The price at Alberta’s AECO hub fell below zero at the start of last week, and closed at minus 81 Canadian cents per gigajoule on Friday, the lowest level in data extending back to 1999. The benchmark has been on a downward trend since hitting a high for the year of C$3.68 in early February.

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Gas production and inventories surged before the LNG Canada export plant started operations at the end of June. While the facility hasn’t always operated smoothly, seeing a temporary pause to liquefied natural gas shipments in July, its ramp-up should eventually help to chip away at the glut.

Repairs to the Great Lakes Gas Transmission pipeline — which delivers gas from Western Canada to the east of the country and the US — have also contributed to a build-up in supply.