SECURITIES AND EXCHANGE COMMISSION
                               Washington, D.C.  20549


                                      Form 8-K/A
                                  (Amendment No. 2)
                                           

                  Current Report Pursuant to Section 13 or 15(d) of
                              The Securities Act of 1934
                                           



Date of Report (Date of earliest event reported)    June 11, 1997     
                                                 ------------------------------
    
                                   Tetra Tech, Inc.
- --------------------------------------------------------------------------------
                (Exact name of registrant as specified in its charter)





        Delaware                  0-19566                  95-4148514     
- --------------------------------------------------------------------------------
    (State or other             (Commission             (I.R.S. Employer 
      jurisdiction              File Number)           Identification No.)
    of incorporation)




        670 N. Rosemead Boulevard, Pasadena, California 91107-2190           
- --------------------------------------------------------------------------------
            (Address of principal executive offices)          (Zip Code)  



Registrant's telephone number, including area code     (626) 351-4664
                                                   -----------------------------



                   Not Applicable                                 
- --------------------------------------------------------------------------------
            (Former name or former address, if changed since last report.)
                                           
                                           


    The undersigned Registrant hereby amends the following item of its Current
Report on Form 8-K for the event of June 11, 1997:

ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS.

         (a)  FINANCIAL STATEMENTS OF BUSINESSES ACQUIRED.

              (i)     Independent Auditors' Report of Deloitte & Touche LLP
                      dated August 8, 1997

              (ii)    Independent Public Accountants' Report of Arthur Andersen
                      LLP dated November 1, 1996

              (iii)   Whalen & Company, Inc. Balance Sheets for the Years Ended
                      December 31, 1996 and 1995

              (iv)    Whalen & Company, Inc. Statements of Income for the Years
                      Ended December 31, 1996, 1995 and 1994

              (v)     Whalen & Company, Inc. Statements of Stockholder's Equity
                      for the Years Ended December 31, 1996, 1995 and 1994

              (vi)    Whalen & Company, Inc. Statements of Cash Flows for the
                      Years Ended December 31, 1996, 1995 and 1994

              (vii)   Whalen & Company, Inc. Notes to Financial Statements for
                      the Years Ended December 31, 1996, 1995 and 1994
                      

         (b)  PRO FORMA FINANCIAL INFORMATION.

              (i)     Tetra Tech, Inc. and Whalen & Company, Inc. Unaudited Pro
                      Forma Condensed Consolidated Statement of Operations for
                      the Year Ended September 29, 1996

              (ii)    Tetra Tech, Inc. and Whalen & Company, Inc. Unaudited Pro
                      Forma Condensed Consolidated Statement of Operations for
                      the Nine Months Ended June 29, 1997

              (iii)   Tetra Tech, Inc. and Whalen & Company, Inc. Notes to
                      Unaudited Pro Forma Condensed Consolidated Financial
                      Statements




         (c)  EXHIBITS.

              23.1    Consent of Independent Auditors
              
              23.2    Consent of Independent Public Accountants

              27      Financial Data Schedule




REPORT OF DELOITTE & TOUCHE LLP



To the Board of Directors and Stockholder 
  of Whalen & Company, Inc.:

We have audited the accompanying balance sheet of Whalen & Company, Inc. as of
December 31, 1996, and the related statements of income, stockholder's equity
and cash flows for the year then ended.  We have also audited the statements of
income, stockholder's equity and cash flows for the year ended December 31,
1994.  These financial statements are the responsibility of the Company's
management.  Our responsibility is to express an opinion on the financial
statements based on our audits.

We conducted our audits in accordance with generally accepted auditing
standards.  Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement.  An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements.  An audit also includes
assessing the accounting principles used and significant estimates made by
management as well as evaluating the overall financial statement presentation. 
We believe that our audits provide a reasonable basis for our opinion.

In our opinion, such financial statements present fairly, in all material
respects, the financial position of Whalen & Company, Inc. at December 31, 1996,
and the results of their operations and their cash flows for the years ended
December 31, 1996 and December 31, 1994 in conformity with generally accepted
accounting principles.

