Basis of Presentation	6 Months Ended
Mar. 31, 2013
Basis of Presentation
Basis of Presentation	1. Basis of Presentation The accompanying unaudited condensed consolidated financial statements and related notes of Tetra Tech, Inc. (“we,” “us” or “our”) have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. They do not include all of the information and footnotes required by GAAP for complete financial statements and, therefore, should be read in conjunction with the audited consolidated financial statements and related notes contained in our Annual Report on Form 10-K for the fiscal year ended September 30, 2012. These financial statements reflect all normal recurring adjustments that are considered necessary for a fair statement of our financial position, results of operations and cash flows for the interim periods presented. The results of operations and cash flows for any interim period are not necessarily indicative of results for the full year or for future years. These financial statements include the accounts of our wholly-owned subsidiaries and those joint ventures of which we are the primary beneficiary. For the joint ventures in which we do not have a controlling interest, but exert a significant influence, we apply the equity method of accounting (see Note 11, “Joint Ventures” for further discussion). In the first quarter of fiscal 2013, we implemented a reorganization of our operations to improve future growth and profitability. These activities included the consolidation and realignment of certain operating activities to improve organizational effectiveness and achieve efficiencies in our segment management. This reorganization included the elimination of the Engineering and Architecture Services (“EAS”) segment, and the re-assignment of its operations to the Engineering and Consulting Services (“ECS”) and Technical Support Services (“TSS”) segments (see Note 9, “Reportable Segments” for further discussion). Prior-year amounts for reportable segments have been reclassified to conform to the current-year presentation. For both fiscal 2013 and 2012, “Interest expense – net” on the condensed consolidated statements of income includes $0.2 million and $0.4 million in interest income for the three and six-month periods, respectively.

1. Basis of Presentation

The accompanying unaudited condensed consolidated financial statements and related notes of Tetra Tech, Inc. (“we,” “us” or “our”) have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. They do not include all of the information and footnotes required by GAAP for complete financial statements and, therefore, should be read in conjunction with the audited consolidated financial statements and related notes contained in our Annual Report on Form 10-K for the fiscal year ended September 30, 2012.

These financial statements reflect all normal recurring adjustments that are considered necessary for a fair statement of our financial position, results of operations and cash flows for the interim periods presented. The results of operations and cash flows for any interim period are not necessarily indicative of results for the full year or for future years.

These financial statements include the accounts of our wholly-owned subsidiaries and those joint ventures of which we are the primary beneficiary. For the joint ventures in which we do not have a controlling interest, but exert a significant influence, we apply the equity method of accounting (see Note 11, “Joint Ventures” for further discussion). In the first quarter of fiscal 2013, we implemented a reorganization of our operations to improve future growth and profitability. These activities included the consolidation and realignment of certain operating activities to improve organizational effectiveness and achieve efficiencies in our segment management. This reorganization included the elimination of the Engineering and Architecture Services (“EAS”) segment, and the re-assignment of its operations to the Engineering and Consulting Services (“ECS”) and Technical Support Services (“TSS”) segments (see Note 9, “Reportable Segments” for further discussion). Prior-year amounts for reportable segments have been reclassified to conform to the current-year presentation. For both fiscal 2013 and 2012, “Interest expense – net” on the condensed consolidated statements of income includes $0.2 million and $0.4 million in interest income for the three and six-month periods, respectively.