Pipeline Profiles: Enbridge Mainline

Pipeline system and key points

Section updated June 2020

The Enbridge Mainline system is Canada’s largest transporter of crude oil, moving Western Canadian crude oil production to markets in eastern Canada and the U.S. Midwest. The Mainline also transports refined petroleum products to Saskatchewan and Manitoba and natural gas liquids to Sarnia, Ontario. The first leg of the Mainline from Edmonton, Alberta to Superior, Wisconsin was built in 1950. In 1953 it was extended to Sarnia, Ontario. The Mainline has been expanded and upgraded during the last thirty years to its current configuration and capacity.

The Mainline originates in Edmonton, Alberta and extends east across the Prairies. It receives western Canadian crude oil from feeder pipelines at Edmonton and Hardisty in Alberta, Kerrobert and Regina in Saskatchewan, and Cromer in Manitoba. The Mainline also receives U.S. crude oil from the Wascana Pipeline at Regina and the Enbridge Bakken pipeline at Cromer. The pipeline crosses the Canada-U.S. border near Gretna, Manitoba, where it joins with the Enbridge Lakehead system.

At Clearbrook, Minnesota, the Mainline receives U.S. crude oil from the Enbridge North Dakota pipeline and connects with the Minnesota Pipe Line that can deliver crude oil to refineries in Minnesota and Wood River, Illinois.

At Superior, Wisconsin the Mainline branches in two segments. The northern pipeline passes through northern Wisconsin and Michigan before crossing into Ontario at Sarnia. The southern leg contours south of Lake Michigan to Lockport and Chicago in Illinois before turning northeast passing though Indiana and Michigan. It re-enters Canada at Sarnia, Ontario.

Enbridge Mainline pipeline system map

Source: CER

Text version of this map

This map provides an overview of the Enbridge Mainline Pipeline System.

At Sarnia, the Mainline connects with Line 9 and Line 7, which deliver crude oil to Montreal, Quebec; Nanticoke, Ontario and Warren, Pennsylvania. There is also a lateral pipeline connecting Sarnia to the Mid-Valley pipeline system, which delivers crude oil to refineries in Michigan and Ohio before connecting to a pipeline hub in Texas.

Two laterals (Lines 17 and 79) from Stockbridge, Michigan link the Mainline to refineries in Toledo, Ohio. At Chicago and Flanagan, Illinois, the Mainline links with the Southern Access Extension Pipeline (SAX), Mustang, Spearhead, Flanagan South and Chicap pipelines to deliver crude oil to pipelines and refining hubs at Patoka, Illinois and Cushing, Oklahoma.

Enbridge Mainline System Configuration (2019)

Figure 1: Enbridge Mainline System Configuration Details

Figure 1: Enbridge Mainline System Configuration Details

Source: Enbridge Mainline System Configuration (2019)

Text version of this graphic

This diagram provides an overview of the configuration of the Enbridge Mainline System.

In December 2015, the Line 9B Reversal and Line 9 Capacity Expansion Project became operational, enabling Quebec refiners to access western Canadian crude oil by pipeline.

In 2014 and 2015, Enbridge completed the Canadian portions of the Alberta Clipper (Line 67) Expansion Project, increasing capacity by a total of 55 600 cubic metres per day (m³/d) (350 000 barrels per day (Mb/d)) to the full design capacity of 127 100 m³/d (800 Mb/d). This, together with flexibility enhancements, has resulted in higher throughputs on the Enbridge Mainline.

In 2014, Enbridge filed an application with the CER for the Line 3 Replacement Program which would restore capacity of the pipeline to 127 200 m³/d (760 Mb/d) by 2019. With the recommendation of the Board, the federal Governor in Council approved the project in November 2016.

The $5.3-billion Canadian portion of the Line 3 Replacement Program went into service in December 2019. With the new replacement line operational, the existing Line 3 pipeline in Canada will be decommissioned in accordance with regulatory requirements. Enbridge awaits final permitting before construction can begin on the majority of the US$2.9 billion U.S. portion of the project.

Official CER documents related to the construction, operation and maintenance of the Enbridge Mainline pipeline can be found here: Enbridge Mainline regulatory documents [Folder 92263].

You can see the Enbridge Mainline and all CER-regulated pipelines on the CER’s Interactive Pipeline Map. The map shows more detailed location information, the products carried by each pipeline, the operating status and more. You can also see a map on Enbridge’s website.

