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Long Lake
Enhanced dataInteractive depth contours
Long LakeManitowoc County, WI
Contours load with map Access
Interactive depth contours5-foot typical interval · Sonar-derived depth (C-MAP Genesis) · Gaps interpolated · Not for navigation
Source: C-MAP Genesis community sonar (derived)high confidence · QA passed · Select a contour to inspect its mapped depthDepths decoded from C-MAP Genesis Social Map community sonar recordings (used with permission), covering 93% of the lake. Small gaps between recordings are smoothly connected; larger unrecorded areas follow the lake's depth model calibrated to the DNR-documented 38-ft maximum depth. More accurate than a pure model, but still an estimate. Not for navigation.LakeList assistant
Plan your lake day
Fishing spots, food, lodging, marinas, and rentals around Long Lake.
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Fishing forecast
Best windows for Long Lake
Weather-based planning built from the National Weather Service hourly forecast near this lake.
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Checking wind, precipitation, and near-term weather windows.
Water temperature
Long Lake water temperature today
Modeled surface-temperature estimate built from seasonal climate, lake depth, and live National Weather Service air temperatures near this lake.
75°FPeak summer
Seasonal estimate. Checking current National Weather Service air temperatures…
Warmest water of the year. Fish hold deeper or feed in low light; swimming and watersports are at their best.
Estimates are modeled, not measured. Actual temperatures vary with depth, wind mixing, and recent weather — verify conditions before swimming, boating, or heading onto ice.
Wisconsin DNR water assessment
Impaired waterbody listed
The DNR lists this waterbody as impaired. This notice is not itself a closure; review the official assessment and current guidance before your trip.
303(d) / impairment recordRecreation restrictions noted
Degraded Biological Community, Excess Algal Growth, EutrophicationPollutants: Total Phosphorus
- Status
- TMDL Approved
- Public health
- General Advice
- Recreation
- Recreational Restrictions
- Aquatic life
- Not specified
Water is impaired due to one or more pollutants and associated quality impacts.
Review DNR water quality Check consumption advice Source updated 2026-03-25 · LakeList verified 2026-07-12
DNR water check
Water quality quick take
From Wisconsin DNR / Citizen Lake Monitoring readings at Long Lake - Deep Hole.
Sampled Aug 2025Volunteer monitoring since 1992
Murky, algae-prone water — summer clarity of 1.8 ft ranks among the lowest of monitored Wisconsin lakes.
Based on July–August volunteer averages from 2021–2025; each value shows its own year.73Hypereutrophic5-yr summer TSI
Very nutrient-rich water — heavy algae and plant growth pressure.
Water claritySecchi disk depth
1.8 ftJul–Aug 2025 avg (2 readings)
MurkyImproving — up ~49% vs earlier years
Clearer than 2% of 596 monitored Wisconsin lakes with current readings.
AlgaeChlorophyll-a
85 µg/LJul–Aug 2025 avg (2 readings)
HighStable since 2018
NutrientsTotal phosphorus — fuels plant & algae growth
100.5 µg/LJul–Aug 2021 avg (2 readings)
HighStable since 2016
High phosphorus points to heavy plant/algae growth pressure.
All readings by year · station details · methodology
Summer averages (July/August)
July/August means; counts in parentheses show how many samples went into each average.
| Year | Secchi | Chlorophyll-a | Total phosphorus |
|---|---|---|---|
| 2025 | 1.8 ft (2) | 85.0 µg/L (2) | — |
| 2024 | 2.5 ft (1) | 48.0 µg/L (1) | 117.0 µg/L (1) |
| 2023 | 1.6 ft (2) | 75.5 µg/L (2) | — |
| 2022 | 1.8 ft (3) | 64.0 µg/L (3) | 112.0 µg/L (1) |
| 2021 | 1.1 ft (3) | 76.0 µg/L (3) | 100.5 µg/L (2) |
| 2020 | 1.0 ft (1) | 99.0 µg/L (2) | 102.0 µg/L (1) |
| 2019 | 1.2 ft (3) | 51.0 µg/L (3) | 106.0 µg/L (2) |
| 2018 | 4.5 ft (4) | 43.0 µg/L (2) | — |
| 2017 | 2.9 ft (6) | 85.0 µg/L (2) | 138.7 µg/L (3) |
| 2016 | 5.8 ft (4) | 59.7 µg/L (3) | 82.0 µg/L (1) |
Latest individual samples: Secchi 2 ft (2025-08-25), chlorophyll-a 94 µg/L (2025-08-25), and total phosphorus 117 µg/L (2024-08-05).
