The St. Lawrence River at Québec City is subject to a very significant tide. With the highest of tides, the river can rise up to 21 feet. For ocean-going vessels that dock at the wharves of Québec, this variation is no trouble; they rise and fall with the tide, large enough to be equally accessible at low tide as at high. For the smaller schooners that traditionally carried the burden of local commerce in the St. Lawrence River, this variation was a major challenge; at low tide, they were virtually inaccessible to Québec dock workers.
In the 1870s and 80s, the city fathers fixed the problem by creating a tideless, 60-acre harbor, separated from the river by one lock. The Louise Basin allowed dock workers easy access to commercial schooners regardless of the level of the river itself.
Today, the commercial schooners are gone, replaced by pleasure craft of all sorts.