Water Quality: Docket No. 58-0102-1401 - Final Rule
Rulemaking initiated to update DEQ’s Mixing Zone Policy in the Water Quality Standards
Status of Rulemaking
EPA approved final rule package on December 16, 2019.
Final Idaho Mixing Zone Implementation Guidance, December 2016
Final Rule Package Submitted to EPA - Approved on December 16, 2019
For more information, go to http://www.deq.idaho.gov/epa-actions-on-proposed-standards.
- EPA Approval Letter Dated December 16, 2019
- DEQ Submittal Letter to EPA Dated October 26, 2016
- Mixing Zone Rule Crosswalk
- Attorney General Certification of Amended Idaho Water Quality Standards, Docket No. 58-0102-1401
This submittal also includes documents that exist as part of the rulemaking record and posted below.
- Notice of Adoption of Pending Rule
- DEQ's November 2014 Board Meeting PowerPoint Presentation
- November 2014 Board Meeting Agenda
- Final Proposal for Board Consideration
- Public Comment Summary
- Proposed Rule and Notice
- Negotiated Rulemaking Summary
- Notice of Negotiated Rulemaking
April 11, 2015
This rulemaking docket has been initiated to update DEQ’s Mixing Zone Policy in the Water Quality Standards to take into account modern tools for evaluating mixing, lessons learned from years of implementation, and to provide greater clarity for DEQ and the regulated community.
A mixing zone is defined as “an area or volume of the receiving water surrounding or adjacent to a point source discharge where the receiving water, as a result of the discharge, may not meet all applicable water quality criteria or standards” (IDAPA 58.01.02.010.61). Mixing zones are granted to NPDES dischargers to calculate the “reasonable potential to exceed” (RPTE) water quality criteria, which serve as the basis for effluent limits in discharge permits. If a mixing zone is not granted by DEQ, the discharger receives end-of-pipe limits. End-of-pipe limits are much more stringent and typically require facilities to undertake technology upgrades, which can be very resource intensive. Mixing zones are used as a tool to help meet the goals of the Clean Water Act (CWA) while also giving the regulated community reprieve from meeting more stringent, and often very costly, effluent limits. Use of mixing zones is recognition that usually it is not necessary to meet ambient water quality everywhere in the receiving water in order to support beneficial uses.
DEQ’s current Mixing Zone Policy (IDAPA 58.01.02.060) was adopted over 20 years ago (1991) and contains language that is outdated and/or is no longer relevant. Since the inception of DEQ’s Mixing Zone Policy in 1991, numerous updates to Idaho’s water quality standards have been made. DEQ recognizes that some parts of the current rule need to be revised in order to meet the intent of related policies. DEQ has also determined from working with dischargers that the current mixing zone rule is ambiguous and does not clearly articulate mixing zone requirements.
In recent years, there has been an increasing interest in, and investigation of, the agency’s methods for establishing mixing zones. As technology and information availability have expanded and improved, the methods for establishing mixing zones have also changed. Changes to the rule were made to be reflective of current procedures and tools used to appraise the biological, chemical, and physical properties of the receiving water, and the proposed discharge, in order to best establish mixing zones.
The text of the rule will be drafted by DEQ in conjunction with a negotiating committee made up of persons having an interest in the development of this rule. Idahoans that recreate in, drink from, or fish Idaho’s surface waters and any who discharge pollutants to those same waters may be interested in participating in this rulemaking.
After consideration of public comments, the rule has been revised at Sections 010 and 060.
Submit all written comments by mail, fax or email to:
Idaho Department of Environmental Quality
1410 N. Hilton, Boise, ID 83706
Fax: (208) 373-0481
Comment Period/Proposed Rule
September 3, 2014 through October 3, 2014
Public Hearing/Proposed Rule
No public hearings scheduled
Public Comments/Proposed Rule
|Submitted By||Date Received|
|Idaho Conservation League (ICL)||09/17/14|
|U.S. Fish and Wildlife Service||10/01/14|
|Idaho Mining Association (IMA)||10/02/14|
|National Council for Air and Stream Improvement, Inc. (NCASI)||10/02/14|
|J.R. Simplot Company||10/03/14|
|Idaho Association of Commerce & Industry (IACI)||10/03/14|
|U.S. National Oceanic and Atmospheric Administration (NOAA)||10/03/14|
|U.S. EPA Region 10||10/03/14|
|Idaho Cattle Association||10/07/14|
The text of the proposed rule has been drafted based on discussions held and concerns raised during negotiations conducted pursuant to Idaho Code § 67-5220 and IDAPA 58.01.23.810-815. The Notice of Negotiated Rulemaking was published in the April 2014 Idaho Administrative Bulletin, Vol. 14-4, pages 19 through 20, and a preliminary draft rule was made available for public review. Meetings were held on May 1, June 12, and July 10, 2014. Several members of the public participated in this negotiated rulemaking process by attending the meetings and by submitting written comments. A record of the negotiated rule drafts, written comments received, documents distributed during the negotiated rulemaking process, and the negotiated rulemaking summary is available below.
