Basis of Presentation	9 Months Ended
Jun. 26, 2016
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 27, 2015. 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. We report our water resources, water and wastewater treatment, environment and infrastructure engineering activities in our Water, Environment and Infrastructure (“WEI”) reportable segment. Our Resource Management and Energy (“RME”) reportable segment includes our natural resources, energy, international development, waste management, remediation and utilities services. We report the results of the wind-down of our non-core construction activities in the Remediation and Construction Management (“RCM”) reportable segment. In the first quarter of fiscal 2016, we re-aligned certain operating units within our reportable segments to improve organizational effectiveness by better aligning operations with similar clients and projects. Specifically, we re-aligned certain operations that previously provided natural resources services, primarily mining-related, in the RME reportable segment to the WEI reportable segment. Due to the downturn in the mining industry in recent years, we determined that these operations could be better utilized by supporting infrastructure engineering activities in our WEI reportable segment. Although these activities had revenue of $42.7 million in the first nine months of fiscal 2015, they were approximately break-even in operating income in that period. Prior year amounts for reportable segments have been revised to conform to the current year presentation. As a result of the re-alignment of segment results, WEI’s revenue for the first nine months of fiscal 2015 increased 6.1% and its operating income margin decreased 6.9% compared to the results before the re-alignment. Correspondingly, RME’s revenue for the first nine months of fiscal 2015 declined by 4.6% and its operating income margin increased 5.7% (see Note 10, “Reportable Segments” for further discussion).

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 27, 2015.

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.

We report our water resources, water and wastewater treatment, environment and infrastructure engineering activities in our Water, Environment and Infrastructure (“WEI”) reportable segment. Our Resource Management and Energy (“RME”) reportable segment includes our natural resources, energy, international development, waste management, remediation and utilities services. We report the results of the wind-down of our non-core construction activities in the Remediation and Construction Management (“RCM”) reportable segment. In the first quarter of fiscal 2016, we re-aligned certain operating units within our reportable segments to improve organizational effectiveness by better aligning operations with similar clients and projects. Specifically, we re-aligned certain operations that previously provided natural resources services, primarily mining-related, in the RME reportable segment to the WEI reportable segment. Due to the downturn in the mining industry in recent years, we determined that these operations could be better utilized by supporting infrastructure engineering activities in our WEI reportable segment. Although these activities had revenue of $42.7 million in the first nine months of fiscal 2015, they were approximately break-even in operating income in that period. Prior year amounts for reportable segments have been revised to conform to the current year presentation. As a result of the re-alignment of segment results, WEI’s revenue for the first nine months of fiscal 2015 increased 6.1% and its operating income margin decreased 6.9% compared to the results before the re-alignment. Correspondingly, RME’s revenue for the first nine months of fiscal 2015 declined by 4.6% and its operating income margin increased 5.7% (see Note 10, “Reportable Segments” for further discussion).