Long Lake
Lincoln County, WisconsinOligotrophic
On the LakeGrade rubric, Long Lake pulls an A: clarity at 47.7 ft and 12 µg/L of phosphorus put it in the top bracket for Wisconsin. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.
Trophically, Long Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. Long Lake is unusually deep for Wisconsin at 64 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. Long Lake covers 119 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Long Lake ranks 1 of 21 in Lincoln County, putting it in the upper tier of locally monitored lakes.
Long Lake has at least one documented invasive species (Chinese Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. Bass fishing is part of the appeal: the species list runs to 4, anchored by largemouth and/or smallmouth bass. A documented public access point at Long 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 2025-08-28. Grade methodology: LakeGrade methodology.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 47.7 ft down. Phosphorus level: 12.4 µg/L. Trophic State Index: 31.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 47.7 ft | A |
| Phosphorus | 12.4 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 31 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 64 ft |
| Surface Area | 119 acres |
| Public Access | Yes |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Long Lake (14-day solunar calendar)
→ Is it safe to eat fish from Long Lake? (mercury & PFAS guide)
→ Long Lake fishing regulations (limits, seasons, special rules)
Invasive Species
Water Quality Trend: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.257 m/yr | 7 |
| Phosphorus | ↑ Improving | -1.76 µg/L/yr | 6 |
Recreation & Access
Location
County Ranking
Ranked #1 of 21 lakes in Lincoln County
Nearby Lakes in Lincoln County
More Wisconsin Lake Rankings
State Parks Near Long Lake
Other Grade A Lakes in Wisconsin
Waukesha County · Clarity: 14.6 ft
Waukesha County · Clarity: 13.8 ft
Walworth County · Clarity: 19 ft
Washington County · Clarity: 12 ft
Kenosha County · Clarity: 10.1 ft
Washington County · Clarity: 12.5 ft
Oligotrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1994. 1 station 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
Most recent sample: 2025-08-28
Monitoring stations: 1