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University of Oregon North Campus Conditional Use Permit Project Riparian Assessment and Management Report sloped. The Federal Emergency Management Agency National Flood Hazard Layer shows that the 1% annual chance flood hazard (100-year floodplain) encompasses approximately 14 acres of the PSA. It extends up over the Willamette River’s steep riparian bank and into the flat open space to the south. Figure 2 in Appendix A illustrates the current floodplain conditions within the PSA. Riparian areas act as an important interchange between aquatic and upland habitat. Hence, in order to describe riparian biological and physical functions, it is important to elucidate both aquatic and upland habitat characteristics. Aquatic, upland, and riparian habitats within the PSA are discussed below and are mapped on Figure 3 in Appendix A. 3.1Aquatic Habitat The riparian zone directly affects the health of the waterbody that it surrounds. Hence, riparian habitat with intact physical and biological function improves water quality and condition. Riparian vegetation stabilizes streambanks, slows erosion, moderates stream temperatures, and filters overland runoff to aquatic habitats. Aquatic habitat offers many of the necessary elements for fish, wildlife, and invertebrates to thrive. The PSA includes portions of the Willamette River and the Millrace Slough (Appendix A, Figure 1). The PSA is situated five miles downstream of the confluence of the Middle Fork Willamette River and the Coast Fork Willamette River. The portion of the Willamette River adjacent to the PSA runs east to west and measures approximately 400 feet wide at the OHWM. The Millrace Slough within the PSA flows south to north through the western portion of the PSA. 3.1.1Millrace Slough The Millrace Slough enters the PSA from the south through a concrete box culvert with an adjacent water control structure under the railroad. The slough’s channel is approximately 20 feet wide in this area and flows approximately 20 feet before passing under an unmaintained foot bridge with concrete abutments. The slough flows for approximately 150 feet before entering a culvert under the bike and pedestrian path near the Willamette River TOHB. The culvert under the bike path is constricted on the south side, obstructed by the heavy accumulation of sediment and debris. This constriction point appears to have caused a wider channel (the OHWM measuring approximately 30 feet wide) south (upstream) of the culvert. The area north of the culvert has a narrow OHWM approximately 10 feet wide and continues to the north for approximately 200 feet before its confluence with the Willamette River. During the July 2017 field effort, the Millrace Slough was stagnant, murky, and fairly degraded with English ivy (Hedera helix) dominating the herbaceous vegetation community above OHWM (Appendix B, Photos). However, the overstory was predominantly composed of black cottonwood (Populus trichocarpa), providing shade and cooling the water within the slough. This area provides habitat for amphibians, reptiles, small mammals, and birds to forage, migrate, and reproduce. 3.1.2Willamette River The portion of the Willamette River within the PSA contained many of the morphological components necessary for a healthy river ecosystem. These components included: Pools and riffles, gravel bars, seasonally exposed vegetated benches, large woody debris, mud flats, page 4