A 713-mile pipeline carrying natural gas from Colorado to Missouri is up and running. It's the first phase of the Rockies Express pipeline operation that ultimately will deliver natural gas from the West to the East Coast.

Officials with the Rockies Express or REX pipeline said Tuesday the completion of the first phase boosts capacity to 1.5 billion cubic feet per day.

The next phase is a 638-mile pipeline segment extending from Missouri to Clarington, Ohio. The entire project is expected to be fully operational by June 2009 if the builders obtain all regulatory approvals.

The pipeline is a a joint venture of Kinder Morgan Energy Partners LP, Sempra Pipelines and Storage and ConocoPhillips.