Clearwater Lake
Oneida County, WisconsinOligotrophic
On the LakeGrade rubric, Clearwater Lake pulls an A: clarity at 16.8 ft and 10 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.
A TSI value of 37 puts Clearwater Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake bottoms out at 48 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. The lake's 360 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. Within Oneida County's 134 graded waters, Clearwater Lake sits at rank 15, near the top of the local distribution.
Eurasian watermilfoil has been documented at Clearwater Lake, requiring shoreline management to keep dense mats from crowding native vegetation. Walleye are documented at Clearwater Lake, one of 6 fish species on record for the lake. 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 2025-10-13. Grade methodology: LakeGrade methodology.
Watch Clearwater Lake water quality
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 16.8 ft down. Phosphorus level: 10 µg/L. Trophic State Index: 37.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16.8 ft | A |
| Phosphorus | 10 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 48 ft |
| Surface Area | 360 acres |
Fish Species
Click a species to see every graded lake where it is documented.
→ Best fishing times for Clearwater Lake (14-day solunar calendar)
→ Is it safe to eat fish from Clearwater Lake? (mercury & PFAS guide)
→ Clearwater 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: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.893 m/yr | 3 |
| Phosphorus | ↑ Improving | -0.7 µg/L/yr | 4 |
Location
County Ranking
Ranked #15 of 134 lakes in Oneida County
Nearby Lakes in Oneida County
More Wisconsin Lake Rankings
Other Grade A Lakes in Wisconsin
Washington County · Clarity: 11.8 ft
Washington County · Clarity: 12.6 ft
Walworth County · Clarity: 11 ft
Waukesha County · Clarity: 11.3 ft
Walworth County · Clarity: 20.2 ft
Kenosha County · Clarity: 10 ft
Oligotrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 2017. 2 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
Most recent sample: 2025-10-13
Monitoring stations: 1
Where to stay near Clearwater Lake
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