Southend’s notorious Three Shells Lagoon could be completely demolished less than 11 years after opening, with the council proposing to spend £800,000 removing the troubled seafront attraction and returning the area to a natural beach.
The lagoon, beside Adventure Island and Southend Pier, cost £1.95 million to construct and opened in July 2016. It was designed to give families somewhere to paddle and enjoy the water even when the tide was out.
But the attraction has become infamous for its unpleasant rotten-egg smell, caused by trapped and decomposing seaweed and algae, while accumulated silt and more recent safety concerns have left the site fenced off and unusable.
Southend City Council has already spent approximately £90,000 attempting to tackle the problems, including covering the silt with a layer of sand. Although this helped reduce the smell, the surface has not become sufficiently firm in all areas to allow the lagoon to reopen.
Now, a report going before the council’s Cabinet on Monday 16 November recommends removing the entire structure, including the rocks and steel walls beneath the beach.
Councillor Matt Dent, Cabinet Member for Business, Culture, Music and Tourism, said: “For years, Three Shells Lagoon has been a costly headache for the council and a source of frustration for residents.
“The current administration inherited a site that has consumed significant public money over many years. Management of the lagoon has become increasingly difficult with increased restrictions on what maintenance works can be done. Despite investment under previous administrations, the Lagoon remains fenced off and unusable, and there is no realistic option that avoids further substantial cost.
“We have reached the point where we need to cut our losses. The lagoon has become a monstrosity that is no longer fit for purpose, and restoring the site to a natural public beach environment is the most practical and sustainable long-term solution.”
Who paid for Three Shells Lagoon?
The original project was jointly funded by:
- £1.25 million from the government’s Coastal Communities Fund
- £600,000 from Southend Council
- £100,000 from Stockvale Group, the company behind Adventure Island
Stockvale also covered the costs of preparing the site and securing planning permission.
Responding to residents’ questions, Cllr Dent confirmed that the original lagoon concept came from Stockvale Group, describing it as “essentially, their idea from the start.”
He also acknowledged that council taxpayers would ultimately bear the cost of removing the lagoon.
The Cabinet report proposes funding the £800,000 demolition from the council’s existing capital budget for structures, subject to approval of a viable business case.
Stockvale is not currently responsible for delivering the proposed removal, although the council intends to consult the company if the scheme goes ahead.
With £1.95 million spent on construction, approximately £90,000 on attempted fixes and another £800,000 potentially required for demolition, the lagoon’s combined construction, remedial and removal costs could reach around £2.84 million.
That figure does not include any additional ongoing maintenance or management costs incurred over the years.
Why has the lagoon been such a problem?
According to the council’s report, the lagoon’s design prevents sufficient tidal water from flowing through the enclosed area throughout the year.
Its rock barriers trap seaweed and algae, which decompose and release gases responsible for the distinctive rotten-egg smell.
Changes to marine licensing requirements in 2019 also made routine maintenance and the removal of accumulated material increasingly difficult.
The council says the precise timing and cause of the deeper silt accumulation cannot be established with certainty. It may have built up gradually or been deposited during a significant storm.
During 2025 and 2026, sand was moved from another part of the seafront to cover the silt. While this reduced much of the unpleasant odour, safety concerns remained.
Following a safety incident in 2026 and further inspections, the lagoon was closed to public access. Attempts to improve drainage by removing small sections of the structure were also unsuccessful.
The council has considered alternatives to demolition, including creating a wider opening to improve tidal flow or removing the visible rocks while leaving some buried steelwork in place.
However, these options would cost an estimated £300,000 or more and £700,000 or more respectively, while potentially leaving ongoing safety, environmental and maintenance problems.
Complete removal is now considered the most practical long-term solution.
What happens next?
Cabinet members will consider the demolition recommendation on Monday 16 November 2026.
If approved, and subject to planning permission, marine licences and final funding approval, work could begin in early to mid-spring 2027.
The demolition is expected to take approximately eight to ten weeks.
The proposed work would involve removing the surrounding rock armour, excavating the beach to extract buried steel sheet piles and other structures, and regrading the area to restore its natural appearance.
Some of the rocks could be reused as part of the planned East Beach sand dune restoration scheme in Shoeburyness, reducing the need to import new materials.
The timing of the work would also need to account for environmental restrictions designed to protect wildlife along Southend’s coastline.
If the scheme proceeds, the council says the aim is to return Three Shells to a natural public beach, removing the long-term maintenance burden and allowing natural coastal processes to resume.
For now, the lagoon remains closed, with a final decision on its future still to be made.
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