Anti-pipeline activists on Saturday vowed to continue to fight the PennEast Pipeline, a $1.2 billion project to deliver Marcellus Shale natural gas from Pennsylvania to New Jersey that received critical federal approval Friday.

Environmental groups and residents along the 120-mile pipeline route said they would mount legal challenges and increase political pressure in New Jersey to deny the project the state water permits it needs to begin construction.

But Friday’s approval by the Federal Energy Regulatory Commission (FERC) of a certificate of public convenience means the pipeline, which is being built by a subsidiary of UGI Corp. of Valley Forge, can begin to acquire easements by eminent domain, if necessary.

"Approval of the PennEast Pipeline is a major victory for New Jersey and Pennsylvania families and businesses," Anthony Cox, chair of the PennEast Pipeline Co. LLC, said in a statement. He said consumers will benefit from lower gas and electricity prices, and reduced emissions from gas displacing other fuels.

The pipeline's owners said the recent cold snap underscored the need for the pipeline, when natural gas prices soared near New York City because demand exceeded the capacity of existing pipelines.

But pipeline opponents say the project is unnecessary, and will endanger residents and the environment.

"New Jersey doesn't need or want this damaging pipeline, and has the power to stop it when it faces a more stringent state review," said Tom Gilbert, campaign director, New Jersey Conservation Foundation.

Pipeline opponents took heart that the courts recently upheld the right of New York State environmental regulators to block the FERC-approved Constitution Pipeline, which aimed to tie New York and New England into Pennsylvania's gas fields.

The FERC voted 4-1 to approve the pipeline, but included 56 environmental conditions the company needs to meet before construction begins. The project's design and survey work is incomplete because many landowners declined to permit the company to access their property.

PennEast says it aims to start construction this year and begin operations in 2019. The pipeline is designed to deliver 1 billion cubic feet of gas a day. About 90 percent of the pipeline capacity is subscribed by a dozen customers, including New Jersey Natural Gas, South Jersey Gas, Elizabethtown Gas, PSEG Power, and ConEd.