American Fisheries Society Symposium 47:193–212, 2005 © 2005 by the American Fisheries Society Relationships of Field Habitat Measurements, Visual Habitat

Abstract.—We evaluated several approaches for measuring natural and anthropogenic habitat char-acteristics to predict benthic macroinvertebrate assemblages over a range of urban intensity at 85 stream sites in the Santa Clara Valley, California. Land cover was summarized as percentage urban land cover and impervious area within upstream buffers and the upstream subwatersheds. Field measurements characterized water chemistry, channel slope, sediment, and riparian canopy. In addition to applying the visual-based habitat assessment in U.S. Environmental Protection Agency’s rapid bioassessment protocol, we developed a simplified urban habitat assessment index based on turbidity, fine sediment deposition, riparian condition, and channel modification. Natural and anthropogenic habitat variables covaried along longitudinal stream gradients and were highly corre-lated with elevation. At the scale of the entire watershed, benthic macroinvertebrate measures were equally correlated with variables expressing natural gradients and urbanization effects. When natu-ral gradients were reduced by partitioning sites into ecoregion subsection groupings, habitat vari-ables most highly correlated with macroinvertebrate measures differed between upland and valley floor site groups. Among the valley floor sites, channel slope and physical modification of channel and riparian habitats appeared more important than upstream land cover or water quality in deter-mining macroinvertebrate richness and ordination scores. Among upland sites, effects of upstream reservoir releases on habitat quality appeared important. Rapid habitat evaluation methods ap-peared to be an effective method for describing habitat features important to benthic macroinvertebrates when adapted for the region and the disturbance of interest