Exhibit 1.1

Execution Copy

2,000,000 Shares

CALIFORNIA WATER SERVICE GROUP

COMMON STOCK

UNDERWRITING AGREEMENT

October 5, 2006

October 5, 2006

ROBERT W. BAIRD & CO. INCORPORATED
A.G. Edwards & Sons, Inc.
Edward D. Jones & Co., L.P.
J.J.B. Hilliard, W.C. Lyons, Inc.
Stifel, Nicolaus & Company Incorporated
As Representatives of the Several Underwriters
     Identified in Schedule I Annexed Hereto
c/o Robert W. Baird & Co. Incorporated
777 East Wisconsin Avenue
Milwaukee, Wisconsin 53202

Ladies and Gentlemen:

     California Water Service Group, a Delaware corporation (the “Company”), proposes to issue and sell to the several Underwriters named in Schedule I hereto (the “Underwriters”) 2,000,000 shares of the Common Stock, par value $0.01 per share, of the Company (the “Firm Shares”).

     The Company also proposes to issue and sell to the several Underwriters up to an additional 300,000 shares of Common Stock, par value $0.01 per share, of the Company (the “Additional Shares”), if and to the extent that you, Robert W. Baird & Co. Incorporated (“Baird”) and A.G. Edwards & Sons, Inc., Edward D. Jones & Co., L.P., J.J.B. Hilliard, W.C. Lyons, Inc. and Stifel, Nicolaus & Company Incorporated (“Managers”), as managers of the offering, shall have determined to exercise, on behalf of the Underwriters, the right to purchase such shares of common stock granted to the Underwriters in Section 2 hereof. The Firm Shares and the Additional Shares are hereinafter collectively referred to as the “Shares.” The shares of Common Stock, par value $0.01 per share, of the Company to be outstanding prior to giving effect to the sales contemplated hereby are hereinafter referred to as the “Common Stock.”

     The Company has prepared and filed, in accordance with the Securities Act of 1933, as amended (the “Securities Act”), and the rules and regulations thereunder, with the Securities and Exchange Commission (the “Commission”) a registration statement on Form S-3 (file number 333-136844), including a prospectus, relating to the Shares, which registration statement and prospectus incorporate or are deemed to incorporate by reference documents that the Company has filed, or will file, with the Commission in accordance with the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations thereunder. The registration statement as amended at the time it becomes effective for purposes of Section 11 of the Securities Act (as such section applies to the Underwriters), including the documents filed as part thereof and information contained or incorporated by reference in the prospectus (the “Incorporated Documents”) or otherwise deemed to be part of the registration statement at the time of effectiveness pursuant to Rule 430A or Rule 430B under the Securities Act, is

hereinafter referred to as the “Registration Statement.” If the Company files an abbreviated registration statement to register additional shares of Common Stock pursuant to Rule 462(b) under the Securities Act (the “Rule 462 Registration Statement”), then any reference herein to the term “Registration Statement” shall be deemed to include such Rule 462 Registration Statement. The Company has also filed with, or transmitted for filing to, or shall promptly after the date of this Agreement file with or transmit for filing to, the Commission a prospectus supplement (in the form first used to confirm sales of the Shares (or in the form first made available to the Underwriters by the Company to meet requests of purchasers pursuant to Rule 173 under the Securities Act), the “Prospectus Supplement”) pursuant to Rule 424 under the Securities Act. The term “Base Prospectus” means the prospectus dated September 27, 2006, relating to the Shares, in the form in which it has most recently been filed with the Commission as part of the Registration Statement on or prior to the date of this Agreement. The term “Prospectus” means the Base Prospectus as supplemented by the Prospectus Supplement. The term “Preliminary Prospectus” means any preliminary form of Prospectus (including without limitation the preliminary Prospectus Supplement dated September 27, 2006, filed with the Commission pursuant to Rule 424).

     For purposes of this Agreement, “free writing prospectus” has the meaning set forth in Rule 405 under the Securities Act; “Time of Sale Prospectus” means the Base Prospectus and the Preliminary Prospectus, together with the free writing prospectuses, if any, each identified in Schedule II hereto (each, a “Permitted Free Writing Prospectus”), and other information conveyed to purchasers of the Shares at or prior to the Time of Sale as set forth in Schedule II hereto; “Time of Sale” means 8:00 p.m. (Central Time) on the date of this Agreement; and “road show” has the meaning set forth in Rule 433(h)(4) under the Securities Act. As used herein, the terms “Registration Statement,” “Base Prospectus,” “Preliminary Prospectus,” “Time of Sale Prospectus” and “Prospectus” shall include the Incorporated Documents, including, unless the context otherwise requires, the documents, if any, filed as exhibits to such Incorporated Documents. The terms “supplement,” “amendment” and “amend” as used herein with respect to the Registration Statement, the Base Prospectus, the Time of Sale Prospectus, any Preliminary Prospectus, the Prospectus or any free writing prospectus shall include all documents subsequently filed by the Company with the Commission pursuant to the Exchange Act that are deemed to be incorporated by reference therein.

     1. Representations and Warranties of the Company. The Company represents and warrants to and agrees with each of the Underwriters on the date hereof, on the Closing Date (as defined in Section 4) and on each Option Closing Date (as defined in Section 2), if any, that:

     (a) The Registration Statement has become effective under the Securities Act; no stop order suspending the effectiveness of the Registration Statement or preventing or suspending the use of any Preliminary Prospectus or the Prospectus is in effect, and to the Company’s knowledge, no proceedings for such purpose are pending before or threatened by the Commission. For purposes of this Agreement,

“knowledge” means the actual knowledge of the executive officers and directors of the Company following reasonable inquiry.

     (b) The Base Prospectus and any Preliminary Prospectus filed as part of the registration statement as originally filed or as part of any amendment thereto, or filed pursuant to Rule 424 under the Securities Act, complied when so filed in all material respects with the Securities Act and the rules and regulations thereunder (including, without limitation, Rule 430B(a) or 430A(b)).

     (c) (i) Each document, if any, filed or to be filed pursuant to the Exchange Act and incorporated by reference in the Time of Sale Prospectus or the Prospectus complied or will comply when so filed in all material respects with the Exchange Act and the applicable rules and regulations of the Commission thereunder; (ii) each part of the Registration Statement, when such part became effective, did not contain and each such part, as amended or supplemented up to the Closing Date (as defined in Section 4) or any Option Closing Date (as defined in Section 2), if applicable, will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; (iii) the Registration Statement complies and, as amended or supplemented, if applicable, will comply in all material respects with the Securities Act; the conditions to the use of Form S-3 in connection with the offering and sale of the Shares as contemplated hereby have been satisfied; the Registration Statement meets, and the offering and sale of the Shares as contemplated hereby complies with, the requirements of Rule 415 under the Securities Act (including without limitation Rule 415(a)(5)); (iv) at no time during the period that began on the earlier of the date of the Preliminary Prospectus and the date on which the Preliminary Prospectus was filed with the Commission and ended immediately prior to the execution of this Agreement did any Preliminary Prospectus contain any untrue statement of a material fact or, when considered with the Incorporated Documents, omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading; (v) the Time of Sale Prospectus does not, and at the Applicable Time, at the Closing Date (as defined in Section 4) and, if applicable, each Option Closing Date (as defined in Section 5), the Time of Sale Prospectus, as then amended or supplemented by the Company, if applicable, will not, contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading; (vi) each Permitted Free Writing Prospectus does not conflict with the information contained in the Registration Statement, the Time of Sale Prospectus or the Prospectus; (vii) each road show, when considered together with the Time of Sale Prospectus, does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading; and (viii) the Prospectus, as of the date it is filed with the Commission pursuant to Rule 424, at the Closing Date and at each Option Closing Date, if any, will comply in all material respects with the Securities Act (including without limitation Section 10(a) of the Securities Act) and will not contain any untrue statement of a material fact or omit to state a material fact

necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided, however, that the representations and warranties set forth in this Section 1(c) do not apply to statements or omissions in the Registration Statement, the Time of Sale Prospectus, any Preliminary Prospectus, any Permitted Free Writing Prospectus, any road show Prospectus or any amendments or supplements thereto based upon information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Managers expressly for use therein, it being agreed that the only information furnished by the Underwriters to the Company expressly for use therein are the names of the Underwriters on the front cover, back cover and in the “Plan of Distribution” section of the Prospectus Supplement (and preliminary Prospectus Supplement), and the statements contained in the “Discounts and Commissions” and “Stabilization” sections of the “Plan of Distribution” section of the Prospectus Supplement (and preliminary Prospectus Supplement).

