Stormwater run-off is an important component of the hydrologic cycle of urban watersheds. There is increasing concern with the water quality of stormwater run-off, in addition to the effects of flooding. Changes in the structure of watersheds and in human behavior are important to improve stormwater quality. These changes often require support for government programs and voluntary actions. Environmental knowledge and social cohesion may be two important factors that affect support for urban watershed improvements. We compared temperate Baltimore, MD and arid Phoenix, AZ to examine the relationships among watershed knowledge and social cohesion and support for taxes or voluntary actions to improve local urban watersheds. We also test two social concepts—the “crowding out” and “snowball” effects. Crowding out effects suggest that government activities will crowd out a willingness to volunteer. Snowball effects suggest that voluntary actions are more likely when they complement existing government activities. Using a telephone survey (n = 3,273), we find that watershed knowledge is positively associated with both taxes and volunteering in Baltimore and had no relationship in Phoenix. Social ties are negatively associated with support for taxes and positively associated with volunteering in both cities. We found evidence for the snowball effect: participants who supported a tax were twice as likely to support volunteering. These findings are relevant to the long term dynamics of urban watersheds because the deterioration or improvement of urban watersheds is critically tied to the willingness and capacity of social actors to intervene.
Article published in Landscape and Urban Planning.