MS HB594

Defines "Ordinary High Water Mark (OHWM)" as a mark determined by Department of Marine Resources staff based on physical and biological characteristics including water stains, soil changes, scour lines, debris lines, and plant community changes

Revises the definition of "coastal wetlands" to reference the ordinary high water mark instead of the previous "watermark of ordinary high tide" language

Specifies that OHWM determinations cannot be made during high tide when characteristics are not observable

Clarifies that OHWM is distinct from mean high water and cannot be used to determine boundaries between private property and public trust tidelands—only for regulated activity purposes

Effective date: July 1, 2021