The leak is reported to have come from the Wytch Farm oil field and processing facility, and was discovered on 26 March.

A major incident was declared and members of the public have been urged not to swim in the harbour or nearby until further notice.

The pipeline is operated by gas company Perenco, under Ower Bay. Perenco has reported “no risk” of further leakage, and said the surface slick is “already dispersing.”  They stressed the situation is “under control” with the discharge of fluids stopped and “the spill being contained.” The pipeline had been shut down, and booms placed either side of the leak.

Poole Harbour Commissioners reported that an estimated 200 barrels of reservoir fluid “has been released into the water column in Poole Harbour.”

Poole is the largest natural harbour in Europe. Paul Morton from the charity Birds of Poole Harbour, said: “Poole Harbour is an incredibly important area environmentally. It has multiple protective designations in place including the Poole Harbour SPA (Special Protection Area), the Poole Harbour SSSI (Site of Special Scientific Interest) as well as being a designated RAMSAR site in which it is recognised as an internationally important wetland. The reason it has such a high level of protection is because of the important range of habitats and species that call Poole Harbour home.

“Although we don’t know the full extent of yesterday’s spill yet, the fact it’s happened right in the middle of such an environmentally important area is incredibly worrying. Poole Harbour hosts nationally and internationally important numbers of wetland birds each winter and equally important numbers of other species including Sandwich and Common Terns which nest on Brownsea each summer. Right now we’re in that important transition period where our winter birds are leaving, and our summer birds are arriving, many of which use the southern shore of the harbour for feeding, nesting and hunting. Each month we conduct Wetland Bird Surveys across the harbour to monitor populations of over-wintering birds. The last survey which was conducted on March 5th logged 5450 birds along the southern shore in the spill area.

“The local community have an incredibly strong attachment to the harbour and its environment which was highlighted yesterday morning when our male osprey arrived back safely from West Africa, exciting thousands of people as he landed on the nest seen via a camera we installed this winter. With the female expected to arrive back in early April, they are the only pair of osprey in southern Britain, having bred for the first time in 2022 after an absence of 200 years. The elation of the males safe return home yesterday morning was soon dashed by late afternoon when news of the oil spill was announced. Ospreys exclusively eat fish, and our pair hunt in the harbour about 95% of the time during the spring and summer season feeding on grey mullet, flounder and bass.

“Over the next few weeks both Sandwich and common tern will be arriving back from their wintering grounds to nest on Brownsea, and will be reliant on fishing in the harbour to feed their young. Breeding waders have just begun courtship with oystercatcher and redshank currently settling on the beaches of Poole Harbours islands and salt marsh. Right now huge numbers of birds are on the move, having over-wintered further south and will soon be using Poole Harbour as a service station to feed up before continuing north. When it comes to an issue like this there are several areas of concern. One is that any birds that come into physical contact with this substance can see their feathers damaged and become less water resistant. The substance will also encourage any affected birds to preen constantly, meaning they could ingest the hazardous liquid. The other unknown is how much of the oil will settle on the mud and harbour shorelines and what impact that will have on marine invertebrates. There are so many unanswered questions currently, although thankfully, as of yet there have been no confirmed reports of any birds showing signs of distress as a result of the incident, although it is still early days.

“We will be in constant communication with local partners and the community over the coming days to ensure we’re able to support where we can and ask that the public remain vigilant and report any birds that look in distress to ourselves so we can report it to the relevant organisations.”

Birds of Poole Harbour is a charity set up by Poole local Mark Constantine, Co-Founder and CEO of Lush (one of the largest businesses in the area).