Canada's national energy regulator has given Trans Mountain Pipeline permission to dig a trench through the Salmon River near Fort 91Ô­´´ to replace a section of the company's oil pipeline.

Trans Mountain, which is owned by the federal government, applied to the Canadian Energy Regulator (CER) in May for permission to replace about 370 metres of existing pipeline in a stretch that crosses both the river and Glover Road.

The company said it needs te replace the pipe section because of concern over earthquakes, to "ensure the safe operation and long-term integrity of the pipeline system."

To put the new section in place, the company said it will use an "open cut crossing method" in the Salmon River.

The Department of Fisheries and Oceans raised objections to this plan.

"Based on review of the referenced information, we have concluded that the proposed project is likely to result in the death of fish by means other than fishing and/or the harmful alteration, disruption or destruction of fish habitat," a letter from DFO to the energy regulator said.

The letter also said the trench crossing would have "prohibited effects" on aquatic species at risk.

Trans Mountain can go forward with the project if it receives an authorization under the Fisheries Act.

The CER authorized the construction under a list of 11 conditions, including the DFO authorization.

"We're really concerned about this," Gerry Reist, a director of the Salmon River Enhancement Society said of the trenching.

Reist said this fall there have been large coho returning to the Salmon River, an encouraging sign for the local habitat.

But he said trenching across the river will disrupt the environment.

"There's fish in this river year-round," Reist said. 

According to Trans Mountain, the trenching will be done with an "isolated watercourse crossing method," in which river water is diverted or pumped around the crossing while the trench is dug and the pipe is installed. The trench will then be backfilled.

"Trans Mountain is committed to ensuring environmental protection remains a top priority wherever we operate, including operations and maintenance projects," the company said in a statement.

Fisheries biologists would "salvage" fish from isolated areas and release them farther upstream.

The pipeline company has its application under review by the DFO and is waiting for authorization. If approved, the work is expected to be done starting next spring, with restoration work done in 2026.

Reist said he is also worried about another aspect of the project – a large chunk of the replaced pipe is being left in the ground, where it will be filled with grout.

Reist is worried that what remains in the pipe, which is used for shipping oil products from northern Alberta to a refinery and shipment point in Burnaby, will eventually leach into the ground around the creek.

The CER approved the project in mid-November, finding it to be in the public interest. However, Trans Mountain must meet 11 conditions, including getting the sign-off from the DFO. The company has to start the work no later than November 2027.