DELOITTE & TOUCHE LLP


San Jose, California
August 8, 1997
                                           



                       REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS
                                           
                                           
                                           
To the Management of 
Whalen & Company, Inc.:

We have audited the accompanying balance sheet of Whalen & Company, Inc. (the
Company) as of December 31, 1995, and the related statements of operations,
stockholder's equity and cash flows for the year then ended.  These financial
statements are the responsibility of the Company's management.  Our
responsibility is to express an opinion on these financial statements based on
our audit.

We conducted our audit in accordance with generally accepted auditing standards.
Those standards require that we plan and perform the audit to obtain reasonable
assurance about whether the financial statements are free of material
misstatement.  An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements.  An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation. 
We believe that our audit provides a reasonable basis for our opinion.

In our opinion, the financial statements referred to above present fairly, in
all material respects, the financial position of Whalen & Company, Inc. as of
December 31, 1995, and the results of its operations and its cash flows for the
year then ended, in conformity with generally accepted accounting principles.

ARTHUR ANDERSEN LLP


San Francisco, California,
  November 1, 1996




                                WHALEN & COMPANY, INC.
                                    BALANCE SHEETS
                        YEARS ENDED DECEMBER 31, 1996 AND 1995
                                           



 

(In thousands, except share amounts)                               1996         1995   
                                                                 ---------    ---------

                                          ASSETS
                                                                              
CURRENT ASSETS:
  Cash and equivalents . . . . . . . . . . . . . . . . . .       $   3,126    $     783
  Accounts receivable, less allowance for doubtful accounts 
    of $2,020 and $195 in 1996 and 1995, respectively. . .          24,941       15,205
  Prepaid expenses and other . . . . . . . . . . . . . . .             472          566
                                                                 ---------    ---------

       Total current assets. . . . . . . . . . . . . . . .          28,539       16,554

PROPERTY AND EQUIPMENT, Net. . . . . . . . . . . . . . . .             705          456

OTHER ASSETS . . . . . . . . . . . . . . . . . . . . . . .             682          360
                                                                 ---------    ---------

TOTAL  . . . . . . . . . . . . . . . . . . . . . . . . . .       $  29,926    $  17,370
                                                                 ---------    ---------
                                                                 ---------    ---------


                           LIABILITIES AND STOCKHOLDER'S EQUITY

CURRENT LIABILITIES:
  Accounts payable . . . . . . . . . . . . . . . . . . . .       $   1,119    $     804
  Accrued employee benefits. . . . . . . . . . . . . . . .           2,830        2,766
  Other accrued liabilities. . . . . . . . . . . . . . . .             509           --
  Deferred revenue . . . . . . . . . . . . . . . . . . . .              --        2,511
  Note payable to stockholder. . . . . . . . . . . . . . .           1,446           --
                                                                 ---------    ---------

       Total liabilities . . . . . . . . . . . . . . . . .           5,904        6,081
                                                                 ---------    ---------

COMMITMENTS AND CONTINGENCIES (Note 5)

STOCKHOLDER'S EQUITY:
  Common stock, $1 par value; 150,000 shares authorized;
    100 shares issued outstanding. . . . . . . . . . . . .              10           10
  Retained earnings. . . . . . . . . . . . . . . . . . . .          24,012       11,279
                                                                 ---------    ---------

       Total stockholder's equity. . . . . . . . . . . . .          24,022       11,289
                                                                 ---------    ---------

TOTAL  . . . . . . . . . . . . . . . . . . . . . . . . . .       $  29,926    $  17,370
                                                                 ---------    ---------
                                                                 ---------    ---------

 

                          See notes to financial statements.
                                           



                                WHALEN & COMPANY, INC.
                                 STATEMENTS OF INCOME
                     YEARS ENDED DECEMBER 31, 1996, 1995 AND 1994
                                           



(In thousands)                                                     1996         1995         1994   
                                                                 ---------    ---------    ---------
                                                                                        
NET REVENUES:
  Management fees. . . . . . . . . . . . . . . . . . . . .       $  45,773    $  44,733    $  41,145
  Per-site fees. . . . . . . . . . . . . . . . . . . . . .          10,783        7,366        3,888
  Contract termination fee . . . . . . . . . . . . . . . .              --           --          900
                                                                 ---------    ---------    ---------

       Total net revenues. . . . . . . . . . . . . . . . .          56,556       52,099       45,933

FIELD OPERATING EXPENSES . . . . . . . . . . . . . . . . .          26,058       29,586       23,890
                                                                 ---------    ---------    ---------

