A Guide To Ohio EPA'S Antidegradation Rule - effective July 1, 2003

Antidegradation provisions describe the conditions under which water quality may be lowered in surface waters. Existing beneficial uses must be maintained and protected. Further, water quality better than that needed to protect existing beneficial uses must be maintained unless lower quality is deemed necessary to allow important economic or social development (existing beneficial uses must still be protected).

Provisions addressing antidegradation are in the Water Quality Standards chapter of the Ohio Administrative Code (OAC Chapter 3745-1).  Within that chapter, rule 3745-1-54 [PDF 657K] addresses antidegradation provisions for wetlands and rule 3745-1-05 addresses antidegradation provisions for other surface waters of the state.  Amendments to rule 3745-1-05 were proposed on March 25, 2002 and are effective on July 1, 2003.

Download the July 1, 2003 antidegradation rule:

• OAC 3745-1-05 Antidegradation [PDF 96K] - effective July 1, 2003
• Note: The rule was updated on March 15, 2010 to make submittal, public notice and public hearing requirements for Section 401 water quality certification projects consistent with ORC 6111.30.
  • OAC 3745-1-05 Antidegradation [PDF 110K] - effective March 15, 2010 
• Note: The rule was also updated on March 1, 2011 to make clarifications to rule applicability exemptions for existing sources, assimilative capactiy reserve allocations for outstanding state waters and superior high quality waters, and assimilative capacity set aside revision petition procedures.
  • OAC 3745-1-05 Antidegradation [PDF 116K] - effective March 1, 2011

The following materials provide additional information and guidance on how the rule will be implemented.

• Antidegradation Addendum
• Alphabetical List of Special High Quality Waters (SHQW, OSW) [PDF 32K]
• Modeling Guidance No. 5 - Antidegradation and the Wasteload Allocation Process [PDF 31K]

The following documents were made available during the 2002-2003 antidegradation rule-making.  They provide additional background and detail.

• Responsiveness summary [PDF 123K] - This document summarizes the rule-making steps taken by Ohio EPA, the public comments submitted on the proposed rule and Ohio EPA's responses to the comments.
• OAC 3745-1-05 as adopted [PDF 273K] - This version of the rule shows the changes from the previously adopted rule (effective May 1, 1998).  In this version, text that was deleted is struck out and text that was added is underlined.
• Fact Sheet [PDF 112K] - This document summarizes the proposed revisions and contains additional background information.
• Support Documents - These documents provide justifications for water body classifications in the new antidegradation rule.  Note: State Resource Waters (SRW) in the proposed rule were renamed Outstanding State Waters (OSW) in the final rule.
  • Antidegradation Classifications Assigned to State and National Scenic Rivers in Ohio under Proposed Rules, March 25, 2002 [PDF 132K]
  • Methods and Documentation Used to Propose State Resource Water (SRW) and Superior High Quality Water (SHQW) Classifications for Ohio's Water Quality Standards [PDF 209K]
    • Appendix 1.  Ohio Streams and Rivers:  Antidegradation Tier Justification, SRW & SHQW [PDF 973K]
    • Appendix 2.  Water Bodies Placed into SRW/SHQW "Holding Category" [PDF 32K]

For additional information contact:

Mark Stump
Permits & Compliance Section
(614) 644-2028

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