The Tidal Inlet that became the Lagoon
This estimate is based on historic photographs (see the photos in this story) which show the pre-Lagoon shoreline at various tide levels.
At a high tide, the shore line of the pre-Lagoon inlet would have been similar to the current shoreline of the Lagoon.
A later bridge across the tidal inlet at the present location of the Causeway, looking north. The large gravel bar on the north side greatly narrowed the mouth of the inlet and made it an obvious place for the bridge.
In fact, the tidal inlet looked similar to the shores of Kwilákm near the Causeway today – a shallow tidal inlet that largely dried at very low tides, exposing extensive sand flats deposited by Terminal Creek. A gravel bar near the mouth of this small inlet created a narrows that was the chosen site for several generations of bridges that preceded construction of the Causeway at the same location.
During a very high tide, the inlet would look much like the Lagoon today, but during lower tides, beaches and tidal flats would be exposed. The damming Terminal Creek by the Causeway changed the tidal inlet to the brackish water (mixed salty and fresh) pond we now call the Lagoon.
The photo is taken during a low tide, the inlet is largely
empty of ocean water, and Terminal Creek flows across a gravel flats to the sea in what is now the Lagoon. Note the two bridges that crossed the inlet. Photo:Courtesy of Bowen Island Museum and Archives.