An Evaluation of Management Objectives Used to Assess Stream Habitat Conditions on Federal Lands within the Interior Columbia Basin

Abstract

We evaluated eight habitat objectives used by land management agencies within the Interior Columbia Basin to determine if the current riparian management objectives (RMOs) were representative of conditions found at reference sites, had values which differed significantly between reference and managed watersheds, and whether these RMOs could be consistently applied across the study area. We found that many of the reference reaches did not meet objectives such as wetted width‐to‐depth, percent undercut banks, number of pieces of large wood, and numbers of days exceeding 15°C. We also found no significant difference between randomly selected managed and reference reaches for four objectives: wetted width‐todepth ratio, bank stability, percent undercut, and pool frequency. Finally we found that some RMO values differed among forest types. As a result of these findings, none of 726 reference or managed reaches we evaluated exceeded all objectives when applied to a site. We recommend that objectives, if adopted, should be selected using the following guidelines: (1) be based on consistently collected data from the area of interest, (2) show a demonstrated response to management, and (3) account for landscape characteristics that may influence the value of the objective. Such an approach would insure more managed sites than reference sites exceed the objective, that the difference would be due to management rather than differences in landscape setting, and that the objective is based on data rather than professional opinion.