Here is the opinion in Yazzie v. EPA. Here is the opinion in Hopi Tribe v. EPA. The Yazzie opinion is the lead opinion and has more details.
Materials in the Yazzie appeal are here. Materials in the Hopi appeal are here (some of the Yazzie briefs are here, too).
Here is the petition in National Parks Conservation v. EPA (CA9):
Envtl Groups Petition
Hopi’s petition is here.