(Adds comment from Trans Mountain, background on project)

HOUSTON, March 19 (Reuters) - Line fill of Canada's

Trans Mountain crude oil pipeline expansion will be complete by

the end of May, with the first waterborne exports from the

expanded system starting a month later, Alberta Premier Danielle

Smith said on Tuesday in an interview,

Her comments on the sidelines of the CERAWeek energy

conference in Houston are in line with March 1 statements by

oil producer MEG Energy ( MEGEF )

that Trans Mountain has called for 2.1 million

barrels in April and the same amount of oil in May.

The Canadian government-owned C$30.9 billion ($22.8

billion) pipeline expansion will nearly triple the flow of crude

from Alberta to Canada's Pacific Coast to 890,000 barrels per

day, but has been plagued by years of delays and cost overruns.

Line fill is the last step before the expanded pipeline

begins service, providing additional access for Canadian oil to

refineries on the U.S. West Coast and in Asia.

Asked for comment, Trans Mountain reiterated that it

expects to begin service on the pipeline expansion in the

second quarter

.