The Blackwater Estuary is an inlet of the North Sea, approximately 15 km long and 2.5 km wide at its mouth. Flood defence has a long legislative history but modern legislation concerning flood defence starts with the Land Drainage Act 1930, which gave powers to construct flood defence works to newly formed catchment boards. The Royal Society for the Protection of Birds was drawing attention to the need for an integrated coastal zone management and was pressing for there to be a statutory duty on local authorities to prepare Estuary Management Plans. Essex County Council's Interim Coastal Protection Policy produced in response to the government requests covered an area up to five miles inland of the coast. Management of seawalls in the Blackwater Estuary has evolved from a policy of fighting nature so as to 'improve' agricultural productivity to a situation where the importance of working with nature is recognised.