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<br />002874 <br /> <br />Sed iment <br /> <br />There is only a small amount of historic daily suspended-sediment data <br />available for the Yampa River basin. These data are as follows: (1) station <br />09251000 for 1951-58, and (2) station 09259950 for 1960-64. Daily sediment <br />data are available for two stations in Utah on the Green River located above <br />and below the confluence of the Yampa River. Station 09261000, located down- <br />stream, has been active since 1948, and station 09234500, upstream, was active <br />during 1957-59. <br /> <br />During the reconnaissance survey (August-September 1975), 15 suspended- <br />sediment samples were collected. Intermittent sediment samples were collected <br />at selected sites during the spring-runoff flow of 1975 as part of the U.S. <br />Geological Survey's basic-data program. Two daily-sediment stations have been <br />initiated recently as part of the U.S. Geological Survey-U.S. Bureau of land <br />Management cooperative program; these monitor priority leasing areas. <br /> <br />As part of the assessment project, sediment data-collection activities at <br />the two downstream NASQAN sites, stations Q9251000 (daily) and 09260000 (week- <br />ly), will be revised to evaluate current sediment discharge of these mainstem <br />streams. The sediment data available on the Green River above and below the <br />confluence of the Yampa River will be evaluated in Phase I to see what the <br />basin-wide sediment yield has been during recent years. The data currently <br />being collected on the Yampa River might be used in conjunction with sediment- <br />yield model ing studies (Phase II). <br /> <br />Trace Elements <br /> <br />Historic data are available at two NASQAN stations described earl ier <br />(Ficke and Hawkinson, 1975). Quarterly analyses for dissolved and total con- <br />centrations of the following trace elements have been collected as part of the <br />NASQAN project: arsenic, cadmium, chromium, cobalt, copper, iron, lead, man- <br />ganese, mercury, selenium, and zinc. During the areal reconnaissance survey <br />(August-September 1975), trace-element data were collected as follows: <br /> <br />a. Dissolved and total concentration--cadmium, copper, cobalt, iron, <br />lead, manganese, mercury, nickel, selenium, vanadium, and zinc; <br /> <br />b. Stream-bottom sediments--antimony, arsenic, chromium, copper, iron, <br />lead, mercury, and nickel. <br /> <br />The bottom-sediment samples, however, were collected only where fine materials <br />were present. <br /> <br />At 26 of the reconnaissance-site locations described earlier (designated <br />by code "M" in table 2) sampl ing wi 11 be conducted quarterly for 1 year for <br />the above trace elements. Supplemental trace-element data will be provided at <br />an additional 24 stations funded under separate programs. <br /> <br />Historic trace-element data and also trace-element data collected during <br />the reconnaissance study will be used to assess the ambient water-quality con- <br />ditions in the basin. The continued quarterly sampling will give some indica- <br />tion of the seasonal variations of trace-element concentrations at selected <br />sites. <br /> <br />13 <br />