Little Long Lake
Forest County, WisconsinLimited DataMesotrophic
Little Long Lake comes in at a B on the grading rubric — a respectable showing for a Wisconsin lake of its size and depth.
Mesotrophic conditions dominate at Little Long Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. Little Long Lake reaches 30 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. The lake's 101 acres and partial shoreline records put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Little Long Lake sits at rank 22 of 34 in Forest County, in the lower half of the local distribution.
An invasive species record — Chinese Mystery Snail — has been logged at Little Long Lake; Wisconsin DNR maintains the official infested-waters list. The fishery is bass-led, with 3 documented species across the lake's records. 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 2025-08-27. Grade methodology: LakeGrade methodology.
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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 13.1 ft. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13.1 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 30 ft |
| Surface Area | 101 acres |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Little Long Lake (14-day solunar calendar)
→ Is it safe to eat fish from Little Long Lake? (mercury & PFAS guide)
→ Little Long 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 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -1.88 m/yr | 2 |
Location
County Ranking
Ranked #22 of 34 lakes in Forest County
Cleaner Lakes Within 30 Miles
Little Long Lake holds Grade B. 3 nearby lakes hold higher grades.
Nearby Lakes in Forest 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 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
Most recent sample: 2025-08-27
Monitoring stations: 1