A Zero Tide

Friday the 13th was special for more than its usual notoriety. Just after noon, we had a zero tide. This is a relatively rare event, often not happening for a number of years. The “zero tide” refers to the tide height. Typically for this area “a low tide” is measured in the range of 2 to 4 feet and a “high tide” 14 to 16 feet. The tide seldom drops to 0.0 feet, a point known as chart datum (CD). On extremely rare occasions a negative tide will occur, dipping a few tenths of a foot below chart datum.

The rightmost column is the tide height in feet. The zero tide occurred at 11:42 Pacific Standard Time (PST) which is 12:42 Pacific Daylight Time (PDT). The zero tide or any real low tide is always fun to explore as many plants and animals normally under water are left exposed. Eelgrass beds, crabs, horse clams and cockles are some of the sights.

This Red Rock crab was left vulnerable to predators.
Cockle shell.

Friday the 13th lived up to its reputation for this cockle. We rarely see cockles except on the lowest of tides. They live in that part of the tidal zone where most of the time they are safe. You wonder how they figure out that depth of water and will they eventually learn to move into just a little bit deeper water?

A horse clam is left high and dry, a common sight on a low tide and not unique to a zero tide.
Horse clams are big, this shell easily containing my sunglasses.
The beach at its greatest extent.
Low tide, runs out 200 metres.
High tide, a difference of 16.4 feet (almost five metres) measured vertically.

Leave a Reply

Your email address will not be published. Required fields are marked *