Turbidity maxima in estuaries are important due to their influence on primary production, pollutant flushing, fish migration and dredging. There is a need for a better understanding of the dynamics of turbidity maxima. Results are given for the response of turbidity maxima and salinity in the tidal Trent and (Yorkshire) Ouse over time scales of a semidiurnal tide to an annual cycle with respect to tidal and fluvial influences. Under low fresh water flow conditions sediment moves landward and the turbidity maximum is observed upstream of the fresh–salt water interface. Longitudinal dispersion processes governing salinity appear to be dominated by transverse shear induced effects. Suspended solids concentrations within the turbidity maximum are strongly influenced by tidal asymmetry and suspended solids vertical concentration gradient effects and their associated influences. It is proposed that the higher concentrations of suspended solids in the Ouse estuary, compared with the tidal Trent, are due to the influence of the lower fluvial discharge in the appropriate reaches.