What happened

Enbridge suspended crude shipments on the Norman Wells Pipeline, or Line 21, after monitoring identified slope instability near its Mackenzie River crossing east of Fort Simpson. The shutdown was precautionary: the reviewed regulatory record documents a potential safety concern, not a rupture or oil spill. Because Line 21 was Norman Wells' only crude-export route, Imperial reduced production and then temporarily shut the field while Enbridge pursued approvals for an approximately C$53 million replacement project. Canada's National Energy Board approved a new 2.5-kilometre segment in January 2018, including a deep trenchless crossing beneath the river; the old crossing was cleaned, grouted and capped. Construction was completed in September, Line 21 restarted in late September and Imperial announced the safe resumption of Norman Wells production in October 2018. Authoritative records consistently place the initial shutdown in November or December 2016 but do not establish the proposed 18 November day. A separate CBC-derived record ties 18 November to Imperial's posting of oilfield-cleanup financial security, so this incident retains the supported month-level date.

When cited sources give different casualty, damage or spill figures for this event, they’re reported side by side above rather than merged into one number. See how confidence levels work.