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DRAFT WILLAMETTE RIVER GREENWAY DESIGN PLAN Both TOB (bankfull stage) and OHW rely on annual or biennial water levels as their determining characteristic, with TOB being the more encompassing definition because of the reliance on flood events as opposed to ordinary events. This analysis supports the use of TOB for the purposes of applying the Greenway setback because both state law and the Eugene Code (EC), as discussed subsequently, define TOB, in addition to reasons stated. Top of bank is defined in EC 9.4920 as: "The highest point at which the bank meets the grade of the surrounding topography, characterized by an abrupt or noticeable change from a steeper grade to a less steep grade, and, where natural conditions prevail, by a noticeable change from topography or vegetation primarily shaped by the presence and/or movement of the water to topography not primarily shaped by the presence of water. Where there is more than one such break in the grade, the uppermost shall be considered the top of the high bank." Unlike the Greenway Boundary, which is digitized in the RLID Database and is shown as an overlay on the Metro Plan Diagram, there is no digitized or mapped TOB line in existence for Eugene. In cases where proposed development is proximate to the river, the landowner or applicant is responsible for determining the TOB line and whether any encroachment is proposed. The determination process typically involves field investigation, survey, and planning services, and may involve services of an environmental consultant. As noted previously, the purpose of this project is to update Willamette Greenway permit regulations to provide an administrative review process and clear and objective standards for the development of housing within the Greenway, and to remove barriers to the development of housing. The current, individualized TOB determination process presents potential barriers to development of housing in the Greenway due to the time and cost required to meet the evidentiary requirements. This project sets out to establish a digitized TOB line to be used as an alternative to the individualized determination process described above and as the basis for the establishment of a Greenway setback, one of the requirements of the Greenway permit approval process. Neither this Design Plan nor the newly established Greenway Setback make any changes to the previously adopted Greenway Boundary. 1.3 TOB DETERMINATION City of Eugene Planning Division staff obtained and utilized 2009 LiDAR9 data from the Lane Council of Governments (LCOG) to map a top of bank (TOB) line for the portions of the Willamette River within Eugene's city limits. The 2009 LiDAR data used by staff was originally prepared by Watershed Sciences for the Oregon Department of Geology and Mineral Industries (DOGAMI)10 and represents the most comprehensive publicly available dataset for the geographical area encompassing the Eugene city limits. 9 Light Detection and Ranging. According to the National Oceanic and Atmospheric Administration, LiDAR is a remote sensing method that uses pulsed lasers to measure ranges to the Earth. These light pulses-combined with other data recorded by the airborne system - generate precise, three-dimensional information about the shape of the Earth and its surface characteristics. 10 Oregon Department of Geology and Mineral Industries (DOGAMI) contracted with Watershed Sciences to collect the data, produce the Jas and bareearth and highest hit grid files. The point density of the Jas files is 8.14 points/scl meter. The relative accuracy is .163 feet and the absolute accuracy has a RMSE of.13 feet. The LiDAR data was delivered in 2009 in Oregon Statewide Lambert Conformal Conic, NAD83 (HARN) horizontal datum, NAVD88 (Geoid03) vertical datum in international feet. The 2-foot contours were generated from the bareearth grid by LCOG under the direction of Eugene PWE. - Page 59 of 91 WILLAMETTE RIVER GREENWAY CODE AMENDMENTS 24