FERC and the U.S. Fish and Wildlife Service (USFWS) have extended an ongoing Endangered Species Act review of the Mountain Valley Pipeline (MVP) by 60 days due to missing information, a regulatory filing this week shows.

Earlier this year, the Federal Energy Regulatory Commission asked the USFWS to reopen its review of the 2 Bcf/d, 300-mile Appalachia-to-Southeast pipeline due to new concerns over the project’s potential impacts to several protected species.

That request triggered a 90-day consultation period that was set to expire this week, but the agencies opted to extend the consultation period to Feb. 10 as USFWS looks to address “identified data gaps” and complete its review.

USFWS requested information from MVP, and the developers “provided a partial response,” according to a letter submitted to FERC this week by a USFWS official. “Based on an initial review of the responses and the fact that all of the information has not been provided at this time, the service determined that additional time is needed to receive and review the requested information and prepare the biological opinion.”

The USFWS Endangered Species Act review, a required component of MVP’s FERC certificate, has come under legal scrutiny in the U.S. Court of Appeals for the Fourth Circuit, a judicial body that has shown it won’t hesitate to toss key permits for natural gas projects.

Days after environmental groups asked the Fourth Circuit to look at how the USFWS issued its Endangered Species Act approvals for MVP, the pipeline’s developers voluntarily halted construction in some areas. The Fourth Circuit still opted to stay the USFWS approvals.

Project opponents have accused the USFWS of failing to protect the endangered Roanoke logperch in its original review of MVP’s plans. They have also claimed that the agency didn’t set limits for the number of threatened or endangered bats that could be harmed or killed by the pipeline’s construction, an argument that caused problems for the similarly routed Atlantic Coast Pipeline.

USFWS had previously indicated it expected to reissue its Biological Opinion (BiOp) for MVP by around Jan. 11, according to analysts at ClearView Energy Partners LLC.

“That timing appears to have been premised on the consultation concluding” earlier this week, they said. “…Based on its earlier representations to the court, we assume Fish & Wildlife plans to complete the BiOp within 30 days of the conclusion of the consultation. Therefore, we do not expect MVP to be able to resume full construction until sometime on or around March 10, contingent on the pipeline providing the necessary information to Fish & Wildlife by or before Feb. 10.”

MVP is a joint venture between EQM Midstream Partners LP; NextEra Capital Holdings Inc.; Con Edison Transmission Inc.; WGL Midstream; and RGC Midstream LLC. MVP received its FERC certificate in late 2017 and started construction shortly after that. According to the developers, the project was 90% complete as of August.