OPERATING INCOME . . . . . . . . . . . . . . . . . . . . .          30,498       22,513       22,043
  
GENERAL AND ADMINISTRATIVE EXPENSES. . . . . . . . . . . .          11,220        6,193        3,976
                                                                 ---------    ---------    ---------

INCOME FROM OPERATIONS . . . . . . . . . . . . . . . . . .          19,278       16,320       18,067
                                                                 ---------    ---------    ---------

OTHER INCOME (EXPENSE), Net:
  Interest income. . . . . . . . . . . . . . . . . . . . .              66          533           79
  Interest expense . . . . . . . . . . . . . . . . . . . .             (35)        (110)        (234)
  Other expense, net . . . . . . . . . . . . . . . . . . .             (74)        (756)         (48)
                                                                 ---------    ---------    ---------

       Total other expense, net. . . . . . . . . . . . . .             (43)        (333)        (203)
                                                                 ---------    ---------    ---------

INCOME BEFORE INCOME TAXES . . . . . . . . . . . . . . . .          19,235       15,987       17,864

STATE INCOME TAXES . . . . . . . . . . . . . . . . . . . .             385          500          357
                                                                 ---------    ---------    ---------

NET INCOME . . . . . . . . . . . . . . . . . . . . . . . .       $  18,850    $  15,487    $  17,507
                                                                 ---------    ---------    ---------
                                                                 ---------    ---------    ---------


 

                          See notes to financial statements.
                                           



                                WHALEN & COMPANY, INC.
                          STATEMENTS OF STOCKHOLDER'S EQUITY
                     YEARS ENDED DECEMBER 31, 1996, 1995 AND 1994
                                           
                                           


 

                                                Common Stock                            Total    
(In thousands, except share amounts)      ----------------------      Retained      Stockholder's
                                           Shares         Amount      Earnings          Equity   
                                          -------        -------     ----------     -------------
                                                                                  
BALANCES, January 1, 1994. . . . . .          100        $    10     $      705     $         715

Net income . . . . . . . . . . . . .           --             --         17,507            17,507
                                          -------        -------     ----------     -------------

BALANCES, December 31, 1994. . . . .          100             10         18,212            18,222

Stockholder distribution . . . . . .           --             --        (22,420)          (22,420)
Net income . . . . . . . . . . . . .           --             --         15,487            15,487
                                          -------        -------     ----------     -------------

BALANCES, December 31, 1995. . . . .          100             10         11,279            11,289

Stockholder distribution . . . . . .           --             --         (6,117)           (6,117)
Net income . . . . . . . . . . . . .           --             --         18,850            18,850
                                          -------        -------     ----------     -------------

BALANCES, December 31, 1996. . . . .          100        $    10     $   24,012     $      24,022
                                          -------        -------     ----------     -------------
                                          -------        -------     ----------     -------------


 

                          See notes to financial statements.
                                           



                                WHALEN & COMPANY, INC.
                               STATEMENTS OF CASH FLOWS
                     YEARS ENDED DECEMBER 31, 1996, 1995 AND 1994


 
(In thousands)                                                                1996        1995        1994  
                                                                            --------    --------    --------
                                                                                                
CASH FLOWS FROM OPERATING ACTIVITIES:
  Net income . . . . . . . . . . . . . . . . . . . . . . . . . . . .        $ 18,850    $ 15,487    $ 17,507
  Reconciliation of net income to net cash provided by
    operating activities:
    Depreciation . . . . . . . . . . . . . . . . . . . . . . . . . .             510         170          60
    Provision for doubtful accounts. . . . . . . . . . . . . . . . .           1,825         195          --
    Changes in assets and liabilities:
       Accounts receivable . . . . . . . . . . . . . . . . . . . . .         (11,561)      1,001     (14,119)
       Prepaid expenses and other. . . . . . . . . . . . . . . . . .              94        (151)       (291)
       Contract termination receivable . . . . . . . . . . . . . . .             180         180        (540)
       Other assets. . . . . . . . . . . . . . . . . . . . . . . . .            (502)         --          --
       Accounts payable. . . . . . . . . . . . . . . . . . . . . . .             315         755          35
       Accrued employee benefits . . . . . . . . . . . . . . . . . .              64         422       1,495
       Other accrued liabilities . . . . . . . . . . . . . . . . . .             509        (782)        553
       Deferred revenue. . . . . . . . . . . . . . . . . . . . . . .          (2,511)      2,511          --
                                                                            --------    --------    --------

