The Pictou Landing First Nation launched the lawsuit in 2010 demanding the province clean up nearby Boat Harbour and build a new treatment plant for effluent from a pulp mill now run by Northern Pulp.
Residents voted Wednesday to take $100,000 from the Boat Harbour Settlement Trust to help pay for some of the associated costs.
The money will be used to make an application to the court ordering the province to cover the band's legal fees.
A notice posted on the reserve last week from the chief and council said there was not enough money in the band's operating budget for the lawsuit.
Of the 96 ballots cast in Wednesday's referendum, 71 were in favour of using money from the settlement trust.
Chief Andrea Paul says the vote is a step forward for the community.