The extent to which the water quality of receiving bodies is driven by sediment load inputs from catchments can be unclear due to coincident processes, such as tidal or wind resuspension of benthic sediments within a coastal water body. We examined whether historical monitoring programs contain information on the linkage between catchment and receiving water body that can help to define the likely effectiveness of catchment erosion management at improving receiving water quality. We used 14 years of turbidity monitoring in rivers draining to Western Port to estimate daily sediment load time-series. We compared loads with remote sensing records of coastal water quality, to define the strength and temporal persistence of the catchment to receiving water linkage. Results were evaluated in the context of knowledge about long-term sediment sources to and storage volumes within the bay. The potential for long-term effects of reducing fine sediment inputs to the bay was considered, as existing deposits are redistributed and stabilised. The findings will help to guide priorities for protecting bay ecosystems and for managing erosion in the catchments and within the bay. Aspects of monitoring programs which can be improved to facilitate these types of analyses are considered, including sampling protocols and satellite-derived products such as MODIS estimations of suspended sediment. The efficiency of sediment delivery to the bay, historical changes in seagrass extent within the bay, and conceptual modelling of seagrass responses to sediment inputs are considered in companion papers.