Laserfiche WebLink
<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br /> FWS BUREAU OF RECLAMATION <br /> L. Kaeding, r- Biological Support Branch <br /> Field Supervisor R. Williams, Contract Officer's <br /> 1/ Technical Representative <br /> NPS <br />P Perry, H, Wickware, <br /> Superintendents <br /> UDWR <br /> M. Moretti, <br /> Regional Biologist BIO/WEST, Inc. BUREAU <br /> R, Valdez, - OF RECLAMATION <br /> Principal Investigator R, Williams, S. Tully, <br /> Biologists <br /> I I I -- <br /> LARVAL FISH TAG-A-LONG TOURS FIELD CREW <br /> LABORATORY R. Jones, 8. Masslich, L. Crist <br />R. Muth, D. Snyder Logistical Support Field Coordinators, <br /> BIO/WEST Inc, <br /> <br />Figure 1. Administration of the Cataract Canyon Studies. <br /> <br />downst.ream to the confluence (Figure 2). Access to this study area was by motorized craft from launch <br />sites at either Potash or Mineral Bottom. Detailed maps of the Green and Colorado Rivers in this study . <br />area are available in two river guides (Belknap and Belknap 1974, Baars 1987). A photographic record <br />is provided in Appendix A of this document and referenced accordingly. The reader should note that <br />the confluence of the Green and Colorado Rivers is RM 216.4, which represents the distance upstream <br />from Lee's Ferry below Glen Canyon Dam. The confluence is also designated as RM 0 as the st.art of <br />the mileage upstream from the confluence on either the Colorado or Green Rivers. <br /> <br />Fish habitat in this st.udy area was largely determined or indicated by shoreline. Four types of <br />shoreline habitats were present including: (1) tamarisk/willows, (2) talus slopes, (3) rock ledges, and (4) <br />vertical walls (Photos A-1 through A-4). The tamarlsk/wlllow habitat was the most. common, particularly <br />along silt/sand banks of bottomland areas. This habitat was characterized by dense growths of tamarisk <br />and willow with overhanging and submerged branches and root wads. Talus slope habitat was present <br />below st.eep unconsolidated slopes where boulders and other colluvial materials had spilled into the <br />river. The boulder and cobble jetties formed by these talus slopes often created eddies and slackwaters <br />which were important fish habitat. Rock ledge habitat was present where low walls of metamorphic <br />or igneous rock overhung the river. These ledges characteristically had depressions and pockets worn <br />by water action. Vertical wall habitat was most. prevalent in the lower portion of the Green and <br />Colorado Rivers just. above their confluence. This habitat was created by high, st.eep walls of <br />sedimentary or metamorphic rock emerging from below the water surface. These smooth walls had but <br />few irregularities' created by water action. Rock ledges and vertical walls were initially suspected of <br />providing good habitat for chubs, a complex of species that in the upper basin are closely associated <br />with rock substrates (Valdez et a1. 1981). However, the prevalence of adjacent shifting sand substrate <br />with its apparent low productivity reduCed this habitat value. <br /> <br />3 <br />