By Jeffrey Jones

CALGARY, Alberta (Reuters) - An Enbridge Inc
pipeline that ruptured in Michigan more than a month
ago won't resume oil shipments until at least next week, now
that a key pressure test on the damaged section has been
delayed until Monday.

The line, which ruptured on July 26, was expected to be put
through a hydrostatic test early this week after a series of
excavations to judge its safety. Regulators require the results
of the test to rule on Enbridge's plan to restart oil flows.

One of the dig sites near the rupture, south of Marshall,
Michigan, is in a pond and it has taken longer than expected to
pump out water, forcing the delay in testing, Enbridge
Vice-President Steve Wuori said Wednesday.

The company requires a go-ahead from the U.S. Department of
Transportation's Pipeline and Hazardous Materials Safety
Administration to perform the test, which will take about eight
hours.

"As soon as the dig results are all communicated to PHMSA,
that's when we would expect the approval to go ahead and do the
pressure test," Wuori told reports during a conference call.

The test involves pumping water through the section at high
pressure to gauge the integrity of the pipe.

A PHMSA spokeswoman said the regulator had nothing to
report on Enbridge's plan to restart the pipeline, leaving the
timing of resuming the flow of oil up in the air.

The outage of the 190,000 barrel a day Line 6B, which
extends to Sarnia, Ontario, from Griffith, Indiana, has
weakened prices for Canada heavy crude, which normally flows
through the line to refineries in Ohio, Michigan, Pennsylvania
and southern Ontario.

Earlier this week, Enbridge chopped its shippers'
nominations for September crude shipments on two of its other
major U.S. pipelines, after companies scrambled to find other
conduits, a practice known as apportionment.

The pipeline break spilled about 19,500 barrels of heavy
Cold Lake crude into the Kalamazoo River system. Officials with
the U.S. Environmental Protection Agency said Wednesday that
the cleanup was progressing well, with more than 8 million
gallons of oily water having been removed from the river.

Meanwhile, a U.S. congresswoman called Wednesday for an
expanded probe into problems with the pipeline, which crosses
the United States-Canada border under the St. Clair River.

Michigan Representative Candice Miller said an upcoming
congressional hearing into the Enbridge oil spill should
include investigation of a dent in the pipeline discovered
under the river a year ago. It has yet to be repaired.

"An accident similar to the event that occurred in Marshall
would be simply catastrophic to our region," Miller said in a
statement. "Not only would it negatively affect our drinking
water supply, but could possibly shut down one of the busiest
shipping lanes in our nation and have a devastating impact on
our economy."

Enbridge executives said the dent was not a deep one and it
posed no danger, especially under a self-imposed pressure
restriction. There is no current schedule for making repairs,
Wuori said.

Shares in Enbridge rose 41 Canadian cents to C$52.70 on the
Toronto Stock Exchange. Its U.S. affiliate, Enbridge Energy
Partners, fell 24 cents to $54.73 in New York.

($1=$1.06 Canadian)
(Additional reporting by Ayesha Rascoe in Washington; editing
by Rob Wilson)