National Trust sinks three barges to create new bird island

The National Trust has sunk three decommissioned Thames lighters in the Blackwater Estuary and is using up to 8,000 cubic metres of sediment to build a 0.55-hectare island intended as habitat for wading and seabirds.

The National Trust has sunk three decommissioned barges in the Blackwater Estuary, close to Northey Island in Essex. The vessels are flat‑bottomed Thames lighters from the 1950s that were prepared by contractors and towed into place. Holes were cut into their hulls so they could be sunk and then filled with mud to secure them. The sunken barges are being surrounded and topped with sediment to create a new island above the highest tides. Project details: - The three vessels are decommissioned Thames lighters, measuring about 20 to 32 metres in length. - Holes were cut in the hulls to sink the barges, which were then filled with sediment to weigh them down and secure them in place. - Up to 8,000 cubic metres of sediment — roughly the volume of three Olympic swimming pools — is being used to fill and surround the vessels. - A dredge barge will make around 170 trips from Maldon harbour to move the mud for the project. - Once completed the new landform will add about 0.55 hectares (1.4 acres) of habitat just off the eastern shore of Northey Island. - The National Trust says the island is intended to provide refuge for species such as dunlin, curlew, lapwing, ringed plover, little terns and avocets, and to help reduce erosion of nearby saltmarsh. Summary: The sunk barges and added sediment will form a 0.55‑hectare island that the National Trust says will offer refuge for a range of wading and seabirds and help shelter Northey Island's saltmarsh. Work will continue topping the island with gravel and sediment, and the trust will monitor when birds begin to use the new habitat.