Mean High Water Mark

01/15/26

“What’s the legal and scientific boundary for a water body?”

Water bodies will expand and contract over land, whether it’s a small river or a massive tidal bay. The point delineating the high tide mark from the land has massive geological and ecological implications, given the difference in water saturation. The Mean High Water Mark is the average high tide mark over a long period of time. The mean high water mark often delineates the legal and scientific boundary for a water body, making it very important to quantify.