Magnor Lake
Polk County, WisconsinEutrophic
Magnor Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.
At a TSI of 60, Magnor Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake bottoms out at 26 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 229 acres, Magnor Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Magnor Lake sits at rank 54 of 74 in Polk County, in the lower half of the local distribution.
Magnor Lake has at least one documented invasive species (Banded Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. The fishery includes walleye alongside the lake's other 4 documented species — a notable draw for Wisconsin anglers. A documented public access point at Magnor Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-08-25. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Murky, only visible to about 4 ft. Phosphorus level: 57.7 µg/L. Trophic State Index: 60.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4 ft | D |
| Phosphorus | 57.7 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 60 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 26 ft |
| Surface Area | 229 acres |
| Public Access | Yes |
Fish Species
Click a species to see every graded lake where it is documented.
→ Best fishing times for Magnor Lake (14-day solunar calendar)
→ Is it safe to eat fish from Magnor Lake? (mercury & PFAS guide)
→ Magnor Lake fishing regulations (limits, seasons, special rules)
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: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.075 m/yr | 4 |
| Phosphorus | ↓ Declining | +10.27 µg/L/yr | 4 |
Recreation & Access
Location
County Ranking
Ranked #54 of 74 lakes in Polk County
Cleaner Lakes Within 30 Miles
Magnor Lake holds Grade C. 3 nearby lakes hold higher grades.
- AClear LakePolk County · mi · Two grade letters higher (C → A)
- BBig Moon Lake atBarron County · mi · Higher grade (C → B)
- CUnnamed LakePolk County · mi · Higher overall water quality score
Nearby Lakes in Polk County
More Wisconsin Lake Rankings
State Parks Near Magnor Lake
Other Grade C Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 2000. 2 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
EPA Impairment Status
Magnor 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 WI10005066 · Official waterbody report
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
Fish and recreation data from Wisconsin DNR Lakes
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2025-08-25
Monitoring stations: 1
Where to stay near Magnor Lake
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