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bluehead sucker habitat would become unsuitable long before dace habitat loss would <br />become problematic. Therefore, meso-habitat availability for speckled dace and another <br />small-bodied native fish, the mottled sculpin (Cottus bairdi) were not modeled in this <br />study. It was necessary, however, to include these species in an ancillary analysis <br />because the dace and sculpin populations have been noticeably impacted on the Yampa <br />River during low-flow scenarios. <br />Study Objectives: <br />1). Quantify fish habitat on warm water sections of the Yampa, Colorado and <br />Dolores rivers using 2-D flow models <br />2). Determine community structure, density and biomass for fish assemblages <br />for the three study rivers <br />3). Determine relationships between habitat availability and fish abundance for <br />the native species bluehead sucker, flannehnouth sucker and roundtail chub <br />4). Develop biologically based instream flow recommendations for the Yampa <br />River and Colorado Rivers in the 15-mile reach <br />5) Provide validation for meso-habitat suitability values used in the 2-D model <br />and for predicting habitat as a function of flow <br />STUDY AREA <br />Yampa River <br />There are three study areas on the Yampa River. The two sites established in <br />1998 are called the Sevens and Duffy stations. A third site at Lily Park was added in <br />2000. The Sevens station is located at River Mile (RM) 63 and is 1.8 mile in length. <br />Duffy is at River Miler (RM) 109 and is 1.3 miles in length (Figure 1). Sevens and Duffy <br />were electro-fished in 1998, 1999, 2000 and 2001. The habitat was mapped in 1999. The <br />Lily Park site is located just below Cross Mountain Canyon and just above the mouth of <br />the Little Snake River (Figure 1). The Lily Park site extends 19 miles from RM 52.7 to <br />RM 54.5. The bridge on County Road (CR) 25 is located at RM 52.5. <br />15 <br />