APS 2011 Annual Report Download - page 180

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Because of the inherent limitations of internal control over financial reporting, including the
possibility of collusion or improper management override of controls, material misstatements due to
error or fraud may not be prevented or detected on a timely basis. Also, projections of any evaluation
of the effectiveness of the internal control over financial reporting to future periods are subject to the
risk that the controls may become inadequate because of changes in conditions, or that the degree of
compliance with the policies or procedures may deteriorate.
In our opinion, the consolidated financial statements referred to above present fairly, in all material
respects, the financial position of Arizona Public Service Company and subsidiary as of December
31, 2011 and 2010, and the results of their operations and their cash flows for each of the three years
in the period ended December 31, 2011, in conformity with accounting principles generally accepted
in the United States of America. Also, in our opinion, such financial statement schedule, when
considered in relation to the basic consolidated financial statements taken as a whole, present fairly,
in all material respects, the information set forth therein. Also, in our opinion, the Company
maintained, in all material respects, effective internal control over financial reporting as of December
31, 2011, based on the criteria established in Internal Control — Integrated Framework issued by the
Committee of Sponsoring Organizations of the Treadway Commission.
Phoenix, Arizona
February 24, 2012