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as barriers to movement between runs and pools. Each subject area will be presented in a separate chapter. STUDY AREA The study area includes the lower 135 miles ofthe Yampa River (Figure 1). The lower 58 miles, with the exception of Lily Park, is a canyon-bound river reach characterized by high gradient and variable substrate size. The lower 47 river miles of this reach are located within Dinosaur National Monument. The upper reach of the study area is characterized by a lower gradient and floodplain (except Juniper Canyon) adjacent to the river. For logistical reasons, the study area was divided into two reaches, from its confluence with the Green River to Cross Mountain Canyon (River Mile - RM 58), and from Cross Mountain Canyon to near the city of Craig (RM 135). Data collection in the lower portion of the study area was conducted by the U.S. Fish and Wildlife Service and the Colorado Division of Wildlife supervised data collection in the upper reach. The annual flow ofthe Yampa River is approximately 1.2 million acre feet of water per year, of which about 28% is contributed by the Little Snake River (Tyus and Karp 1989). Bankfull flow, defined as the channel forming flow, usually has a recurrence interval of about 1.5 years (Gordon et al. 1992) but may be on the order of one in five years for arid southwestern rivers such as the Yampa River. The 1.5 year peaks flow on the Yampa River at Maybell (above confluence of the Little Snake River) is 8,440 cfs. The two, five, 10, and 50 year flood peaks are 9,940, 12,340, 14,300, and 20,000 cfs respectively. Currently, approximately 110,000 acre feet of water per year is depleted for out-of-river-use, which represents about 10% of the flow at Maybell (Hydrosphere 1995). During the median flow year above Maybell, flows range from a low of about 200 cfs to a peak of nearly 7,000 cfs (Figure 2). The lowest flow typically occurs in September, a time with dry natural conditions and high demand for water diversion (Figure 3). F or the period of record (1916 to 1996), halfthe years had a minimum flow above 174 cfs, 80% had a minimum flow of above 81 cfs, and 20% had a minimum flow of more than 320 cfs (Figure 3). Historically, one in five years has minimum flows less than 95 cfs. Flows in 1994 were very low, dropping to a minimum of 8 cfs in September and remaining under 100 cfs until early October (Figure 4). In contrast 1995 was a high flow year and maintained higher than average flows in August and September (Figure 5). The 1996 flow year was above normal in the spring, but dropped to fairly low conditions during August and September (Figure 6). CHAPTER 1: RADIO TELEMETRY Methods Radio telemetry monitoring was designed to provide information on range of movement during the low flow period, specific habitat use during the low flow period, and daily habitat use and movement for Colorado squawfish and humpback chub. Northern pike and 7