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Show PART VII NEED FOR ADDITIONAL HYDROLOGIC DATA Stream Gaging The hydrologic data collection networks generally are adequate to meet the needs associated with water resource development in the area. Systematic collection of streamflow data began in 1894 with the establishment of gaging stations on Colorado and Gunnison Rivers at Grand Junction, Colorado; Green River at Green River, Utah; and Price River at Wellington, Utah. Stream gaging expanded slowly, and by 1911 records were being obtained at 116 sites. The number of stations decreased between 1911 and 1929. In the latter year the Congress adopted a program of cooperation on a 50/50 basis with the states for stream gaging by the Geological Survey. This cooperative arrangement, coupled by the serious droughts of the 1930's and the needs of the Bureau of Reclamation for more streamflow data gave impetus to the stream gaging program. The number of stream gaging stations in the region currently being operated is about 322. In addition gages are maintained at 40 of the over 100 large reservoirs (over 1,000 acre- feet) to record stage fluctuations. Water Quality Sampling Systematic collection of chemical-quality data began in 1928-29 when chemical quality stations were established on Colorado River near Cisco, Utah, on Green River at Green River, Utah, and on San Juan River near Bluff, Utah. At the present time water quality is being monitored daily at about 139 stations. In addition to the daily records of chemical quality, chemical analyses are available for more than 850 miscellaneous sites, most of which are at, or near stream gaging stations. Sediment Sampling The collection of suspended sediment data was initiated in 1905 at five sites but discontinued after 1906. It was not resumed until 1929, when daily samples were taken on the Green River at Green River, Utah, San JTuan River near Bluff, Utah, and Colorado River at Lees Ferry, Arizona. Between 1948 and 1951 the number of daily suspended sediment sampling stations was greatly increased and by 1957 daily suspended sediment data had been obtained at 21 sites. At the present time daily suspended sediment data is being obtained at 13 sites and suspended-sediment samples are being collected periodically at about 200 other sites. 28 |