Urbanization effect models were developed and verified at whole watershed scales to predict and differentiate between effects on aquatic life from diffuse, non-point source (NPS) urbanization in the watershed and effects of known local, site-specific origin point sources, contaminated sediment sites. Using U.S. Environmental Protection Agency (US EPA) Environmental Monitoring and Assessment Program (EMAP) data from the New England Wadeable Stream Survey and datasets from States of Maine (ME) and Connecticut (CT), we derived macroinvertebrate community response curves for watersheds with different levels of urban development (n = 731 watersheds). Taxonomy, resolution, and indicator values were standardized across datasets to facilitate watershed comparisons.