There are some complex issues going on with that land, including that it was reservation land initially, was illegally taken at one point, and after fighting to get it back for decades, the tribe won a court case.  However, they were not awarded the land back, instead they were paid for it.   But the Indians have never accepted the money, it stays in the account into which it was paid, and they want the land back.  

I don't care what the risk is.   It's not the Indians' problem, or if there was justice, it wouldn't be.   Notification to the tribe that was required to run that pipeline half a mile away from the reservation before they began work, notification that didn't happen.