Contrasting long-term trends of near-coast river turbidity across major catchments draining to the Great Barrier Reef Lagoon

River water quality upstream of the Great Barrier Reef Lagoon represents a history of the catchment changes. We investigated multi-decadal trends of river turbidity at five sites close to the river mouth within each of the Barron, Herbert, Burdekin, Fitzroy and Mary catchments. We estimated trends by an advanced water quality statistical model, the Weighted Regression of Time, Discharge and Season (WRTDS). End-of-catchment turbidity has increased in Fitzroy (the most turbid catchment analyzed), and decreased for Burdekin (the second most turbid catchment analyzed). Trends of Herbert, Barron and Mary catchments are highly uncertain. Apart from the Barron, most of the turbidity trends cannot be explained by long-term changes in streamflow, pointing to the likely influences of historical land use/land cover changes, land management and other major catchment changes. Our study provides a first step towards assessment and attribution of time changes in sediment export for the catchments studied.