# STATE OF COLORA.OO

John W. Hickenlooper, Governor Christopher E. Urbina, MD, MPH

Executive Director and Chief Medical Officer
Dedicated to protecting and improving the health and environment of the people of Colorado

4300 Cherry Creek Dr. S. Laboratory Services Division Denver, Colorado 80246·1530 8100 Lowry Blvd. Phone (303) 692-2000 Denver, Colorado 80230-6928 Located in Glendale, Colorado (303) 692-3090 http://www.cdphe.state.co.us

May 10,2011 ColoradoDepartment ofPublicHealth andEnvironment

Deborah Lebow Air Program Director U.S. Environmental Protection Agency, Region VIII 1595 Wynkoop Street Denver, CO 80202-1129

RE: Colorado's Interstate Transport State Implementation Plan (SIP) and Greenhouse Gas (GHG) Permitting Authority

DearMs. Lebow:

The State ofColorado ("the State") is writing to clarify ambiguities in the Interstate Transport SIP submitted to EPA on March 31, 2010, and the Infrastructure SIP certification submittedto EPA on January 7, 2008. The Interstate Transport SIP submittal addressed the requirements ofsection 110(a)(2)(D)(i) ofthe Clean Air Act (CAA) for the 1997 ozone and PM2.5 NAAQS, and the Infrastructure SIP certification addressed the requirements ofCAA sections 11O(a)(l) and (2) for the 1997 ozone NAAQS. In the Interstate Transport SIP, the State indicated that it relied on its current SIPapproved Prevention ofSignificant Deterioration (PSD) permitting program to satisfy the requirement of CAA section llO(a)(2)(D)(i)(II) that SIPs contain adequate provisions preventing interference with other states' required PSD programs. The submittal date ofMarch 31, 2010 for the Interstate Transport SIP was priorto EPA's December 30, 2010 promulgation ofthe Limitation of Approvalof Prevention of SignificantDeteriorationProvisions Concerning Greenhouse Gas Emitting-Sources in State Implementation Plans ("PSD SIP Narrowing Rule") (75 FR 82536), which withdrew approval of Colorado's PSD program to the extentthat the program applied PSD permittingto GHG emissions increases from GHG-emitting sources with emissions belowthe thresholds established in EPA'sJune 3, 2010 Prevention of SignificantDeterioration and Title VGreenhouse Gas Tailoring Rule ("Tailoring Rule") (75 CFR 31514). The State wishes to clarify that, to satisfythe requirement ofCAA section 110 (a)(2)(D)(i)(II) that SIPs contain adequate provisions preventing interference with other states' required PSD programs, the State's Interstate Transport SIP submission should be read to rely only onthe portion ofColorado's PSD programthat remains approved after the PSD SIP Narrowing Rule took effect on December 30, 2010.

Page lof2Similarly. the Infrastructure SIP certification was submitted to EPA on January 7, 2008, priorto the December 30, 2010 promulgation ofthe PSD SIP Narrowing Rule. In that certification, the State indicated that itrelied on its current SIP-approved PSD program to meetthe requirements ofCAA sections IIO(a)(2)(C) and (J). The State wishes to clarify that, to satisfy the requirements ofCAA sections 110(a)(2), the State's Infrastructure SIP certification should be read to rely only onthe portion ofColorado's PSD program that remains approved afterthe PSD SIPNarrowing Rule took effect

on December 30, 1010.

Ifyou have any questions, please work with Dena Wojtach at (303) 692-3147 ordena.wojtach@state.co.us ofmy staffregarding this issue.

# ~------ Paul Tourangeau, Director Colorado Air Pollution Control Division

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