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University of Oregon North Campus Conditional Use Permit Project Riparian Assessment and Management Report The PSA includes approximately 3 acres of riparian habitat, defined in this report as the area between the OHWM and TOHB along the Willamette River and Millrace Slough, and approximately 33 acres of upland habitat. Aquatic habitat comprises less than an acre of the PSA and is primarily Millrace Slough and Willamette River shoreline. The conservation setback encompasses 14 acres and overlaps with all three habitat types within the PSA. A paved bike and pedestrian path runs east to west within the PSA. The PSA includes a landscaped access ramp south of the Frohnmayer Bridge. The Frohnmayer Bridge serves as a bike and pedestrian bridge that spans Willamette River and connects the North Campus area to Alton Baker Park and Autzen Stadium on the north side of the river outside of the PSA. East of a roundabout within the PSA, the bike and pedestrian pathway merges with Riverfront Parkway which continues to the south under the railroad bridge and outside of the PSA. The open space east of the Millrace Slough within the PSA was historically used for agriculture followed by a sand and gravel mining and processing operation owned by the Eugene Sand and Gravel Company (L.R. Squier Associates, Inc., 1990). The property was purchased by the UO in 1968. This area now includes two recreation fields, bicycle path, mowed pastures with trees scattered throughout, several unmaintained foot paths, and Himalayan blackberry (Rubus armeniacus) patches. The portion of the PSA west of the Millrace Slough was historically a gravel and concrete plant and an EWEB transmission pole yard (L.R. Squier Associates, Inc., 1990). This area currently includes a large fenced field with several small depressions created from years of soil compaction from industrial use that may display wetland characteristics. 2.0METHODS MB&G biologists conducted TOHB and OHWM determinations and a riparian assessment within the PSA on July 25, 26, and 27, 2017. During the field effort, aquatic, riparian, and upland areas within and around the PSA were examined and photographed. Prior to the field effort, MB&G biologists reviewed 2015 3-foot LiDAR-derived digital elevation models (DEMs) along with 1-foot interpolated contours and aerial imagery (OLC 2015). MB&G biologists created 30 target field points to focus the field effort to areas with unreliable or low point density LiDAR data. These target points identified both TOHB and OHWM sampling areas that required further information gathering in the field. 2.1Top of High Bank Determination MB&G determined the TOHB line by visual identification of the highest point at which the bank met the grade of the surrounding topography \[EC 9.4920 (1)c1\]. The TOHB locations were recorded with a Trimble GeoXT 6000 series GPS unit capable of sub-meter accuracy. MB&G collected 27 TOHB points along the Willamette River and Millrace Slough in the PSA. MB&G post-corrected these points using Trimble Pathfinder software and compared them to known monument locations near the PSA, resulting in an absolute accuracy of less than 2 feet. MB&G used the post-corrected points to select contour lines representative of the TOHB line and to serve as guidance in areas where LiDAR data were ambiguous. Finally, MB&G biologists reviewed the TOHB line in-office and refined the line using field photos and riparian information collected on site. 2.2Ordinary High Water Mark Determination MB&G determined the OHWM by visual identification of one or more of the following \[EC 9.4920 (1)c2\]: “a. A clear, natural line impressed on the bank by the presence of water, flowing water or waves. b.Changes in the characteristics of soils. c.The presence of water-borne litter and debris. d.The uppermost limit of destruction of terrestrial vegetation by the presence of water, flowing water or waves.” page 2