UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION IX 75 Hawthorne Street San Francisco, CA 94105·3901 March 19 7 2010

In Reply Refer To: AIR-3 SAC 06-01 Jon Maring Pacific Gas and Electric Company 915 Highland Point Drive, Suite 130 Roseville, CA 95678


### RE: Final Amended PSD Permit for the Colusa Generating Station
Dear Mr. Maring:
Enclosed is an Amended PSD Permit issued in accordance with the Prevention of Significant Deterioration (PSD) requirements ofthe Clean Air Act, as amended (42 U.S.C. § 7401 et seq.), for the construction and operation ofthe Colusa Generating Station (CGS) in Colusa County, California. This Amended PSD Permit revises the PSD permit that the U.S. Environmental Protection Agency Region 9 (EPA) issued for the CGS on September 29,2008, based on information provided in the application dated November 18 , 2008.
EPA requested public comments on a draft permit addressing these revisions (Draft Amended Permit) through a public notice published on September 9, 2009 in the Colusa Sun

-Herald, Willows Journal, and Orland Press Register. On October 21 , 2009 , EPA granted a request to extend the public comment period by announcing, through a public notice published in the same three newspapers, the extension ofthe comment period on the Draft Amended Permit to November 23,2009. We mailed these public notices to the necessary parties according to 40 CFR Part 124 and made the administrative record for the Draft Amended Permit available at our Region 9 office

. .. Additionally, we made the Draft Amended Permit, the Ambient Air Quality Impact Report (AAQIR) , and other supporting documents available on the EPA Region 9 website.
EPA received comments from one member ofthe public. We have enclosed a copy ofour responses to these comments with the final Amended PSD Permit. These documents, along with other documents relevant to the final Amended PSD Permit and the index for the entire administrative record, are available online at htt p :// www.epa. govlregion09/air/permitlr9 -pen nits-issued

.htmL The Amended PSD Permit will take effect thirty (30) days after the date ofissuance, unless a petition for review is timely filed.

Printed on Recycled PapaEPA's Procedures for Decisionmaking at 40 CFR Part 124 require that we notify the permit applicant and each person who submitted written comments or requested notice ofthe final permit decision and advise them ofthe process for petitioning the Environmental Appeals Board (EAB) to review any condition ofthe permit decision. Any petition must include a statement ofthe reasons supporting review, including a demonstration that any issues raised in the petition were raised during the public comment period to the extent required by the regulations and, when appropriate, a showing that the permit condition in question is based on: (1) A finding offact or conclusion oflaw which is clearly erroneous; or (2) An exercise ofdiscretion or an important policy consideration which the EAB should, in its discretion, review.
A petition to the EAB for review ofthe permit decision must be filed not later than thirty (30) days after EPA has issued the final permit decision.
Ifyou have any questions regarding this matter, please contact Shaheerah Kelly of the Permits Office at (415) 947-4156.Sincerely,

# D~**f1W** Director, Air Division

Enclosures: (1) Final Amended PSD Permit (2) Response to Comments

cc: Steve Royal, Pacific Gas & Electric (via email) Charles Price, Pacific Gas & Electric (via email) Harry Krug, Colusa County Air Pollution Control District T. 1. Gomez, Colusa County Air Pollution Control District Robert Fletcher, California Air Resources Board Dale Rundquist, California Energy Commission Chris Davis, California Energy Commission Jerry Salamy, CH2M Hill