Attachment A.2 <br />CAMERON McCARTHY <br />LANDSCAPE ARCHITECTURE & PLANNING <br />MEMORANDUM <br />Willamette River Greenway Code Amendments (CA 22-1) <br />To: Gabe Flock, Principal Planner <br />From: Colin McArthur, AICP <br />Lauren Ransome, ASLA <br />Zak Johnson, ASLA <br />Date: February 9, 2023 <br />Subject: Native Landscape Buffer <br />The proposed Willamette River Greenway Permit approval criteria include a new standard (EC 9.8810(3)(a)) that would <br />require a 10-foot native landscape buffer for development proposals reviewed under the new clear and objective track. <br />The buffer is required along the length of the Willamette River Greenway Setback. During Planning Commission <br />deliberations on January 24, 2023, Commissioners inquired about the width of setback, basis for the 10-foot width, and <br />whether the width was sufficient for plantings to reach mature health over time especially given the requirement for <br />exclusively native plantings. Commissioners also discussed the native plant list included in the code, the City's adopted list <br />of plant species for sites at or below 500 feet in elevation (Exhibit F to Ordinance No. 20351), and whether the list was <br />suitable for application in the Willamette River Greenway. This memorandum address and expands upon both topics. <br />LANDSCAPE AREA <br />As proposed, EC 9.8812(3)(a) would require that a "landscape area that meets the requirements of EC 9.6210 Low Screen <br />Landscape Standard (L-2) shall be provided along the length of the Willamette River Greenway setback" at a "minimum <br />depth of 10 feet". The proposed width is consistent with other setback and buffer standards in EC, in addition to having a <br />basis in best practices for plant establishment. Following are a few of the other setback standards in EC: <br />• All Residential zones and the C-1 Neighborhood Commercial zone have a 10-foot minimum front yard building <br />setback. <br />• The Public Land zone includes 10-foot minimum front yard and interior yard setback. <br />• The E-1, E-2, 1-2, and 1-3 zones require "landscaping that is at least 10 feet in width" for interior yard setbacks <br />abutting residential zones. <br />The proposed 10-foot landscape area width is consistent with best practices for healthy plant growth and mature sizing of <br />canopy trees and low shrubs, as required by the L-2 Low Screen Landscape Standard. Recommended planting area widths <br />and spacing can vary widely by species, however established recommendations in other documents in use provide guidance <br />on minimum width recommendations. The City of Eugene's Approved Street Tree List includes an 8-9 foot planting area <br />minimum requirement for many of the approved tree species included in Exhibit F to Ordinance No. 20531.1 Other regional <br />jurisdictions follow similar width recommendations to accommodate mature tree growth, including the City of Portland, <br />Eugene I Portland I Bend <br />cameronmccarthy.com <br />Page 23 of 65 <br />