Publication Summary

The purpose of this document is to provide a consistent, technically sound and legally defensible methodology for locating the OHWM - one that meets the intent of the Shoreline Management Act.

The purpose of this document is to provide a consistent, technically sound and legally defensible methodology for locating the OHWM - one that meets the intent of the Shoreline Management Act. Knowing the location of the OHWM is often necessary for Shoreline Permit purposes and Hydraulic Project Approvals. Local governments may also require OHWM delineations for permit approvals or for administration of Critical Area Ordinances (CAO). Licensed surveyors must make OHWM determinations concerning legal property boundaries and ownerships under State law.

That said, determining the OHWM is not a precise practice. An OHWM determination results from considering various biological and hydrological factors, observations, and measurements, and may even include an assessment of historical patterns. The OHWM on any particular site is not a static line or elevation and may change over time due to natural events or because of permitted actions.

Professional OHWM delineations require documentation of the methodology followed and the field indicators used to make a determination. We prepared this document to provide guidance to professionals making OHWM determinations. In addition, the appendices contain a field form and descriptions of indicators, which should aid in understanding the evidence viewed at the site. Since documentation is required for permit review by state or local reviewing agencies, we also provide the reporting recommendations for justifying an OHWM determination.