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 addresses antidegradation provisions for wetlands and rule 3745-1-05 addresses antidegradation provisions for other surface waters of the state.

Rules

• OAC 3745-1-05 Antidegradation  - effective July 1, 2003
• 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  - effective March 15, 2010 
• The rule was updated on March 1, 2011, to clarify rule applicability exemptions for existing sources, assimilative capacity reserve allocations for outstanding state waters and superior high quality waters, and assimilative capacity set-aside revision petition procedures.
  • OAC 3745-1-05 Antidegradation - effective March 1, 2011

Guidance

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

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

Supporting Documents

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

• Responsiveness summary  - 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  - 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  - 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
  • Methods and Documentation Used to Propose State Resource Water (SRW) and Superior High Quality Water (SHQW) Classifications for Ohio's Water Quality Standards 
    • Appendix 1.  Ohio Streams and Rivers:  Antidegradation Tier Justification, SRW & SHQW
    • Appendix 2.  Water Bodies Placed into SRW/SHQW "Holding Category"

Contact

Erin Sherer
(614)-644-2018

Walter Ariss
(614)644-3075