An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Tribal Governments Role in Safe Drinking Water on Tribal Lands

Tribal Primacy

On this page:


Primacy is the process through which states and tribes implement and enforce federal environmental regulations. Under the Safe Drinking Water Act (SDWA), EPA can delegate primacy and grant “Treatment in the Same Manner as a State (TAS)” to tribes meeting certain requirements. These tribes implement programs like the Public Water System Supervision (PWSS) and enforce regulations within their jurisdiction.

Since 1976, Congress has appropriated funds under the SDWA for grants to help states develop and implement their PWSS programs.

Because of their unique status, tribes were not eligible to assume primacy in the original Act. Instead, EPA Regions were responsible for primary enforcement authority of the PWSS program in Indian country. Amendments to SDWA in 1986 allowed federally recognized tribes to receive primacy.

To receive primacy for the PWSS program, a tribe must apply for and receive TAS status. The Navajo Nation is the only tribe with TAS status and primacy over the PWSS program. Having primacy, the Navajo Nation enforces SDWA regulations and program requirements for public water systems within their jurisdiction.

EPA Regional offices serve as the primacy agency for tribes that do not have primacy. As the primacy agency, EPA directly implements the PWSS program and enforces SDWA regulations.

Top of Page

What are the advantages and responsibilities of primacy?

Tribal primacy for the PWSS program allows the tribes to more fully exercise their sovereign powers by establishing and enforcing environmental regulations for PWSS within their jurisdiction.

Tribes that assume primacy also take over many of the responsibilities otherwise managed by EPA. These include, but are not limited to:

  • Adopting and implementing the NPDWRs;

  • Enforcing and responding to regulations;

  • Maintaining compliance data systems;

  • Certifying laboratories; and

  • Performing sanitary surveys.

Top of Page

Eligibility Requirements for TAS

Primacy and TAS are sought out in conjunction, not separately. In order to be determined eligible for TAS in the PWSS program, a tribe must meet the following criteria:

  • Be recognized by the Secretary of the Interior;
  • Have a functional tribal government responsible for the health, safety and welfare of the tribal community;
  • Demonstrate that the regulatory functions to be performed in the public water systems are within the Indian Tribal government’s jurisdiction; and
  • Be capable of administering an effective PWSS program consistent with the SDWA and all applicable regulations.

Top of Page

Additional Resources and Contact Information about Tribal Primacy

The TAS Regulation has more information on TAS eligibility requirements and application procedure. For more information on the process of obtaining TAS for the Public Water System Supervision (PWSS) Program, contact your Regional Tribal Drinking Water Direct Implementation Coordinator.

Top of Page