WASHINGTON — The State Department is ordering the developer of a pipeline that would carry oil from western Canada to Texas to reroute it around environmentally sensitive areas of the state of Nebraska.

That means possibly delaying a final U.S. decision until after the 2012 election.

The decision to order Calgary-based TransCanada Corp. to figure out a way around an area that supplies water to eight states will require an environmental review of the new section. That review probably would take at least a year.

Calgary-based TransCanada Corp. is seeking to build the $7 billion pipeline to carry oil derived from tar sands in Alberta, Canada, to refineries on the Texas Gulf Coast.

Part of the 1,700-mile pipeline as designed now would pass through Nebraska’s Sandhills region and the massive Ogallala aquifer.