Mallard Lake
St. Louis County, WisconsinEutrophic
Mallard Lake is a productive, nutrient-rich eutrophic lake in St. Louis County, MO. Water quality is graded F based on 3 sampling years through 2024. Compared to the 8 other monitored lakes in St. Louis County, Mallard Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-09-19. Grade methodology: LakeGrade methodology.
Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 1.9 ft of visibility. Phosphorus level: 84 µg/L. Chlorophyll-a: 32.2 µg/L. Trophic State Index: 67.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.9 ft | F |
| Phosphorus | 84 µg/L | D |
| Chlorophyll-a (Algae) | 32.2 µg/L | F |
| Trophic State Index (TSI) | 67 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Location
County Ranking
Ranked #3 of 9 lakes in St. Louis County
Cleaner Lakes Within 30 Miles
Mallard Lake holds Grade F. 5 nearby lakes hold higher grades.
- DLake 36St. Charles County · 12.8 mi · Higher grade (F → D)
- DSimpson Park LakeSt. Louis County · 10.1 mi · Higher grade (F → D)
- DSimpson Park LakeSt. Louis County · 10.1 mi · Higher grade (F → D)
- DForest Park PondSt. Louis city County · 12.1 mi · Higher grade (F → D)
- DLake 35St. Charles County · 12.5 mi · Higher grade (F → D)
Nearby Lakes in St. Louis County
More Wisconsin Lake Rankings
Other Grade F Lakes in Wisconsin
Jackson County · Clarity: 2 ft
St. Charles County · Clarity: 2.3 ft
St. Francois County · Clarity: 1.1 ft
Saline County · Clarity: 2.3 ft
Polk County · Clarity: 1.2 ft
Callaway County · Clarity: 1.7 ft
Eutrophic Lakes in Wisconsin
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-19
Monitoring stations: 1