Halvergate Marshes were an estuary in Roman times. Around 400 years ago the land was drained and converted to grazing marsh. In the 1980s, further draining was untertaken to convert the area to arable farming, especially oil seed rape whose cultivation was encouraged by the then European Community (now the European Union). Under the Common Agricultural Policy (CAP), the EC guaranteed to buy all the oil seed rape produced. This led to overproduction.
All this meant that wildlife habitats were damaged or lost. The area was then designated as an Environmentally Sensitive Area (ESA), and traditional marshland grazing and water level management was encouraged through cooperation with farmers and landowners. Recently, the Royal Society for the Protection of Birds (RSPB) and the local landowner were awarded the designation of a Site of Special Scientific Interest (SSSI) from English Nature. The farmer had controlled the water level with two dams linked to freshwater underground springs; this provided ideal habitats for marshland plants and animals.
The Marshes are dotted with windpumps, many without sails or even caps. Among the best preserved are Stracey Arms Mill on the River Bure, Lockgate Mill, Mutton's Mill, High's Mill, Cadge's Mill, Kerrison's Level Mill and Runham Swim Mill.
The village of Halvergate is to the west of the Marshes.