Clean-up of Norwich River Wensum continues after 3,000 fish die

Hebditch said the incident was “particularly significant” due to the River Wensum being a protected chalk river. She added that these events were likely to increase in frequency due to climate change.

There have also been reports of fish found dead elsewhere in the county on the River Yare in Trowse and at Cantley, east of Norwich.

Anglian Water said a storm overflow discharged at the Trowse pumping station on the River Yare for two hours last Thursday and subsequently people reported fish and other aquatic life in distress.

The company said it was working with the Environment Agency to investigate the incident.

Oxygen levels have now “improved significantly”, the firm added.

Storm overflows are used to prevent flooding and discharge excess sewage and rainwater into rivers and coastal waters.

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The stretch of the River Wensum where the incident was discovered is a popular spot for paddle boarders and people using canoes, with multiple hire firms located in the city.

Anglian Water workers continue to clean up the Wensum, and Norwich City Council and the Broads Authority are also assisting.

Council workers said they had collected about 1,200 fish in two days, focusing on larger species, while Anglian Water said it has collected 2,126.

People have complained there has been a strong smell along the river in the past few days.