Until 1995, when purchased by the RSPB, the land now forming the reserve was heavily farmed arable land. Since then, the 740-acre (3.0 km2) site has been turned back into the reed beds and grazing marshes that would once have been common in the area. To achieve this, over 2 km of ditches were re-shaped with shallow sloping sides so as to encourage reed growth and to provide feeding areas, particularly suited to great bitterns. A number of sluices were installed to enable water levels to be controlled. In addition to the existing ditches, over 4 km of water channels were dug to re-circulate water around the site.