          Net cash provided by operating activities. . . . . . . . .           7,773      19,788       4,700
                                                                            --------    --------    --------

CASH FLOWS FROM INVESTING ACTIVITIES:
  Purchase of long-term investment . . . . . . . . . . . . . . . . .              --          --         (25)
  Sale of long-term investment . . . . . . . . . . . . . . . . . . .              --          25          --
  Purchases of property and equipment. . . . . . . . . . . . . . . .            (763)       (369)       (173)
  Proceeds from sale of property and equipment . . . . . . . . . . .               4          16          --
                                                                            --------    --------    --------

          Net cash used in investing activities. . . . . . . . . . .            (759)       (328)       (198)
                                                                            --------    --------    --------

CASH FLOWS FROM FINANCING ACTIVITIES:
  Issuance of note payable to stockholder. . . . . . . . . . . . . .           1,500          --       1,002
  Repayments of notes payable to stockholder . . . . . . . . . . . .             (54)     (3,069)       (251)
  Distribution to stockholder. . . . . . . . . . . . . . . . . . . .          (6,117)    (22,420)         --
                                                                            --------    --------    --------

          Net cash provided by (used in) financing activities. . . .          (4,671)    (25,489)        751
                                                                            --------    --------    --------

NET CHANGE IN CASH AND EQUIVALENTS . . . . . . . . . . . . . . . . .           2,343      (6,029)      5,253

CASH AND EQUIVALENTS, Beginning of year. . . . . . . . . . . . . . .             783       6,812       1,559
                                                                            --------    --------    --------

CASH AND EQUIVALENTS, End of year. . . . . . . . . . . . . . . . . .        $  3,126    $    783    $  6,812
                                                                            --------    --------    --------
                                                                            --------    --------    --------

SUPPLEMENTAL DISCLOSURE OF CASH FLOW
  INFORMATION:
  Cash paid for interest . . . . . . . . . . . . . . . . . . . . . .        $     --    $    110    $    234
                                                                            --------    --------    --------
                                                                            --------    --------    --------

  Cash paid for income taxes . . . . . . . . . . . . . . . . . . . .        $     53    $    495    $     40
                                                                            --------    --------    --------
                                                                            --------    --------    --------


 

                          See notes to financial statements.




                                WHALEN & COMPANY, INC.
                            NOTES TO FINANCIAL STATEMENTS
                     YEARS ENDED DECEMBER 31, 1996, 1995 AND 1994
                                            
1.  SIGNIFICANT ACCOUNTING POLICIES

    DESCRIPTION OF BUSINESS - Whalen & Company, Inc. (the "Company") is a
Delaware Chapter S corporation that was formed effective August 25, 1987.  Dan
Whalen is the founder and sole stockholder of the Company.

    The Company provides program and turnkey project development consulting
services on a contract basis to customers who build and operate wireless
networks.  The Company offers a range of services from single-site deployments
to the implementation of complete wireless network systems.   The Company has
consulting experience in PCS, cellular, ESMR, wireless, air-to-ground,
microwave, paging, fiber optic and switching center systems.

    The Company provides services in North America, South America, Asia,
Australia and Europe.

    FINANCIAL STATEMENT ESTIMATES - The preparation of financial statements in
conformity with generally accepted accounting principles requires management to
make estimates and assumptions that affect the reported amounts of assets and
liabilities and disclosure of contingent assets and liabilities at the date of
the financial statements and the reported amounts of revenues and expenses
during the reporting period.  Significant estimates include a provision for
doubtful accounts.  Actual results could differ from estimates.

    CASH AND EQUIVALENTS - Cash and equivalents include cash and highly liquid
debt instruments with original maturities of three months or less.

    ACCOUNTS RECEIVABLE - Accounts receivable includes billed and unbilled
accounts receivable.  Total unbilled accounts receivable were $6,794,000 and
$3,061,000 as of December 31, 1996 and 1995, respectively.

    CONCENTRATION OF CREDIT RISK - Financial instruments which potentially
subject the Company to concentrations of credit risk consist primarily of cash
and equivalents and accounts receivable.  The Company places its cash and
equivalents for safekeeping with high-credit-quality financial institutions. 
The Company performs ongoing credit evaluations of its customers and generally
requires that customers remit payment for billed revenue within 30 days.  The
Company maintains reserves for estimated credit losses.  See Note 7 concerning
significant customers.

