Recent efforts by nongovernmental organizations (NGOs) to reduce the environmental impacts of water impoundment and diversion have pursued two distinct but interacting strategies in California's complex water resources management system: (1) the private acquisition of water rights (wherein the NGO dealt directly with a private citizen and purchased water rights through a willing seller model) for instream or environmental flows or, through water rights transfers, in order to avoid further diversion of groundwater or surface water that could cause environmental harms and (2) active participation in public policy-making processes that attempt to influence the implementation of regulatory mechanisms, federal contracts or other forms of governmental influence to affect the diversion of water or the allocation of water rights in ways that directly address the environmental consequences of water impoundment or diversion. Determining the relative effectiveness of these two distinct (but complementary) strategies and how they interact is therefore relevant to a wide range of water stakeholders. This article compares the relative effectiveness of these two approaches, as well as their interactions, through an evaluation of efforts funded by the Packard Foundation in its Conserving California Landscapes Initiative from 1998–2002.