     (d) Prior to the execution of this Agreement, the Company has not, directly or indirectly, offered or sold any Shares by means of any “prospectus” (within the meaning of the Securities Act) or used any “prospectus” (within the meaning of the Securities Act) in connection with the offer or sale of the Shares, in each case other than the Preliminary Prospectus and/or the Permitted Free Writing Prospectuses; the Company has not, directly or indirectly, prepared, used or referred to any free writing prospectuses, without the prior written consent of Baird, other than the Permitted Free Writing Prospectuses and road shows furnished or presented to the Managers before first use. Each Permitted Free Writing Prospectus has been prepared, used or referred to in compliance with Rules 164 and 433 under the Securities Act; assuming that such Permitted Free Writing Prospectus is so sent or given after the Registration Statement was filed with the Commission (and after such Permitted Free Writing Prospectus was, if required pursuant to Rule 433(d) under the Securities Act, filed with the Commission), the sending or giving, by any Underwriter, of any Permitted Free Writing Prospectus will satisfy the provisions of Rule 164 and Rule 433 (without reliance on subsections (b), (c) and (d) of Rule 164); the conditions set forth in one or more of subclauses (i) through (iv), inclusive, of Rule 433(b)(1) under the Securities Act are satisfied, and the registration statement relating to the offering of the Shares contemplated hereby, as initially filed with the Commission, includes a prospectus that, other than by reason of Rule 433 or Rule 431 under the Securities Act, satisfies the requirements of Section 10 of the Securities Act; neither the Company nor the Underwriters are disqualified, by reason of subsection (f) or (g) of Rule 164 under the Securities Act, from using, in connection with the offer and sale of the Shares, free writing prospectuses pursuant to Rules 164 and 433 under the Securities Act; and each Permitted Free Writing Prospectus that the Company has filed, or is required to file, pursuant to Rule 433(d) under the Securities Act or that was used or referred to by the Company complies or will comply in all material respects with the requirements of the Securities Act.

     (e) The Company was, at the time of the Registration Statement was initially filed and when it became effective, eligible to use Form S-3 to register the offering of the Shares contemplated hereby. The Company was not an “ineligible

issuer” (as defined in Rule 405 under the Securities Act) as of the eligibility determination date for purposes of Rules 164 and 433 under the Securities Act with respect to the offering of the Shares contemplated by the Registration Statement.

     (f) For purposes of Rule 2710(b)(7)(C)(i) of the National Association of Securities Dealers, Inc. (“NASD”) Conduct Rules, the Shares have been registered with the Commission on Form S-3 under the Securities Act pursuant to the standards for such Form S-3 in effect prior to October 21, 1992.

     (g) Shares of Common Stock are listed on the New York Stock Exchange (“NYSE”), and the Company has not received any notice from the NYSE regarding the delisting of such shares from the NYSE. The Shares are duly listed, and admitted and authorized for trading, subject to official notice of issuance, on the NYSE. To the Company’s knowledge, there are no affiliations or associations between (i) any member of the NASD and (ii) the Company or any of the Company’s officers, directors or 5% or greater security holders or any beneficial owner of the Company’s unregistered equity securities that were acquired at any time on or after the 180th day immediately preceding the date the Registration Statement was initially filed with the Commission, except as disclosed in the Registration Statement (excluding the exhibits thereto), the Time of Sale Prospectus and the Prospectus.

     (h) The Company has been duly incorporated, is validly existing as a corporation in good standing under the laws of the jurisdiction of its incorporation, has the corporate power and authority to own its property and to conduct its business as described in the Time of Sale Prospectus and is duly qualified to transact business and is in good standing in each jurisdiction in which the conduct of its business or its ownership or leasing of property requires such qualification, except to the extent that the failure to be so qualified or be in good standing would not (i) have a material adverse effect on the assets, business, condition (financial or otherwise), results of operation or prospects of Company and its Subsidiaries (as defined below), taken as a whole, (ii) prevent or materially interfere with consummation of the transactions contemplated hereby, or (iii) result in the delisting of shares of Common Stock from the NYSE (the occurrence of any such effect, prevention, interference or result described in the foregoing clauses (i) (ii) or (iii) being herein referred to as a material adverse effect).

     (i) Each significant subsidiary (as defined in Rule 405) (each, a “Subsidiary” and together, the “Subsidiaries”) of the Company has been duly organized, is validly existing as a corporation or limited liability company in good standing under the laws of the jurisdiction of its organization, has the corporate power and authority to own its property and to conduct its business as described in the Time of Sale Prospectus and is duly qualified to transact business and is in good standing in each jurisdiction in which the conduct of its business or its ownership or leasing of property requires such qualification, except to the extent that the failure to be so qualified or be in good standing would not have a material adverse effect; all of the issued shares of capital stock of each Subsidiary of the Company have been duly

and validly authorized and issued, are fully paid and non-assessable and are owned directly by the Company, free and clear of all liens, encumbrances, equities or claims.

     (j) This Agreement has been duly authorized, executed and delivered by the Company.

     (k) The authorized and outstanding capitalization of the Company is as set forth in its condensed consolidated balance sheet as of June 30, 2006, incorporated into the Time of Sale Prospectus and will be as set forth in the condensed consolidated balance sheet as of June 30, 2006, subject, in each case, to the issuance of shares of Common Stock upon exercise of stock options and warrants disclosed as outstanding in the Time of Sale Prospectus, the Prospectus or the Incorporated Documents, as the case may be, and the grant of options under existing stock option plans described in the Time of Sale Prospectus, the Prospectus or the Incorporated Documents. The authorized capital stock of the Company conforms and will conform as to legal matters to the description thereof contained in the Time of Sale Prospectus, the Prospectus and the Incorporated Documents.

     (l) The shares of Common Stock outstanding prior to the issuance of the Shares have been duly authorized, are validly issued, fully paid and non-assessable, have been issued in compliance with applicable securities laws and were not issued in violation of any preemptive or similar rights.

     (m) The Shares have been duly authorized and, when issued and delivered in accordance with the terms of this Agreement, will be validly issued, fully paid and non-assessable, and the issuance of such Shares will not be subject to any preemptive or similar rights.

     (n) Neither the execution and delivery by the Company of, nor the performance by the Company of its obligations under, this Agreement will conflict with, contravene, result in a breach or violation of, or imposition of any lien, charge or encumbrance upon any assets of the Company or any of its Subsidiaries pursuant to, or constitute a default under (i) any statute, law, rule, regulation, judgment, order or decree of any governmental body, regulatory or administrative agency or court having jurisdiction over the Company or any Subsidiary; (ii) the certificate of incorporation or bylaws of the Company or any of its Subsidiaries; or (iii) any contract, agreement, obligation, covenant or instrument to which the Company or any of its Subsidiaries (or any of their respective assets) is subject or bound, except in the case of clauses (i) and (iii) to the extent such conflicts, contraventions, breaches, violations, liens, charges and encumbrance, if any, would not have a material adverse effect.

