Developers of the Mountain Valley pipeline urged federal regulators Monday to greenlight the project by late May, a request immediately met with criticism from environmental groups.

A lawyer representing the joint venture behind the pipeline said construction is nearing completion, and the project will be ready for service in May, according to a filing with the Federal Energy Regulatory Commission (FERC). 

The joint venture called upon the director of FERC's Office of Energy Projects to issue the necessary approval "no later" than May 23, stating that "no further work remains at any of the above-ground facilities."

"Timely authorization is critical to allow Mountain Valley to finalize in-service preparations and Project customers to make final preparations for supplies, scheduling, and nominations," Matthew Eggerding, the project's deputy general counsel, said in the filing.

The joint venture comprises Equitrans Midstream, NextEra Energy, Consolidated Edison, AltaGas and RGC Resources.

The five-page letter addressed FERC's acting secretary, Debbie-Anne Reece, noted that Mountain Valley had finished all water and wetland crossings. According to the letter, about 63% of the 303-mile pipeline was fully restored, meaning its right of way is as close to its original condition as possible after construction.

Environmentalists, however, slammed the request, arguing for further scrutiny and potential damage to sensitive ecosystems.