Under natural conditions, very little surface runoff occurs. The vast majority of precipitation either infiltrates into groundwater or goes into the atmosphere as water vapor.
By contrast, developed land significantly contributes to runoff.
In addition, in many areas, particularly in the Northeast and Great Lakes regions, stormwater and municipal wastewater is carried in the same pipes, and the combined system is designed to overflow to surface waters in certain rain events. That means untreated domestic sewage going to our waterways.
Clean Rivers, Clean Lake -- Rooftops to Rivers Study-- Karen Hobbs
Smart, Green Solutions to a Major Water Pollution ChallengeStopping Runoff Pollution and Sewer Overflows Karen Hobbs Natural Resources Defense Council
Combined Sewer Overflows Newtown Creek, Brooklyn Image: RiverkeeperImage: Seattle Public Utilities
Green Infrastructure as a solution: What is Green Infrastructure? Portland streetscape Navy Yard Bioretention Photo courtesy of Martina Keefe Photo courtesy of LID Center
Portland’s stormwater street planters. Photo courtesy ofthe Portland Bureau of Environmental Services. NRDC, Stormwater Strategies Chicago City Hall Green Roof. Photo courtesy ofPermeable Pavement, City of Portland, BES Roofscapes, Inc.
Green Infrastructure as a solution: Other non-water benefits• Reduced energy use• Increased property values• Improved air quality• Lower air temperature• Reduced urban heat island effect• Conservation of water
Overview: Rooftops to Rivers II• Demonstrates how cities use green infrastructure to improve stormwater management and achieve multiple benefits.• The report includes: – Economic benefits of green infrastructure – Case studies on 14 cities – Encouragement for EPA to learn from the work of these cities and advance these solutions nationwide