Water Conservation / Supply Reconnaissance Study Part 1

Home Browse Search

3. GENERAL DESCRIPTION OF THE PLATTE 0 RIVER STUDY AREA A. Study Regions • The critical habitat area, which extends from near Lexington to Chapman, is the focus of this study. Flows through the critical habitat area affect several threatened and endangered species, including the whooping crane, pallid sturgeon, piping plover, and the least tern. The Platte River provides migratory bird habitat within the central flyway of North America. In addition to being federally designated critical migratory habitat for the whooping crane, the critical habitat in central Nebraska provides essential nesting habitat for the least tern and piping plover and other migratory species. Habitat conditions within the channels have changed over the last 150 years as a result of the diversion and storage projects associated with water resources development in the basin. Flows in the central Platte have been reduced from historic conditions, resulting in reduced sediment transport loads. Consequently, much of the original open, braided river sections is now dominated by riparian woodlands and surrounded by croplands (USFWS, July 1997). The two main tributaries of the Platte River originate in the Rocky Mountains of Colorado. The North Platte's headwaters are located in Jackson County, Colorado; it then flows north into Wyoming. The South Platte originates southwest of Denver, Colorado in Park County and flows northeast through the Denver metropolitan area. The main stem of the Platte River is formed by the confluence of the North Platte and South Platte Rivers near North Platte, Nebraska. The Platte River then flows across Nebraska to its confluence with the Missouri River. The Platte is a meandering and braided river through central Nebraska in the critical habitat area. The total basin area is about 90,000 square miles. Average annual precipitation across the basin ranges from about 14 -18 inches along Colorado's Front Range to approximately 32 inches at the confluence with the Missouri River (McLaughlin, 1997). Snowmelt provides the majority of the flow in the North Platte and South Platte rivers at the headwater areas. Flow in the South Platte basin is increased by contributions from major tributaries that receive transbasin diversions from west of the Continental Divide. The Platte River Basin has been divided into three regions in the context of the Platte River Research Cooperative Agreement. Each region is subsequently divided into reaches, which are defined at the upstream and downstream ends by USGS streamflow gages. There are 19 Platte River study reaches, as shown in Figure 3.1. 3 -1