The amount, connectivity, and distribution of impervious cover (i.e. rooftops, roads, and other hard surfaces) in an urban watershed alters the amount, characteristics, and flow patterns of surface drainage (i.e. stormwater). These changes degrade the hydrological, physical, chemical, and biological attributes of small, first-order urban streams and creeks, which in turn, degrade greater environmental and social conditions. The challenge of our communities becoming – and remaining – sustainable will increase as the global population grows and becomes more urban.

There are, however, numerous policies cities can adopt for more sustainable urban surface drainage; policies that will reduce, if not eliminate, these negative impacts. Cities can maintain and disconnect impervious cover in order to reduce the quantity and improve the quality of stormwater that drains to waterways. They can also reduce and concentrate it in order to reduce the quantity of stormwater created in the first place.

Despite this array of recommendations, little systematic research exists on the policies cities have actually adopted (and in what combinations), or how selection and implementation occurred, and to what degree of success. In addition to synthesizing existing literature on impervious cover problems and policies, this dissertation takes an initial step in building greater knowledge about these matters through detailed case studies about the evolution and current application of policies in two cities recognized as national leaders in the field: Portland, Oregon and Seattle, Washington. Through a literature review and semi-structured interviews, this study describes and analyzes the policy alternatives and instruments Portland and Seattle use; the bureaucratic arrangements and dynamics through which policies are selected and implemented; and the elements that drive, facilitate, and constrain the process. Analysis and synthesis of the case studies provides additional insight as well as a point of departure for further research.