lake are listed below.
Top-rated places to stay near Mud Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
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Fishing Mud Lake
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Improving6 years
Phosphorus
Improving-6.8 µg/L/yr6 years
Chlorophyll-a
Worsening+1.13 µg/L/yr6 years
Nearby Lakes in Washington County
Frequently asked questions about Mud Lake
Where is Mud Lake?
- Mud Lake is a lake in Washington County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Mud Lake?
- Mud Lake in Washington County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.2 ft visibility. Phosphorus: 89 µg/L. Chlorophyll-a (algae): 87 µg/L.
Is Mud Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Mud Lake?
- Mud Lake typically sits around 51°F at the surface in October, from 18 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
Can I fish at Mud Lake?
- Public access to Mud Lake is listed as no on the lake record, so confirm before you make the trip. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Mud Lake across LakeQuality
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Fish species and best lakes in Washington County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the St. Croix Watershed, ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
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Hypereutrophic Lakes in Minnesota
Where this data comes from
28 measurements from 1 monitoring station, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA28 samples · 2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Analysis of Chlorophyll in Periphyton and Plankton
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.