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<br />as barriers to movement between runs and pools. Each subject area will be presented in a <br />separate chapter. <br /> <br />STUDY AREA <br /> <br />The study area includes the lower 135 miles of the Yampa River (Figure I), The lower 58 <br />miles, with the exception of Lily Park, is a canyon-bound river reach characterized by high <br />gradient and variable substrate size. The lower 47 river miles of this reach are located within <br />Dinosaur National Monument. The upper reach of the study area is characterized by a lower <br />gradient and floodplain (except Juniper Canyon) adjacent to the river. For logistical reasons, the <br />study area was divided into two reaches, from its conlluence with the Green River to Cross <br />Mountain Canyon (River Mile, RM 58), and from Cross Mountain Canyon to near the city of <br />Craig (RM 135). Data collection in the lower portion of the study area was conducted by the C.S. <br />Fish and Wildlife Service and the Colorado Division of Wildlife supervised data collection in the <br />upper reach. <br /> <br />The annual flow of the Yampa River is appro:\imalely 1.2 million acre feet of water per <br />year, of which about 28% is contributed by the little Snake River (Tyus and Karp] 989). <br />Bankfull flow, defined as the channel forming flow. usually has a recurrence interval of about 1.5 <br />years (Gordon et a!. 1992) but may be on the order of one in five years for arid southwestern <br />rivers such as the Yampa River. The 1.5 year peaks nt'W on the Yampa River at Maybell (above <br />confluence of the Little Snake River) is 8.440 efs. The two. live. 10, and 50 year flood peaks are' <br />9,940,12,340,14,300, and 20,000 cfs respectivelv. Currently. approximately 110,000 acre feel <br />of water per year is depleted for out-ot~river-use. which represents about 10% of the Ilow at <br />Maybell (Hydrosphere 1995). During the median now \ear above Maybell, flows range from a <br />IowaI' about 200 cfs to a peak of nearl, 7.000 cfs IF1gure 2). The lowest flow typically occurs in <br />September, a time with dry natural conditions and high demand for water diversion (figure 3 i. <br />For the period of record (1916 to 1 '!96), half the years had a minimum flow above 174 cfs. 80"", <br />had a minimum flow of above 81 cfs, and 20% had a minimum flow of more than 320 cis <br />(Figure 3). Historically, one in five years has minimulll flows less than 95 cfs. flows in 1994 <br />were very low, dropping to a minimulll of 8 cis in September and remaining under 100 cfs umi I <br />early October (Figure 4). In contrast 1995 was a high ilow year and maintained higher than <br />average Dows in August and September (Figure') rhe 1996 !low year was above normal in the' <br />spring, but dropped to fairly low conditions during ;\ugust and September (Figure 6). <br /> <br />CHAPTER 1: RADIO TEl.EMETRY <br /> <br />t\'1 cthod, <br /> <br />Radio tclen1ctry l1lonitoring \Vas designl'd lu l....r(l\-i(k lllJ"ormation on range of I1lllVClllL'111 <br />during the kn\ flrn\' pcrilhl specific habitat ll~l~ dll:'il1~ the l~)\\ l1Cl\\' period. and daily habitat U;,\.-' <br />and movement fN Colorado sqwl\vlish and humpl,:!ci.: chub. Northern pike and <br />