A methodology for assessing aquatic and riparian habitat quality at the watershed scale (Utah)

A data collection and analysis procedure was developed for quantifying and classifying instream and riparian habitat quality within the Santa Clara River watershed in southwestern Utah. This assessment was intended to provide information necessary for maintaining and improving habitat for the native fish community, including the rare Virgin spinedace (Lepidomeda mollispinis mollispinis). This study involved identifying and collecting relevant habitat variables, developing a ranking system for quantitatively describing the condition of the habitat variables, and evaluating the quality of habitat based on the assigned rankings. Of the 86.1 km of total stream length evaluated within the entire watershed, 16% has poor habitat quality, 49% has fair quality, 28% has high quality, and 7% is dewatered due to diversions. The highest percentage of poor quality habitat occurs in the Santa Clara River (21%). The primary cause of poor habitat quality throughout the watershed is depressed flow conditions resulting from water development.