The rationing was prompted by unplanned outages. Enbridge's announcement for an apportionment on parts of the Mainline network is the second in two months, sparking worry about a glut. Another two-week suspension of TransCanada's Keystone pipeline following a leak also caused a build of crude oil inventories in Alberta, pressuring prices downward. Environmental regulators are currently investigating the cause of the 5,000-barrel leak at Keystone, causing an extended decrease in capacity.