Hasbrook Lake
Oneida County, WisconsinOligotrophic
On the LakeGrade rubric, Hasbrook Lake pulls an A: clarity at 68.9 ft and 10 µg/L of phosphorus put it in the top bracket for Wisconsin. 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.
A TSI value of 27 puts Hasbrook Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. Hasbrook Lake is unusually deep for Wisconsin at 50 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. Hasbrook Lake covers 307 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Hasbrook Lake ranks 36 of 140 in Oneida County — solidly in the upper half of the local distribution.
Eurasian watermilfoil is established at Hasbrook Lake, which can dampen recreational access and pressure the native plant community. Walleye are documented at Hasbrook Lake, one of 5 fish species on record for the lake. A documented public access point at Hasbrook 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 2025-08-31. 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 68.9 ft down. Phosphorus level: 10.3 µg/L. Trophic State Index: 27.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 68.9 ft | A |
| Phosphorus | 10.3 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 27 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 50 ft |
| Surface Area | 307 acres |
| Public Access | Yes |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Hasbrook Lake (14-day solunar calendar)
→ Is it safe to eat fish from Hasbrook Lake? (mercury & PFAS guide)
→ Hasbrook 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 | -0.143 m/yr | 7 |
| Phosphorus | ↑ Improving | -0.7 µg/L/yr | 5 |
Recreation & Access
Location
County Ranking
Ranked #36 of 140 lakes in Oneida County
Nearby Lakes in Oneida County
More Wisconsin Lake Rankings
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 1990. 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: 2025-08-31
Monitoring stations: 1