Water level at Sasamat Lake could drop by 2 metres if aging dam removed

Imperial Oil's dam onSasamatLake has been in place for a century, but the company says it's now considering its removal.

The decision could have wide-ranging effects on the Port Moody, B.C., lake, which is a popular destination for Metro Vancouver residents.

"We really don't have a need for the dam anymore,'' said Ali Tejpar, project manager of theSasamatLake Dam Project.

Imperial Oil sent a delegation to Port Moody council on Jan. 10, presenting two possible options for the future of the site: decommissioning, or replacing the dam.

SasamatLake Dam was installed on the northwest corner of the lake around 100 years ago to draw water for operations at the refinery on Ioco Road in the Port Moody Arm.

The lake hassince grown into a popular recreational area for the region, containing White Pine Beach, theSasamatOutdoors Centre, a pedestrian floating bridge and walking trails.

The dam was replaced in the 1960s. However, since the Ioco refinery was converted into a terminal in 1995, the company's operational usage of the dam has lessened considerably.

In August 2019, the Ministry of Forest, Lands and Natural Resource Operations conducted an inspection of the dam and observed seepage.

It ordered Imperial Oil to create a plan to address the issue.

The company first thought it could repair the dam, according to Tejpar, but a review by a consultant showed repairs would only result in a temporary fix to long-term safety and reliability issues.

2 options

Since March 2021, Imperial Oil has come up with two options, and is consulting with stakeholders and local First Nations to hear further concerns.

It has contracted Stantec, an engineering company, to conduct a series of environmental impact studies for both options.

Further geotechnical exploration is slated to begin in February.

Tejpar said Imperial Oil's primary responsibility is to ensure the dam is "adequately maintained and safe."

Option 1is to replace the dam with a similar structure installed under modern engineering specifications and regulations.

There would be almost no change to the existing water levels, and limited impactto vegetation, wildlifeand fish habitats only in the immediate area of the dam footprint, according to Joel Pineu, a geotechnical engineer with Stantec.

Some of these impacts could be easily mitigated during construction, he added.

Option 2would be decommissioning the dam Imperial's preferred option, according to Tejpar.

This would involve the complete removal of the existing dam down to the bedrock surface, lowering the water level ofSasamatLake by around two metres.

Pineu said there would be some long-term changes and residual effects to the wetlands and riparian vegetation, though it's not expected to affect local wildlife permanently.

There would also be some temporary impacts to fish habitat and fish productivity, as it would reduce shallow water areas until new wetlands could form, he added.

SasamatLake naturally flows into Windemere Creek in Belcarra, and environmental impact and flood-routing studies were conducted to examine what would happen if the dam were removed.

Pineu said the creek has limited fish habitat, and there would be minimal differences between replacement and decommissioning options.

He said they don't expect any impact to Belcarra residences or local bridges should a one-in-100-year flood occur in a "rainfall-only'' scenario.

In either design option, Imperial Oil would include a pedestrian bridge to cross the lake, Tejpar said.

Council comments

Lesley Cabbot, engagement specialist with Stantec, told Port Moody council they hadbeen in contact with Metro Vancouver, the villages of Belcarra and Anmore,SasamatOutdoors Centre, and First Nations in the area, with the Tsleil-Waututh Nation taking the lead.

Tejpar said there was too much feedback to go over during thepresentation to council, but saidmost concerns were voiced over the decommissioning option.

He said Imperial Oil is trying to make a "fact- and data-driven'' decision, and to understand the scope of concerns. At this point, however, the company does not plan on conducting any engagement with the general public.

Mayor Meghan Lahti advised the company to consider engaging with the people who use theSasamatLake facilities.

Coun. Haven Lurbiecki agreed, calling further engagement "absolutely critical'' and describing the area as a recreational asset for the entire region.

The company's flood modelling for Windemere Creek was questioned by Coun. Amy Lubik, whoasked if there were any more extreme models beyond a "rainfall only'' scenario if flooding occurred should the dam be removed.

Pineu said studies were based off Belcarra'sone-in-100-year flood modelling, and the only events that resulted in some flooding were heavy rainfall on top of snowmelt.

But Lubik said the climate is rapidly changing, highlighting the recent atmospheric river events in B.C., and questioned whether Belcarra's modelling was sufficient.

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