The characterization of urban land cover is central to municipal separate storm sewer system MS4 communities that rely on modeling efforts to evaluate the impacts of land development on receiving water bodies at the watershed and site-specific scales. Models such as HSPF, SWMM, SLAMM, TR-55, TR-20, and the rational method are commonly used tools to estimate watershedwide pollutant loadings for permitting purposes e.g., total maximum daily loads, national pollutant discharge elimination system or to determine the water quality treatment volume requirements for site-level storm water practices. Impervious cover IC is a key modeling parameter used to evaluate these impacts and assess needs to reduce pollutant loadings in urban watersheds. The focus of urban watershed management on IC has resulted in limited research to study the effects of pervious land cover on stream health and site hydrology. Pervious land cover can either mitigate or accentuate the impacts of impervious cover on aquatic resources in urban watersheds. The effect of pervious land cover depends on the type, extent, management, and location within a watershed, some of which are included in models that evaluate the impact of land development on receiving waters. A better understanding of how pervious land covers function and the ability to accurately characterize pervious land cover types are needed to better predict the impacts of land development on receiving waters. The need to characterize pervious land cover types in urban watersheds from a storm water practitioner’s perspective is to understand the influence soil compaction may have to accurately model the runoff from these areas and to identify suitable locations for storm water treatment practices e.g., best management practices BMPs . For example, there is an emerging trend in storm water management to reduce runoff volume and improve water quality through the use of environmentally sensitive design ESD practices that reduce and disconnect impervious cover, maximize pervious cover, and use pervious areas for infiltration. Consequently, watershed professionals and storm water practitioners have a need to better understand the role of both impervious and pervious land covers in watershed and site hydrology. This paper presents key findings from research studies to illustrate, first, the potential significance urban pervious land cover may have on watershed health, and second, the need to account for the