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LakeQuality
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Long Lake

Lincoln County, WisconsinOligotrophic

On the LakeGrade rubric, Long Lake pulls an A: clarity at 47.7 ft and 12 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.

Trophically, Long Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. Long Lake is unusually deep for Wisconsin at 64 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. Long Lake covers 119 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Long Lake ranks 1 of 21 in Lincoln County, putting it in the upper tier of locally monitored lakes.

Long Lake has at least one documented invasive species (Chinese Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. Bass fishing is part of the appeal: the species list runs to 4, anchored by largemouth and/or smallmouth bass. A documented public access point at Long 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 2025-08-28. 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 47.7 ft down. Phosphorus level: 12.4 µg/L. Trophic State Index: 31.

MetricValueGrade
Water Clarity (Secchi Depth)47.7 ftA
Phosphorus12.4 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)31Oligotrophic

Low nutrients, clear water, excellent for swimming

Lake Details

CharacteristicValue
Maximum Depth64 ft
Surface Area119 acres
Public AccessYes

Fish Species

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

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

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

Long Lake fishing regulations (limits, seasons, special rules)

Invasive Species

Chinese Mystery Snail

Water Quality Trend: Improving

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

MetricTrendChange/YearYears
Water Clarity Stable+0.257 m/yr7
Phosphorus Improving-1.76 µg/L/yr6

Recreation & Access

1
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #1 of 21 lakes in Lincoln County

Nearby Lakes in Lincoln County

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1994. 1 station on file (most recent sample 2025).

DNR Assessment
Excellent · Deep Seepage lake
Trophic State Index 38 (oligotrophic) · 5-year average

Fish Species (DNR-rated)

Panfish(Common)Largemouth Bass(Common)Northern Pike(Common)Musky(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: 2025-08-28

Monitoring stations: 1