     (o) No approval, authorization, consent or order of or filing with any federal, state, local or foreign governmental or regulatory commission, board, body, authority or agency, or of or with any self-regulatory organization or other non-governmental regulatory authority, or approval of the Company’s stockholders, is required in connection with the issuance and sale of the Shares or the consummation

of the transactions contemplated hereby, other than (i) registration of the Shares under the Securities Act, which has been effected (or, with respect to any Rule 462 Registration Statement, will be effected in accordance Rule 462(b) under the Securities Act), (ii) the supplemental listing application to be filed with the NYSE to list the Shares, or (iii) any necessary qualification under the securities or blue sky laws of the various jurisdictions in which the Shares are being offered by the Underwriters.

     (p) There are no actions, suits, claims, investigations or proceedings pending or, to the Company’s knowledge, threatened to which the Company or any of its Subsidiaries or any of their respective directors or officers (in their capacity as a director or officer of the Company or a Subsidiary) is a party or of which any of their respective properties is or would be subject at law or in equity, before or by any federal, state, local or foreign governmental or regulatory commission, board, body, authority or agency, or before or by any self-regulatory organization or other non-governmental regulatory authority (including, without limitation, the NYSE) (i) other than any such action, suit, claim, investigation or proceeding accurately described in the Time of Sale Prospectus and the Incorporated Documents which, if resolved adversely to the Company or any of its Subsidiaries, would not, individually or in the aggregate, have a material adverse effect or (ii) that are required to be described in the Time of Sale Prospectus and are not so described. There are no statutes, regulations, contracts or other documents that are required to be described in the Registration Statement or the Prospectus or to be filed as exhibits to the Registration Statement that are not described or filed as required.

     (q) The Company is not, and after giving effect to the offering and sale of the Shares and the application of the proceeds thereof as described in the Prospectus will not be, required to register as an “investment company” as such term is defined in the Investment Company Act of 1940, as amended.

     (r) The financial statements included in the Registration Statement, the Time of Sale Prospectus, the Prospectus and the Incorporated Documents, together with the related notes and schedules, present fairly the consolidated financial position of the Company and its Subsidiaries as of the dates indicated and the consolidated results of operations, cash flows and changes in stockholders’ equity of the Company for the periods specified and have been prepared in compliance with the requirements of the Securities Act and Exchange Act and in conformity with U.S. generally accepted accounting principles applied on a consistent basis during the periods involved; the other financial and statistical data contained in the Registration Statement, the Time of Sale Prospectus, the Prospectus and Incorporated Documents, are accurately and fairly presented and prepared on a basis consistent with the financial statements and books and records of the Company; there are no financial statements (historical or pro forma) that are required to be included or incorporated by reference in the Registration Statement, the Time of Sale Prospectus or the Prospectus that are not included or incorporated by reference as required; and the Company and its Subsidiaries do not have any material liabilities or obligations,

direct or contingent (including any off-balance sheet obligations), not described in the Time of Sale Prospectus, the Prospectus or the Incorporated Documents.

     (s) All statistical or market-related data included in the Time of Sale Prospectus, the Prospectus, the Permitted Free Writing Prospectuses and Incorporated Documents, are based on or derived from sources that the Company reasonably believes to be reliable and accurate, and the Company has obtained the written consent to the use of such data from such sources to the extent required. Each “forward-looking statement” (within the meaning of Section 27A of the Securities Act or Section 21E of the Exchange Act) contained in the Registration Statement, the Time of Sale Prospectus, the Prospectus, the Permitted Free Writing Prospectuses and Incorporated Documents, has been made or reaffirmed with a reasonable basis and in good faith.

     (t) The Company and its Subsidiaries (i) are in compliance with any and all applicable federal, state and local laws and regulations relating to the protection of human health and safety, the environment or hazardous or toxic substances or wastes, pollutants or contaminants (“Environmental Laws”), (ii) have received all permits, licenses or other approvals required of them under applicable Environmental Laws to conduct their respective businesses and (iii) are in compliance with all terms and conditions of any such permit, license or approval, except where such noncompliance with Environmental Laws, failure to receive required permits, licenses or other approvals or failure to comply with the terms and conditions of such permits, licenses or approvals would not have a material adverse effect. There are no costs or liabilities associated with Environmental Laws (including, without limitation, any capital or operating expenditures required for clean-up, closure of properties or compliance with Environmental Laws or any permit, license or approval, any related constraints on operating activities and any potential liabilities to third parties) which would have a material adverse effect.

     (u) There are no contracts, agreements or understandings between the Company and any person granting such person the right to require the Company to file a registration statement under the Securities Act with respect to any securities of the Company or to require the Company to include such securities with the Shares registered pursuant to the Registration Statement.

     (v) Subsequent to the respective dates as of which information is given in each of the Registration Statement, the Time of Sale Prospectus, the Prospectus and the Incorporated Documents, (i) there has not occurred any material adverse change, or any development involving a prospective material adverse change, in the assets, business, condition (financial or otherwise), management, operations or earnings of the Company and its Subsidiaries, taken as a whole (the occurrence of any such change being herein referred to as a material adverse change); (ii) the Company and its Subsidiaries have not incurred any material liability or obligation, direct or contingent, nor entered into any material transaction; (iii) the Company has not purchased any of its outstanding capital stock, nor declared, paid or otherwise made any dividend or distribution of any kind on its capital stock other than ordinary

and customary dividends; and (iv) there has not been any material change in the capital stock, short-term debt or long-term debt of the Company and its Subsidiaries, except in each case as described in each of the Registration Statement, the Time of Sale Prospectus, the Prospectus and the Incorporated Documents.

     (w) The Company and its Subsidiaries have good and marketable title in fee simple to all real property and good and marketable title to all personal property owned by them which is material to the business of the Company and its Subsidiaries, in each case free and clear of all liens, encumbrances and defects except such as are described in the Time of Sale Prospectus or Incorporated Documents, or such as do not materially affect the value of such property and do not materially interfere with the use made and proposed to be made of such property by the Company and its Subsidiaries; and any real property and buildings held under lease by the Company and its Subsidiaries are held by them under valid, subsisting and enforceable leases with such exceptions as are not material and do not interfere with the use made and proposed to be made of such property and buildings by the Company and its Subsidiaries, in each case except as described in the Time of Sale Prospectus or Incorporated Documents.

     (x) Each of the Company and its Subsidiaries owns or possesses all inventions, patent applications, patents, trademarks (both registered and unregistered), trade names, service names, copyrights, trade secrets and other proprietary information described in the Registration Statement, the Time of Sale Prospectus, the Prospectus and the Incorporated Documents, as being owned or licensed by it or which is necessary for the conduct of, or material to, its businesses (collectively, the “Intellectual Property”), and the Company has no knowledge of any claim to the contrary or any challenge by any other person to the rights of the Company or any of its Subsidiaries with respect to the Intellectual Property. To its knowledge, neither the Company nor any of its Subsidiaries has infringed or is infringing the intellectual property of a third party, and neither the Company nor any of its Subsidiaries has received notice of a claim by a third party to the contrary.

