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I I 3.0 1989 FIELD DATA COLLECTION I I I I I I I 3.1 Introduction The 1989 field data collection effort included air reconnaissance, stream gaging, sediment sampling, and raftjboat reconnaissance of important reaches of the Yampa, Little Snake, and Green Rivers. The data collection program was designed to extend the efforts of previous researchers, utilize ongoing measurements, and add new data stations to better quantify the body of information available for these river systems. The work also supported stream flow and sediment transport analyses in the basin as described in subsequent sections of this report. 3.2 Reconnaissance 3.2.1 Air Reconnaissance. Air reconnaissance of the Green, Yampa, and Little Snake River basins was completed in two overflights during the fall of 1988 and spring of 1989. The primary objective of the overflights was to gain insight and perspective, particularly in a systemwide context, on the geomorphic, hydraulic, and geologic conditions in the watersheds. I I The first flight concentrated on the Yampa Canyon and Green River portion of the system. The Yampa River was flown from Steamboat Springs, Colorado to the confluence with the Green River, near the Colorado/Utah border. Reconnaissance of the Green River included the Flaming Gorge to Jensen, Utah reach. The flight returned along the right bank of the Yampa River to the confluence with the Little Snake River. In addition, the lower 25 miles of the Little Snake River was also flown from the confluence with the Yampa River to about Nine Mile Hill Ranch. From there, the overland terrain south of Greasewood Gulch and north of the Yampa River was examined during the return flight to Steamboat Springs. I I I I I I I I The second overflight began at Steamboat Springs, Colorado and proceeded downstream along the Yampa River, paying particular attention to the left bank tributaries contributing to the Yampa from the south. The confluence area of the Little Snake and the Yampa Rivers was examined, and the Little Snake was followed upstream nearly to its headwaters in the Elkhead mountains at the confluence with the Middle Fork of the Little Snake. To evaluate sediment source areas the major tributaries were flown, including Sand Wash, Powder Wash Creek, Greasewood Gulch, Sand Creek, Four mile Creek, Muddy Creek, Willow Creek, Savery Creek, Battle Creek, and the various forks of the Little Snake in the upper most portions of the basin. Strong contrasts in hydrology and geology could readily be seen from the wetter, easterly basins and the near-desert western and southern basins. During the aerial reconnaissance, reaches were established that could readily be sampled from bridge sites, and seven stream gaging locations were selected within the two basins. Detailed observations on geology and sediment source areas are summarized in Section 63 and Appendix D. 3.2.2 Yampa Canyon and Green River Float Reconnaissance. Reconnaissance of the Yampa and Green Rivers was completed by raft and jon boat during June, 1989. The raft trip began at Deerlodge Park and ended at Split Mountain, allowing observation of critical spawning areas in the Yampa Canyon. The jon boat trip began at Split Mountain and ended below the Jensen gage, allowing observation of critical backwater habitat areas on the Green River. These trips included both hydrologists/river engineers and fisheries biologists, providing a unique opportunity for interaction on the river regarding rare fish habitat requirements and geomorphic processes. The multi-disciplinary team was assembled from the Colorado River Water Conservation District, the Wyoming Water Development Commission, the Fish and Wildlife Service, BiojWest, Inc., and Resource Consultants, Inc. (Appendix E contains a summary memorandum of the reconnaissance, photographic documentation, and some preliminary field data). 3-1