Correction: Corrected September 17, 2026: the water-level paragraph now reports the archived NOAA station observations and their limits. Unsupported navigation implications were withdrawn. NOAA measurement context.
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The Soo Locks ran two Tregurthas in opposite directions before Monday's first light, and the timing is worth a second look.
Lee A. Tregurtha cleared upbound with a 23:40 Sunday ETA, its position logged at the locks themselves. Paul R. Tregurtha came through downbound a few hours later, logged at the same locks with a 3:48 a.m. Monday ETA. Same waterway, opposite headings, same overnight window.
By the time the two had sorted themselves out, the next wave was already closing. Algoma Equinox was tracking in from 9 Mile Point with a 5:42 a.m. ETA. Presque Isle came down from Point Iroquois with a 5:33 a.m. slot. Algoma Strongfield and Ontario Venture were still inbound from Detour, both due in the 6:22 to 6:26 a.m. range. Four vessels queuing within roughly one hour, after two had already traded chambers in the dark.
For anyone who drove up to the locks overnight, it was the kind of morning that pays: two known hulls threading the same passage in opposite directions, and a column of lights stacking up behind them before sunrise.
Federal Seto was working upbound through the Detroit River at 4:52 a.m. Monday, logged near the Detroit River Light with a Port Huron ETA of 10:54 a.m. The foreign-flag vessel adds a salty note to a St. Clair corridor that has been running mostly lakers.
American Patriot was downbound in the Detroit River at the same hour, spotted near Algonac at 4:15 a.m. with an 8:05 a.m. ETA at the Dossin Museum checkpoint. Two ships, opposite directions, same river reach, same early-morning window.
Capt. Henry Jackman entered the Welland Canal inbound at Port Weller with a 3:42 a.m. Monday ETA, the freshest transit on that feed by a comfortable margin. Viking Octantis, the expedition vessel we tracked at the Soo earlier this week, was an hour out from Duluth at 4:29 a.m. Monday with a 5:25 a.m. arrival ETA there.
Archived NOAA station observations: Lake Superior, Sault Ste. Marie (NOAA station 9076027): 1.332 feet relative to local Low Water Datum, observed 2026-08-23 23:54 local standard time. Lake Michigan, Chicago (NOAA station 9087031): 1.844 feet relative to local Low Water Datum, observed 2026-08-23 23:54 local standard time. Lake Huron, Harbor Beach, MI (NOAA station 9075002): 2.26 feet relative to local Low Water Datum, observed 2026-08-23 23:54 local standard time. Lake Erie, Cleveland (NOAA station 9063053): 2.717 feet relative to local Low Water Datum, observed 2026-08-23 23:54 local standard time. Lake Ontario, Rochester, NY (NOAA station 9052030): 3.494 feet relative to local Low Water Datum, observed 2026-08-23 23:54 local standard time. These are individual gauge readings, not lake-wide averages or channel depths. They do not establish vessel clearance, cargo limits or comparative navigability.
Lake Huron is the rough corner today, with post-frontal northwest flow keeping conditions breezy and waves reported at 5. Lake Michigan is running 4-foot seas in the northern third under northwest winds from a low lingering in eastern Ontario. Lake Superior and Lake Erie are the quieter stretches, both at 2-foot seas, with Lake Ontario reporting 3. The high pressure building behind the front should ease the chop on Huron and Michigan through tonight.
The Dutch general cargo vessel Thamesborg completed a Northwest Passage transit this month, passing within a few nautical miles of the uncharted shoal where it grounded on the same route last year. The Wagenborg vessel is not a stranger here: it has visited the Great Lakes in 2017, 2020, and 2025. It left Matane, Quebec, on August 8 and is scheduled to reach Onsan, South Korea, on September 3. The passage itself ran roughly five days, from August 13 to August 18.