A group of energy companies has cleared its last regulatory hurdle before piping West Texas natural gas beneath 143 miles of largely untouched Big Bend-area land and into Mexico. 

The Federal Energy Regulatory Commission on Thursday signed off on a stretch of the Trans-Pecos Pipeline that would cross below the Rio Grande, handing a setback to a coalition of ranchers, environmentalists and landowners that sought to thwart the project.

The 42-inch-wide pipeline would start at the Waha storage hub near Fort Stockton and cut through Pecos, Brewster and Presidio counties before crossing the border near the town of Presidio. It could bring up to 1.4 billion cubic feet of gas each day into Mexico, where officials have recently opened up the energy sector to private companies.

Read MoreIn Pristine Big Bend, a Pipeline Could Run Through It

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Its planners include Energy Transfer Partners and Mexico’s Carso Energy — a partnership that links Dallas billionaire Kelcy Warren with Carso's Carlos Slim, one of the world’s richest men. 

Vicki Granado, an Energy Transfer Partners spokeswoman, said the company was “very pleased” with the permit and will finalize construction plans in the coming weeks. It expects to switch on the pipeline by early 2017, she added.

Supporters say the pipeline will bring jobs to West Texas — even if most are temporary — and yield a few million dollars in local tax revenue. Bringing natural gas into Mexico could help wean the nation's border cities off dirtier-burning coal, wood and heating oil.

Opponents say the pipeline will at least temporarily mar the near-pristine landscape and come with safety risks such as explosions and wildfires. Others simply don’t want to lose their land to eminent domain.

The Big Bend Conservation Alliance said it was not surprised by the federal agency’s decision.

“While most of us are likely disgusted, along with a host of similar negative emotions, we already knew that FERC never met a pipeline it didn’t like and that this was the most likely outcome,” the group said in a statement.

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Locals protest the proposed Trans Pecos Pipeline in downtown Alpine in June 2015.

The federal commission considered only the 1,093-foot stretch of pipeline that crosses below the Rio Grande and into Mexico. In the approval order Thursday, it wrote that the segment would have “minimal impact” on landowners and would disturb 7.1 acres of land, and only 1.3 of those acres permanently.

Texas has authority over the rest of the project, which is considered an “intrastate” pipeline. But the state plays no role in routing pipelines or studying environmental effects.

About 426,000 miles of pipeline — about one-sixth of the nation’s network — crisscross Texas, carrying oil, gas and other hazardous liquids. Huge swaths of the Big Bend area are pipeline-free, largely because the region – with its mountains, state and national parks and famously dark skies — is so secluded.

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