Most current pollution management in cities is based on treating pollution at the end-of-the pipe, after pollution is generated. This paradigm worked well for treating municipal sewage and industrial effluents - point sources of pollutants. Pollution from these sources has been greatly reduced since passage of the Clean Water Act in 1972. However, the remaining pollution problem in post-industrial cities is mostly caused by nonpoint sources - runoff from lawns, erosion from construction sites, gradual decomposition of automobiles (e.g., erosion of tire particles containing zinc and brake pad linings with copper), and added road salt from de-icing operations. The next section of this chapter shows why the end-of-pipe paradigm cannot be the primary approach for dealing with these types of pollution and why new approaches are needed.