     (y) No material labor dispute with the employees of the Company or any of its Subsidiaries exists, except as described in the Time of Sale Prospectus or Incorporated Documents, or, to the knowledge of the Company, is threatened; and the Company has no knowledge of any existing or threatened labor disturbance by the employees of any of its principal suppliers, manufacturers or contractors that could have a material adverse effect on the Company and its subsidiaries, taken as a whole. Neither the Company nor any of its Subsidiaries is in violation of any provision of the Employee Retirement Income Security Act of 1974, as amended, or the rules and regulations promulgated thereunder, except for such violations as would not have a material adverse effect.

     (z) The Company and each of its Subsidiaries are insured by insurers of recognized financial responsibility against such losses and risks and in such amounts as are prudent and customary in the businesses in which they are engaged; other than as described in the Registration Statement, neither the Company nor any of its

Subsidiaries has been refused any insurance coverage sought or applied for, except such as would not have a material adverse effect; and neither the Company nor any of its Subsidiaries has any knowledge that it will not be able to renew its existing insurance coverage as and when such coverage expires or to obtain similar coverage from similar insurers as may be necessary to continue its business at a cost that would not have a material adverse effect.

     (aa) The Company and its Subsidiaries possess all material certificates, authorizations and permits issued by the appropriate federal, state or regulatory authorities necessary to conduct their respective businesses, and neither the Company nor any of its Subsidiaries has received any notice of proceedings relating to the revocation or modification of any such certificate, authorization or permit which, singly or in the aggregate, if the subject of an unfavorable decision, ruling or finding, would have a material adverse effect.

     (bb) Except as otherwise would not have a material adverse effect, no Subsidiary of the Company is subject to any material direct or indirect prohibition on paying any dividends to the Company, on making any other distribution on such Subsidiary’s capital stock, on repaying to the Company any loans or advances to such Subsidiary from the Company or on transferring any of such Subsidiary’s property or assets to the Company or any other Subsidiary of the Company, except as described in the Time of Sale Prospectus.

     (cc) The Company maintains “internal control over financial reporting” (as defined in Rules 13a-15 and 15d-15 under the Exchange Act) in compliance with the requirements of the Exchange Act. The Company’s internal control over financial reporting has been designed by the Company’s principal executive officer and principal financial officer, or under their supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles and it is effective in performing the functions for which it was established. Except as described in the Time of Sale Prospectus or Incorporated Documents, since the end of the Company’s most recent audited fiscal year, there has been (i) no significant deficiency or material weakness in the design or operation of the Company’s internal control over financial reporting (whether or not remediated) which is reasonably likely to adversely affect the Company’s ability to record, process, summarize and report financial information, and (ii) no change in the Company’s internal control over financial reporting that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting.

     (dd) The Company maintains “disclosure controls and procedures” (as such term is defined in Rules 13a-15 and 15d-15 under the Exchange Act); such disclosure controls and procedures are designed to ensure that material information relating to the Company, including its consolidated Subsidiaries, is made known to the Company’s Chief Executive Officer and Chief Financial Officer by others within those entities, and such disclosure controls and procedures are effective in

performing the functions for which they were established; the principal executive officers (or their equivalents) and principal financial officers (or their equivalents) of the Company have made all certifications required by the Sarbanes-Oxley Act of 2002 and any related rules and regulations promulgated by the Commission (the “Sarbanes-Oxley Act”), and the statements made in each such certification are accurate; the Company, its Subsidiaries and, to its knowledge, its directors and officers are each in compliance in all material respects with the applicable provisions of the Sarbanes-Oxley Act.

     (ee) Neither the Company nor any of its Subsidiaries has sent or received any communication regarding termination of, or intent not to renew, any of the material contracts or agreements referred to or described in the Time of Sale Prospectus or the Prospectus, or referred to or described in, or filed as an exhibit to, the Registration Statement, and no such termination or non-renewal has been threatened by the Company or any of its Subsidiaries or, to the Company’s knowledge, any other party to any such contract or agreement, except as would not have a material adverse effect.

     (ff) All tax returns required to be filed by the Company or any of its Subsidiaries have been timely filed, and all taxes and other assessments of a similar nature (whether imposed directly or through withholding) including any interest, additions to tax or penalties applicable thereto due or claimed to be due from such entities have been timely paid, other than those being contested in good faith and for which adequate reserves have been provided.

     (gg) Neither the Company nor any of its Subsidiaries nor, to the knowledge of the Company, any director, officer, agent, employee or affiliate of the Company or any of its Subsidiaries is aware of or has taken any action, directly or indirectly, that would result in a violation by such persons of the Foreign Corrupt Practices Act of 1977, as amended, and the rules and regulations thereunder; and the Company and its Subsidiaries have instituted and maintain policies and procedures designed to ensure continued compliance therewith, including without limitation a system of internal accounting controls sufficient to provide reasonable assurances that (i) transactions are executed in accordance with management’s general or specific authorization, (ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain accountability for assets, (iii) access to assets is permitted only in accordance with management’s general or specific authorization, and (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences.

     (hh) Except as described in the Time of Sale Prospectus, the Company has not sold, issued or distributed any shares of Common Stock during the six-month period preceding the date hereof, including any sales pursuant to Rule 144A under, or Regulation D or S of, the Securities Act, other than shares issued pursuant to employee benefit plans, qualified stock option plans or other employee compensation plans or pursuant to outstanding options, rights or warrants.

     (ii) Neither the Company nor any of its Subsidiaries nor, to its knowledge, any of their respective directors, officers, affiliates or controlling persons has taken, directly or indirectly, any action designed, or which has constituted or might reasonably be expected to cause or result in the stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Shares.

     2. Agreements to Sell and Purchase. The Company hereby agrees to issue and sell 2,000,000 Firm Shares to the several Underwriters at a price of $36.75 per share (the “Purchase Price”), and each Underwriter, upon the basis of the representations and warranties herein contained, but subject to the conditions herein set forth, agrees, severally and not jointly, to purchase from the Company at the Purchase Price the number of Firm Shares set forth opposite the name of such Underwriter set forth in Schedule I hereto.

     Moreover, the Company hereby agrees to issue and sell up to 300,000 Additional Shares to the Underwriters at the Purchase Price, and the Underwriters, upon the basis of the representations and warranties contained herein, but subject to the terms and conditions herein set forth, shall have the right (but not the obligation) to purchase, severally and not jointly, the Additional Shares at the Purchase Price. The Managers may exercise this right on behalf of the Underwriters in whole or from time to time in part by giving written notice not later than 30 days after the date of this Agreement. Any exercise notice shall specify the number of Additional Shares to be purchased by the Underwriters and the date on which such shares are to be purchased. Each purchase date must be at least one business day after the written notice is given and may not be earlier than the Closing Date (as defined in Section 4) or later than ten business days after the date of such notice. Additional Shares may be purchased as provided in Section 4 hereof solely for the purpose of covering over-allotments made in connection with the offering of the Firm Shares. On each day, if any, that Additional Shares are to be purchased (an “Option Closing Date”), each Underwriter agrees, severally and not jointly, to purchase the number of Additional Shares (subject to such adjustments to eliminate fractional shares as the Managers may determine) that bears the same proportion to the total number of Additional Shares to be purchased on such Option Closing Date as the number of Firm Shares set forth in Schedule I hereto opposite the name of such Underwriter bears to the total number of Firm Shares. No Additional Shares shall be sold or delivered unless the Firm Shares previously have been, or simultaneously are, sold and delivered.

