Concrete plays an integral role in urban development, from the fabrication of underground sewer lines to the construction of bridges and interstate highways. However, this development increases impervious surfaces that, in turn, generate more stormwater runoff, which often carries pollutants produced by the activities that occur on the impervious surfaces. These pollutants can include trash and debris, sediment, nutrients, dissolved metals, and petroleum hydrocarbons. Increased stormwater runoff also can erode and degrade the urban streams that ultimately receive the flow and may cause flooding issues for existing development downstream. The quality and quantity of stormwater runoff can threaten wildlife, natural systems and aesthetics. Fortunately, concrete also is part of the solution to these problems.