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
Grand Codroy Estuary estuary since 1974. The estuary consists of adjoining marine and intertidal habitats with an elevation no more than one metre. Four islands are located within the estuary, and the intertidal sandbars give way to mudflats "supporting rich growths of Zostera". The site is surrounded by cultivated grasslands. The marine area is shallow, at most two metres deep in intertidal areas, and somewhat deeper in the river channel. It is bounded by privately owned land, the Codroy Valley Provincial Park, and the Gulf of Saint Lawrence. Nearby are the Grand Codroy and Little Codroy rivers, which are popular fishing destinations. The