     3. Terms of Public Offering. The Company is advised by the Managers that the Underwriters propose to make a public offering of their respective portions of the Shares as soon after this Agreement have become effective as in the Managers’ judgment is advisable. The Company is further advised by the Managers that the Shares are to be offered to the public initially at $36.75 per share (the “Public Offering Price”) and to certain dealers selected by the Managers at a price that represents a concession not in excess of $0.825 per share under the Public Offering Price, and that any Underwriter may allow, and such dealers may reallow a

concession, not in excess of $0.10 per share, to any Underwriter or to certain other dealers.

     4. Payment and Delivery. Payment for the Firm Shares shall be made to the Company in Federal (same day funds) by wire transfer to an account at a bank acceptable to the Company and the Underwriters, against delivery of such Firm Shares for the respective accounts of the several Underwriters at 9:00 a.m., Central Time, on October 12, 2006, or at such other time on the same or such other date, not later than October 19, 2006, as the Underwriters and the Company determine. The time and date of such payment are hereinafter referred to as the “Closing Date.”

     Payment for any Additional Shares shall be made to the Company in federal (same day funds) by wire transfer to an account at a bank acceptable to the Company and the Underwriters, against delivery of such Additional Shares for the respective accounts of the several Underwriters at 9:00 a.m., Central Time, on the date specified in the corresponding notice described in Section 2 or at such other time on the same or on such other date, in any event not later than November 6, 2006, as the Underwriters and the Company determine.

     The Firm Shares and Additional Shares shall be registered in such names and in such denominations as the Managers shall request in writing not later than two full business days prior to the Closing Date or the applicable Option Closing Date, as the case may be. The Firm Shares and Additional Shares shall be delivered to the Managers on the Closing Date or an Option Closing Date, as the case may be, for the respective accounts of the several Underwriters, with any transfer taxes payable in connection with the transfer of the Shares to the Underwriters duly paid, against payment of the Purchase Price therefor.

     5. Conditions to the Underwriters’ Obligations. The several obligations of the Underwriters are subject to the condition that all representations and warranties on the part of the Company contained in this Agreement are, on the date hereof, on the Closing Date and on each Option Closing Date, if any, true and correct in all material respects (expect that if a representation and warranty is made as of a specific date, and such date is expressly referred to therein, such representation and warranty shall be true and correct in all material respects as of such date), the condition that the Company has performed its obligations required to be performed prior to the Closing Date and the following further conditions:

     (a) Subsequent to the execution and delivery of this Agreement and prior to the Closing Date and each Option Closing Date, if any:

     (i) there shall not have occurred any downgrading, nor shall any notice have been given of any intended or potential downgrading or of any review for a possible change that does not indicate the direction of the possible change, in the rating accorded any of the securities of the Company or any of its Subsidiaries by any “nationally recognized statistical rating

organization,” as such term is defined for purposes of Rule 436(g)(2) under the Securities Act; and

     (ii) there shall not have occurred any material adverse change, from that set forth in the Time of Sale Prospectus that, in the Managers’ reasonable judgment, is material and adverse and that makes it, in the Managers’ reasonable judgment, impracticable or inadvisable to offer or sell the Shares on the terms and in the manner contemplated in this Agreement and the Time of Sale Prospectus.

     (b) The Underwriters shall have received on the Closing Date and each Option Closing Date, if any, a certificate, dated the Closing Date or such Option Closing Date, as the case may be, and signed by the Chief Executive Officer and Chief Financial Officer of the Company, to the effect that, to the knowledge of such officers, the representations and warranties of the Company contained in this Agreement are true and correct as of the Closing Date or such Option Closing Date, as the case may be, and that the Company has complied with all of the agreements and satisfied all of the conditions on its part to be performed or satisfied hereunder on or before the Closing Date or such Option Closing Date, as the case may be, and as to such other matters as the Managers may reasonably request. The delivery of the certificate provided for in this Section 5(b) shall constitute a representation and warranty of the Company as to the statements made in such certificate.

     (c) The Underwriters shall have received on the Closing Date and each Option Closing Date, if any, an opinion of Gibson, Dunn & Crutcher LLP, outside counsel for the Company, dated the Closing Date or such Option Closing Date, as the case may be, to the effect that:

     (i) the Company is validly existing as a corporation in good standing under the laws of the jurisdiction of its incorporation, has the corporate power and authority to execute and deliver this Agreement and to perform its obligations hereunder, and is duly qualified to transact business and is in good standing in California;

     (ii) each subsidiary of the Company listed in an annex to such opinion, has been duly organized, is validly existing as a corporation or limited liability company in good standing under the laws of the jurisdiction of its organization;

     (iii) the Company has an authorized capitalization as set forth in the Time of Sale Prospectus and the Prospectus;

     (iv) the Shares have been duly authorized and, when issued and delivered and paid for in accordance with the terms of this Agreement, will be validly issued, fully paid and non-assessable, and the issuance of such

Shares will not be subject to any preemptive or similar rights pursuant to the Company’s certificate of incorporation or bylaws;

     (v) this Agreement has been duly authorized, executed and delivered by the Company;

     (vi) The execution and delivery by the Company of this Agreement and the issuance by the Company of the Shares to the Underwriters: (x) do not and will not violate the certificate of incorporation or bylaws of the Company; and (y) do not and will not breach the terms of any agreement identified to Gibson, Dunn & Crutcher by the Company as being material to which the Company is a party or any order, judgment or decree of any court or other agency of government identified to Gibson, Dunn & Crutcher of the Company as constituting all orders, judgments or decrees binding on the Company, in each case based solely on Gibson, Dunn & Crutcher’s review of such agreements, orders, judgments or decrees;

     (vii) The execution and delivery by the Company of this Agreement and the issuance by the Company of the Shares to the Underwriters (x) do not and will not violate any law, rule or regulation of the United States of America applicable to the Company or its Subsidiaries that, in such counsel’s experience, is generally applicable to transactions in the nature of those contemplated by this Agreement, or the Delaware General Corporation Law or the laws of the State of Delaware, in each case as currently in effect; it being understood, however, that no opinion need be rendered with respect to federal, state or foreign securities, or any federal or state public utilities code, environmental laws or similar law regulating the conduct of the Company’s business; and (y) do not and will not require any filing with or approval of any governmental authority or regulatory body of the State of Delaware or the United States of America under any law or regulation of the State of Delaware or the United States of America applicable to the Company or the Delaware General Corporation Law , except for such filings or approvals as already have been made or obtained under the Securities Act; and other than the last clause of the preceding sentence, Gibson, Dunn & Crutcher expresses no opinion in this paragraph regarding federal or state securities laws; and

     (viii) the Company is not, and after giving effect to the offering and sale of the Shares and the application of the proceeds thereof as described in the Prospectus will not be, required to register as an “investment company” as such term is defined in the Investment Company Act of 1940, as amended.

     (d) In addition, the Underwriters shall have received on the Closing Date and each Option Closing Date, if any, a letter of Gibson, Dunn & Crutcher LLP, dated the Closing Date or such Option Closing Date, as the case may be, to the effect that no facts have come to Gibson, Dunn & Crutcher’s attention that led it to

believe: (i) that the Registration Statement or the Prospectus (except for the financial statements and financial schedules and other financial or statistical data included therein, as to which such counsel need not express any belief) were not appropriately responsive in all material respects to the requirements of the Securities Act and the applicable rules and regulations of the Commission thereunder; or (ii) that the Registration Statement (except for the financial statements and financial schedules and other financial or statistical data included therein, as to which such counsel need not express any belief), at the time it became effective, contained an untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary to make the statements therein not misleading; or (iii) that the Prospectus, as of its date or as of the Closing Date or Option Closing Date, as the case may be, contained or contains an untrue statement of a material fact or omitted or omits to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. Such letter shall also state that insofar as the statements in the Prospectus under the captions “Description of Common Stock” and “Plan of Distribution” purport to summarize the documents referred to therein, such statements fairly present in all material respects the information required to be disclosed under the Securities Act and the rules and regulations of the Commission relating to registration statements on Form S 3 and prospectuses.

