(CNN) The amount of land impacted by an oil spill in North Dakota is almost 10 times larger than initially reported, officials say. The disclosure comes about a month after the Keystone 1 Pipeline leaked about 383,040 gallons of oil.

TC Energy, the company that owns the pipeline, shut down it down on October 29 after discovering that the oil had leaked from the pipe into the surrounding wetlands. The pipeline was returned to service on November 10 following approval by the US Pipeline and Hazardous Materials Safety Administration, TC Energy says.

Initial reports of the leak released by TC Energy and North Dakota's Department of Environmental Quality estimated about 2,500 square yards of land were affected by the spill.

Now, they have both revised the size of the impacted area to 4.8 acres, or 23,232 square yards -- that's almost ten times the original estimate.

About 9,120 barrels of oil were leaked into surrounding wetlands on October 28, 2019.

The new estimate includes both the surface and subsurface impact of the leak. The initial 2,500-square-yard estimate was based on visual observations alone, the company told CNN.

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