Explorer Pipeline notified the NRC that they had a pipe line break and reported they had an estimated release of 4500 barrel. However, the actual release approximately 7000 barrels. START was activated at 6:30 PM on 7/14/07. START reported at approximately 1.5 miles of Turkey Creek has been impacted but the spill is contained. The Response Duty OSC was dispatched on 7/15/07.