At least five fire crews will continue efforts to extinguish the suspicious blaze that broke out in Blenheim on Saturday evening.
Around 60 homes were evacuated at one stage when flames threatened a subdivision near the banks of the Taylor River.
Marlborough principal rural fire officer Richard McNamara says while the fire has been contained, a lot of work will continue on Sunday.
"We're bringing in two earth movers because the fire has dug itself deep into some old tree roots, stumps and an old dump site. That's going to have to be dug out, and the only way you can really do that is if diggers are supported by ground crew and heavy water tankers."
Investigators are looking into whether the fire is linked to at least four other suspicious blazes in the area.
Access in the area is restricted to residents only.
The Taylor River walkway and the Wither Hills Farm Park are closed.
Thirty firefighters and six helicopters were used to bring the fire under control.
A total fire ban is in place in Marlborough.
A fire that swept through the Wither Hills on Boxing Day 2000 burned out of control for two days, threatened the town boundary, scorched pasture and killled stock.
NZN / Newshub.