Secchi clarity is how deep a black-and-white disk stays visible from the surface — more feet means clearer water.
Chlorophyll-a is an algae pigment; higher values signal more algae in the water column.
Total phosphorus is a nutrient that feeds algae and aquatic plants. It is not a weed survey — depth, bottom type, water movement, and management change the actual lake experience.
Long Lake - Deep HoleStation 363310 · TSI based on chlorophyll
Modeled from DNR/CLMN monitoring — not a safety or swim-condition report. Verify current conditions locally. LakeList verified 2026-07-12.Official Wisconsin information
Plan with DNR sources
LakeList links to the authoritative record so you can verify maps, rules, and current notices before leaving.
Historical DNR depth maps2 converted map sheetsFishing regulationsVerify current seasons, limits, and restrictionsOfficial DNR lake pageFacts, advisories, boating, and water qualityWater quality reportsMonitoring stations, clarity, and DNR reportsInvasive speciesVerified, observed, and historical AIS recordsBoating ordinancesLocal slow-no-wake and water-use restrictionsFish consumption advisoriesStatewide and waterbody-specific health guidance
Historical depth maps are not for navigation. Verify regulations and access at the official source before your trip.
Historical Wisconsin DNR maps
Long Lake depth maps
2 converted map sheets. These historical surveys are not for navigation.
Navigable depth map
Long Lake · sheet 1
Pan, zoom, and inspect the converted Wisconsin DNR historical map image in the browser. Historical survey — not for navigation.
Source: Wisconsin DNR · WBIC 77500 · image navigation only; spatial alignment pending · Historical lake maps are not for navigation.
Source: Wisconsin Department of Natural Resources. Converted for browser access with source URLs, checksums, and retrieval dates retained. Historical lake maps are not for navigation.
Official fishing intelligence
Fishing reports and forecasts
LakeList matched these official resources by exact lake name and county. Report text stays with the publisher.
Largemouth bass2026–2027 season · Wisconsin DNRSource verified 2026-07-13Panfish2026–2027 season · Wisconsin DNRSource verified 2026-07-13
Forecasts describe DNR survey findings and expected opportunities; they are not real-time catch reports or a guarantee of fishing conditions.
Wisconsin DNR fisheries survey
Fish population survey
Structured LakeList extraction from the 2017 DNR fisheries survey. Population estimates, density, and catch-rate indices use different units, methods, and scopes, so each value is presented in its original form rather than normalized against a different measure.
Survey indicatorsValues keep their source unit and method; unlike measures are not scaled or compared.
Management contextLong Lake (WBIC 77500) only
Human-reviewed 2017 fyke-net, mark-recapture and electrofishing metrics for Long Lake.
- Historical survey snapshot; not current regulations or navigation guidance.
- Only explicit report observations and estimates were promoted; management targets, comparison-lake values and unsupported chart-only values were excluded.
- Metric source pages, survey years, methods, units and exact waterbody scope are retained.
