Private provision of public goods by environmental groups.

Many environmental nonprofit groups are assumed to provide public goods. While an extensive literature examines why donors join and give to nonprofits, none directly tests whether donations actually provide public goods. We seek such a test by using a common form of environmental organization: watershed groups. We find their increased presence resulted in lower dissolved oxygen deficiency and higher proportions of swimmable and fishable water bodies. Increased donations to and expenditures by the groups also improved water quality. Thus, private groups likely played a role in mitigating environmental problems. Overall, our results indicate private provision of a public good by nonprofit organizations.