Colonial waterbird breeding is an important indicator of wetland health, with active colonies providing a vital sign of a healthy functioning river system. In flood years tens of thousands of colonially-nesting waterbirds can breed in floodplain habitats of the Murray-Darling Basin. Monitoring these breeding events, which now occur less frequently than in the past, is crucial for informing wetland management and policy. Long-term (5-, 10- and 20-year) objectives and targets for waterbirds and other ecological themes have recently been developed by Commonwealth and state governments. These ecological objectives include increased opportunities for waterbird breeding. We collated available breeding records for a 15-year period (2008-2023) to document known colony sites and their frequency of use. A combination of ground, drone and/or aerial surveys of more than 80 colony sites in the Murray Darling Basin were also conducted over four large flood years (2010-11, 2016-17, 2021-22, 2022-23) in this period. This monitoring was done as part of a large collaborative effort by government agency staff, researchers, non-government organizations and volunteers. Data on breeding species, colony extent, stage of nesting, water depth, evidence of mortality and disease was shared with environmental water managers to inform the management of flows. Crucially, monitoring information was shared in real-time during the breeding events through technical advisory groups to support decision-making around flow rates and the duration of flows needed to support the water requirements of key species. The transfer of this information was essential for maximising the likelihood of fledgling success. The results of this long-term (more than a decade) of monitoring have improved our knowledge of colonial waterbird responses to flows and supported the planning and delivery of environmental water.