Black Crappie
4,611 fish2017 fyke net catch count · p. 894.1 fish/net-night2017 fyke net cpue · p. 84.6 inches2017 min length · p. 811.7 inches2017 max length · p. 8
Bluegill
1,044 fish2017 fyke net catch count · p. 821.3 fish/net-night2017 fyke net cpue · p. 83.3 inches2017 min length · p. 88 inches2017 max length · p. 8
Largemouth Bass
84 fish2017 fyke net catch count · p. 81.7 fish/net-night2017 fyke net cpue · p. 83.2 inches2017 min length · p. 820 inches2017 max length · p. 8
Northern Pike
297 fish2017 fyke net catch count · p. 86.1 fish/net-night2017 fyke net cpue · p. 813.2 inches2017 min length · p. 837.2 inches2017 max length · p. 8
Pumpkinseed
6 fish2017 electrofishing catch count · p. 222.8 fish/mile2017 electrofishing cpue · p. 223.4 fish/hour2017 electrofishing cpue per hour · p. 224.1 inches2017 min length · p. 22
Walleye
61 fish2017 fyke net catch count · p. 81.2 fish/net-night2017 fyke net cpue · p. 815.6 inches2017 min length · p. 826.9 inches2017 max length · p. 8
Yellow Perch
7 fish2017 fyke net catch count · p. 80.1 fish/net-night2017 fyke net cpue · p. 86.4 inches2017 min length · p. 88.4 inches2017 max length · p. 8
Long Lake 2017 Survey ReportMatched by exact wbic name county · WBICs 77500 · verified 2026-07-20Wisconsin DNR fisheries report; LakeList operator documented permission to leverage this public report with source attribution.
Wisconsin DNR · 2026–2027 season
Lake-specific fishing regulations
Rule text published by the DNR for this waterbody, cached by WBIC and verified 2026-07-12.
All species
Catch and release fishing for largemouth and smallmouth bass is open year round unless otherwise noted. Motor Trolling is allowed with up to 3 hooks, baits, or lures, per angler.
Catfish
Season Dates: Open All Year. No minimum length limit and the daily bag limit is 10.
Cisco and whitefish
Season Dates: Open All Year. No minimum length limit and the daily bag limit is 10.
Lake sturgeon
Season Dates: Closed. No fishing allowed.
Largemouth and smallmouth bass
Season Dates: May 2, 2026 to March 7, 2027. The minimum length limit is 14" and the daily bag limit is 5.
Muskellunge and hybrids
Season Dates: May 2, 2026 to December 31, 2026 on open water. The minimum length limit is 40" and the daily bag limit is 1.
Northern pike
Season Dates: May 2, 2026 to March 7, 2027. The minimum length limit is 26" and the daily bag limit is 2.
Paddlefish
Season Dates: Closed. No fishing allowed.
Panfish
Season Dates: Open All Year. No minimum length limit and the daily bag limit is 25, but only 5 can be bluegill.
Rock, yellow, and white bass
Season Dates: Open All Year. No minimum length limit and the daily bag limit is unlimited.
Rough fish
Season Dates: Open All Year. No minimum length limit and the daily bag limit is unlimited.
Shovelnose sturgeon
Season Dates: Closed. No fishing allowed.
Trout and salmon
See Trout regulations layer.
Urban waters gamefish
This waterbody is not considered an urban water, Urban Waters Gamefish regulations do not apply.
Walleye, sauger, and hybrids
Season Dates: May 2, 2026 to March 7, 2027. The minimum length limit is 15" and the daily bag limit is 3.
Regulations can change. The official DNR page controls; verify seasons, boundaries, bag limits, and emergency rules before fishing.
119surface acres
38max depth feet
1public access points
44.1360, -88.0396latitude, longitude
Access
Public access points
Boat launchLong Lake Boat Ramp44.14423, -88.03367Managed by COUNTYTOWN OF ROCKLANDRamp surface: PavedADA-accessible feature: YesVerified 2026-07-12
Nearby
Trip-planning places
No nearby trip-planning places yet
Fishery
Notable species
Largemouth BassNorthern PikePanfish
Depth FAQ
How deep is Long Lake?
Long Lake is 38 feet deep at its deepest point, according to Wisconsin DNR records.
Is there a free depth map of Long Lake?
Yes. LakeList publishes a free interactive depth contour map of Long Lake at a typical 5-foot interval, with an optional 3D underwater view, derived from C-MAP Genesis community sonar (derived) survey data.
Where does the Long Lake depth map come from?
The interactive depth contours are derived from C-MAP Genesis community sonar (derived). Each contour set passes a visual QA review against the source document before it is published. The depths are derived from community sonar recordings (C-MAP Genesis Social Map, used with permission), with gaps between recordings interpolated; not for navigation.
Trust and freshness
Where this lake data comes from
Wisconsin DNR Lake Pagesname, coordinates, county, source identifiers
LakeList record updated 2026-07-12
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