The Edmonds Planning Board heard a presentation from the Washington Department of Fish and Wildlife on Sept. 24 that recommended replacing traditional DNR buffer categories with riparian management zones (RMZs) sized to provide full riparian functions. WDFW advised using the site-potential tree height at age 200 as the preferred RMZ width and, where that is infeasible, a minimum RMZ of 100 feet to support pollution removal functions.

WDFW presentation: Kara Whitaker, land-use conservation and policy section manager (WDFW), described the agency's 2020 "best available science" synthesis and riparian management recommendations. Whitaker said riparian functions important to water quality, bank stability, shade, wood input and terrestrial habitat occur along all stream types, including non-fish-bearing streams, and that the DNR water-typing-and-buffer approach was developed for non-urban forest-practice settings and does not justify smaller buffers upstream: "We found no scientific justification for protecting non fish bearing streams less than fish bearing streams," Whitaker told the board. She described a two-step delineation: map the site-potential tree height at 200 and the 100-foot pollution-removal distance, and use the wider of the two as the RMZ outer edge.

Board questions and staff context: Board members asked whether the RMZ would replace existing buffer language in the city's critical areas ordinance (CAO); Whitaker and staff recommended replacing "buffer" terminology with RMZs. The board raised practical questions about applying RMZ widths in an urban context where current buffers already abut developed lots. Staff said the CAO rewrite to date reorganizes and clarifies review procedures and that explicit incorporation of RMZ delineation and implementation is a next step: "We're in the second section after the... general provisions. We'll have brief critical area review processes and then it's really clearly spelled out," staff said.

Practical implications flagged by the board included whether RMZs are mapped on both sides of a stream (staff said yes), how applicants would demonstrate site-potential tree height (WDFW offers an online mapping tool and a field measurement protocol), and how RMZs would affect redevelopment of already-developed parcels (staff said existing building footprints are handled differently, and staff will assess how to reconcile the WDFW recommendations with urban realities).

What the board did: The item was informational; no ordinance was adopted. The board asked staff to study implementation, confirm how WDFW site-potential tree height data could be integrated into city permitting (applicant-provided tool or GIS support), and to return with proposed CAO language and maps for future review.

Ending: Staff said the CAO update will incorporate the RMZ approach in subsequent drafts and present analysis about impacts on existing developed parcels and urban stream reaches.