     (e) The Underwriters shall have received on the Closing Date and each Option Closing Date, if any, an opinion of John S. Tootle, Corporate Counsel for the Company, dated the Closing Date or such Option Closing Date, as the case may be, that no consent or approval by, or any notification of or filing with, any court, public body or authority is required to be obtained or effected by the Company in connection with the execution and delivery by the Company of this Agreement and the issuance by the Company of the Shares to the Underwriters, except for the authorization of the California Public Utilities Commission, which authorization has been duly obtained and is in full force and effect; and such opinion shall be limited to the applicable present public utilities codes.

     (f) The Underwriters shall have received on the Closing Date and each Option Closing Date, if any, an opinion of Michael Best & Friedrich LLP, counsel for the Underwriters, dated the Closing Date or such Option Closing Date, as the case may be, covering the matters referred to in Sections 5(c)(iv), 5(c)(v), and 5(d) (but only as to the statements in each of the Time of Sale Prospectus and the Prospectus under “Description of Common Stock” and “Underwriters”) and 5(d) above.

     With respect to Section 5(d) above, Gibson, Dunn & Crutcher LLP and Michael Best & Friedrich LLP may state that their opinions and beliefs are based upon their participation in the preparation of the Registration Statement, the Time of Sale Prospectus and the Prospectus and any amendments or supplements thereto and review and discussion of the contents thereof, but are without independent check or verification, except as specified.

     The opinions of Gibson, Dunn & Crutcher LLP described in Section 5(c) and of John Tootle described in Section 5(e) above shall be rendered to the Underwriters at the request of the Company and shall so state therein.

     (g) The Underwriters shall have received, on each of the date hereof, the Closing Date and each Option Closing Date, if any, a letter dated the date hereof, the Closing Date or the Option Closing Date, as the case may be, in form and substance satisfactory to the Underwriters, from KPMG LLP, independent public accountants, containing statements and information of the type ordinarily included in accountants’ “comfort letters” to underwriters with respect to the financial statements and certain financial information contained in the Registration Statement, the Time of Sale Prospectus and the Prospectus; provided that the letter delivered on the Closing Date shall use a “cut-off date” not earlier than the date hereof.

     (h) No stop order suspending the effectiveness of the Registration Statement or preventing or suspending the use of any Preliminary Prospectus, the Time of Sale Prospectus or the Prospectus shall have been issued, and no proceedings for such purpose shall have been instituted or, to the knowledge of the Company, threatened by the Commission; no notice of objection of the Commission to the use of the Registration Statement shall have been received; and all requests for additional information on the part of the Commission shall have been complied with to the Manager’s reasonable satisfaction.

     (i) The “lock-up” agreements, each substantially in the form of Exhibit A hereto, between the Managers and certain stockholders, officers and directors of the Company relating to sales and certain other dispositions of shares of Common Stock or certain other securities, delivered to Managers on or before the date hereof, shall be in full force and effect on the Closing Date.

     (j) The Shares shall have been approved for listing on the NYSE.

     The several obligations of the Underwriters to purchase Additional Shares hereunder are subject to the satisfaction on and as of the Option Closing Date of the conditions set forth in this Section 5, except that if such Option Closing Date is other than the Closing Date, the certificates, opinions and letters referred to in this Section 5 shall be dated as of the Option Closing Date and the opinions shall be revised to reflect the sale of Additional Shares.

     6. Covenants of the Company. The Company covenants with each Underwriter as follows:

     (a) To furnish to the Managers, without charge, six signed copies of the Registration Statement (including exhibits thereto) and for delivery to each other Underwriter, upon request, a conformed copy of the Registration Statement (without exhibits thereto) and to furnish to the Managers in Milwaukee, Wisconsin, without charge, prior to 10:00 a.m. Central Time on the business day next succeeding the date of this Agreement and during the period mentioned in Section 6(f) or 6(g)

below, as many copies of the Time of Sale Prospectus, the Prospectus and any supplements and amendments thereto or to the Registration Statement as the Managers may reasonably request in writing.

     (b) Before amending or supplementing the Registration Statement, the Time of Sale Prospectus or the Prospectus, to furnish to the Managers a copy of each such proposed amendment or supplement and not to file any such proposed amendment or supplement to which the Managers reasonably object, and to file with the Commission within the applicable period specified in Rule 424(b) under the Securities Act any prospectus required to be filed pursuant to such Rule.

     (c) To furnish to the Managers a copy of each proposed free writing prospectus to be prepared by or on behalf of, used by, or referred to by the Company and not to use or refer to any proposed free writing prospectus to which the Managers reasonably object.

     (d) Not to take any action that would result in an Underwriter or the Company being required to file with the Commission pursuant to Rule 433(d) under the Securities Act a free writing prospectus prepared by or on behalf of the Underwriter that the Underwriter otherwise would not have been required to file thereunder.

     (e) To advise the Managers promptly of any request by the Commission for amendments or supplements to the Registration Statement, Base Prospectus, any Preliminary Prospectus, Prospectus Supplement or Prospectus or for additional information with respect thereto, or of notice of institution of proceedings for, or the entry of a stop order, suspending the effectiveness of the Registration Statement or preventing or suspending the use of any Preliminary Prospectus, the Time of Sale Prospectus or the Prospectus; and if the Commission should enter such a stop order, to use its commercially reasonable efforts to obtain the lifting or removal of such order as soon as possible.

     (f) If the Time of Sale Prospectus is being used to solicit offers to buy the Shares at a time when the Prospectus is not yet available to prospective purchasers and any event shall occur or condition exist as a result of which it is necessary to amend or supplement the Time of Sale Prospectus in order to make the statements therein, in the light of the circumstances, not misleading, or if any event shall occur or condition exist as a result of which the Time of Sale Prospectus conflicts with the information contained in the Registration Statement then on file, or if, in the opinion of counsel for the Underwriters, it is necessary to amend or supplement the Time of Sale Prospectus to comply with applicable law, forthwith to prepare, file with the Commission and furnish, at its own expense, to the Underwriters and to any dealer upon request, either amendments or supplements to the Time of Sale Prospectus so that the statements in the Time of Sale Prospectus as so amended or supplemented will not, in the light of the circumstances when delivered to a prospective purchaser, be misleading or so that the Time of Sale Prospectus, as amended or supplemented, will no longer conflict with the

Registration Statement, or so that the Time of Sale Prospectus, as amended or supplemented, will comply with applicable law.

     (g) If, during such period after the first date of the public offering of the Shares the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) under the Securities Act) is required by law to be delivered in connection with sales by an Underwriter or dealer, and the Company reasonably determines, or in the reasonable opinion of counsel for the Underwriters, any event shall occur or condition exist as a result of which it is necessary to amend or supplement the Prospectus in order to make the statements therein, in the light of the circumstances when the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) under the Securities Act) is delivered to a purchaser, not misleading, or if the Company reasonably determines, or in the reasonable opinion of counsel for the Underwriters, it is necessary to amend or supplement the Prospectus to comply with applicable law, forthwith to prepare, file with the Commission and furnish, at its own expense, to the Underwriters and to the dealers (whose names and addresses Managers will furnish to the Company) in writing to which Shares may have been sold by Managers on behalf of the Underwriters and to any other dealers upon request, either amendments or supplements to the Prospectus so that the statements in the Prospectus as so amended or supplemented will not, in the light of the circumstances when the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) under the Securities Act) is delivered to a purchaser, be misleading or so that the Prospectus, as amended or supplemented, will comply with applicable law.

