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<br />• area to the irrigation channel and along the lower terrace to the marshy azea described. <br />Two additional springs contributing to the surface water flow in the unnamed drainage <br />were identified approximately 75 feet downgradient from the first spring. Based on <br />prior inspections, the spring flow, and consequently surface flow, is discontinuous <br />throughout the year. <br />One additional spring was identified within the study area. Along the terrace slope, in <br />the northeast corner of the study area, a flowing spring was identified. This spring <br />appears above a group of narrow-leaf cottonwood trees, and has been historically <br />developed. Wooden timbers have been placed to build a rough spring box. <br />Soils of the study area are alluvial and lcessial in origin. Depth of the soils is variable <br />dependent on topographic location, land management practices, historic disturbance, <br />and vegetation cover. The texture of the soils is generally silty trending towazd sand as <br />the alluvia] pazent material is approached. Significant clay horizons are found within <br />the unnamed drainage channel. <br />Present vegetation of the study area has been determined by historic land management <br />practices. Currently, there are four distinct vegetation communities present within the <br />study area. A dry mountain shrub community dominates the north-facing terrace slope <br />at the northern boundary of the study area. This community is dominated by the large <br />shrubs serviceberry (Amelanchier altifolia), skunkbush sumac (Rhus trilobata), and big <br />sagebrush (Artemesia tridentata), and is found on the shallow cobble soils on the north- <br />facing terrace slope. Along the fringes of the drainages traversing the site, outside the <br />areas converted to agricultural or pasture usage, is a patchy greasewood/prickly pear <br />vegetation community. This vegetation community is dominated by black greasewood <br />(Sarcobatus r~ermicu/atus) and prickly pear cactus (Opuntia polyacantha). The third <br />vegetation community within the study area is a cottonwood Swale community. This <br />community is dominated by narrow-leaf cottonwood trees (Populus angustifalia), <br />willow shrubs (Sa/ir sp.), and cool season grasses (Bromus inermis, E/ymus junceus, <br />and Poa pratensis). This community is limited to the drainage bottoms and swales <br />along Spring Creek and the unnamed drainage. These communities appear to be relict <br />to a time and condition when these drainages were connected to surface water source <br />areas to the south of the railroad, highway, and airport. The last vegetation community <br />present within the study area is an old field community dominated by cool season <br />grasses (wheatgrasses, predominantly}, with sub-dominant biennial and perennial <br />leguminous (orbs (alfalfa, yellow sweetclover), and occasional annual forts (field <br />bindweed, Canada thistle). The old field community is present over the majority of the <br />study area on the upper and lower alluvial terraces. <br /> <br />-2- <br />