Over the past two decades, the Murray–Darling Basin has developed a diverse portfolio of ecological monitoring and evaluation programs. Initiatives including the Sustainable Rivers Audit, The Living Murray, Long Term Intervention Monitoring, Flow-MER, Basin Plan Evaluation and the emerging Sustainable Diversion Limit (SDL) Assessments have progressively expanded our ability to assess ecological condition, evaluate management interventions and report environmental outcomes at catchment and Basin scales. Collectively, these programs represent an evolution in both the questions being asked and the evidence available to answer them.
As expectations have grown, so too has the need to draw together evidence from multiple monitoring programs to assess broad ecological outcomes, including species recovery, ecosystem resilience and Basin Plan success. While these programs are often considered collectively, they were established for different purposes, operate at different spatial and temporal scales, and support different types of ecological inference.
Using examples from native fish, waterbirds and floodplain vegetation, we examine how the objectives, design and interpretation of major Basin monitoring programs have evolved, and what ecological questions each approach can legitimately answer. We compare the strengths and limitations of condition monitoring, intervention monitoring and Basin-scale evaluation, highlighting where existing evidence provides robust support for management decisions, where assumptions are required when extrapolating beyond the original objectives of monitoring programs, and where ecological models and multiple lines of evidence strengthen confidence in Basin-scale conclusions.
Rather than proposing new monitoring frameworks, we argue that the next step is to better understand the inferential strengths and limitations of the evidence systems already in place. Reflecting on two decades of monitoring in the Murray–Darling Basin provides an opportunity to identify where existing approaches are well aligned to management questions, where important gaps remain, and how future monitoring, modelling and evaluation can be better integrated to support assessments of ecological recovery.