Sir Peter said he and his fellow producers were deeply shocked and saddened to learn of Hopkins' death, Radio New Zealand reported.
He said many actors, directors, production and post-production crew who were lucky enough to work with him would miss him deeply.
Under Mike Hopkins' guidance New Zealand became recognised as one of the leading hubs of post-production sound in the world, Sir Peter said.
Mr Hopkins was genuine, caring and warm hearted with a great sense of humour.
Their collaboration dated from Braindead in 1992.
Film editor and producer Jamie Selkirk, who also won an Oscar for his work on The Lord of the Rings, said he employed Hopkins when he was a school leaver to run errands in his production company.
But he quickly proved his aptitude in the pioneering area of cinematic sound.
Greytown man Bruce Slater, who was an experienced boatie and was called to the river at about 4pm yesterday, told APNZ the group were "so unlucky".
"To be honest they had all the equipment - they had life jackets, helmets, everything and if they'd been a half an hour or hour earlier they would have got through before the flood came.
"If they were half an hour later they wouldn't have launched the boat because it came down as a wave of water."
The 64-year-old farmer, who is an experienced jet boater, said he and his son Andrew launched the boat from Kuratawhiti street, near the Waiohine Bridge.
The pair picked up Hopkins' wife about 12km along the river.
"She was in a state of shock.''
Mr Slater said when she was rescued, the other man in the recreational rafting group had managed to escape the river but Hopkins had already been picked up by the Westpac Rescue Helicopter.
Hopkins, along with Ethan Van der Ryn, won an Oscar for their sound editing work on King Kong in 2006.
The pair also won an Oscar for best sound editing on the second The Lord of the Rings movie - Lord of the Rings: The Two Towers in 2003.
He was nominated for a Golden Globe for his work on the Transformers movie, but did not win.
Hopkins had a career in sound editing for more than 60 movies and television shows spanning four decades.
He worked on all three Lord of the Rings movies, as well as Kung Fu Panda, and Dreamgirls.
He also worked as sound editor on Sir Peter's 1994 film Heavenly Creatures.