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Fishing Report

Grand Portage Lake Fishing Report

Mercer, WI

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Modeled from live National Weather Service data as of Aug 31, 2026 at 11:44 PM CDT, plus solunar and sun/moon times computed in-house. This is a computed report, not an eyewitness catch report.

46.173115, -90.049417

Est. water temp

70.1°F

v1 estimate from air temperature — not a sensor reading

Max depth

33 ft

Deepest measurement on record

Mean depth: 15 ft

Max depth: Stachelek et al. (2021), LAGOS-US DEPTH v1.0, Environmental Data Initiative (CC BY 4.0)

Notes from anglers

Imported from GNIS. Nearest town: Mercer (Iron County, WI).

Today’s bite

Largemouth Bass fishing report

Excellent · 81/100

Best window today: 11 PM (Excellent · 81/100)

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Species on record

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Species detail

How to catch them at Grand Portage Lake

Location

Grand Portage Lake · 46.1731, -90.0494

Map data © OpenFreeMap, OpenMapTiles, OpenStreetMap contributors

Nearby

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FAQ

Common questions

What fish are in Grand Portage Lake?

State surveys have confirmed Largemouth Bass, Muskellunge, Northern Pike, Smallmouth Bass, and Walleye in Grand Portage Lake.

When's the best time to fish Grand Portage Lake?

Black Crappie feed most actively at Dawn and Dusk, when activity runs about 16% above the daily average across all four light windows. Check today's bite forecast for Grand Portage Lake to see the best window for current conditions.

Where is Grand Portage Lake?

Grand Portage Lake is near Mercer, WI, at 46.1731, -90.0494.

Plan your trip to Grand Portage Lake

Get the hour-by-hour bite forecast and the best times to fish Grand Portage Lake, scored against live National Weather Service weather for this exact spot — showing what every input contributed and how well the evidence supports it.