Here is the petition in Coachella Valley Water District v. Agua Caliente Band of Cahuilla Indians:

Coachella Cert Petition

Question presented:

Whether, when, and to what extent the federal reserved right doctrine recognized in Winters v. United States, 207 U.S. 564 (1908), preempts state-law regulation of groundwater.

Lower court materials here.

UPDATE (8/14/17):

17-40 -42 Agua Caliente Amicus Brief