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<br />OJ <br />if) <br />r-.. <br />.-~ <br />(.;) <br />C <br /> <br />5.2 <br /> <br />Identify, Protect, and Restore Habitats Within the San Juan River Basin <br />Necessary for Recovery of the Endangered Fish Species and Management of <br />the Native Fish Community. <br /> <br />5.2.1. Characterize Historic and Current Stream Channel Geomorphology and <br />Associated Riparian Zones. <br /> <br />5.2.1.1. <br /> <br />Determine Geomorphically Distinct Reaches. <br /> <br />Studies by Bliesner and Lamarra (1993, 1994, 1995) represent the only intensive quantitative efforts <br />to identify and characterize geomorphic reaches in the San Juan River. Earlier studies by Meyer and <br />Moretti (1988) and Platania (1990) were the first to divide the San Juan study area into "distinct <br />geomorphologic areas." However, these divisions, based primarily on aerial photograph <br />interpretation, gross fluvial characteristics, geology, and habitat availability, were mostly qualitative <br />in nature. Other researchers have used various methods for partitioning the San Juan River, most <br />often for the purposes oflogistics or data analysis. Various reach subdivisions of the San Juan River <br />used during individual SJRRlP studies since 1987 are summarized by Holden and Masslich (1995). ' <br /> <br />Eight geomorphic ally distinct subreaches between Lake Powell and Navajo. Darn were defined by <br />Bliesner and Lamarra (1995) in 1994 based on analysis of 49 factors grouped into the following <br />categories: <br /> <br />1. River Valley Geometry <br />2. Channel Contact Geology <br />3. Riparian Vegetation <br />4. Channel Gradient <br />5. Channel Pattern <br />6. Tributary Influence <br />7. Man's Influence <br />8. Aquatic Habitat <br /> <br />Twenty-one of the 49 factors analyzed were found to be most useful in identifying differences <br />between reaches and included parameters such as valley width, sinuosity, adjacent irrigated land, <br />channel slope, low flow total water area, and high flow total water area. A more complete <br />description of factors and analysis used to identify geomorphic subreaches is presented by Bliesner <br />and Lamarra (1993, 1994, 1995) and summarized by Holden and Masslich (1995). <br /> <br />Preliminary results of ongoing studies by Bliesner and Lamarra (1996) included collection of <br />additional data on various physical and biological attributes of the system that should further <br />enhance descriptions of the geomorphic subreaches. Some of the parameters continuing to be <br />evaluated based on geomorphic reach designations include substrate characteristics, plant biomass, <br />macro invertebrate biomass, detritus biomass, and backwater productivity. Utilizing information that <br />has been presented by Bliesner and Lamarra (1995, 1996), a generalized description of the eight <br />geomorphic reaches was developed and is presented below. <br /> <br />San Juan River Recovery Implementation Program <br />Summary Report <br /> <br />5 <br /> <br />17 January 1997 <br />PR-576-2 <br />