Catchment rainfall, runoff and evaporation were required to support the development of a new response-based estuary classification system based on dilution (from catchment runoff) and flushing characteristics. The classification system was used to stratify estuaries in NSW for the development of reference conditions and the design of a sampling program of chlorophyll a, turbidity and associated water quality parameters to assess estuary health. ; ; Catchment rainfall, runoff and evaporation were also required to support estimation of the loads of Total Suspended Solids, Total Nitrogen and Total Phosphorus exported from estuary catchments.; ; Monthly time series of estimated stream flow, surface flow and base flow were modelled for 197 coastal NSW catchments. Stream flow was estimated using the 2CSalt model.