SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   SCHEDULE TO
                                 (Rule 14d-100)
         Tender Offer Statement Pursuant to Section 14(d)(1) or 13(e)(1)
                     of the Securities Exchange Act of 1934


               PUTNAM CALIFORNIA INVESTMENT GRADE MUNICIPAL TRUST
                       (Name of Subject Company (Issuer))

                            MILDRED B. HOREJSI TRUST
                       (Name of Filing Persons (Offerors))

                    COMMON STOCK, PAR VALUE $0.001 PER SHARE
                         (Title of Class of Securities)

                                    746446103
                      (CUSIP Number of Class of Securities)

                             Stephen C. Miller, Esq.
                            Joel L. Terwilliger, Esq.
                           2344 Spruce Street, Suite A
                             Boulder, Colorado 80302
                                 (303) 442-2156

                                    Copy to:
                              Thomas Stephens, Esq.
                    Bartlit Beck Herman Palenchar & Scott LLP
                         1899 Wynkoop Street, Suite 800
                                Denver, CO 80202
                                 (303) 592-3144
            (Name, Address and Telephone Numbers of Person Authorized
       to Receive Notices and Communications on Behalf of Filing Persons)

                            Calculation of Filing Fee

    Transaction Valuation*                         Amount of Filing Fee**
 ____________________________                   ____________________________

         $63,985,486                                      $6,847.00

_________________

*    Estimated  for  purposes  of  calculating  the  amount of filing  fee only.
     Transaction  value derived by multiplying  4,509,649  shares of the subject
     company  (number of shares  sought) by $14.16 (the purchase price per share
     offered by the Mildred B. Horejsi Trust).
**   The amount of the filing fee, calculated in accordance with Rule 0-11 under
     the Securities Exchange Act of 1934, as amended, equals $107 per million of
     the aggregate amount of the cash offered by the Mildred B Horejsi Trust.

|_|  Check  the  box if any  part  of the  fee is  offset  as  provided  by Rule
     0-11(a)(2)  and  identify  the  filing  with which the  offsetting  fee was
     previously  paid.  Identify the previous filing by  registration  statement
     number, or the Form or Schedule and the date of its filing.


    Amount Previously Paid: $0.00                Filing Party:


    Form or Registration Number:                 Date Filed:

|_|  Check the box if the filing relates  solely to  preliminary  communications
     made before the commencement of a tender offer.

Check the  appropriate  boxes below to designate any  transactions  to which the
statement relates:

      |X|  third-party tender offer subject to Rule 14d-1.

      |_|  issuer tender offer subject to Rule 13e-4.

      |_|  going private transaction subject to Rule 13e-3.

      |_|  amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results
of the tender offer: |_|





                                   SCHEDULE TO

     This Tender Offer  Statement on Schedule TO ("Schedule  TO") relates to the
offer by the Mildred B. Horejsi Trust, an irrevocable grantor trust administered
in accordance with Alaska  administrative  statutes and governed by Alaska trust
law (the "Trust"),  to purchase up to 100% of the  outstanding  shares of common
stock,  par  value  $0.001  per  share  (the  "shares"),  of  Putnam  California
Investment Grade Municipal Trust, a Massachusetts  business trust ("PCA"),  at a
price of $14.16 per  share,  net to the seller in cash  (subject  to  applicable
withholding of United States federal,  state and local taxes), without interest,
upon the terms and subject to the  conditions set forth in the Offer to Purchase
(the "Offer to Purchase")  dated January 22, 2007,  and in the related Letter of
Transmittal,  copies of which are attached as Exhibits (a)(1) and (a)(2) hereto,
respectively. This Schedule TO is being filed on behalf of the Trust.

     The information set forth in the Offer to Purchase,  including  Schedules I
and II thereto, is hereby incorporated by reference in answer to Items 1 through
11 of this  Schedule TO, and is  supplemented  by the  information  specifically
provided  herein.  Defined terms used but not otherwise  defined herein have the
meanings given to them in the Offer to Purchase.

Item 3.    Identity and Background of Filing Persons.

     The Trust and, to the best knowledge of the Trust,  Badlands,  Mr. Horejsi,
Ms.  Ciciora,  Dr. Sippy or any of the persons listed on Schedule I to the Offer
to Purchase  have not been  convicted in a criminal  proceeding in the past five
years (excluding  traffic violations or similar  misdemeanors).  During the past
five years, none of the Trust or, to the best knowledge of the Trust,  Badlands,
Mr. Horejsi,  Ms. Ciciora,  Dr. Sippy or any of the persons listed on Schedule I
to the Offer to Purchase, was a party to a judicial or administrative proceeding
during the last five years  (except  for  matters  that were  dismissed  without
sanction or  settlement)  that  resulted  in a  judgment,  decree or final order
enjoining future violations of, or prohibiting activities subject to, federal or
state  securities  laws or a finding  of federal or sate  securities  laws.  Mr.
Horejsi,  Ms.  Ciciora,  Dr.  Sippy and each person  listed on Schedule I to the
Offer to Purchase are all citizens of the United States.

Item 5.    Past Contacts, Transactions, Negotiations and Agreements.

