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LakeQuality
B

North Bay Lake

Vilas County, WisconsinLimited DataMesotrophic

North Bay Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Mesotrophic conditions dominate at North Bay Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. The lake bottoms out at 19 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. North Bay Lake covers 270 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. North Bay Lake ranks 179 of 202 in Vilas County — at the lower end of the locally monitored distribution.

Eurasian watermilfoil has been documented at North Bay Lake, requiring shoreline management to keep dense mats from crowding native vegetation. The fishery includes walleye alongside the lake's other 5 documented species — a notable draw for Wisconsin anglers. A documented public access point at North Bay 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 2022-10-05. Grade methodology: LakeGrade methodology.

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.

MetricValueGrade
Water Clarity (Secchi Depth)13.1 ftB
PhosphorusNo data
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)40Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth19 ft
Surface Area270 acres
Public AccessYes

Fish Species

Click a species to see all Wisconsin and Minnesota lakes where it is found.

→ Best fishing times for North Bay Lake (14-day solunar calendar)

→ Is it safe to eat fish from North Bay Lake? (mercury & PFAS guide)

North Bay Lake fishing regulations (limits, seasons, special rules)

Invasive Species

Chinese Mystery SnailEurasian Water-Milfoil

Water Quality Trend: Improving

Based on 7 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.188 m/yr7
Phosphorus Improving-1.13 µg/L/yr6
See year-by-year chart →

Recreation & Access

1
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #179 of 202 lakes in Vilas County

Cleaner Lakes Within 30 Miles

North Bay Lake holds Grade B. 2 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Vilas County

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1991. 10 stations on file (most recent sample 2025).

DNR Assessment
Good · Shallow Lowland lake
Trophic State Index 61 (eutrophic) · 5-year average

Fish Species (DNR-rated)

Musky(Common)Panfish(Common)Northern Pike(Common)Walleye(Common)Largemouth Bass(Present)

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: 2022-10-05

Monitoring stations: 1