     (h) If, at the time this Agreement is executed and delivered, the Company determines that it is necessary or appropriate for a post-effective amendment to the Registration Statement, or a Registration Statement under Rule 462(b) under the Securities Act, to be filed with the Commission and become effective before the Shares may be sold, the Company will use its commercially reasonable efforts to cause such post-effective amendment or such Registration Statement to be filed and become effective, and will pay any applicable fees in accordance with the Securities Act, as soon as practicable; and the Company will advise Managers promptly and, if requested by the Managers, will confirm such advice in writing, (i) when such post-effective amendment or such Registration Statement has become effective, and (ii) if Rule 430A under the Securities Act is used, when the Prospectus is filed with the Commission pursuant to Rule 424(b) under the Securities Act (which the Company agrees to file in a timely manner in accordance with such Rules).

     (i) If, at any time during the period when a prospectus is required by the Securities Act to be delivered (whether physically or through compliance with Rule 172 under the Securities Act or any similar rule) in connection with any sale of Shares, the Registration Statement shall cease to comply with the requirements of the Securities Act with respect to eligibility for the use of the form on which the Registration Statement was filed with the Commission, to (i) promptly notify the Managers, (ii) promptly file with the Commission a new registration statement under the Securities Act, relating to the Shares, or a post-effective amendment to the

Registration Statement, which new registration statement or post-effective amendment shall comply with the requirements of the Securities Act and shall be in a form reasonably satisfactory to the Managers, (iii) use its commercially reasonable efforts to cause such new registration statement or post-effective amendment to become effective under the Securities Act as soon as practicable, (iv) promptly notify the Managers of such effectiveness and (v) take all other reasonable action necessary or appropriate to permit the public offering and sale of the Shares to continue as contemplated in the Prospectus; all references herein to the Registration Statement shall be deemed to include each such new registration statement or post-effective amendment, if any;

     (j) To file in a timely manner all reports and any definitive proxy or information statements required to be filed by the Company with the Commission pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act subsequent to the date of the Prospectus and for so long as the delivery of a prospectus (or, in lieu thereof, the notice referred to in Rule 173(a) under the Securities Act) is required in connection with the offering or sale of the Shares.

     (k) Promptly to furnish such information or to take such action as the Managers may reasonably request and otherwise to qualify the Shares for offer and sale under the securities or “blue sky” laws of such jurisdictions as the Managers shall reasonably request, and to comply with such laws so as to permit the continuance of sales and dealings therein in such jurisdictions for as long as may be necessary to complete the distribution of the Shares; provided, however, that the Company shall not be required to qualify as a foreign corporation or to file a consent to service of process in any jurisdiction or so subject itself to taxation in respect of doing business in any jurisdiction in which it is not otherwise so subject; and to promptly advise the Managers of the receipt by the Company of any notification with respect to the suspension of the qualification of the Shares for offer or sale in any jurisdiction or the initiation or threatening of any proceeding for such purpose.

     (l) To make generally available to the Company’s security holders and to the Managers as soon as practicable an earning statement covering a period of at least twelve months beginning after the effective date of the Registration Statement (as defined in Rule 158(c) under the Securities Act), which shall satisfy the provisions of Section 11(a) of the Securities Act and Rule 158 thereunder.

     (m) To use its commercially reasonable efforts to cause the Shares to be listed on the NYSE.

     (n) During the period beginning on the date of the Underwriting Agreement and continuing to and including 90 days after the date of the Prospectus, and without the prior written consent of Baird, not to (1) issue, offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock, (2)

enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Common Stock, whether such transaction described in clause (1) or (2) above is to be settled by delivery of the Common Stock or such other securities, in cash or otherwise, (3) file any registration statement with the Commission relating to the offering of any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock, or (4) publicly announce an intention to effect any transaction specified in clause (1), (2) or (3). The restrictions contained in the preceding sentence shall not apply to: (i) the Shares to be sold hereunder; (ii) the grant of options to purchase Common Stock or the sale of shares of Common Stock to employees of the Company pursuant to the Company’s written stock option plans and/or written employee stock purchase plans in existence as of the date of this Agreement; (iii) the issuance by the Company of shares of Common Stock upon the exercise of an option or warrant or the conversion of a security outstanding on the date of this Agreement of which Baird has been advised in writing; (iv) the filing by the Company of any registration statement with the Commission on Form S-8 relating to the offering of securities pursuant to the terms of a stock incentive plan of the Company in effect on the date hereof; or (v) the issuance by the Company of shares of Common Stock in connection with acquisitions of other companies up to an amount equal to 19.9% of the Company’s fully-diluted Common Stock (measured as of the Closing Date) on a transaction-by-transaction basis. Notwithstanding the foregoing, if (1) during the last 17 days of the 90-day restricted period the Company issues an earnings release or material news or a material event relating to the Company occurs; or (2) prior to the expiration of the 90-day restricted period, the Company announces that it will release earnings results during the 16-day period beginning on the last day of the 90-day period, the restrictions imposed by this agreement shall continue to apply until the expiration of the 18-day period beginning on the issuance of the earnings release or the occurrence of the material news or material event. The Company shall promptly notify Baird of any earnings release, news or event that may give rise to an extension of the initial 90-day restricted period.

     (o) To prepare, if the Managers so request, a final term sheet relating to the offering of the Shares, containing only information that describes the final terms of the Shares or the offering in a form consented to by the Managers (such consent not to be unreasonably withheld), and to file such final term sheet within the period required by Rule 433(d)(5)(ii) under the Securities Act following the date the final terms have been established for the offering of the Shares.

     (p) Intentionally Left Blank

     (q) To comply with Rule 433(d) under the Securities Act (without reliance on Rule 164(b) under the Securities Act) and with Rule 433(g) under the Securities Act.

     (r) Not to take, directly or indirectly, any action designed, or which will constitute, or has constituted, or might reasonably be expected to cause or result in

the stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Shares.

     (s) Not, at any time at or after the execution of this Agreement, to offer or sell any Shares by means of any “prospectus” (within the meaning of the Securities Act) or use any “prospectus” (within the meaning of the Securities Act) in connection with the offer or sale of the Shares, except in each case other than the Prospectus.

     (t) To maintain a transfer agent and, if necessary under the jurisdiction of incorporation of the Company, a registrar for the Common Stock.

     (u) To apply the net proceeds to the Company from the sale of the Shares in the manner set forth under the caption “Use of Proceeds” in the Prospectus Supplement.

     7. Covenants of the Underwriters. Each Underwriter hereby severally agrees as follows:

     (a) To not use or refer to, or authorize any other person to use or refer to, or participate in the planning for use of, any free writing prospectus, as defined in Rule 405 under the Securities Act (which term includes use of any written information furnished to the Commission by the Company and not incorporated by reference into the Registration Statement and any press release issued by the Company) other than (i) a free writing prospectus that contains no “issuer information” (as defined in Rule 433(h)(2) under the Securities Act) that was not included in the Preliminary Prospectus or a previously filed free writing prospectus, (ii) any free writing prospectus listed on Schedule II hereto, or (iii) any free writing prospectus prepared by such Underwriter and approved by the Company in advance in writing (each such free writing prospectus referred to in clauses (i) or (iii), an “Underwriter Free Writing Prospectus”).

     (b) To not distribute any Underwriter Free Writing Prospectus referred to in Section 8(a)(i) in a manner reasonably designed to lead to its broad unrestricted dissemination.

