LakeList
FavoritesStateWisconsin
Mercer Lake
Enhanced dataInteractive depth contours
Mercer LakeIron County, WI
Contours load with map Access
Interactive depth contours5-foot typical interval · Modeled depth estimate · Not a survey · Not for navigation
Source: LakeList depth modelmedium confidence · QA passed · Select a contour to inspect its mapped depthModeled depth estimate: contours computed from the lake's shoreline shape and its documented 24-ft maximum depth (depth grows with distance from shore, calibrated to the documented mean depth where available). This is a smooth mathematical model, not a survey - real holes, bars, and drop-offs will differ. Community sonar (C-MAP Genesis) overlays where recorded. Not for navigation.LakeList assistant
Plan your lake day
Fishing spots, food, lodging, marinas, and rentals around Mercer Lake.
Start here
Fishing forecast
Best windows for Mercer Lake
Weather-based planning built from the National Weather Service hourly forecast near this lake.
Loading latest forecast…
Checking wind, precipitation, and near-term weather windows.
Water temperature
Mercer Lake water temperature today
Modeled surface-temperature estimate built from seasonal climate, lake depth, and live National Weather Service air temperatures near this lake.
74°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.
DNR water check
Water quality quick take
From Wisconsin DNR / Citizen Lake Monitoring readings at Mercer Lake - Deep Hole.
Sampled Jul 2025Volunteer monitoring since 2001
Clear, low-algae water — summer clarity of 12.3 ft puts it among the clearest quarter of monitored Wisconsin lakes.
Based on July–August volunteer averages from 2021–2024; each value shows its own year.Water claritySecchi disk depth
12.3 ftJul–Aug 2021 avg (2 readings)
ClearImproving — up ~25% vs earlier years
Clearer than 79% of 596 monitored Wisconsin lakes with current readings.
AlgaeChlorophyll-a
2.5 µg/LJul–Aug 2024 avg (2 readings)
Very lowImproving — down ~35% vs earlier years
No recent nutrient readings — last measured 2018.
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 | 14.0 ft (1) | 1.0 µg/L (1) | — |
| 2024 | 13.3 ft (1) | 2.5 µg/L (2) | — |
| 2023 | 12.0 ft (1) | 2.0 µg/L (1) | — |
| 2022 | 10.5 ft (1) | 3.0 µg/L (1) | — |
| 2021 | 12.3 ft (2) | 2.5 µg/L (2) | — |
| 2020 | — | 3.0 µg/L (1) | — |
| 2019 | 8.8 ft (3) | 3.0 µg/L (2) | — |
| 2018 | 9.3 ft (2) | 3.5 µg/L (2) | 11.0 µg/L (1) |
| 2017 | 9.5 ft (2) | 3.0 µg/L (2) | — |
| 2016 | 10.2 ft (3) | 3.0 µg/L (2) | — |
Latest individual samples: Secchi 14 ft (2025-07-27), chlorophyll-a 1 µg/L (2025-07-27), and total phosphorus 11 µg/L (2018-07-29).
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.
Mercer Lake - Deep HoleStation 263126
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
Mercer Lake depth maps
1 converted map sheet. These historical surveys are not for navigation.
Navigable depth map
Mercer 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 2313600 · 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.
181surface acres
24max depth feet
1public access points
46.1599, -90.0593latitude, longitude
Access
Public access points
Boat launchMercer Lake Access46.16364, -90.06447Managed by TOWNSHIPTOWN OF MERCERRamp surface: ConcreteADA-accessible feature: YesVerified 2026-07-12
Nearby
Trip-planning places
No nearby trip-planning places yet
Fishery
Notable species
Largemouth BassMuskyNorthern PikePanfishWalleyeSmallmouth BassSturgeon
Wisconsin DNR stocking
Fish stocking history
The latest published year is 2018, when 85,202 fish were recorded across 2 entries.
2018
MuskellungeUpper Chippewa River · Large Fingerling
20212.1 in average
2018
WalleyeMississippi Headwaters · Fry
85,0000.3 in average
2016
WalleyeMississippi Headwaters · Fry
250,0000.3 in average
2015
WalleyeUnspecified · Small Fingerling
4007.0 in average
2013
MuskellungeUpper Chippewa River · Large Fingerling
9211.6 in average
2011
MuskellungeUnspecified · Large Fingerling
12012.0 in average
2010
WalleyeUnspecified · Large Fingerling
7009.0 in average
2010
WalleyeMississippi Headwaters · Small Fingerling
6,4401.7 in average
Depth FAQ
How deep is Mercer Lake?
Mercer Lake is 24 feet deep at its deepest point and averages about 11 feet, according to Wisconsin DNR records.
Is there a free depth map of Mercer Lake?
Yes. LakeList publishes a free interactive depth contour map of Mercer Lake at a typical 5-foot interval, with an optional 3D underwater view, derived from LakeList depth model survey data.
Where does the Mercer Lake depth map come from?
The interactive depth contours are derived from LakeList depth model. Each contour set passes a visual QA review against the source document before it is published. The depths are a modeled estimate calibrated to the lake's documented maximum depth - not a survey, and 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
Keep exploring