That "article" is somewhat confusing.....mixing rates of change with absolute water level heights....whatever that means. Take a look at the cross-section of the Panama Canal.....locks go up the same amount, right at 85 ft, as down eh.Wrong
From NOAA
Most people are surprised to learn that, just as the surface of the Earth is not flat, the surface of the ocean is not flat, and that the surface of the sea changes at different rates around the globe. For instance, the absolute water level height is higher along the West Coast of the United States than the East Coast.
So what's the difference in sea level between the west and east coasts again? Is there one?