Publication Summary

The comment period for this document closed on May 30, 2010. Comments are currently being reviewed.

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 consistent, technically sound, and legally defensible methods for determining the location of the regulatory OHWM on streams and rivers under the SMA in Washington State. The methods in this document are recommendations for practitioners. These methods provide a systematic course to follow. They are based on the collective experiences over many years of many people working in the field. Ecology has systematically and openly solicited feedback for the past several years as we developed this written record of our field methods. Finally, results based on these methods have consistently been upheld by hearing boards and courts, supporting the value of a clearly documented OHWM determination. The Department of Ecology staff use these methods. But the methods are not required.

Determining the OHWM is not a precise practice. The definition clearly indicates that an OHWM determination results from the consideration of various biological, hydrologic, and geomorphic factors, observations, and measurements, and may even include an assessment of historical patterns (more discussion on this is in Chapter Two). The OHWM on any particular site is not a static line or elevation and may change over time due to natural events or permitted actions. The level of effort and documentation provided to support a defensible OHWM determination should be proportionate to the risk to the resource, environment, adjacent properties and infrastructure from the proposed action and the geomorphic complexity of the site.

Project proponents may want to provide more-detailed documentation when a project may be contentious or controversial. Defensible OHWM delineations require documentation of the method followed and the field indicators used to make a determination. Well-documented OHWM determinations, based on the SMA, have generally been supported by hearings boards and courts.

This document provides guidance to professionals making regulatory OHWM determinations to define the extent of the shoreline management area under the SMA. The appendices contain a field form and descriptions of indicators, which should aid in understanding the evidence viewed at the site. Since documentation of a proposed project′s location and impacts is required for permit review by state or local reviewing agencies, we also provide the reporting recommendations for justifying an OHWM determination.

Please note that this document does not amend or change the methods by which licensed surveyors make OHWM or riparian boundary determinations concerning property boundaries and ownerships under State law. The regulatory OHWM may or may not have any relation to the OHWM or other property boundaries determined for purposes of land ownership. As with all property boundaries, the OHWM or other line that defines the extent of aquatic land ownership requires determination by a licensed surveyor. Please consult with a licensed surveyor if you need a property ownership boundary established.