Laserfiche WebLink
<br />South Platte River, Chatfield Downstream Channel Improvement Project- Vegetation Management Plan <br /> <br />II. STUDY AREA DESCRIPTION <br /> <br />Environmental Setting <br />The South Platte River is the major landscape feature within the project site. The headwaters <br />originate at approximately 12,500 feet in elevation in the northern Mosquito Range of the <br />Rocky Mountains on the east of the Continental Divide in Colorado (USGS 2002), and flows <br />northeast for over 100 miles descending to the project site which is in the elevation range of <br />5,330-5,280 feet. The South Platte River is classified as a fifth order stream within the <br />project area and tributaries flowing into in include: Lee Gulch, Dutch Creek, Little's Creek, <br />Big Dry Creek, and Bear Creek. These tributaries serve as important fish and wildlife <br />corridors that connect the mountains, foothills, and plains ecosystems. Land use adjacent to <br />in the project site is dominated by residential, commercial, and industrial urban development <br />with two golf courses and some preserved natural areas along the river. The South Platte <br />River, within South Platte Park on the southern boundary of the project site, is not <br />channelized. The Mary Carter Greenway Trail is along the upper bank of the river. That <br />trail is heavily utilized by joggers, walkers, pet owners, and cyclists. <br /> <br />Watershed Description <br />Historically flows in this portion of the South Platte River were influenced by spring snow <br />melts which corresponded with seasonal high flows, but drought, localized heavy rain fall, <br />and floods have impacted the flow regime (Galat et al. 2005). Chatfield Reservoir, <br />approximately 3 miles upstream from the project site, was completed in 1975 after the Great <br />Flood of 1965. Heavy rains on Plum Creek resulted in flood discharges as high as 100,000 <br />cubic feet per second (cfs) in the South Platte River which heavily impacted the city of <br />Denver (CWCB 2008). The South Platte River, which was once a braided stream in the area, <br />was channelized downstream after the completion of the dam. Water flows became regulated <br />and large scouring events and floods extending throughout the floodplains no longer occur. <br />Average annual discharge from 1997 to 2007 calculated from the USGS gage "South Platte <br />River Below Union Ave, at Englewood" was 165.14 cfs with a maximum of 410.4 cfs and a <br />minimum of88.2 cfs) (USGS 2008). The climate is semi-arid, with a mean annual <br />precipitation of approximately 16 inches. The average winter temperature is 30.60F and <br />average summer temperature is 69 of (CSU 2003, WRCC 2006). <br /> <br />Threatened and Endangered Species <br />The purpose of the Endangered Species Act (ESA) of 1973 (as amended, 16 USC 1531 et <br />seq.) is to provide a means whereby the ecosystems upon which endangered and threatened <br />species may be conserved and to provide a program for the conservation of such species. <br />The ESA requires that consultation regarding protection of such species be conducted with <br />the U.S. Fish and Wildlife Service (USFWS) prior to implementation of projects. Threatened <br />and endangered species were researched (Appendix B) for this project to ensure that any <br />potential impacts could be avoided. It was determined that the VMP would have no adverse <br />effects upon any of the species. Block Clearances regarding Ute ladies' -tresses orchid <br />(Spiranthes diluvialis), and Preble's meadow jumping mouse (Zapus hudsonius preblei), <br />have been provided from the USFWS. Their decision resulted from previous studies and <br />surveys (USFWS 2006, ERO 2006, ERO 2007, Ark Ecological Services LLC 2006). <br /> <br />Page 8 <br />Final Report - April 30, 2008 <br />