HALIFAX -- Nova Scotia conducted sufficient consultations with the Sipekne'katik First Nation on a controversial project to store natural gas in underground caverns north of Halifax, the environment minister has ruled.

Margaret Miller released her decision Monday as part of a review sparked by the first nation's appeal of the province's industrial approval for the Alton Gas project near Shubenacadie.

Miller also determined the province's terms and conditions are sufficient to protect the environment.

"The record ... reflects extended efforts by the province to understand, explain, and mitigate against the impacts the Alton Natural Gas Storage project ... would have on fish, fish habitat and Aboriginal rights," Miller said in a letter to the first nation's lawyer, Raymond Larkin.

"I conclude that the level of consultation was appropriate to the circumstances and to the Aboriginal and treaty rights as asserted."

Alton Gas plans to pump water from the Shubenacadie River to an underground site 12 kilometres away, where it will be used to flush out salt deposits, and create up to 15 storage caverns.

The company has been continuing to work on the project, and its status would only have been jeopardized had the minister ruled that there wasn't sufficient consultation with the Mi'kmaq by the Alberta-based firm.

Protesters have gathered at the site for several years, arguing that the plan poses dangers to the traditional fisheries of the Mi'kmaq and risks harming the 73-kilometre river used by Aboriginal populations for thousands of years.

"For me, that river is also sacred," Miller told reporters on Monday, noting she had grown up near it.

However, she said there are safeguards in place to prevent excessive salinity in the river.

Miller said the approval has been amended to require Alton Gas to meet all applicable provincial, federal and municipal laws, including any future amendments to them.

The company is also required to develop an improved communication plan for sharing information with Sipekne'katik First Nation on environmental issues that may require an amendment to the approval.

Miller's ruling comes after a 2017 Nova Scotia Supreme Court ruling that quashed the minister's original decision to dismiss the first nation's appeal after she approved the project in 2016.

Justice Suzanne Hood concluded the first nation was not supplied with the proper documents to mount a proper appeal, although she did not order a stay of the minister's project approval.

The first nation and the company have 30 days to appeal Miller's latest decision.

Neither the first nation nor its lawyer were immediately available for comment.

Lenore Zann, the NDP's environment critic, said she was disappointed by the decision.

"The minister's decision to uphold the industrial approval and say Sipekne'katik was sufficiently consulted is disappointing. There are very real concerns about the affect the Alton Gas project will have on the Shubenacadie River and the Minister continues to side with the company over the water protectors," she said in a statement.

The company has obtained an injunction limiting protesters to a designated area of about 22 metres by 38 metres. Those who don't comply face arrest by the RCMP.