Canvey Island barriers spanning Benfleet Creek to the north and East Haven Creek in the west. The drainage system consists of sewers, culverts, natural and artificial dykes and lakes which feed seven pumping stations and gravity sluices that discharge the water into the Thames and creeks. Four of the discharge sites are "high flow" stations capable of discharging 600 litres of water per second at any tide level. The levels within the system are managed by a further five "low flow" pumping stations. The Environment Agency's Thames Estuary 2100 flood defence plan includes Canvey Island as one site for alleviating the flood
River Sheppey where it joins Whites River and then the River Brue near Westhay. The water quality is generally good; however, there have been some discharges from sewage treatment works in the area that can contribute to nutrient levels in rivers. Signs of nutrient enrichment are noticeable at times of low flow and the ecology of the Sheppey is adversely affected in its upper reaches. It would appear that the Sheppey was only so called in the late 19th century. Prior to then, if it was called anything, it was probably Doulting Water or the River Brae. The Sheppey has been used