Challies, EdwardTadaki, MarcSinner, JimKilvington, MargaretTane, ParateneRobb, ChristinaDiprose, DavidFluerty, PhillipGreening, RioMason, LeePaterson, BrentRobinson, MartyShearer, Michael2025-07-302025-07-302025-061965-01754AN0D (isidoc)https://hdl.handle.net/10182/19291Water quality decline has proven to be an intractable policy problem worldwide due to the complexity of multiple interests in land and water use. In Aotearoa New Zealand, a proliferation of local catchment groups, including collectives of farmers and other land users and stakeholders, raises important questions about the scope for government to direct collective management towards water policy implementation, and the opportunities and pitfalls of doing so. This paper draws on evidence from a collaborative research project in Aotearoa New Zealand to consider how an emerging catchment-group–led approach might address water policy goals. We examine the emergent policy narrative around catchment groups as a water management solution, and the investment in this approach by government agencies, industry bodies and non-governmental organisations. We then explore a diversity of experiences across four case study catchments. Our focus is on group membership, purpose, relationships, structure and resourcing, with the aim of illustrating how these characteristics of catchment groups influence their ability to carry out policy-relevant actions. We argue that efforts to enlist catchment groups in policy implementation have uneven consequences and that agencies and catchment groups alike should pay attention to the alignment between policy goals and group purpose, to the value of diversity and difference among groups, and to the fine line between supporting and instrumentalising groups towards implementing freshwater policy.pp.440-461en© 2025 The authors.action researchAotearoacollective managementInstitutional Analysis and Development (IAD) frameworkpolicy implementationwatershed groupsJournal Article1965-0175ANZSRC::400411 Water treatment processesANZSRC::310304 Freshwater ecologyANZSRC::370704 Surface water hydrologyANZSRC::440704 Environment policyhttps://creativecommons.org/licenses/by-nc-sa/4.0/Attribution-NonCommercial-ShareAlike