Protecting the environment continues to be one of Trans Mountain’s most important priorities. We share the value Canadians place on environmental protection, and that’s why we’ve carefully developed measures to protect our ecosystems and mitigate the impacts of our operations.

We are committed to protecting fish and fish habitat, and we push to continuously improve our performance and minimize the impacts of our activities today and long into the future.

Recently, a reporter contacted Trans Mountain regarding allegations made by a biologist who questioned the quality of our work, our commitment to protecting fish and their habitat, and our ability to properly build and maintain infrastructure through watercourses.

Hundreds of watercourse crossings traverse the pipeline route, and when we need to conduct in-stream safety or maintenance work, substantial consideration and efforts go into determining potential environmental impacts and prescribing mitigation methods to reduce the impact to fish and fish habitat.

We are required to submit our plans for operations and maintenance work to our regulatory agencies who assess and approve the work, and inspect the outcome. In addition, third-party environmental professionals conduct environmental assessments, prepare environmental management plans and oversee our works and site restoration projects.

We are also involved with a number of programs to enhance fish and fish habitat. In 2017, Trans Mountain signed an MOU with Pacific Salmon Foundation (PSF) for multi-year salmon programs, including a third-party assessment by PSF of Trans Mountain Expansion Project construction across sensitive salmon-bearing watercourses in British Columbia. The agreement provides $2.5 million in funding to support grants to community groups for salmon conservation, coastal research and a post-secondary education bursary program and up to $500,000 for the third-party construction assessment.

The reporter cited concerns from an individual who was pointing to work done on a 17-metre stretch of Stewart Slough in the Fraser Valley to mitigate the shallow depth of cover over the pipeline. It’s important to note that Stewart Slough provides marginal fish habitat and suitable spawning habitat for salmonids is not present at this location.

From an engineering and habitat perspective, the Stewart Slough crossing is functioning as designed. The ArmorFlex® articulated concrete matting was used to minimize the instream and riparian footprint to the extent possible by providing functional armouring of the pipeline, while also preventing permanent adverse habitat alteration. 

(December 20, 2018. Upstream of the Trans Mountain Pipeline (TMPL) right-of-way (ROW) during a post-construction site inspection.)


The erosion control system allows the natural stream profile and thalweg to be maintained with no alteration of the stream channel and no obstruction to fish migration during summer low-flow conditions. 

(September 17, 2018. Upstream of the TMPL ROW following completion of installation.)


Mitigation measures, including application of gravels and soils over the blocks, were prescribed with the design so the crossing would provide habitat that was functionally similar or improved from the pre-project conditions.

(October 2, 2018. Upstream of the TMPL ROW following completion of installation of topsoil, hydroseeding and riparian planting above the high-water mark.)


Comments made regarding stones being swept away by currents and leaving concrete blocks exposed are inaccurate. There has been no detectable level of mobilization of gravels.

(October 2, 2018. Downstream of Stewart Slough following completion of installation of topsoil, hydroseeding, and riparian planting above the high-water mark.)


Per the original design, gravels were used to infill the open-celled blocks below the high-water mark in order to hasten accumulation of native substrate material (i.e. fine sand, silt and organics) by natural recruitment and re-establish pre-construction in-stream habitat conditions.

(October 2, 2018. West bank of Stewart Slough following completion of construction to show the accumulation of native substrate materials by natural recruitment.)


Qualified Environmental Professionals work with the project Engineer to provide definitive prescriptions for placement of topsoil and gravel materials respective of the high-water mark. The rationale for not applying soils below the high-water mark during site restoration last September was this would have led to increased susceptibility of sedimentation of Stewart Slough.

As construction and site restoration was completed in September 2018, the expectation was it would require a period of sustained high-water levels and flows to allow accumulation of material.

(December 20, 2018. Immediately downstream of the TMPL ROW during a post-construction site inspection showing high-water levels have reached the delineated high water mark. Sustained conditions such as these will lead to further accumulation of native substrate by natural recruitment.)


Consultation was completed with the Yarrow Ecovillage, prior to and during construction, including development of mitigation measures to prevent adverse impacts to the Organic Farm, monitoring during construction activities and engagement for restoration plans. In addition, Indigenous communities were consulted regarding the planned activities to avoid adverse effects to their interests.