A traditional Cook Island leader of an area near Rarotonga's Muri lagoon says dredging should be done now to save the waterway.
A combination of factors is believed to be behind the algal growth which has been spreading in the tourist hotspot since late 2015 and consultants have been engaged to find a solution within 18 months.
Manavaroa Mataiapo Tutara of Avana, Philip Nicholas, said there was no time to wait for another consultants' report and drastic action was needed.
He said one of the channels into the lagoon, the Avana-Ngatangiia harbour, was virtually silted up affecting not only Muri but the local community and fishers.
"If we can get in there and remove all that sand, dredge that sand out, we should see an immediate improvement in the flushing of the whole lagoon from Muri down to Avana."
Mr Nicholas said the sand had been building up over the years, going from 4.5 metres to 1.5 metres deep in some areas.