United States
Environmental Protection
  Office of Water
EPA 820-F-16-004
     May 2016
Revised Interpretation  of Clean Water
Act Tribal Provision
Section 518 of the Clean Water Act (CWA) authorizes
EPA to treat eligible Indian tribes with reservations
in a manner similar to states (TAS) for a variety of
purposes, including administering each of the
principal CWA regulatory programs and receiving
grants under several CWA authorities.
EPA's interpretive rule streamlines how tribes apply
for TAS under CWA section 518 for CWA regulatory
programs including the water quality standards
program. This reinterpretation facilitates tribal
involvement in the protection of reservation water
quality as intended by Congress.

Since 1991, EPA has followed a cautious approach
that requires applicant tribes to demonstrate
inherent authority to regulate waters and activities
on their reservations under principles of federal
Indian common law.
The agency has consistently stated that its approach
was subject to change in the event of further
congressional or judicial guidance addressing tribal
authority under section 518 of the CWA.
Based on such guidance, and after considering public
comments, EPA concludes definitively that section
518 includes an express delegation of authority by
Congress to Indian tribes to administer regulatory
programs over their entire reservations, subject to
the eligibility requirements in section 518.
                            This interpretive rule will reduce burdens on
                            applicants associated with the existing TAS
                            application process and has no significant cost.
                            What does the reinterpretation do?
                            This reinterpretation eliminates the need for
                            applicant tribes to demonstrate inherent authority
                            to regulate under the CWA, thus allowing tribes to
                            implement the congressional delegation of
                            The reinterpretation also brings EPA's treatment of
                            tribes under the CWA in line with EPA's treatment of
                            tribes under the Clean Air Act, which has similar
                            statutory language addressing tribal regulation of
                            Indian reservation areas.

                            What would not change under the
                            This reinterpretation does not revise any EPA
                            Regulatory provisions remain in effect  requiring
                            tribes to identify the boundaries of the reservation
                            areas over which they seek to exercise authority, as
                            do provisions allowing the adjacent state(s) to
                            comment to EPA on an applicant tribe's assertion of

                            Does the reinterpretation  affect the
                            geographic scope of TAS?
                            No. The reinterpretation neither expands nor
                            contracts the geographic scope of potential tribal
                            TAS eligibility. Under the CWA,  tribes can only obtain
                            TAS status over waters within the borders of their

reservations. (Tribal trust lands are reservation lands
even if they are not within a formal reservation.)

Does the reinterpretation affect any existing
limitations on tribal criminal enforcement
No. The reinterpretation relates solely to civil
regulatory authority.

What if my tribe or state has special
circumstances affecting CWA regulatory
There could be instances where special
circumstances limit or preclude a particular tribe's
ability to accept or effectuate the congressional
delegation of authority over its reservation. For
example, there could be a separate federal statute
establishing unique jurisdictional arrangements for a
specific state or reservation. EPA takes no position in
this reinterpretation regarding whether any
particular tribe or Indian reservation is subject to any
such circumstances. Any such issue would be
addressed on a case-by-case basis and with the
benefit of a full record of relevant information that
would be developed during the processing of a
particular tribe's application for eligibility to regulate
under the CWA.

Who is potentially affected by the
Federally recognized Indian tribes with reservations
that could  potentially seek eligibility to administer
CWA regulatory programs, and other interested
States adjacent to potential applicant tribes.
Industries or municipalities discharging pollutants to
waters within or adjacent to reservations of
potential applicant tribes.

Does the reinterpretation affect previous
EPA approvals of TAS for water quality
No. It does not affect previous EPA approvals of
tribal TAS for water quality standards.
Does the reinterpretation affect the scope
of existing state regulatory programs
approved by EPA under the CWA?
No. The reinterpretation does not affect the scope of
existing EPA-approved state regulatory programs
under the CWA.

Is EPA providing additional funding for
tribes with TAS for regulatory programs?
EPA will continue to consider tribal resource issues
in its budgeting and planning process. However, EPA
cannot assure tribes that additional funding will be
available for a tribe to develop or implement a CWA
regulatory program.

Where can I find more information?
Contact Thomas Gardner by email at or by phone at (202) 566-
0386, or visit EPA's website at: