How Is the High Tide Line Within MPAs Determined and Enforced?

March 19, 2015

Question: In MPA zone mapping, who and how determines what is the “mean high tide” boundary? How is this enforceable to determine if you are in the MPA zone or not? (Anonymous)

Answer: The shoreline shown on nautical charts represents the line of contact between the land and water at a selected vertical datum. In areas affected by tidal fluctuations, this is usually the mean high-water line. In confined coastal waters of diminished tidal influence, a mean water level line may be used. The shoreline of interior waters (rivers, lakes) is usually a line representing a specified elevation above a selected datum. A shoreline is symbolized by a heavy line.

That explains it.

That explains it.