Morton Lake
Vilas County, WisconsinLimited DataMesotrophic
Morton Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. 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.
The lake sits in the mesotrophic zone — the band where most well-managed Wisconsin lakes fall. Morton Lake reaches 29 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. Morton Lake covers 165 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Morton Lake sits at rank 121 of 191 in Vilas County, in the lower half of the local distribution.
Morton Lake has no invasive species recorded in Wisconsin state databases as of 2025, though prevention practices still apply at all access points. Walleye are documented at Morton Lake, one of 5 fish species on record for the lake. 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, Wisconsin DNR Surface Water, last sampled 2025-08-24. Grade methodology: LakeGrade methodology.
Watch Morton Lake water quality
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Good clarity, visible to about 10.5 ft. Trophic State Index: 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.5 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 29 ft |
| Surface Area | 165 acres |
Fish Species
Click a species to see every graded lake where it is documented.
→ Best fishing times for Morton Lake (14-day solunar calendar)
→ Is it safe to eat fish from Morton Lake? (mercury & PFAS guide)
→ Morton Lake fishing regulations (limits, seasons, special rules)
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.75 m/yr | 5 |
| Phosphorus | ↑ Improving | -5.5 µg/L/yr | 2 |
Location
County Ranking
Ranked #121 of 191 lakes in Vilas County
Cleaner Lakes Within 30 Miles
Morton Lake holds Grade B. One nearby lake has a higher grade.
Nearby Lakes in Vilas County
More Wisconsin Lake Rankings
Other Grade B Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1990. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
EPA Impairment Status
Morton 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 WI10007538 · Official waterbody report · Matched by proximity (2.03 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
Fish and recreation data from Wisconsin DNR Lakes
Most recent sample: 2025-08-24
Monitoring stations: 1
Where to stay near Morton Lake
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