* Lines 1 and 5 down after Michigan leak
* Restart seen later Thursday
* Line 5 to run at lower pressure after starting
CALGARY, Alberta, Feb 16 (Reuters) - Enbridge Inc said on Thursday it shut down two pipelines on its Canada-to-U.S. oil transport system after detecting what it termed to be small leak in the northern Lower Peninsula region of Michigan.
Enbridge said it expected to have the pipelines back in operation after repairing the leak later on Thursday, but pressure will be lowered as it investigates other possible trouble spots.
Line 5, a 491,000 barrel a day pipeline that runs to Sarnia, Ontario, from Superior Wisconsin, is down after crews discovered some spilled crude in soil in Arenac County, Michigan, spokeswoman Lorraine Little said in an email.
Enbridge also shut Line 1, a 237,000 bpd line that extends to Superior from Edmonton, Alberta, due to high inventories at the end of that segment, Little said. It is expected to restart once Line 5 is back in operation.
Another Enbridge pipeline was shut down for several weeks in 2010 after more than 20,000 barrels of heavy Alberta crude gushed into the Kalamazoo River system in Michigan following a rupture, prompting a $700 million cleanup effort.
The latest leak, discovered during maintenance is estimated at less than three barrels, Little said.
Discounts on Canadian crude have widened following the outage.