Northern Australia is notable for its expansive river catchments, which represent vital components of the region's hydrological and ecological systems. In the Gulf Country of north-western Queensland, the 'wet season' constitutes a pivotal period during which copious rainfall inundates the landscape, often extending into the seascape as flood plumes, driving renewed productivity and biodiversity in coastal and oceanic ecosystems. While the current water plan for this region has been largely effective in advancing sustainable water resource management, it does not necessarily support growth in irrigated agriculture or the emerging critical minerals industry, and a water plan review is currently underway. Here, we have utilized 20 years of satellite imagery to quantify flood plume extent and chlorophyll-a production during peak wet season flows in the Gulf of Carpentaria. We found a high correlation between flow volume, total plume extent, and chlorophyll-a production, and we modeled how reduced flows through water reallocation and/or climate change could affect this system. Due to high variability in annual rainfall, not all years have large flow events, and increased water allocation during low-flow years could be catastrophic for coastal biodiversity, fisheries, and migrating birds.