The probable cause of the Montara oil spill was outlined by the operator of the Montara Platform, PTTEP, in its submission to the Montara Commission of Inquiry (MCI). According to the submission by PTTEP to the MCI, an initial uncontrolled hydrocarbon release (UHR) (containing approximately 40–60 bbl) occurred on the Montara Well Head Platform on the H1 Well at 05:30 on 21 August 2009.