Summary of fluvial sediment collected at selected sites on the Gunnison River in Colorado and the Green and Duchesne Rivers in Utah, Water Years 2005-2008

The Colorado River Basin provides habitat for 14 native fish, including four endangered species protected under the Federal Endangered Species Act of 1973 - Colorado pikeminnow (Ptychocheilus lucius), razorback sucker (Xyrauchen texanus), bonytail (Gila elegans), and humpback chub (Gila cypha). These endangered fish species once thrived in the Colorado River system, but water-resource development, including the building of numerous diversion dams and several large reservoirs, and the introduction of nonnative fish, resulted in large reductions in the numbers and range of the four species. Knowledge of sediment dynamics in river reaches important to specifc life-stages of the endangered fishes is critical to understanding the effects of flow regimes on endangered fish habitats. The U.S. Geological Survey, in cooperation with the Upper Colorado River Endangered Fish Recovery Program, Bureau of Reclamation, U.S. Fish and Wildlife Service, and Wyoming State Engineer's Office, implemented daily sediment sampling at three locations in critical habitat reaches in the Upper Colorado River Basin. This report presents a summary of data collected at these sites, including water and suspended-sediment discharge, streambed compositions, and channel and flood-plain topography. The locations are at U.S. Geological Survey streamflow-gaging stations 09152500, Gunnison River near Grand Junction, Colorado; 09261000, Green River near Jensen, Utah; and 09302000, Duchesne River near Randlett, Utah.