The GLRI Urban Stormwater Monitoring effort brings together the expertise of the USGS with local and national partners to assess the ability of green infrastructure to reduce stormwater runoff in Great Lakes urban areas. The term "urban stormwater" refers to rainfall or snowmelt that is not absorbed by the ground, but rather flows off impervious surfaces such as road, roofs, and parking lots. Urban stormwater flows into storm drains that are typically routed directly to receiving water bodies. During heavy rainfall, excess stormwater runoff can cause localized flooding and lead to combined sewer overflows. This web page provides an overview of USGS's research about urban stormwater monitoring. It includes related research, partners, maps, and multimedia (Introduction).