Divers have entered the water on the outskirts of Norwich in a bid to halt sewage spewing into Norwich's rivers.
Work is believed to have been carried out between Monday, February 20 and Wednesday, February 22 in the River Yare at Thorpe St Andrew.
The work, undertaken by Broadland District Council, is in default of a drainage notice issued to prevent sewage from entering the river from the Hearts Cruisers site at Thorpe Island.
IN PICTURES: Look back at Thorpe St Andrew in the 1970s
The exploratory work by divers will establish the scale of work required and ensure there is satisfactory provision for drainage.
River users in Thorpe St Andrew raised fears over environmental hygiene in February 2022, with one reporting waste in the area - popular with paddleboarders, canoeists and kayakers - more than three years ago.
Conservative Broadland District Councillor for Thorpe St Andrew, Ian Mackie, said: "I am very pleased to see action being taken at long last.
"Let’s hope this important step will deliver this pipe as soon as possible.
"It is critical for public health and safety."
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