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Harpt Lake
Enhanced dataHistorical depth chart
Harpt LakeManitowoc County, WI
Historical source depth chart available1 converted source DNR map sheet can be panned and zoomed in the browser. Interactive contours stay hidden until visual QA passes. Historical survey — not for navigation.
View browser depth chartLakeList assistant
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Fishing spots, food, lodging, marinas, and rentals around Harpt Lake.
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Fishing forecast
Best windows for Harpt 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
Harpt Lake water temperature today
Modeled surface-temperature estimate built from seasonal climate, lake depth, and live National Weather Service air temperatures near this lake.
72°FWarm
Seasonal estimate. Checking current National Weather Service air temperatures…
Comfortable summer pattern. Bass and panfish are active; early and late hours beat the midday heat.
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
High Phosphorus Levels, Excess Algal GrowthPollutants: 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 Harpt Lake - Deep Hole.
Sampled Jun 2026Volunteer monitoring since 2003
Somewhat hazy, algae-prone water — summer clarity of 3.5 ft ranks among the lowest of monitored Wisconsin lakes.
Based on July–August 2025 averages across 6 volunteer readings.62Eutrophic5-yr summer TSI
Nutrient-rich, greener water — more algae and plant growth, common in shallower lakes.
Water claritySecchi disk depth
3.5 ftJul–Aug 2025 avg (3 readings)
HazyDeclining — down ~22% vs earlier years
Clearer than 9% of 597 monitored Wisconsin lakes with current readings.
AlgaeChlorophyll-a
43 µg/LJul–Aug 2025 avg (3 readings)
HighWorsening — up ~401% vs earlier years
NutrientsTotal phosphorus — fuels plant & algae growth
125 µg/LLatest single sample · 2026-06-15
HighHigh 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 | 3.5 ft (3) | 43.0 µg/L (3) | — |
| 2024 | 2.0 ft (2) | 196.0 µg/L (2) | 127.0 µg/L (1) |
| 2023 | 8.5 ft (2) | 6.5 µg/L (2) | — |
| 2022 | 5.0 ft (2) | 21.0 µg/L (2) | — |
| 2021 | 6.0 ft (1) | 19.0 µg/L (1) | — |
| 2020 | 7.0 ft (1) | 9.0 µg/L (1) | — |
| 2019 | 9.0 ft (2) | 9.5 µg/L (2) | — |
| 2018 | 8.0 ft (2) | 7.5 µg/L (2) | — |
| 2017 | 6.5 ft (2) | 11.5 µg/L (2) | — |
| 2016 | 10.5 ft (2) | 7.0 µg/L (2) | — |
Latest individual samples: Secchi 3 ft (2025-08-23), chlorophyll-a 24 µg/L (2026-06-15), and total phosphorus 125 µg/L (2026-06-15).
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.
Harpt Lake - Deep HoleStation 363068 · 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 maps1 converted map sheetView DNR depth mapHistorical map · not for navigationFishing 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
Harpt Lake depth maps
1 converted map sheet. These historical surveys are not for navigation.
Navigable depth map
Harpt 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 84600 · 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.
32surface acres
54max depth feet
1public access points
44.2957, -87.7342latitude, longitude
Access
Public access points
Boat launchHarpt Lake Boat Ramp44.29816, -87.73255Managed by COUNTYTOWN OF GIBSONRamp surface: ConcreteADA-accessible feature: NoVerified 2026-07-12
Nearby
Trip-planning places
No nearby trip-planning places yet
Fishery
Notable species
PanfishLargemouth BassNorthern PikeWalleye
Depth FAQ
How deep is Harpt Lake?
Harpt Lake is 54 feet deep at its deepest point and averages about 20 feet, according to Wisconsin DNR records.
Is there a free depth map of Harpt Lake?
Yes. 1 scanned Wisconsin DNR lake survey map sheet is free to view and zoom on LakeList. These historical surveys are not for navigation.
Where does the Harpt Lake depth map come from?
The map sheets are converted from official Wisconsin DNR lake survey documents, with the source URL, checksum, and retrieval date retained for every sheet. Historical surveys are not for navigation.
Trust and freshness
Where this lake data comes from
Wisconsin DNR Lake Mapsname, coordinates, county, source identifiers
LakeList record updated 2026-07-14