It is the policy of the Government of British Columbia to eliminate all combined sewer overflows (CSOs). To give effect to this policy, the provincial Municipal Sewage Regulation establishes requirements for how overflows must be managed and controlled. In response, local municipalities, including the City of Vancouver, have embarked on a long-term program to eliminate combined sewer systems and replace them with separate sanitary sewer and storm drainage pipelines.
The primary objective of this approach is to separate stormwater from wastewater so that rainwater can be discharged directly into receiving waters, thereby reducing the volume of flow being delivered to wastewater treatment facilities such as the Iona Island Wastewater Treatment Plant (IIWWTP). In the absence of separated systems, these facilities can become overwhelmed during periods of heavy rainfall. When this occurs, operators are forced to discharge untreated overflow into nearby receiving waters. This, in turn, has resulted in elevated levels of E. coli, at times exceeding recommended guidelines, along Vancouver’s beaches. The large portion of these overflow events are generally discharged into the Inner Harbour of Burrard Inlet and the Fraser River.
Beyond reducing pollution, separating stormwater from wastewater creates new opportunities for cities to use rainwater as a valuable resource. Stormwater can be captured and managed to support green spaces, replenish local ecosystems, and improve resilience to flooding by increasing system capacity and flexibility.
By establishing the Liquid Waste Management Plan in 2011, the City has committed to eliminate all combined sewer infrastructure by 2050. To guide this effort, the City launched the Healthy Waters Plan in 2021, establishing a long-term, 50-year strategy to achieve complete separation. While this initiative marks a significant step forward, the concept itself is not new.
Following a typhoid outbreak in 1910, the Lea Report recommended the separation of sewer and stormwater systems in Vancouver. However, the proposal was not adopted at the time due to the significant costs involved. A second typhoid outbreak in 1937 led to the recommendation to construct the Iona Island Wastewater Treatment Plant, which was ultimately completed in 1967. Despite this progress, combined sewer overflows into local waterways remained a concern, particularly for First Nations communities. Legal action brought by the Union of BC Chiefs against Metro Vancouver resulted in the construction of a deep-sea outfall, which became operational at IIWWTP in 1988.
As Vancouver’s population has grown, the frequency and impact of overflow events have continued to increase, affecting the environmental and recreational value of the Fraser River, Burrard Inlet, and False Creek. These issues remain a key consideration today, especially as plans move forward to upgrade the Iona Island facility. One of the critical challenges is ensuring that the upgraded plant is appropriately sized to handle current and future flows. This makes it even more important for the City to accelerate its sewer-separation efforts.
Between 1973 and 2021, the City successfully separated and removed approximately 445 kilometres of combined sewer mains. Despite this progress, an estimated 44% of the combined sewer network remains to be separated within the relatively short timeframe between now and 2050.
The City of Vancouver recognises that this undertaking will require significant investment and that achieving complete separation by 2050 may be challenging. Historically, an average of $36 million per year was invested between the 1990s and 2021. Looking forward, it is estimated that this figure will need to increase to approximately $99 million per year in the near term in order to remain on track. While the effort is further complicated by rising construction costs, delivery capacity, and affordability constraints, the commitment remains clear. Nevertheless, these challenges presents the City with an opportunity.
With continued planning, sustained investment, and collaboration across governments and communities, Vancouver has a meaningful opportunity to significantly reduce pollution loading to its receiving waters, modernise aging infrastructure, and establish a resilient, integrated urban water management system for future generations.
References
Foundations for a Healthy Waters Plan – January 2023
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