    PROPERTY AND EQUIPMENT - Property and equipment are stated at cost. 
Depreciation is computed using the straight-line method over the estimated
useful lives of the assets ranging from two to seven years.




    REVENUE RECOGNITION - The Company recognizes management fee revenue as
project management and consulting services are performed in accordance with
customer contracts.  The recognition of revenue related to per-site fees is
deferred until milestones in the Company's customer contracts have been met and
collection is reasonably assured.  Per-site fees in 1996 include $8,407,000 from
a single customer of which $2,511,000 were related to 1995 and had been deferred
as of December 31, 1995 due to the uncertainty of collection as of that date.

    REIMBURSABLE EXPENSES - Certain expenses incurred by the Company are passed
on to customers in accordance with customer contract agreements.  The Company
records the expense and reimbursement on a gross basis.  The amounts included in
management fees and field operating expenses were $6,861,000, $7,122,000 and
$6,128,000 in 1996, 1995 and 1994, respectively.

    FAIR VALUE OF FINANCIAL INSTRUMENTS - Financial instruments include cash
equivalents and long-term obligations.  Cash equivalents are stated at cost
which approximates fair market value based on quoted market prices.  The
carrying amount of the Company's long-term obligations approximates fair market
value.

    INCOME TAXES - The Company's stockholder elected to be taxed as an S
corporation under the provisions of the Internal Revenue Code.  Under these
provisions, the Company does not pay federal corporate income taxes on its
taxable income.  As a Chapter S corporation, the Company is required to pay
state income taxes to the states in which it conducts business.

    RECLASSIFICATIONS - Certain reclassifications to the 1995 financial
statements have been made to conform to the 1996 presentation.


2.  PROPERTY AND EQUIPMENT, NET

    Property and equipment at December 31 consist of the following (in
thousands):
    
                                                      1996           1995 
                                                     ------         ------

         Furniture and fixtures                      $  197         $  168
         Office equipment                               247            127
         Computer equipment                             814            281
         Computer software                               89            191
                                                     ------         ------
                                                      1,347            767
         Accumulated depreciation                      (642)          (311)
                                                     ------         ------
                                                     $  705         $  456
                                                     ------         ------
                                                     ------         ------
         



3.  LONG-TERM RECEIVABLE

    On December 8, 1994, the Company reached a settlement on a contract
termination with a customer relating to a contract to provide construction
administration services that was canceled prior to December 8, 1994.  The
customer agreed to pay, as a settlement of all past and future amounts due,
$900,000 over five years beginning in 1994.  As of December 31, 1996, $360,000
of the settlement amount is still outstanding.
    
    The Company has included $180,000 of the outstanding balance in current
accounts receivable for the portion due in 1997.  The remaining amount of
$180,000 is due during 1998 and is included in other assets.
    
    The principal amount of the receivable is adjusted each year for increases
in the Consumer Price Index.
         
         
4.  LINE OF CREDIT

    The Company has a revolving line of credit with a bank under which it may
borrow up to $5,000,000 through February 1998.  Borrowings bear interest at the
bank's reference rate (8.25% at December 31, 1996) and are personally guaranteed
by the sole stockholder.  There were no borrowings outstanding under the
revolving line of credit at December 31, 1996.
     
     
5.  COMMITMENTS AND CONTINGENCIES

    The Company leases office space for its corporate facilities.  All leases
are classified as operating leases.  The following is a schedule of the future
minimum rental payments required under operating leases that have initial or
remaining noncancelable terms in excess of one year as of December 31, 1996 (in
thousands):
    
         1997. . . . . . . . . . . . . . . . . . . .     $    87
         1998. . . . . . . . . . . . . . . . . . . .          13
         1999. . . . . . . . . . . . . . . . . . . .          13
         2000. . . . . . . . . . . . . . . . . . . .          13
         2001. . . . . . . . . . . . . . . . . . . .          12
                                                         -------

         Total minimum lease payments. . . . . . . .     $   138
                                                         -------
                                                         -------

    Lease payments charged to operations totaled $222,000, $153,000 and $80,000
for 1996, 1995 and 1994, respectively.




