Urbanization has a pervasive and growing impact on aquatic communities.  Moreover, the successful management of urban streams is difficult because of the wide variety of urban-related stressors impacting water quality.  The objective of this study was to examine the relationship between urban disturbance gradients and biological indices in the Santa Clara basin to determine the biological potential of a water body at a given site.  Several urban gradients were developed and tested using univariate and multivariate regression analyses.  The urban gradient that best characterized stressors associated with urbanization contained the variables urban land use, road density, and population density.  Multimetric biological indices represented ecological attributes of macroinvertebrate assemblages including taxa composition and richness (number of taxa in the insect orders of Ephemeroptera, Plecoptera, and Trichoptera), functional feeding group (number of taxa designated as shredders), and habit (percent of individuals that cling to the substrate).  Quantile regression was used to define the biological potential of each site along an urban gradient and to identify critical factors affecting biological condition in this region.  This process can serve as a framework for environmental managers to prioritize urban stream sites for restoration and protection.