Metro Vancouver outlines options for new reservoir dams to increase water supply

Jul 30 2020, 12:42 pm

With a growing population and economy, Metro Vancouver Regional District is thinking long-term with the region’s water supply strategy. The region’s population is expected to grow from 2.5 million today to 3.6 million by 2050, and up to about 5.5 million in a century from now.

Water demand will grow from about 390 billion litres per year today to over 600 billion litres per year by 2120.

This requires the regional district to examine options for some serious new water supply infrastructure, especially when the factors of climate change are compounded. It will result in a smaller snow pack that typically acts as a bank for water storage during the dry and warm months, when demand is highest.

Seven future water supply options have been shortlisted in a new report by the regional district, including new dams and flooded areas in the North Shore’s valleys:

Second dam for Capilano Watershed

A second dam with a height of 70 metres (230 ft) and reservoir could be built on the upper portion of the Capilano Watershed to store an additional 100 billion litres of water.

Raising the existing Cleveland Dam at the reservoir is likely unfeasible due to reasons such as land use.

metro vancouver new water supply dams reservoirs

Upper Capilano Reservoir dam option. (Metro Vancouver Regional District)

Upper Seymour Watershed Dam

A 50-metre (164-ft) high additional dam could be built upstream of the existing Seymour Reservoir. This would increase storage capacity by 40 billion litres.

metro vancouver new water supply dams reservoirs

Upper Seymour Reservoir dam option. (Metro Vancouver Regional District)

Lower Seymour Watershed Dam

Another option for the Seymour Watershed is to build a new secondary dam downstream of the existing reservoir, within the Lower Seymour Conservation Reserve, currently used for recreation and education uses.

This would be a 60-metre (197-ft) tall dam to store about 65 billion litres of water.

metro vancouver new water supply dams reservoirs

Lower Seymour Reservoir dam option. (Metro Vancouver Regional District)

Raised Seymour Falls Dam

The existing Seymour Falls Dam could be raised, but the cost and complexity of raising the structure would likely be greater than building a new dam.

The option of a new 53-metre (174-ft) tall dam would be built immediately downstream of the existing dam. It would provide the Seymour Reservoir with an additional storage capacity of 145 billion litres.

metro vancouver new water supply dams reservoirs

Seymour Reservoir raised dam or new dam option. (Metro Vancouver Regional District)

Fraser River Intake

The Fraser River intake option would be located near Fort Langley, but it would require higher levels of water treatment due to the discharges from industrial and agricultural uses. A new water treatment plant would be required near the location.

This location also takes into account future increases in upstream salinity due to potential sea-level rise.

metro vancouver new water supply dams reservoirs

Fraser River Intake option. (Metro Vancouver Regional District)

Harrison Lake Intake

Of all of the options, the Harrison Lake Intake location has the highest construction and operational costs due to the need to build 87 km of new water main, significant pumping capacity, and a new treatment plant. Water quality in this large body of water is “variable,” requiring higher levels of treatment.

metro vancouver new water supply dams reservoirs

Harrison Lake Intake option. (Metro Vancouver Regional District)

Pitt Lake Intake

A large intake structure at Pitt Lake, located northeast of Coquitlam, would take advantage of the lake’s high capacity to store volume of water throughout the dry season. The mid-lake intake would be near the existing transmission system. But Pitt Lake currently has many water uses, and water quality is generally lower than the pristine mountain watersheds, requiring higher levels of treatment including a new water treatment plant. The operating costs are deemed to b relatively high due to the pumping and treatment required.

metro vancouver new water supply dams reservoirs

Pitt Lake Intake option. (Metro Vancouver Regional District)

The regional district has determined the Pitt Lake Intake option could meet regional needs, especially if future regional growth is more focused within Metro Vancouver’s eastern municipalities.

But it could be many decades before any of these options need to be implemented, as the region can still increase its water supply by optimizing existing infrastructure, and making its operations and the region’s residents and businesses become more efficient with their water consumption.

metro vancouver new water supply dams reservoirs

New water supply options for Metro Vancouver. (Metro Vancouver Regional District)

metro vancouver new water supply dams reservoirs

New water supply options for Metro Vancouver. (Metro Vancouver Regional District)

Some of the regional district’s largest upcoming capital projects will allow more water to be tapped from Coquitlam Lake, the largest of the three main water reservoirs.

A new $485-million water main in Coquitlam will be completed by 2026, and second intake for Coquitlam Reservoir with new treatment facilities at a cost of $2.3 billion will be ready by 2035. The second intake tunnel will be built much deeper to ensure the reservoir’s supply can still be optimally used when the water level drops during the summer.

Another project is the new 2.3-km-long Annacis Water Supply Tunnel below the Fraser River between New Westminster and Surrey at a cost of $448 million.

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