     Except as  described  in the Offer to  Purchase,  during the past two years
there have not been any negotiations,  transactions or material contacts between
the Trust, or, to the best knowledge of the Trust,  Badlands,  Mr. Horejsi,  Ms.
Ciciora,  Dr.  Sippy or any of the persons  listed on Schedule I to the Offer to
Purchase, on the one hand, and PCA or any of its directors,  executive officers,
or affiliates,  on the other hand, that are required to be disclosed pursuant to
this item.

Item 8. Interest in Securities of the Subject Company.

     Except as described in the Offer to Purchase, none of the Trust and, to the
best knowledge of the Trust,  Badlands,  Mr. Horejsi, Ms. Ciciora, Dr. Sippy, or
any of the  persons  listed  on  Schedule  I to the  Offer to  Purchase,  or any
associate or  majority-owned  subsidiary of the Trust or Badlands,  Mr. Horejsi,
Ms.  Ciciora,  Dr. Sippy or any of the persons listed on Schedule I to the Offer
to  Purchase,  beneficially  owns any  equity  security  of PCA;  and  except as
described in the Offer to Purchase,  none of the Trust or, to the best knowledge
of the Trust,  Badlands,  Mr.  Horejsi,  Ms.  Ciciora,  Dr.  Sippy or any of the
persons  listed on  Schedule I to the Offer to  Purchase,  or any  associate  or
majority-owned  subsidiary of the Trust or Badlands,  Mr. Horejsi,  Ms. Ciciora,
Dr.  Sippy or any of the persons  listed on Schedule I to the Offer to Purchase,
has effected any  transaction  in any equity  security of PCA during the past 60
days.

Item 10.    Financial Statements.

     Not applicable.

Item 12.    Exhibits.

          (a)  (1) Offer to Purchase, dated January 22, 2007

               (2)  Letter of Transmittal.

               (3)  Notice of Guaranteed Delivery.

               (4)  Letter  to  Brokers,   Dealers,   Commercial  Banks,   Trust
                    Companies and Other Nominees.

               (5)  Letter to Clients  for Use by Brokers,  Dealers,  Commercial
                    Banks, Trust Companies and Other Nominees.

               (6)  Guidelines  for  Certification  of  Taxpayer  Identification
                    Number on Substitute Form W-9

               (7)  Summary  Advertisement,  as published in the western edition
                    of the Wall Street Journal on January 22, 2007.

               (8)  Form of press release issued January 22, 2007

               (9)  Form of Request  for  Stockholder  List as  provided  to the
                    Trustees of PCA and dated January 22, 2007

               (10) Form  of  Request  for  Stockholder  List  Pursuant  to Rule
                    14d-5(a) under the Exchange Act of 1934

               (11) Form of  Shareholder  Communications  Insert

               (12) Form of Cover Letter Provided to Shareholders


          (b)  (1)  Cash Management Account Agreement between the Trust and
                    Merrill Lynch, Pierce, Fenner & Smith Incorporated.

          (b)  (2)  Revolving  Line of Credit  Between the Trust and the Lola
                    Brown Trust No. 1B

          (d)  Not Applicable

          (g)  Not Applicable

          (h)  Not Applicable


Item 13. Information Required by Schedule 13E-3.

     Not applicable.

                                    SIGNATURE

     After due inquiry  and to the best of my  knowledge  and belief,  I certify
that the information set forth in this statement is true, complete and correct.


                                     Mildred B. Horejsi Trust

                                     By:  Badlands Trust Company, LLC, trustee

                                     By:  /s/ Stephen C. Miller
                                          Name: Stephen C. Miller
                                          Title: President


                                     Dated: January 19, 2007



                                  EXHIBIT INDEX

          (a)  (1) Offer to Purchase, dated January 22, 2007

               (2)  Letter of Transmittal.

               (3)  Notice of Guaranteed Delivery.

               (4)  Letter  to  Brokers,   Dealers,   Commercial  Banks,   Trust
                    Companies and Other Nominees.

               (5)  Letter to Clients  for Use by Brokers,  Dealers,  Commercial
                    Banks, Trust Companies and Other Nominees.

               (6)  Guidelines  for  Certification  of  Taxpayer  Identification
                    Number on Substitute Form W-9

               (7)  Summary  Advertisement,  as published in the western edition
                    of the Wall Street Journal on January 22, 2007.

               (8)  Form of press release issued January 22, 2007

               (9)  Form of Request  for  Stockholder  List as  provided  to the
                    Trustees of PCA and dated January 22, 2007

               (10) Form  of  Request  for  Stockholder  List  Pursuant  to Rule
                    14d-5(a) under the Exchange Act of 1934

               (11) Form of Shareholder Communications Insert

               (12) Form of Cover Letter Provided to Shareholders

          (b)   (1) Cash Management Account Agreement between the Trust and
                    Merrill Lynch, Pierce, Fenner & Smith Incorporated.

          (b)   (2) Revolving  Line of Credit  Between the Trust and the Lola
                    Brown Trust No. 1B

          (d)  Not Applicable

          (g)  Not Applicable

          (h)  Not Applicable