Furious anglers claimed on Friday that the Broads Authority had failed to properly listen to their concerns that dredging Heigham Sound on the Upper Thurne could trigger a bloom of fish-killing algae.

Furious anglers claimed on Friday that the Broads Authority had failed to properly listen to their concerns that dredging Heigham Sound on the Upper Thurne could trigger a bloom of fish-killing algae.

Representatives of Norwich and District Pike Club (NDPC) looked on as the Authority's planning committee approved a scheme to dredge Heigham Sound and then use the spoil to restore an eroded spit of land that once separated the waterway from Duck Broad.

In the public speaking section of the meeting, NDPC committee member John Currie voiced anglers' fears that disturbing sediment through dredging could trigger a repeat of the 1969 catastrophe when an outbreak of the algae prymnesium parva decimated fish stocks in the Thurne system.

He claimed prymnesium, which releases a deadly toxin when it dies, was like a “time-bomb” and said experts at English Nature and the Environment Agency had backed up their concerns over the possible danger of triggering a bloom by disturbing the sediment.

Mr Currie questioned why the Authority had not consulted known experts from other countries and said it had failed to provide the meeting with sufficient details of how it intended to monitor prymnesium levels during the dredging and spit construction.

After the meeting he said: “Although I was allowed to speak, when I later interrupted to answer the Broads Authority's claim that there is no documented link between dredging and prymnesium outbreaks, I was told to shut up. That is not democracy.”

He said he was not satisfied by the committee's agreement that the initial reclaiming of a 20sq m trial area using mesh baskets filled with spoil would only be followed by construction of the full spit - 240m long and 40m wide - after a review by interested parties, including the Environment Agency and angling groups. “Consultation at that stage could be too late,” he said.

Rob Rogers, the Authority's head of construction and facilities, gave an assurance that water monitoring would be carried out on a weekly basis and work would stop if prymnesium levels rose.

He said it was agreed that after the trial, no further construction would take place until everyone was happy.

The Authority was also working with the Environment Agency to ensure emergency fish rescue plans were in place, he added.

Members of the planning committee also responded.

Martin Broom said: “This application is about the construction of the island as planning permission is not needed for dredging.

“The fact there is going to be all this monitoring should be a comfort for anglers. If a ready site for disposing of the spoil had been available, dredging would have just taken place and this imaginative scheme would not have been necessary.”

Alan Mallett said that while everything was being done to address concerns, there was a genuine need to dredge Heigham Sound as boats running aground there was a common problem.

Elizabeth Burrows said while recognising the long-term need to dredge Heigham Sound, it was a nationally renowned fishing area and listening to the anglers' concerns had to be part of the way forward.