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EXHIBIT 23.1
INDEPENDENT AUDITORS' CONSENT
We consent to the incorporation by reference in this Registration Statement
of Tetra Tech, Inc. on Form S-3 of our reports dated November 16, 1999
(except for Note 5, as to which the date is December 24, 1999), appearing in
and incorporated by reference in, the Annual Report on Form 10-K of Tetra
Tech, Inc. for the year ended October 3, 1999, and to the reference to us
under the heading "Experts" in the Prospectus, which is part of this
Registration Statement.
/s/ Deloitte & Touche LLP
Los Angeles, California
August 16, 2000
