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The Division of Waterโ€™s Antidegradation Implementation Methods Regulations under the Water Quality Standards (18 AAC 70) were filed on March 7, 2018 with an effective date of April 6, 2018 and approved by the EPA on July 26, 2018. The approved regulations are now in effect for actions regulated under the federal CWA and specifically apply to APDES permits and CWA section 401 water quality certifications. Please refer to the links under Additional Information.

The Division decided to separate the Tier 3 - ONRW nomination and designation process in order to obtain additional stakeholder input and to continue to work on a more comprehensive Tier 3 nomination and designation process that will work statewide, now and in the future. Therefore, the regulations only include implementation methods for the antidegradation analyses relating to APDES permitted discharges. The 'Developing a Tier 3 Process' tab has additional information about these waters and the current designation process.

To keep informed about the development of antidegradation regulations, you may sign up for email notifications through the DEC Antidegradation Listserv. If you have questions on antidegradation, please feel free to contact

Antidegradation is a tool used to protect the water quality in the State of Alaska. Antidegradation implementation is the method or process for determining whether and to what extent the water quality may be lowered.

The Federal Clean Water Act requires states to have an anti-degradation policy and implementation methods. Federal regulation at 40 CFR 131.12 (PDF) specifies States must have an antidegradation policy that:

  • Protects existing uses
  • Authorizes the lowering of water quality in high quality waters, where necessary for social or economic importance
  • Provides a mechanism to provide additional protection for water of exceptional ecological or recreational significance. These are often called ONRW or Tier 3 waters.

Alaska's antidegradation policy (adopted in 1997) and implementation methods, are found in the 18 AAC 70 - Water Quality Standards regulations at 18 AAC 70.015 and 18 AAC 70.016 respectively.

DEC began the most recent antidegradation efforts in 2008 with a contractor produced report that outlined several options for the State to develop antidegradation implementation guidance and policy.

Then in 2009, DEC hosted a public workshop on antidegradation issues. The purpose of the conference was to inform policy makers, wastewater discharge permittees, permit writers and interested public regarding options for implementation procedures. From information gathered in the workshop, DEC formulated and adopted the Interim Antidegradation Implementation Methods in 2010.

In 2012, DEC assembled a stakeholder workgroup, comprised of representatives from state resource agencies, industry and non-governmental sources, to evaluate options and to provide recommendations on various core elements for the final antidegradation implementation methods to be developed by DEC.

In January 2013, the workgroup completed a final report that highlighted key issues and made recommendations for drafting new antidegradation implementation regulations. The Division drafted proposed regulations based on the workgroup recommendations and departmental input, review and approval.

The proposed regulations were noticed for public comment on January 17, 2014 for 60 days, the comment period was extended for an additional 30 days, and closed April 16, 2014. The Division received comments and based on the public feedback decided to hold additional workshop(s) in 2015 to discuss and evaluate select issues that were raised during the comment period.

The Division held a public workshop May 13-14, 2015, to discuss issues identified during the initial public comment period on the Draft Antidegradation Implementation Method regulations. The Division evaluated the recommendations and information provided at the workshop for regulation revisions and noticed the revised regulations for a second public comment period.

The proposed revised regulations were noticed on June 2, 2017 for a 67 day public comment period and closed on August 7, 2017. The Division also conducted a question/answer session followed by a public hearing on July 20, 2017. The Division reviewed all comments submitted during the public comment period, revised the regulations as appropriate, and submitted the regulatory package for adoption. The regulations were filed on March 7, 2018 with an effective date of April 6, 2018 and approved by EPA on July 26, 2018.

What are Tiers 1, 2, and 3 in Alaska's Water Quality Standards?

Per the Clean Water Act, Alaska's water quality antidegradation policy creates three classifications, or "tiers," of waters.

  • Tier 1 waters are waters for which not all water quality criteria are met. This can be due to naturally occurring constituents in the water, or can be due to pollutants introduced by humans
  • Tier 2 waters are high quality waters, which include the vast majority of waters in Alaska. In these waters, all water quality criteria are met.
  • Tier 3 waters are waters that are required to be preserved in their current status.

Hierarchy of Waterbody Tiers

40 CFR 131.12(a)(3): "Where high quality waters constitute an outstanding National resource, such as waters of the National and State parks and wildlife refuges and waters of exceptional recreational or ecological significance, that water quality shall be maintained and protected."

Developing a Tier 3 Process for Alaska

Currently, nominations for Tier 3 water designation in the State of Alaska may be submitted directly to your legislator for consideration. The State is in the process of developing more comprehensive nomination and designation implementation methods, and these methods once developed, will specify who will designate Tier 3 waters.

During the 2016 legislative session, the Governor introduced legislation (SB163 and HB283) to establish this Tier 3 nomination and designation process. The Governor requested the bills be set aside and committed to more dialog with Tribes and stakeholders before offering another proposal. The process needs to work well for all Alaskans and for all waters of the state, now and in the future. The process should be transparent and allow any Alaskan to submit a nomination. The process should provide opportunity for local input, and for the thorough evaluation and vetting of a nomination using defined criteria.

To start the conversation, the Department developed three possible alternative nomination and designation processes. Please note that in providing these three alternative processes we are in no way trying to limit the discussion. The Tier 3 process that Alaska arrives at must answer several distinct questions, including:

  1. Which waters can be Tier 3 waters? What criteria should be applied before a water can be eligible for Tier 3 designation
  2. Who can nominate a water for Tier 3 designation, and what requirements should exist for the nomination process?
  3. Once the nomination is received, who should evaluate the nomination to determine the eligibility criteria are met, that the water is a valid candidate for Tier 3 designation?
  4. How will this evaluation process be paid for?
  5. What kind of public process should exist so that Alaskan citizens can weigh in on a Tier 3 decision?
  6. Once a nomination is determined to be a valid candidate for Tier 3 designation, who should make the final decision that the water should indeed be a Tier 3 water?

EPA's Water Quality Handbook provides additional information in Chapter 4 (Antidegradation Chapter) (PDF). Section 4.7 is specific to ONRWs or Tier 3 Waterbodies.

Public Workshop Information for Tier 3 Waterbodies

Draft Tier 3 Waterbody Nomination Criteria

The draft nomination criteria, vetting process and broad conceptual options for designation authority:


Earl Crapps
Section Manager
Domestic & Industrial Utilities

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