The Coastal Floodplain Prioritisation Study covered seven estuaries on the NSW floodplain. The study included an extensive data collection and collation process to improve understanding of the processes and areas that contribute to poor water quality and improve overall floodplain management. The data delivered here includes information on floodplain drainage infrastructure, soil stratigraphy and hydraulic conductivity, sea level rise vulnerability and drain cross sections. The final outcomes of the prioritisation for the Tweed River floodplain with respect to acid and blackwater generation is also provided.