White Paper - Protection of Marine Riparian Functions in Puget Sound, Washington

This document was developed to provide shoreline planners and managers with a summary of current science and management recommendations to inform protection of ecological functions of marine riparian areas (defined in Section III). Washington Administrative Code (WAC 173-26-186(8)) directs that Shoreline Master Programs (SMPs) "include policies and regulations designed to achieve no net loss of those ecological functions." The Washington State Department of Ecology has produced guidelines to help achieve this standard on marine shorelines of Washington. In addition, the state's Aquatic Habitat Guidelines (AHG) program developed recommendations for protecting marine riparian functions: Protecting Nearshore Habitat and Function in Puget Sound: An interim Guide (2007). The AHG program is a partnership of state agencies dedicated to providing science guidance for protection of marine, freshwater, and riparian ecosystems. The AHG program develops guidance documents that can aid local governments updating Shoreline Master Programs (SMP) and Critical Areas Ordinances (CAO).

This information contained in this report will help inform local decisions regarding what is needed to protect ecological functions of marine riparian areas. Specifically, we summarize the range of marine riparian buffer widths (Appendix G) needed to meet particular levels of ecosystem function based on a literature review and input from an expert panel workshop.

Protection of marine riparian areas

Puget Sound's marine shorelines and riparian areas have been altered over the last 160 years by human activities including agriculture, forestry and development. Nearly all of the merchantable timber along the marine shorelines of Puget Sound was harvested or burned by 1884 (Chasan, 1981). Although natural regeneration of riparian vegetation occurred in the years that followed, human manipulation of vegetation continues to influence marine shorelines today.

During the past three decades, an extensive body of research has emerged documenting the importance of riparian areas in providing ecological functions. These functions include:

• Water quality maintenance
• Fine sediment control
• Large woody debris (LWD) delivery and retention
• Microclimate moderation
• Nutrient delivery and retention
• Fish and wildlife habitat creation and maintenance
• Hydrology/slope stability

Most riparian research has focused on stream and riverine ecosystems. Attention to marine riparian processes and functions has only emerged in the literature during the past decade, and research in this area is increasing. Nevertheless, riparian areas provide ecological functions regardless of whether they are adjacent to freshwater or marine water bodies (Desbonnet et al. 1994, 1995; NRC 1996; NRC 2002; Brennan and Culverwell 2004).

Organization of document

In addition to the Introduction above, this document contains the following sections:

• Methodology used to compile information.
• Overview of marine riparian areas.
• Description of the seven most ecologically important riparian functions and recommendations for protecting (sustaining?) these functions.
• Impacts to riparian functions from activities associated with development, agriculture and forest practices.
• Recommendations to protect and sustain marine riparian functions.