Mud Lake
Hennepin County, MinnesotaHypereutrophic
On the LakeGrade rubric Mud Lake fails the cutoffs — a TSI of 77 and persistent algal pressure put it in the bottom tier. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.
Hypereutrophic conditions mean the lake is operating at the upper end of the productivity scale, with all the bloom risk that implies. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Within Hennepin County's 95 graded lakes, Mud Lake ranks 59 — below the local median, though not at the bottom.
Eurasian watermilfoil has been documented at Mud Lake, requiring shoreline management to keep dense mats from crowding native vegetation. The state fisheries records do not list documented species for Mud Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2021-09-13. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 0.9 ft of visibility. Phosphorus level: 150 µg/L. Trophic State Index: 77.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.9 ft | F |
| Phosphorus | 150 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 77 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
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 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.065 m/yr | 5 |
| Phosphorus | ↑ Improving | -2.45 µg/L/yr | 5 |
Location
County Ranking
Ranked #59 of 95 lakes in Hennepin County
Cleaner Lakes Within 30 Miles
Mud Lake holds Grade F. 5 nearby lakes hold higher grades.
- BZumbra-Sunny LakeCarver County · mi · Two grade letters higher (F → B)
- CWaconia LakeCarver County · mi · Two grade letters higher (F → C)
- CAuburn LakeCarver County · mi · Two grade letters higher (F → C)
- CEast Auburn LakeCarver County · mi · Two grade letters higher (F → C)
- DWhaletail LakeHennepin County · mi · Higher grade (F → D)
Nearby Lakes in Hennepin County
More Minnesota Lake Rankings
State Parks Near Mud Lake
Other Grade F Lakes in Minnesota
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 MN10-0042-00 · Official waterbody report · Matched by proximity (1.47 km)
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2021-09-13
Monitoring stations: 1