Co-management through local collective action appeals as a way of effectively responding to critical groundwater management issues, including groundwater quality degradation and pumping that lowers water tables. Co-management may also build sufficient trust for stakeholders to agree to investigate, and potentially implement, new opportunities for the use and management of groundwater resources. This paper examines the potential of collective action to underpin co-management and lead to improved groundwater management. The case study is the Angas Bremer (AB) irrigation district in South Australia, which provides a rare example of community-lead groundwater management since the late 1970s. The key questions were: (1) Was the AB an example of collective action, and did that spark successful co-management? and, (2) What were the key outcomes of collective action throughout the years? Data were gathered through semi-structured interviews with key stakeholders. By working together, and with government departments, AB irrigators successfully recovered an aquifer that was at risk of depletion and salinization. Drawing on this evidence, it is suggested that co-management through local collective action may be a useful option for those setting out to improve the social acceptability of new groundwater initiatives in farming landscapes, including managed aquifer recharge (MAR) and conjunctive use of surface water and groundwater.