Throughput and capacity

Section updated quarterly (early March, mid-May, mid-August and mid-November)

Note: The physical capacity of a pipeline is based on many factors such as the products being carried, direction of flow, pipeline pumping capacity, and maintenance work or other pressure restrictions. The actual physical capacity of the pipeline may, at times, be higher than the assumed operational capacity stated here.

Open data can be freely used and shared by anyone for any purpose. The data for these graphs are available.

Nomination and Verification Procedures

Section updated June 2020

Pipeline tariffs specify the procedures by which shippers are to submit nominations for transportation service, including the form and timing of nominations. The tariffs also set out the rights and authorities of pipeline companies to verify nominations. The CER regulates and determines compliance with tariffs for pipelines under its jurisdiction, which include the major export pipelines from western Canada. Pipeline companies and shippers are required to follow the rules and regulations of transportation service as set out in the tariffs.

Enbridge uses three types of verification on the Enbridge Mainline. First, supply is verified by requiring each shipper to submit a certificate, executed by an officer of the shipper company, confirming that the shipper has the capability and intent to tender each crude type and volume, and that the nomination has not been inflated to factor in apportionment. Second, volumes must be verified by the connecting upstream facility. Third, each downstream destination facility must submit monthly verification affidavits, attesting that it is capable of receiving, and intends to receive, the crude oil volumes nominated to it.


Section updated June 2020

A shipper must submit nominations each month to it wishes to move its oil on a pipeline. Shippers must submit nominations for both committed (or contracted) transportation service, if available, as well as uncommitted transportation service. If the total volume of nominations for uncommitted capacity is more than what is available, the pipeline company must “apportion” the nominations.

Apportionment is the percentage by which each shipper’s nominated volume is reduced in order to match the pipeline’s uncommitted capacity. Generally, apportionment is applied equally across all shippers seeking to use that capacity: for example, if shipper A nominates 100 barrels and shipper B nominates 1 000 barrels, then, under 10% apportionment, shipper A will be able to ship 90 barrels, and shipper B will ship 900 barrels.
The interactive graph below shows data for nominations and apportionment on the Enbridge Mainline.

Open data can be freely used and shared by anyone for any purpose. The data for these graphs are available.


Section updated June 2020

A toll is the price charged by a pipeline company for transportation and other services. Tolls allow pipeline companies to safely operate and maintain pipelines. Tolls also provide funds for companies to recover capital (the money used to build the pipeline), pay debts, and provide a return to investors. The interactive graph below shows the tolls for key paths on the pipeline since 2006.

Open data can be freely used and shared by anyone for any purpose. The data for these graphs are available.

Mainline tolls are set according to a negotiated settlement, the Competitive Toll Settlement (CTS), which is in effect from 2011 until 2021. The tolls are fixed, meaning they don’t change a lot from year to year. However, tolls are adjusted annually with the gross domestic product index and other factors. Because tolls are fixed, if throughput decreases Enbridge faces additional financial risks compared to the previous cost of service tolling method. Shippers pay international joint tolls for crude oil shipped from Canada to the U.S., or Canadian tolls for crude oil shipped solely within Canada. These tolls are based on volumes, the various pipeline routes (combinations of receipt and delivery points) and the qualities of the crude oil to be shipped.

The Enbridge Mainline currently provides entirely uncommitted capacity to its shippers. In December 2019, Enbridge filed an application with the CER for approval of a new service and tolling framework, seeking to have it in place when the current CTS expires. Enbridge proposes to offer long-term contracts on the Mainline for up to 90% of the capacity, with at least 10% of capacity remaining available for uncommitted service. [Folder 3895249]

Official CER documents related to the traffic, tolls and tariffs for the Enbridge Mainline can be found here: Enbridge Mainline toll documents [Folder 155829].

Abandonment funding

Section updated June 2020

The CER requires pipeline companies to set aside funds to safely cease operations of a pipeline at the end of its useful life. In 2016, Enbridge Pipelines Inc. estimated it would cost $1 743 million to do this for the Enbridge Mainline. These funds will be collected over 40 years and are being set aside in a trust.

Table 1: Enbridge Mainline’s abandonment trust fund balance
  2015 2016 2017 2018 2019
Trust fund balance ($) 33 800 000 80 181 000 120 700 000 182 600 000 226 100 000

Official CER documents related to abandonment funding can be found here, sorted by year and by company: abandonment funding documents [Folder 3300366].

