Alder Lake
Vilas County, WisconsinLimited DataMesotrophic
Alder Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.
The lake sits in the mesotrophic zone — the band where most well-managed Wisconsin lakes fall. A maximum depth of 30 ft puts Alder Lake in the middle of Wisconsin's depth distribution. At 264 acres, Alder Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Alder Lake ranks 82 of 191 in Vilas County — solidly in the upper half of the local distribution.
An invasive species record — Banded Mystery Snail — has been logged at Alder Lake; Wisconsin DNR maintains the official infested-waters list. Walleye are documented at Alder Lake, one of 6 fish species on record for the lake. Public access is available — the lake is on the Wisconsin DNR public-access list. 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 2025-08-29. Grade methodology: LakeGrade methodology.
Watch Alder 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 10.2 ft. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.2 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 30 ft |
| Surface Area | 264 acres |
| Public Access | Yes |
Fish Species
Click a species to see every graded lake where it is documented.
→ Best fishing times for Alder Lake (14-day solunar calendar)
→ Is it safe to eat fish from Alder Lake? (mercury & PFAS guide)
→ Alder 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: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.035 m/yr | 5 |
Recreation & Access
Location
County Ranking
Ranked #82 of 191 lakes in Vilas County
Cleaner Lakes Within 30 Miles
Alder 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. 4 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Data Sources
Water quality data from the EPA Water Quality Portal
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: 2025-08-29
Monitoring stations: 1
Where to stay near Alder Lake
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