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description of topography, geomorphic features, vegetation, hydrology, soils, wildlife, structures, and land use at <br />the site. <br />Wetland Feature Jurisdictional Status <br />Total Area of all <br />existin wetlands <br />. Bi Thom son River JD trib to S. Platte River not measured <br />B. Tailwater Wetlands Non-JD artificial) irri red 13.92 acres <br />C. Oxbow or Channel wetlands JD surface c nnected 6.94 acres <br />C' Isolated Oxbow wetlands Non-JD isolated 0.25 acres <br />D. Sideslo a See Wetlands JD surface connected 5.51 acres <br />E. Toeslo a Wetlands JD surface connected 3.45 acres <br />Total 30.12 acres <br />Existing Topography and Geomorphic Features <br />The most significant topographic features of the properties aze the Big Thompson River and associated terraces. <br />The Big Thompson River flows from northwest to southeast across the northeast comer of the Croissant property. <br />Approximately the north half of each of the Croissant and Green properties aze within the primary alluvial terrace <br />of the Big Thompson River. A 25-30 foot high slope separates the Big Thompson primary alluvial terrace and the <br />terrace above. This slope begins along the south edge of the Croissant property and winds through the Green <br />property to County road 13. The upper terrace comprising the south half of the Green property is comprised of <br />outwash deposits from the Front Range as well as aeoIian deposits. <br />The primary alluvial terrace within the Croissant and Green properties contains relict meanders of the Big <br />Thompson River that exhibit distinct topography and vegetation. The Green property contains three man-made <br />farm ponds, two adjacent to the residence on the west side of the property and one along the slope neaz the east <br />boundary of the property. Several irrigation and drainage ditches have been excavated on the Croissant and Green <br />properties. <br />Existing Vegetation <br />Natural vegetation communities within the properties can be broadly categorized as sedge/rush swales, wet <br />meadow, and mixed grassland. The communifies form a mosaic within the property and intergrade together <br />depending on microtopography, soils, and the ambient hydrologic regime. Each community is briefly described <br />below. <br />Sedge/rush Swale vegetation communities are found within both properties surveyed. Sedge/rush Swale <br />vegetation communities are found in depressions formed by historic alluvial deposition and meandering of the Big <br />Thompson River on both properties and within surface water drainages formed by irrigation tailwater. On both <br />properties sedge/rush swales are also located on the slope between the primary alluvial terrace and secondary <br />terrace. These communities aze generally restricted to topographic depressions. They aze localized and form a <br />mosaic throughout the property. The dominant species are sedges and rushes. The following species were <br />commonly encountered within the sedge/rush swales; three square (Scirpus americanus), Balfic rush (Juncos <br />balticus), foxtail barley (Hordeum jubatum), blue joint (Calamagrostis canadensis), and red and alsike clovers <br />(Trifolium repens and Trifolium pratense). The sedge and rush species often form a dense monoculture in these <br />areas, and species may be segregated by slight differences in the moisture regime caused by drying or <br />microtopography within the Swale or depression. Sedge/rush swales intergrade with the following vegetation <br />community throughout the properties. <br />Project: G[cen & Croissant Aggregate Mining Applicant: Loveland Ready Mix, Inc. Pg 7 of 53 <br />Corps File Yo: 200180205 Waternay: Hig Thompson Wetlands, Weld County, CO <br />