The company says the leak of Line 37 was caused by heavy rainfall, which triggered ground movement on the right-of-way.
Enbridge (TSX:ENB) said Tuesday that the Wood Buffalo pipeline was restarted at reduced pressure pending completion of further geotechnical analysis in the area where the leak occurred.
The company made an initial estimate of a loss of earnings of $1 million a day because of the shutdowns.
The relatively small leak, estimated at up to 750 barrels, occurred on the pipeline from the Long Lake oilsands project to Enbridge's Cheecham Terminal.
The Wood Buffalo pipeline connects at Cheecham with the Waupisoo Pipeline (Line 18), which runs from Cheecham to Edmonton; the Waupisoo Pipeline was returned to service at normal pressure on June 25.
The 540-kilometre Athabasca line can carry up to 570,000 barrels per day of crude from the Athabasca and Cold Lake regions to Hardisty, Alta., a major pipeline hub in eastern Alberta, about 200 kilometres southeast of Edmonton.
The Waupisoo line can carry up to 600,000 barrels per day to Edmonton from Cheecham Terminal, near the site of the spill, about 70 kilometres southeast of Fort McMurray, Alta.