As filed  with the  Securities  and  Exchange  Commission  on  August  11,  2005
--------------------------------------------------------------------------------
                                                                     (333-60810)
                                                                     -----------

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                              ---------------------

                         POST-EFFECTIVE AMENDMENT NO. 1

                                       TO

                                    FORM S-8

                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933


                         CALIFORNIA WATER SERVICE GROUP
                         ------------------------------
             (Exact name of registrant as specified in its charter)


                                    Delaware
                                    --------
         (State or other jurisdiction of incorporation or organization)


                                   77-0448994
                                   ----------
                     (I.R.S. Employer Identification Number)


    1720 North First Street, San Jose, California                 95112-4598
    ---------------------------------------------                 ----------
    (Address of principal executive offices)                      (Zip Code)


             California Water Service Group Long-Term Incentive Plan
             -------------------------------------------------------
                            (Full Title of the Plan)


                                 Richard D. Nye
                         California Water Service Group
                             1720 North First Street
                             San Jose, CA 95112-4598
                             -----------------------
                     (Name and address of agent for service)


                                 (408) 367-8200
                                 --------------
           Telephone Number, Including Area Code, of Agent For Service




                                EXPLANATORY NOTE

On May 11, 2001, the registrant filed a Registration Statement on Form S-8 (File
No.  333-60810)  to register  1,500,000  shares of its common stock  issuable on
exercise  of stock  options  under its  Long-Term  Incentive  Plan.  Options  to
purchase  102,350  shares of common stock are  outstanding  under the  Long-Term
Incentive  Plan and 44,650  shares  have been  issued on  exercise  of  options.
1,350,000 shares remain available for future issuance.

On April 27, 2005, the registrant's  stockholders  approved the California Water
Service Group Equity Incentive Plan which replaces the Long-Term Incentive Plan.
The Equity Incentive Plan provides for the issuance of up to 1,000,000 shares of
the  registrant's  common stock.  No new awards will be made under the Long-Term
Incentive Plan except the Long-Term Incentive Plan will continue to apply to the
102,350 options outstanding.

Pursuant to Section G.  Securities  Act Forms,  Question  89 of the  Division of
Corporation Finance Manual of Publicly Available Telephone Interpretations (July
1997), and Instruction E to Form S-8, the registrant hereby carries forward from
this  registration  statement to a new Registration  Statement on Form S-8 being
filed  concurrently  herewith,  1,000,000  shares of its common stock previously
registered on the  registration  statement being amended hereby.  As a result of
the filing of this amendment,  455,350 shares of the  registrant's  common stock
remain registered and unsold under Registration Statement 333-60810. Pursuant to
the  registrant's   undertakings,   any  securities   remaining  unsold  at  the
termination of the offering represented by Registration Statement 333-60810 will
be removed from registration by means of a post-effective amendment.


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                                   Signatures

The Registrant.

     Pursuant to the requirements of the Securities Act of 1933, as amended, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this amendment to
registration statement to be signed on its behalf by the undersigned,  thereunto
duly  authorized,  in the City of San Jose,  State of California,  on August 11,
2005.


                                  CALIFORNIA WATER SERVICE GROUP



                                  By: /s/ Richard D. Nye
                                     -------------------
                                      Richard D. Nye
                                      Vice President, Chief Financial Officer
                                      and Treasurer


                                       3


                                POWER OF ATTORNEY

     The  officers  and  directors  of  California  Water  Service  Group  whose
signatures  appear  below  hereby  constitute  and  appoint  Peter C. Nelson and
Richard D. Nye, and each of them,  their true and lawful  attorneys  and agents,
with full  power of  substitution,  each with  power to act  alone,  to sign and
execute on behalf of the  undersigned  any  amendment or  amendments  (including
post-effective  amendments)  to  Registration  Statement  on Form S-8  (File No.
333-60810) and to file the same, with all exhibits thereto,  and other documents
in connection therewith,  with the Securities and Exchange Commission,  granting
unto each of said  attorneys-in-fact  and agents full power and  authority to do
everything  necessary to accomplish the  foregoing,  as fully to all intents and
purposes as he or she might or could do in person,  and each of the  undersigned
does hereby ratify and confirm all that each of said  attorneys  and agents,  or
their substitutes, shall do or cause to be done by virtue hereof.

     Pursuant to the  requirements  of the  Securities  Act of 1933, as amended,
this  amendment  to  Registration  Statement  has been  signed by the  following
persons in the capacities and on the dates indicated.



     Signature                             Title
     ---------                             -----
                                                                        
/s/Peter C. Nelson                     President and Chief Executive         May 20, 2005
------------------                     Officer (Principal Executive
Peter C. Nelson                        Officer) and Director


/s/Richard D. Nye                      Vice President, Chief Financial       May 20, 2005
-----------------                      Officer and Treasurer (Principal
Richard D. Nye                         Financial and Accounting Officer)


/s/Robert W. Foy                       
----------------                       Director, Chairman of the Board       May 20, 2005
Robert W. Foy                          of Directors


/s/Douglas M. Brown                    Director                              May 20, 2005
-------------------
Douglas M. Brown


/s/Edward D. Harris, Jr., M.D.         Director                              May 20, 2005
------------------------------
Edward D. Harris, Jr., M.D.


/s/Bonnie G. Hill                      Director                              May 20, 2005
-----------------
Bonnie G. Hill


/s/David N. Kennedy                    Director                              May 20, 2005
-------------------
David N. Kennedy



                                       4




     Signature                             Title
     ---------                             -----
                                                                        
/s/Richard P. Magnuson                 Director                              May 20, 2005
----------------------
Richard P. Magnuson


/s/Linda R. Meier                      Director                              May 20, 2005
-----------------
Linda R. Meier


/s/George A. Vera                      Director                              May 20, 2005
-----------------
George A. Vera



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                                  EXHIBIT LIST
                                  ------------


4.1      Certificate  of   Incorporation   of  California  Water  Service  Group
         (incorporated  by  reference  to  Exhibit A of the  registrant's  Proxy
         Statement dated March 18, 1999*)

4.2      Restated  By-laws  of  California  Water  Service  Group as  amended on
         January  26,  2000  (incorporated  by  reference  to Exhibit 3-2 to the
         registrant's Current Report on Form 8-K dated January 26, 2000*)

4.3      California Water Service Group Long-Term  Incentive Plan  (incorporated
         by reference to Appendix A of the  registrant's  Proxy  Statement dated
         March 17, 2000*)

5        Opinion of counsel as to the legality of securities being registered**

23.1     Consent of counsel (included in Exhibit 5)**

23.2     Consent of independent auditors**

24       Power of attorney  (included  in  signature  page of this  amendment to
         registration statement)***

---------------------
*        File No. 001-13883.
**       Previously filed.
***      Filed herewith.


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