The proposed rule would streamline the TAS process for many tribes seeking eligibility to administer water quality standards and other Clean Water Act programs.

See the Federal Register announcement here.  The deadline for comments is October 6, 2015.

From the announcement:

The effect of this proposal would be to relieve tribes of the need to demonstrate their inherent authority when they apply for TAS to administer CWA regulatory programs. In particular, this proposal would eliminate any need to demonstrate that the applicant tribe retains inherent authority to regulate the conduct of nonmembers of the tribe on fee lands under the test established by the Supreme Court in Montana. Instead, applicant tribes would be able to rely on the congressional delegation of authority in section 518 as the source of their authority to regulate their entire reservations under the CWA, without distinguishing among various categories of on-reservation land. As EPA explained in connection with the CAA, such a territorial approach that treats Indian reservations uniformly promotes rational, sound management of environmental resources that might be subjected to mobile pollutants that disperse over wide areas without regard to land ownership. See 59 FR at 43959. As specifically recognized by the district court in Montana v. EPA, the same holds true for regulation under the CWA. Montana, 941 F. Supp. at 952.