6.  RELATED PARTY TRANSACTIONS

    NOTE PAYABLE TO STOCKHOLDER
    
    The sole stockholder of the Company advances the Company funds through
notes payable that are used for current operating and other costs and are due
upon demand.  In 1994, the stockholder note payable accrued interest at a rate
varying from 7% to 9%.  In January 1995, the note was amended to bear interest
at a rate of 9%.  Total interest expense related to the stockholder note payable
was $21,000, $110,000 and $234,000 for 1996, 1995 and 1994, respectively.

    At December 31, 1994, the Company had an outstanding stockholder note
payable of $3,069,000.  The balance of the note payable was settled during 1995.
The Company paid income taxes and various expenses of the sole stockholder,
which were recorded as a reduction in the stockholder note payable balance.

    In November 1996, the sole stockholder advanced the Company an additional
$1,500,000 which accrues interest at 8.5%.


7.  MAJOR CUSTOMER INFORMATION

    Customers which accounted for 10% or more of total revenues were as
follows:
    
                                                 1996      1995      1994
                                                 ----      ----      ----
    Customer A                                   27%       72%       89%
    Customer B                                   18        --        --
    Customer C                                   16        --        --
    Customer D                                   15        --        --
    Customer E                                   10        --        --
    
    At December 31, 1996, three customers' balances accounted for 40%, 26% and
11% of accounts receivable.  At December 31, 1995, one customer's balance
accounted for 73% of accounts receivable.
    
    
8.  EMPLOYEE BENEFITS PLAN

    The Company maintains a 401(k) plan for employees who have completed 12
consecutive months of service and during that period have worked 1,000 hours. 
The Company makes matching contributions to the plan based on the amounts
contributed by eligible employees.  Company contributions to the plan totaled
$264,000, $223,000 and $105,000 for 1996, 1995 and 1994, respectively.




9.  SUBSEQUENT EVENT

    On June 11, 1997, the Company entered into an Agreement and Plan of
Reorganization with Tetra Tech, Inc., a Delaware corporation (the "Agreement"). 
The Agreement provided for the merger of the Company, along with Whalen Service
Corps Inc., with Tetra Tech, Inc. for aggregate consideration of $52,456,000.
    
    The consideration consisted of 1,680,000 shares of Tetra Tech, Inc. common
stock with a $.01 par value ("Common Stock"), 1,231,840 shares of Tetra Tech,
Inc. Series A convertible preferred stock with a $.01 par value ("Series A
Stock") and $8,051,000 in cash. 

    Each share of Series A Stock will automatically be converted into one share
of Common Stock immediately upon the filing of an amendment to Tetra Tech,
Inc.'s Certificate of Incorporation which increases the number of authorized
shares of Common Stock to a number sufficient to permit the conversion of all
the outstanding shares of Series A Stock.
    
    As part of the Agreement, on the business day prior to the merger, the
Company distributed to the stockholder (i) cash in the amount of $4,138,000 and
(ii) accounts receivable having a net value of $18,456,000. 
                                           
                                      * * * * *
                                           



                     TETRA TECH, INC. AND WHALEN & COMPANY, INC.
          UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS
                        FOR THE YEAR ENDED SEPTEMBER 29, 1996

                         (In thousands except per share data)


 

                                                              Historical (Note 1)            Pro forma (Note 2) 
                                                          ---------------------------   ---------------------------
                                                          Tetra Tech,      Whalen &  
                                                              Inc.      Company, Inc.   Adjustments    Consolidated
                                                          -----------   -------------   -----------    ------------
                                                                                                    
Gross Revenue. . . . . . . . . . . . . . . . . . . . .    $   220,099   $      56,556   $         -    $    276,655
  Subcontractor costs                                          59,062               -             -          59,062
                                                          -----------   -------------   -----------    ------------
Net Revenue. . . . . . . . . . . . . . . . . . . . . .        161,037          56,556             -         217,593

Cost of Net Revenue. . . . . . . . . . . . . . . . . .        122,084          26,058         1,726         149,868
                                                          -----------   -------------   -----------    ------------
Gross Profit . . . . . . . . . . . . . . . . . . . . .         38,953          30,498        (1,726)         67,725

