CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
We hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (Nos. 333-174032, 333-158932, 333-148712, 333-145201, 333-145199, 333-85558 and 333-11757) of Tetra Tech, Inc. of our report dated November 14, 2012 relating to the financial statements, financial statement schedule and the effectiveness of internal control over financial reporting, which appears in this Form 10-K.
/s/ PRICEWATERHOUSECOOPERS LLP
Los
Angeles, California
November 14, 2012