University of Oregon North Campus Conditional Use Permit Project <br />Riparian Assessment and Management Report <br /> <br />MB&G recorded the OHWM using a Trimble GeoXT 6000 series GPS unit capable of sub-meter accuracy. MB&G <br />collected 49 OHWM points along the Willamette River and Millrace Slough. MB&G post-corrected the points using <br />Trimble Pathfinder software and compared them to known monument locations near the PSA, resulting in an <br />absolute accuracy of less than 2 feet. MB&G used the post-corrected points to select contour lines representative <br />of the OHWM line and to serve as guidance in areas where LiDAR data were ambiguous. Finally, MB&G biologists <br />reviewed the OHWM lines in-office and refined them using field photos and riparian information collected on site. <br />2.3Riparian Assessment Points <br />In order to describe the riparian area and functions within the PSA, MB&G created a data model to collect <br />information using MobileMap™ data collection software. The data model included attributes used to characterize <br />the riparian area function and physical structure at 57 riparian area sample points. MB&G documented attributes <br />within a 15-foot radius of each riparian point; the attributes included: <br />% shade <br />Presence of erosion <br />Presence of organic soil <br />Vegetation cover <br />% tree cover <br />o <br />% shrub cover <br />o <br />% herbaceous species cover, and <br />o <br />% bare ground <br />o <br />% invasive vegetation and dominant species <br />River features (large woody debris, pools and riffles, backwater areas, gravel bars) <br />Wildlife sign or potential habitat <br />Ground photo description <br /> <br />The percentage of shade and invasive vegetation was not specific to one vegetation layer, but rather all layers <br />combined (herbaceous, shrub, and tree) within a 15-foot radius of the riparian assessment point. These riparian <br />assessment points allowed MB&G biologists to describe the collective baseline functional conditions within the <br />PSA. <br />3.0EXISTING CONDITIONS <br />Current conditions within the PSA have been altered from historical conditions after periods of development, <br />vegetation management, and soil compaction. Over the years, the amount of fill added to the area has <br />dramatically altered the physical and biological functions of the riparian habitat along the Willamette River. The <br />bank of the Willamette River has been degraded due to use of riprap and other material to armor the bank, erosion <br />from foot traffic, and alteration of existing vegetation communities. Dominant vegetation type and structure is <br />different from historic conditions as a result of introduced flora and fauna and land uses discussed above that <br />promote the spread of invasive species. Still, existing conditions within the PSA provide habitat that supports a <br />wide range of native species associated with riparian areas. The riparian corridor has been historically reduced in <br />size and function but still remains an important resource for terrestrial and aquatic species and provides other <br />important riparian functions discussed below. <br />The PSA contains approximately 33 acres of disturbed riparian and grassland habitat including two grass <br />recreational fields. This open space area is relatively flat and is adjacent to the riparian zone which is steeply <br /> page 3 <br /> <br />