Lake Julia
Oneida County, WisconsinOligotrophic
Lake Julia earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Oneida County. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.
The lake's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. Lake Julia reaches 45 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 404 acres, Lake Julia fits the Wisconsin median for monitored lakes, with partial shoreline records. Lake Julia ranks 52 of 140 in Oneida County — solidly in the upper half of the local distribution.
Lake Julia has at least one documented invasive species (Banded Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. Walleye are documented at Lake Julia, one of 7 fish species on record for the lake. A documented public access point at Lake Julia 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 2025-10-14. 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 23 ft down. Phosphorus level: 11.2 µg/L. Trophic State Index: 35.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 23 ft | A |
| Phosphorus | 11.2 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 35 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 45 ft |
| Surface Area | 404 acres |
| Public Access | Yes |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Lake Julia (14-day solunar calendar)
→ Is it safe to eat fish from Lake Julia? (mercury & PFAS guide)
→ Lake Julia fishing regulations (limits, seasons, special rules)
Invasive Species
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -1.5 m/yr | 2 |
Recreation & Access
Location
County Ranking
Ranked #52 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. 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: 2025-10-14
Monitoring stations: 1