The proportion of the catchment sediment yield stored in a reservoir is a measure of the system's trap efficiency. The use of empirical relationships, such as Brune (1953), has been widespread but in many cases is found to be inappropriate because of local hydrodynamic conditions. Wyresdale Park Reservoir, Lancashire, has been instrumented to evaluate the present suspended sediment transmission and trapping characteristics of the system. A data-based mechanistic approach to modelling suspended sediment routing and deposition at the event scale has been adopted by applying a transfer function model generated by the microCAPTAIN computer software package developed at Lancaster University. The analysis of hysteresis loops from storms provides a method for analysing the delivery of suspended sediments from the catchment as well as the relationship between suspended sediment concentration and discharge at the reservoir outflow.