All comments received during the negotiated rulemaking process were considered by DEQ when making decisions that resulted in drafting the proposed rule. At the conclusion of the negotiated rulemaking process, DEQ formatted the final rule draft for publication as a proposed rule. DEQ is now seeking public comment on the proposed rule.
Negotiated Rulemaking Meeting Schedule
No additional meetings are scheduled.
- July 10, 2014 - Sign-in Sheets | Agenda
- June 12, 2014 - Sign-in Sheets | Agenda
- May 1, 2014 - Sign-in Sheets | Agenda
Draft Negotiated Rule
The draft negotiated rule can be obtained here or by contacting Paula Wilson at email@example.com, (208) 373-0418.
|Draft Negotiated Rule||Date Posted||Written Comment Deadline|
|Preliminary Draft (Draft No. 1)||04/04/14||05/15/14 extended to 05/22/14|
|Draft No. 2||06/05/14||06/27/14|
|Draft No. 3||07/03/14||07/24/14|
|Draft No. 4||07/17/14||07/24/14 extended to 07/28/14|
|Draft No. 5||08/08/14||
The comment period for this negotiated rulemaking has concluded. The comment period on the proposed rule will commence upon publication of the proposed rule in the September 3, 2014 issue of the Idaho Administrative Bulletin.
Written Public Comments/Negotiated Rulemaking
|Written Public Comments||Date Received||Submitted By|
|Comments on Draft 1||04/29/14||U.S. National Oceanic and Atmospheric Administration (NOAA)|
|Comments on Draft 1||05/14/14||U.S. National Oceanic and Atmospheric Administration (NOAA)|
|Comments on Draft 1||05/13/14||Clearwater Paper|
|Comments on Draft 1||05/13/14||U.S. Fish and Wildlife Service, Idaho Fish and Wildlife Office|
|Comments on Draft 1||05/15/14||Idaho Conservation League (ICL)|
|Comments on Draft 1||05/21/14||U.S. EPA Region 10|
|Comments on Draft 1||05/22/14||Idaho Mining Association (IMA)|
|Comments on Draft 1||05/22/14||Idaho Association of Commerce and Industry (IACI)|
|Comments on Draft 1||05/22/14||J.R. Simplot Company|
|Comments on Draft 1||06/02/14||Chris Mebane|
|Comments on Draft 2||06/27/14||U.S. EPA Region 10|
|Comments on Draft 2||06/27/14||Clearwater Paper|
|Comments on Draft 2||06/30/14||U.S. National Oceanic and Atmospheric Administration (NOAA)|
|Comments on Draft 4||07/24/14||Idaho Conservation League (ICL)|
|Comments on Draft 4||07/24/14||J.R. Simplot Company|
|Comments on Draft 4||07/24/14||Idaho Mining Association (IMA)|
|Comments on Draft 4||07/25/14||Clearwater Paper|
|Comments on Draft 4||07/25/14||Idaho Transportation Department (ITD)|
|Comments on Draft 4||07/28/14||U.S. EPA Region 10|
Documents Distributed for Negotiated Rulemaking
|DEQ Policy Discussion Papers and Related Documents||Date Posted|
|Policy Discussion Paper #1|
|Mixing Zones: Unreasonable Interference – Discussion Paper #1 (06/12/14)||06/05/14|
|Policy Discussion Paper #2|
|Effluent Mixing in Non-Flowing Waters - Discussion Paper #2 (07/10/14)||07/03/14|
|Spreadsheet compilation of results of ACWA Query – mixing zones/non-flowing waters/states (07/10/14)||07/03/14|
|Meeting Presentations and Miscellaneous Documents||Date Posted|
Mixing Zones - DEQ PowerPoint Presentation (07/10/14)
Mixing Zones - DEQ PowerPoint Presentation (06/12/14)
Compilation of EPA Mixing Zone Documents, July 2006
|EPA’s Water Quality Standards handbook, Chapter 5 General Policies||04/24/14|
|Technical Support Document for Water Quality-based Toxics Control - EPA, March 1991||04/24/14|