RICHMOND — Environmental groups had planned an event here Tuesday to call on Gov. Ralph Northam (D) to slow the permitting process for two major natural gas pipelines, only to learn that one of the projects got its permits the night before.

The state Department of Environmental Quality announced that it had issued approvals for the Mountain Valley Pipeline after 7 p.m. Monday. Workers on the project have begun clearing trees along its path, but this sign-off from the state will let full construction get underway.

Opponents of the 303-mile pipeline, which runs the length of West Virginia and through the heart of Virginia’s mountainous southwest, said the process was flawed.

Residents along the Mountain Valley route have “been asking Gov. Northam and his administration for one more chance to review these critical water pollution control plans before the DEQ finalized them and allowed construction to proceed. In an affront to all Virginians, this decision shut them out,” Peter Anderson of the group Appalachian Voices said via email.

But the environmental department said the project has been subjected to “enhanced review” and that every step has been open to public scrutiny.

“Protecting water quality and water supplies is our greatest concern,” Department of Environmental Quality Director David K. Paylor said in a news release. “We required [Mountain Valley Pipeline] to submit detailed plans for every foot of land disturbance, and we carefully reviewed all aspects of these plans.”

Ann Regn, spokeswoman for the state environmental agency, said the announcement had been delayed for several weeks as the review was completed. “It is not at all connected to when [the environmental groups] were coming to town. We were trying to get it out as soon as they had the plans up,” Regn said.

The Mountain Valley Pipeline is being built by a coalition of companies, led by EQT Midstream Partners, to carry fracked natural gas.

A bigger project led by Dominion Energy, the Atlantic Coast Pipeline, is being planned simultaneously for the western and southern parts of the state, and is several weeks behind Mountain Valley in the permitting process.

Both won green lights from the State Water Control Board in December, pending review of specific plans for erosion and sediment control, storm water management and impact on the fragile underground geology called karst. It was those plans for the Mountain Valley Pipeline that the state approved this week.

Work on that pipeline has been hindered by protesters. Two opponents have been sitting in trees atop a mountain just across the state line in West Virginia for 27 days and counting. A judge refused to order them to come down, and the pipeline builders have warned that they could face costly delays if the protest continues.

Tuesday’s event in Richmond was to draw attention to both pipeline projects and to deliver petitions to Northam calling for closer review of the environmental impact. Organizers said they had more than 10,000 signatures.

Northam’s spokeswoman said the governor has full faith in the Department of Environmental Quality and its process. The state has subjected the projects to “the most rigorous, thorough and environmentally conscious review process in Virginia history,” Ofirah Yheskel said via email. “The governor is confident in the agency’s plans to monitor any construction activity permitted to occur and its commitment to enforce compliance with its new stop-work authority.”