August 15, 2014 

MEMORANDUM 

To: 316(b) Existing Facility Rule Docket 

FROM: Julie A. Hewitt, OW/OST/EAD/EEAB 

RE: List of Significant Changes Made During Interagency Review 

The following list contains the most significant changes made to the preamble and rule during the 

interagency review process under E.O. 12866 for the final rule, signed on May 19, 2014. For a complete 

list, please consult the document in the public docket that shows the full set of changes made in 

redline/strikeout format. 

1. Inserted further explanation of environmental benefits in I.B. Need for the Rule. 

2. Revised estimates of costs and benefits of the rule in I.C, and inserted table summarizing costs 

and benefits. 

3. Revised definition of new units, in I.D, I.J, V, VI, VII, and IX, and in the rule at 125.92(u) and 

125.98. 

4. Refined discussion of water reuse in section on what is cooling water, in I.E. 

5. Included references to proposed rule on the definition of Waters of the United States, in I.G. 

6. Added clarification regarding impoundments and definition of closed cycle recirculating systems, 

in I.G, V, VI, VII, IX, and X, and in the rule, 122.21(r)(6), 125.92(c). 

7. Included additional justification for applicability threshold of 2 mgd in I.H, and clarified 

justification for 125 mgd AIF threshold for entrainment studies, in I.H and VI. 

8. Deleted some discussion of regulations under other CWA sections, and added discussion of 

changes in rulemaking deadlines, in II.C. 

9. Improved discussion of environmental effects of cooling water intake structures in III. 

10. Inserted corroborating changes to description of final rule in IV. 

11. Clarified the status of EPA's stated preference survey of household willingness-to-pay for fish 

protection, in V and VI, and whether permittees or Directors are required to conduct their own 

stated preference study, in VI, VIII, and X. 

12. Removed from definition of closed cycle recirculating systems the percent reduction in 

withdrawals and cycles of concentration thresholds, in V. 
14. Inserted subsection on overview of the final rule requirements in VI, for readability. 

15. Expanded justification for not considering reduced velocity to be best technology available, in 

VI. 

16. Revised Option Selection section in VI. 

17. Revised discussion of other options considered, in VI, including proposal option 4 variant. 

18. Added clarity to reason for including existing velocity caps as pre-approved technology, in VI. 

19. Added recognition that facilities cannot conduct impingement technology performance 

optimization study if technology is not already installed, in VI, and VII. 

20. Added more information about NPDES permitting process and reference to requirements in the 

NPDES regulations, in VI. 

21. Clarified terminology regarding entrainment studies (122.21(r)(9) to (13)), and Entrainment 

Characterization Study (122.21(r)(9)). 

22. Removed waivability of benefits study as part of requirement to consider costs and benefits, in 

VI, and in the rule at 122.21(r)(11). 

23. Modified provision for Director to impose less stringent requirements on low capacity utilization 

units, in IV, VII, and VIII, and in the rule at 125.94(c)(12). 

24. Changed fixed date by which entrainment requirements were to be included in permits to a 

date based on the effective date of the rule, recognizing delays in issuing the final rule, in VIII, 

and in the rule at 125.95 and 125.98. 

25. Included discussion of permits that are administratively continued, in VIII. 

26. Added reasoning for requiring permit application information of facilities that have already 

adopted closed cycle recirculating systems, in VIII. 

27. Clarified discussion of requirements affected by EPA's consultation with the US Fish and Wildlife 

Service and National Marine Fisheries Services, under section 7 of the Endangered Species Act, 

in VIII, especially VIII.K, and in the rule at 122.21(r)(1)(ii)(H), note to 125.90, 125.94, 125.95, 

125.96, 125.97, and 125.98. 

28. Clarified discussion of social cost estimation, including energy penalty and operation and 

maintenance costs, in VIII. 

29. Modified discussion of de minimis provision in impingement mortality standard, in VIII. 

30. Modified discussion of nuclear safety considerations, in VIII. 
31. Recalculation of social cost estimates, economic impacts, and IPM results, in IX. 

32. Revised discussion of employment effects in IX. 

33. Recalculated estimates of impingement and entrainment losses, and monetized benefits in X. 

34. Revision of social cost of carbon estimates, due to interagency updates, in X. 

35. Added table summarizing benefits, in X. 

36. Revised analysis under Regulatory Flexibility Act, in Xl. 

37. Expanded discussion of efforts taken under Unfunded Mandates Reform Act, in Xl. 

38. Revised discussion of E.0 13211, on energy effects, in Xl. 

39. Removed backstop provision in 122.21(r)(1)(ii)(B) allowing Director to require closed cycle 

recirculating systems when permittees submit incomplete information, and added provision 

allowing Directors to waive some information in (r)(9) to (13). 

40. Added consideration of situation where addition of a new unit causes a facility to exceed the 2 

mgd threshold, in the rule at 122.21(r)(1)(ii)(E). 

41. Included "costs wholly out of proportion" provision to new units requirements in the rule at 

122.21(4)(14), to mimic Phase I requirements. 

42. Removed requirement for facilities using reclaimed water to meet limitations that would have 

applied to the facility from which they obtain the reused water, in the rule at 125.91(c). 

43. Removed definitions for "emergency purposes" and "high energy efficiency" from the rule at 

125.92. 

44. Clarified definition of social benefits, in the rule at 125.92(u). 

45. Modifications to numeric impingement mortality standard in the rule at 125.94(c)(7). 

46. Added Director discretion regarding weight given to factors, and added social costs and social 

benefits to list of "must" consider factors, in the rule at 125.98.