Selling, General and Adminstrative Expenses. . . . . .         21,218          11,220         1,864          34,302
                                                          -----------   -------------   -----------    ------------
Income From Operations . . . . . . . . . . . . . . . .         17,735          19,278        (3,590)         33,423

Interest Expense . . . . . . . . . . . . . . . . . . .          1,076              35           700           1,811
Interest Income. . . . . . . . . . . . . . . . . . . .            300              66             -             366
Other Income (Expense), net. . . . . . . . . . . . . .              -             (74)            -             (74)
                                                          -----------   -------------   -----------    ------------
Income Before Income Taxes . . . . . . . . . . . . . .         16,959          19,235        (4,290)         31,904

Income Tax Expense . . . . . . . . . . . . . . . . . .          6,854             385         5,892          13,131

Net Income . . . . . . . . . . . . . . . . . . . . . .    $    10,105   $      18,850   $   (10,182)   $     18,773
                                                          -----------   -------------   -----------    ------------
                                                          -----------   -------------   -----------    ------------

Net Income Per Common Share (Note 3) . . . . . . . . .           0.70                                          1.08
                                                          -----------                                  ------------
                                                          -----------                                  ------------

Shares Used in Per Share Calculations (Note 3) . . . .         14,452                                        17,364
                                                          -----------                                  ------------
                                                          -----------                                  ------------


 

         See accompanying notes to unaudited pro forma condensed consolidated
                                financial statements.




                     TETRA TECH, INC. AND WHALEN & COMPANY, INC.
          UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS
                       FOR THE NINE MONTHS ENDED JUNE 29, 1997

                         (In thousands except per share data)


 

                                                               Historical (Note 1)           Pro forma (Note 2) 
                                                          ---------------------------   --------------------------
                                                          Tetra Tech,      Whalen &  
                                                              Inc.      Company, Inc.   Adjustments   Consolidated 
                                                          -----------   -------------   -----------   ------------ 
                                                                                                    
Gross Revenue. . . . . . . . . . . . . . . . . . . . .    $   171,406   $      39,624   $         -   $    211,030 
   Subcontractor costs . . . . . . . . . . . . . . . .         38,447               -             -         38,447 
                                                          -----------   -------------   -----------   ------------ 
Net Revenue. . . . . . . . . . . . . . . . . . . . . .        132,959          39,624             -        172,583 

Cost of Net Revenue. . . . . . . . . . . . . . . . . .        100,077          26,519        (3,542)       123,054 
                                                          -----------   -------------   -----------   ------------ 
Gross Profit . . . . . . . . . . . . . . . . . . . . .         32,882          13,105         3,542         49,529 

Selling, General and Adminstrative Expenses. . . . . .         17,390          12,365          (960)        28,795 
                                                          -----------   -------------   -----------   ------------ 
Income From Operations . . . . . . . . . . . . . . . .         15,492             740         4,502         20,734 

Interest Expense . . . . . . . . . . . . . . . . . . .            127               -           525            652 
Interest Income. . . . . . . . . . . . . . . . . . . .            201               -             -            201 
Other Income (Expense) . . . . . . . . . . . . . . . .              -              27             -             27 
                                                          -----------   -------------   -----------   ------------ 
Income Before Income Taxes . . . . . . . . . . . . . .         15,566             767         3,977         20,310 

Income Tax Expense . . . . . . . . . . . . . . . . . .          6,464               -         1,992          8,456 

Net Income . . . . . . . . . . . . . . . . . . . . . .    $     9,102   $         767   $     1,985   $     11,854 
                                                          -----------   -------------   -----------   ------------ 
                                                          -----------   -------------   -----------   ------------ 

Net Income Per Common Share (Note 3) . . . . . . . . .           0.61                                         0.67 
                                                          -----------                                 ------------ 
                                                          -----------                                 ------------ 

Shares Used in Per Share Calculations (Note 3) . . . .         14,918                                       17,784 
                                                          -----------                                 ------------ 
                                                          -----------                                 ------------ 


 

         See accompanying notes to unaudited pro forma condensed consolidated
                                financial statements.




