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
Canvey Island the present island, with a ditch being the current boundary, having the same far eastern points as the Canvey Point and Leighbeck Point marshes. Two Tree Island to the north is also recognisable, if halved in length. The third eastern island or mudflat could well be the Counus i.e. "council" Island where the Trinovantes, Cantiaci and the Catuvellauni counselled with the Iceni, shortly before staging Boudicca's rebellion against the Romans. If so Counus occupies an area from the Canvey Point Sand Bank until just before Shoeburyness, the eastern point of the relatively straight estuary so stretched the whole length of