An iwi and hapu estimate the clean-up of the contaminated Lake Horowhenua near Levin will cost up to $10 million.
This week, the Government along with four other groups announced they'd be putting up $1.27 million to spruce up the rotomoana (lake).
Muaupoko and Ngati Pareraukawa have designed their own restoration proposal for the lake, and the nearby Hokio stream.
Chair of the initiative Whatarangi Winiata says it's a big job, which includes getting rid of sediment and weeds.
He says through its evaluation it could cost between $5 million to $10 million to clean the lake up properly.