Coastal monitoring manager Ricky Eyre said contractors hired by the pontoon's owners had removed the largest chunks from the worst-affected island, Kahangaro, on Monday but many small pieces remained. When he returned on Wednesday about 15 workers were on the island collecting the small pieces and loading them onto a barge. They hoped to finish on Kahangaro by the end of Friday.
Mr Eyre said they were also required to clean up the other islands, such as Motukawanui, the largest in the group, and mainland beaches where the council had also found polystyrene fragments.
The Advocate has received reports of polystyrene washing up at Tapuaetahi, well south of the Cavallis, but Mr Eyre said most had been blown north.
He urged anyone who found polystyrene washing up to call the council's 24-hour environmental hotline, 0800 504 639.
Charter operators and Matauri Bay residents have complained about the three-week delay before the pontoon's owners started cleaning up in earnest, but Mr Eyre said the council's priority for now was ensuring the clean-up was completed.