EXHIBIT 3.4

                                       
                           CERTIFICATE OF AMENDMENT
                                       OF
                         CERTIFICATE OF INCORPORATION
                                       OF
                                TETRA TECH, INC.


Li-San Hwang and Richard A. Lemmon hereby certify that:

A.   They are the President and the Secretary, respectively, of Tetra Tech, 
     Inc., a Delaware corporation (the "Corporation").

B.   The Certificate of Incorporation of the Corporation is amended so that 
     the first paragraph of Article IV is amended and superseded in full by the 
     following paragraph:

                                   "ARTICLE IV

     The total number of shares of stock that the corporation shall have 
     authority to issue is fifty-two million (52,000,000), consisting of 
     fifty million (50,000,000) shares of common stock, par value $.01, and 
     two million (2,000,000) shares of preferred stock, par value of $.01.  
     The designation and the powers, preferences and rights, and the 
     qualifications, limitations or restrictions thereof are as follows:

C.   The foregoing Amendment to Certificate of Incorporation of the 
     Corporation was duly adopted by a majority of the duly elected directors 
     of the Corporation in accordance with the provisions of Section 242 of 
     the Delaware General Corporation Law and in accordance with their 
     direction was submitted to the stockholders of the Corporation.

D.   Thereafter, pursuant to the resolution of the directors of the 
     Corporation, the vote of the stockholders of the Corporation was 
     solicited wherein a majority of the outstanding shares of capital stock 
     of the Corporation entitled to vote thereon approved the foregoing 
     Amendment to the Certificate of Incorporation.

     IN WITNESS WHEREOF, Li-San Hwang and Richard A. Lemmon being the 
President and Secretary, respectively, of the Corporation, do hereby certify 
under penalty of perjury under the laws of the State of Delaware that the 
facts hereinabove stated are truly set forth, and accordingly each of us has 
hereunto set our hands this 14th day of September, 1998.


/s/ LI-SAN HWANG                               /s/ RICHARD A. LEMMON
- -----------------------                        ----------------------------
Li-San Hwang, President                        Richard A. Lemmon, Secretary