-Richard, His Kanubic Travesty indicates:
============
In most States, yes. It's actually described as "the mean high-water
mark."
===============

BC Land Act
R.S.B.C. 1979, c. 214 (as amended)

....In British Columbia, all foreshore is vested in the Crown in right
of the Province... The foreshore is the intertidal area defined by the
high water mark which delineates the natural boundary and that of the
low water mark which delineates the seabed....

frtzw906