Innovative Approaches to Municipal Stormwater Management

Precipitation events produce massive amounts of water, which flow into the nearest body of water following the path of least resistance. In natural settings, pervious surfaces are abundant, allowing water to infiltrate into the ground. However, in built environments, impervious surfaces, such as roads, sidewalks, buildings and parking lots that inhibit the natural infiltration of water, abound. Since water cannot penetrate impervious surfaces it must instead flow over them as runoff. In urban areas excess water is collected in an engineered system of stormwater drains to control flow. Along its path, stormwater runoff may collect debris, sediment, and contaminants, resulting in negative environmental impacts to the water bodies into which it ultimately flows. Additionally, many large U.S. cities have combined sewer and stormwater systems in which large rainfall events may produce high stormwater flows that result in untreated sewage flowing directly into natural water bodies, further contributing to water quality degradation.

Green infrastructure may be implemented in urban and rural areas as a means to manage runoff entering stormwater drainage systems. In contrast to traditional grey infrastructure, such as stormwater drains, green infrastructure mimics natural, pre-development landscapes and their ability to capture, retain, and reuse water on-site. Green systems reduce stormwater flows, help to restore natural hydrology patterns, and improve water quality. Cities across the United States are recognizing the ecological and economic benefits green infrastructure presents and have begun implementing it into their water management plans in a variety of ways. This report highlights various green infrastructure techniques and some of the unique approaches of large municipalities.