Bed sediment was collected from 17 sites in the South Platte River basin during low-flow periods in the summer of 1992. This basin-wide reconnaissance survey is part of the U.S. Geological Survey's National Water Quality Assessment (NAWQA) Program in the South Platte River Basin. Sites sampled included: seven streamflow gaging stations on the South Platte River; seven tributary sites; two reservoirs; and one irrigation ditch.
Particle-size analysis indicated decrease in the <2.00 millimeter size fraction in a downstream direction in the South Platte River. The bed sediment of the tributaries is more fine grained than the South Platte River bed sediment, and the irrigation ditch had the greatest amount of coarse-grained bed sediment (>0.063 millimeters) of all sites sampled. The particle size of bottom sediment in the reservoirs is similar to the particle size of bed sediment in the nearby tributaries, but bias may have been introduced by using an Ekman dredge to sample the reservoirs.
Bed-sediment samples also were collected and processed for analysis of selected organic constituents (<2.00 millimeters) and for selected trace elements (<0.063 millimeters). Results of chemical analyses are pending.
1 U.S. Geological Survey, Box 25046, MS 415, Denver Federal Center, Lakewood, CO 80225