This report presents the findings of a data benchmarking exercise commissioned by the Murray-Darling Basin Authority (MDBA). The report intends to improve understanding of current Aboriginal surface water and groundwater access and basic demographic data across current water management units in the Murray-Darling Basin (MDB). The MDBA commissioned this work following similar research that the lead author completed as part of her PhD at Griffith University (Hartwig, 2020). That work examined Aboriginal water entitlements for only the NSW portion of the MDB (see also Hartwig, Jackson & Osborne, 2020). The specific tasks of this project were to: • Update (2016) Aboriginal population statistics for all regions across the Basin, based on Surface Water Sustainable Diversion Limit (SDL) resource units; • Establish a Basin-wide 2020 Aboriginal water holdings baseline/s that is compatible with Basin Plan water accounting methods; • Where possible, document changes to Aboriginal water holdings over the last 10 years; • Identify features of entitlement and licencing systems and recordkeeping that limit future monitoring of Aboriginal water holdings; and, • Develop recommendations for the MDBA and the Basin States and Territories to improve monitoring of water access for Aboriginal peoples and inform future research. The information contained in this report will be useful to policy-makers and officials from the MDBA, the Indigenous Land & Sea Corporation (ILSC), New South Wales Aboriginal Land Council (NSWALC), and various state and federal government agencies. It will also be of use to Basin Aboriginal peoples and their representative organisations, including (but not limited to) the Murray Lower Darling Rivers Indigenous Nations (MLDRIN) and Northern Basin Aboriginal Nations (NBAN). More specifically, these baselines will be of crucial importance to current government efforts to develop new policies and programs targeted at improving Aboriginal water access in line with national water policy; evaluate and monitor existing plans and programs (including the Basin Plan); and, assist First Nations people to contribute to water policy. It also complements the recent assessment of social and economic conditions in the MDB (Sefton et al., 2020).