                     TETRA TECH, INC. AND WHALEN & COMPANY, INC.
       NOTES TO UNAUDITED PRO FORMA CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
                                           
                                    (In thousands)
                                           
1.  PERIODS PRESENTED

    On June 11, 1997, Tetra Tech, Inc. ("Tetra Tech") purchased 100% of the
capital stock of Whalen & Company, Inc. and Whalen Service Corps Inc.
(collectively, "WAC") for approximately $43,070 consisting of cash and Tetra
Tech common and preferred stock. The common and preferred stock was issued in a
private placement and had a combined value of approximately $33,304. Tetra
Tech's stock was valued based upon the extended restriction period and economic
factors specific to Tetra Tech's circumstances which resulted in a fair
valuation approximately 28% below the then prevailing market price.

    The Unaudited Pro Forma Condensed Consolidated Statements of Operations 
have been prepared by combining the separate historical financial statements 
of Tetra Tech and WAC for the year ended September 29, 1996 and the nine 
months ended June 29, 1997.  The historical statements of operations for WAC 
included in the Unaudited Pro Forma Condensed Consolidated Statement of 
Operations for the year ended September 29, 1996 represent the results of 
operations for the year ended December 31, 1996.  The historical statement of 
operations for WAC included in the Unaudited Pro Forma Condensed Consolidated 
Statement of Operations for the nine months ended June 29, 1997 represents 
the results of operations for the period October 1, 1996 through May 31, 
1997.  The Statement of Operations for the period June 1, 1997 through June 
29, 1997 for WAC is reflected in the historical Condensed Consolidated 
Statement of Operations of Tetra Tech for the period ended June 29, 1997.

    An Unaudited Pro Forma Condensed Consolidated Balance Sheet has not been
prepared as WAC is included in the Unaudited Condensed Consolidated Balance
Sheet at June 29, 1997 for Tetra Tech, Inc. as filed in Tetra Tech's Quarterly
Report on Form 10-Q for the period ended June 29, 1997.


2.  PRO FORMA ADJUSTMENTS RELATED TO THE ACQUISITION

    The adjustments to Cost of Net Revenue of $1,726 and $3,542 and the
adjustments to Selling, General and Administrative Expenses of $547 and $1,947
for the year ended September 29, 1996 and the nine months ended June 29, 1997,
respectively, represent salary and bonus expense adjustments for WAC employees
and WAC's principal stockholder.  Prior to the acquisition, WAC was an S
corporation and made distributions to its principal stockholder in lieu of
increased salary and bonus.  Immediately prior to the acquisition, WAC declared
a one-time bonus of approximately $5,000 for certain employees as a result of
terms negotiated in the acquisition.  The pro forma adjustments reflect the net
effect of the bonus that would have been recognized under Tetra Tech's
established bonus policy, net of the bonuses declared by WAC, 




and the terms of the Employment Agreement between Tetra Tech and the principal
stockholder for each of the periods provided.

    The adjustments to Selling, General and Administrative Expenses of $1,317
and $987 for the year ended September 29, 1996 and the nine months ended June
29, 1997, respectively, represent the amortization of intangible assets
resulting from the acquisition.  The intangible assets are amortized on a
straight-line basis over thirty years.

    The adjustments to Interest Expense of $700 and $263 for the year ended
September 29, 1996 and the nine months ended June 29, 1997, respectively,
represent expense on borrowings under Tetra Tech, Inc.'s existing credit
facility that relate to the acquisition of WAC.  Such adjustments are based upon
the average interest rates and terms of the credit facility for the periods
presented.

    The adjustments to Income Tax Expense of $4,239 and $1,992 for the year
ended September 29, 1996 and the nine months ended June 29, 1997, respectively,
represent the income tax effect of the pro forma adjustments (since WAC was, as
indicated above, an S corporation taxpayer) and an adjustment to reflect the
consolidated effective income tax rate.


3.  EARNINGS PER SHARE

    The adjustments to Shares Used in Per Share Calculations of 2,912 shares
and 2,866 shares for the year ended September 29, 1996 and the nine months ended
June 29, 1997, respectively, represent the number of additional shares that
would have been outstanding had the shares issued in the acquisition been
outstanding for the entire periods reflected.

    The unaudited pro forma consolidated Net Income Per Common Share was
computed by dividing the pro forma consolidated Net Income by the pro forma
weighted average number of common shares and common stock equivalents
outstanding for each period.




                                      SIGNATURES
                                           
         Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

         Date:  August 25, 1997


                                  TETRA TECH, INC.


                                  By:   /s/ James M. Jaska      
                                       -----------------------------
                                       James M. Jaska
                                       Chief Financial Officer