South Dakota tribes are working with non-Indians in an effort to stop the controversial Keystone XL Pipeline from crossing their state. TransCanada, the company behind the project, received a conditional permit from the South Dakota Public Utilities Commission in February 2010. But since construction did not begin within four years, the 313-mile route must be re-certified. That's when tribes and their allies stepped in. They are fighting the re-certification out of concern for their water, the environment and treaty lands.