(Adds comment, details of pipeline, reasons for delay)
By Nia Williams
CALGARY, Alberta, Sept 30 (Reuters) - Canadian regulators approved the hydrotest results of Enbridge Inc's Line 9 crude oil pipeline on Wednesday, clearing the way for the delayed 300,000-barrel-per-day route to the east of the country to start operating.
The newly reversed Line 9 will ship mainly light inland crude from Sarnia, Ontario, to Montreal, Quebec. It previously flowed in the opposite direction, taking imported crude to Ontario.
The line, originally expected to start up in late 2014, was held up after the National Energy Board ordered hydrostatic tests at three locations along the line in June.
Prior to that, regulators had asked for additional data on shut-off valve placements at major water crossings.
The NEB on Wednesday said there were no further pre-operation requirements on Line 9.
"The successful hydrotests confirm the NEB's confidence in the integrity of the pipeline and its confidence that the line can safely be returned to operation," the regulator said in a statement.
However, once the pipeline becomes operational the NEB has imposed conditions including biweekly patrols, quarterly integrity testing and an in-line inspection within the first year of operation.
Enbridge is also required to limit the pressure of the pipeline for its first year of operation.
It was not immediately clear how pressure restrictions would affect the capacity of the pipeline and Enbridge spokesman Graham White said the company was still reviewing the NEB notice.
He did not give an expected in service date for the pipeline. Enbridge has previously said it expected additional testing to wrap up by the end of the year.
"There are still some technical preparations that are required and line-fill is not an exactly timed process, so we will not speculate at this time on a specific date for return to full service," White said.
The Line 9 approval is a rare bright spot for backers of Canadian pipeline projects, which include TransCanada Corp's Keystone XL and Enbridge's Northern Gateway.
These projects have run into fierce environmental opposition, and last week Democratic U.S. presidential candidate Hillary Clinton said she opposed Keystone XL.
The approval is also likely to be welcomed by Line 9's two biggest customers Suncor Energy and Valero Energy Corp , which each own a refinery in Quebec and will benefit from being able to replace imported crude with cheaper inland barrels.
(Reporting by Nia Williams; editing by Christian Plumb and G Crosse)