Financial resource requirements

Section updated June 2020

The Canada Energy Regulator Act requires major oil pipeline companies to set aside $1 billion to pay for the costs of any incident that occurs, such as a spill. See sections 136 to 142 of the Act for more information. Enbridge Pipelines Inc. demonstrated that its has financial resources in excess of $1 billion dollars. Official CER documents related to Enbridge’s financial resources can be found here: Enbridge financial resources requirements documents [Folder 2955535].

Pipeline financial information

Section updated June 2020

Pipeline companies report important financial information to the CER quarterly or annually. A strong financial position enables pipeline companies to maintain their pipeline systems, attract capital to build new infrastructure, and meet the market’s evolving needs. The data in this table comes from Annual Filing of CTS (Competitive Toll Settlement) Reports [Folder 805818] with the CER.

The Enbridge Mainline operates under a negotiated settlement.

Table 2: Enbridge Mainline financial data (excludes Lines 8 and 9)
  2012 2013 2014 2015 2016 2017 2018 2019
Rate base (million $) 5 193 5 683 6 387 8 785 8 824 8 952 8 857 13 608

Corporate financial information

Section updated June 2020

The Enbridge Mainline is owned by Enbridge Pipelines Inc., a subsidiary of Enbridge Inc. In 2016, earning from the Canadian portion of the Mainline accounted for approximately 21% of Enbridge Inc.’s profits. Credit ratings continue to be investment grade.

Credit ratings provide an idea of the financial strength of a company, including its ability to attract capital to build new infrastructure and meet financial obligations. The credit ratings below are expert opinions of how likely the debt issuer is to live up to its obligations.

Table 3: Enbridge Pipelines Inc. credit ratings
  2012 2013 2014 2015 2016 2017 2018 2019
Revenues (million $) 1 242 1 222 697 2 757 3 431 2 327 4 074
DBRS credit rating A A A A A A A A
S&P credit rating A- A- A- BBB+ BBB+ BBB+ BBB+ BBB+

Financial regulatory audits

Section updated June 2020

The CER audits pipeline companies to confirm compliance with the Canadian Energy Act, regulations, CER orders and CER decisions. Financial regulatory audits focus on toll and tariff matters such as detecting cross-subsidies. Enbridge Mainline’s last audit was completed in December 2009. Official CER documents related to Enbridge Mainline’s financial regulatory audits can be found here: [Folder 587320]

Condition compliance

Section updated June 2020

Every pipeline company in Canada must meet federal, provincial or territorial, and local requirements. This includes Acts, Regulations, rules, bylaws, and zoning restrictions. Pipelines are also bound by technical, safety, and environmental standards along with company rules, protocols and management systems. In addition to these requirements, the CER may add conditions to regulatory instruments that each company must meet. Condition compliance is monitored by the CER and enforcement action is taken when required. For a detailed list of conditions that Enbridge must meet, and their status, please see the condition compliance table and search for “Enbridge Pipelines Inc.”

Safety performance

Section updated June 2020

The CER holds the companies it regulates accountable to protect the safety of Canadians and the environment. As part of this accountability, companies must report to the CER events such as incidents and unauthorized third-party activities that happen without the pipeline company’s written consent. For a summary of pipeline incidents and unauthorized activities on the Enbridge Mainline since 2008, visit the Safety performance dashboard and select “Enbridge Pipelines Inc.”

Emergency management

Section updated June 2020

The CER checks to make sure companies are keeping pipelines safe by doing inspections, in-depth safety audits, and other activities. Yet, even with these precautions, an emergency could still happen. Sound emergency management practices improve public safety and environmental protection outcomes, and provide for more effective emergency response.

The CER holds its regulated companies responsible for anticipating, preventing, mitigating, and managing incidents of any size or duration. Each company must have an emergency management program that includes detailed emergency procedures manuals to guide its response in an emergency situation. We oversee the emergency management program of a regulated company’s projects as long as they operate.

The CER requires companies to publish information on their emergency management program and their emergency procedures manuals on their websites so Canadians can access emergency management information. To view Enbridge Mainline’s regional Integrated Contingency Plan, go to Enbridge’s Field Emergency Response Plans website, where the company’s plans are organized by area of operation.

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