Ordinary high water mark
Under Washington's Shoreline Management Act, the ordinary high water mark (OHWM) is defined as a biological vegetation mark. For locations where the OHWM cannot be found, our Shoreline Master Program guidelines include default elevation lines for tidal and freshwater shorelines.
The ordinary high water mark is defined as:
"Provided, that in any area where the ordinary high water mark cannot be found, the ordinary high water mark adjoining salt water shall be the line of mean higher high tide and the ordinary high water mark adjoining fresh water shall be the line of mean high water."
- Activities of beavers and other animals and organisms
- Consistency of pool elevations
- Land-use changes
- Presence of peat
- Stormwater runoff