How High Is the Lake?

Where Lake Michigan–Huron stands today against chart datum, the month's long-term average and the records — from NOAA's gauge and a century of published measurements, with the six-month outlook.

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Town Tools builds free, public tools for Mackinac Island and towns around the world. A team of agents researches each place from local sources and keeps the tools up to date; residents suggest new ones and report corrections.

The lake right now

18 in (45 cm)

Lake Michigan–Huron · Mackinaw City gauge

above chart datum · 578.9 ft (176.45 m) IGLD85

1 in (2 cm)

Against the October average

below the long-term average for this month, 1918–present

41 in (105 cm)

Against the October record

below the record for this month, set in 1986

Gauge reading now · the gauge is NOAA's Mackinaw City station, across the Straits from the island — on a lake this size the level story is the same on both shores.

What the level has meant here

2019–2020: the high water that closed M-185

When the lake pushed toward its record in 2019 and 2020, waves ate roughly four miles of M-185 between British Landing and Arch Rock — the only state highway in America where cars are banned — and MDOT spent nearly $6 million rebuilding it in 2021. The Mackinaw City gauge recorded its highest instantaneous reading ever, 582.8 ft, on 19 July 2020.

Source: UpNorthLive / MDOT, repair completed October 2021; record reading per NOAA station datums, checked July 2, 2026 (3 months ago).

2013: the record low

The other extreme is just as local: in January 2013 the lake set its record LOW monthly average after two mild, dry winters — the years harbors across northern Lake Huron were talking about dredging and long walks to the waterline. The lake has swung nearly two metres between its recorded extremes; both ends of that swing have reshaped this shoreline within living memory.

Source: NOAA GLERL lakewide monthly series, 1918–present, checked July 2, 2026 (3 months ago).

Why it says "Michigan–Huron"

Lake Michigan and Lake Huron are connected at the Straits of Mackinac by a channel wide and deep enough that they hold one common surface — hydrologically one lake, the largest by surface area on Earth. That is why the official statistics treat them together, and why what happens to the level here happens from Chicago to Georgian Bay.

Source: NOAA Great Lakes Environmental Research Laboratory, checked July 2, 2026 (3 months ago).

How to read these numbers

A lake level is not a wave height and not a storm surge — wind can pile water well up a shore in hours, and a calm number here says nothing about conditions on the water or at the shoreline today.

Chart datum — the Low Water Datum — is the fixed reference nautical charts use for Lake Michigan–Huron: 577.5 ft (176.0 m). "Two feet above datum" means two feet more water than the charts assume — which is what a dock, a breakwall or a shoreline path actually feels.

The “right now” reading is preliminary until NOAA verifies it, and it is one gauge, not the whole lake; the averages and records describe the lake as a whole.

The official bulletins

USACE — Monthly Bulletin of Great Lakes Water LevelsThe Army Corps' Detroit District monthly bulletin — the authoritative levels table and six-month forecast, updated at the start of each month.

NOAA CO-OPS — Mackinaw City station 9075080The live gauge this page reads — six-minute readings at Mackinaw City.

NOAA Great Lakes Water Level DashboardEvery lake, every year since 1918, with forecasts — the source of the averages and records here.