     (c) To not, without the prior written consent of the Company, use any free writing prospectus that contains the final terms of the Shares unless such terms have previously been included in a free writing prospectus filed with the Commission.

     (d) Pursuant to reasonable procedures developed in good faith, to retain copies of each free writing prospectus used or referred to by it, in accordance with Rule 433 under the Securities Act.

     (e) If at any time prior to the Closing Date any event shall occur or condition shall exist as a result of which an Underwriter Free Writing Prospectus

conflicted or would conflict with the information then contained in the Registration Statement, the Time of Sale Prospectus or the Prospectus, to immediately notify the Company thereof and forthwith prepare and file with the Commission (to the extent required) and furnish to the Company, such amendments or supplements to such Underwriter Free Writing Prospectus as may be necessary to eliminate or correct such conflict.

     8. Expenses. Whether or not the transactions contemplated in this Agreement are consummated or this Agreement is terminated, the Company agrees to pay or cause to be paid all expenses incident to the performance of its obligations under this Agreement, including: (i) the fees, disbursements and expenses of the Company’s counsel and the Company’s accountants in connection with the registration and delivery of the Shares under the Securities Act and all other fees or expenses in connection with the preparation and filing of the Registration Statement, any Preliminary Prospectus, the Time of Sale Prospectus, the Prospectus, any free writing prospectus prepared by or on behalf of, used by, or referred to by the Company and amendments and supplements to any of the foregoing, including all printing costs associated therewith, and the mailing and delivering of copies thereof to the Underwriters and dealers, in the quantities hereinabove specified, (ii) all costs and expenses related to the transfer and delivery of the Shares to the Underwriters, including any transfer or other taxes payable thereon, (iii) the cost of printing or producing any securities or blue sky memorandum in connection with the offer and sale of the Shares under the securities laws of the jurisdictions in which the Shares may be offered or sold and all expenses in connection with the qualification of the Shares for offer and sale under such securities laws as provided in Section 6(l) hereof, including filing fees and the reasonable fees and disbursements of counsel for the Underwriters in connection with such qualification and in connection with the Blue Sky or Legal Investment memorandum, (iv) all filing fees and the reasonable fees and disbursements of counsel to the Underwriters incurred in connection with the review and qualification of the offering of the Shares by the NASD, (v) all costs and expenses incident to listing the Shares on the NYSE, (vi) the cost of printing certificates representing the Shares, (vii) the costs and charges of any transfer agent, registrar or depositary, (viii) the document production charges and expenses associated with printing this Agreement, (ix) all expenses in connection with any offer and sale of the Shares outside of the United States, including filing fees and the reasonable fees and disbursements of counsel for the Underwriters in connection with offers and sales outside of the United States, and (x) all other costs and expenses incident to the performance of the obligations of the Company hereunder for which provision is not otherwise made in this Section.

     The Underwriters will pay (a) all of their costs and expenses, including fees and disbursements of their counsel, stock transfer taxes payable on resale of any of the Shares by them and any advertising expenses connected with any offers they may make; and (b) whether or not the transactions contemplated in this Agreement are consummated or this Agreement is terminated, the costs and expenses of the Company relating to investor presentations on any “road show” undertaken in

connection with the marketing of the offering of the Shares, including, without limitation, expenses associated with the preparation or dissemination of any road show, expenses associated with the production of road show slides and graphics, fees and expenses of any consultants engaged in connection with the road show presentations with the prior approval of the Company, travel and lodging expenses of the representatives and officers of the Company and any such consultants, and the cost of any aircraft chartered in connection with the road show. Notwithstanding the above, if the sale of the Shares provided for herein is not consummated because any condition to the obligations of the Underwriters set forth in Section 5 is not satisfied, because of any termination of this Agreement by the Underwriters pursuant to Section 10 hereof or because of any refusal, inability or failure on the part of the Company to perform any obligation or covenant hereunder or comply with any provision hereof other than by reason of a default by any of the Underwriters, the Company will reimburse the Underwriters or such Underwriters as have so terminated this Agreement with respect to themselves, severally, through the Managers on demand for all out-of-pocket expenses (including reasonable fees and disbursements of counsel) reasonably incurred by such Underwriters in connection with this Agreement or the offering contemplated hereby.

     The provisions of this Section shall not supersede or otherwise affect any agreement that the Sellers may otherwise have for the allocation of such expenses among themselves.

     9. Indemnity and Contribution. (a) The Company agrees to indemnify and hold harmless each Underwriter, each person, if any, who controls any Underwriter within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act, and each affiliate of any Underwriter within the meaning of Rule 405 under the Securities Act from and against any and all losses, claims, damages and liabilities (including, without limitation, any legal or other expenses reasonably incurred in connection with defending or investigating any such action or claim) caused by, arising out of or based upon (i) any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement or any amendment thereof, or any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, or (ii) any untrue statement or alleged untrue statement of a material fact contained in any Preliminary Prospectus, the Time of Sale Prospectus, any issuer free writing prospectus as defined in Rule 433(h) under the Securities Act, any issuer information that the Company has filed, or is required to file, pursuant to Rule 433(d) of the Securities Act, any road show not constituting a free writing prospectus, or the Prospectus or any amendment or supplement thereto, or any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances in which there were made, not misleading; provided, however, that the Company shall not be liable under this Section 9(a) to the extent that such losses, claims, damages or liabilities are caused by, arise out of or are based upon any such untrue statement or omission or alleged untrue statement or omission made therein in reliance upon and

in conformity with information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Managers expressly for use therein; provided, however, that the foregoing indemnity agreement shall not inure to the benefit of any Underwriter from whom the person asserting any such losses, claims, damages or liabilities purchased Shares, or any person controlling such Underwriter, if a copy of the Time of Sale Prospectus (as then amended or supplemented if the Company shall have furnished any amendments or supplements thereto) was not sent or given by or on behalf of such Underwriter to such person at or prior to the written confirmation of the sale of the Shares to such person, and if the Time of Sale Prospectus (as so amended or supplemented), would have cured the defect giving rise to such losses, claims, damages or liabilities, unless such failure is the result of noncompliance by the Company with Section 6(a) hereof.

     (b) Each Underwriter agrees, severally and not jointly, to indemnify and hold harmless the Company, the directors of the Company, the officers of the Company who sign the Registration Statement and each person, if any, who controls the Company within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act from and against any and all losses, claims, damages and liabilities (including, without limitation, any legal or other expenses reasonably incurred in connection with defending or investigating any such action or claim) caused by, arising from or based upon (i) any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement or any amendment thereof or any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, or (ii) any untrue statement or alleged untrue statement of a material fact contained in any Preliminary Prospectus, the Time of Sale Prospectus, any issuer free writing prospectus as defined in Rule 433(h) under the Securities Act, any Company information that the Company has filed, or is required to file, pursuant to Rule 433(d) of the Securities Act, any road show not constituting a free writing prospectus, or the Prospectus or any amendment or supplement thereto, or any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances in which there were made, not misleading, in each case to the extent, but only to the extent, that such untrue statement or omission or alleged untrue statement or omission was made therein in reliance upon and in conformity with information relating to such Underwriter furnished to the Company in writing by such Underwriter through the Managers expressly for use therein.

     (c) In case any proceeding (including any governmental investigation) shall be instituted involving any person in respect of which indemnity may be sought pursuant to Section 9(a) or 8(b) such person (the “indemnified party”) shall promptly notify the person against whom such indemnity may be sought (the “indemnifying party”) in writing and the indemnifying party, upon request of the indemnified party, shall retain counsel reasonably satisfactory to the indemnified party to represent the indemnified party and any others the indemnifying party may designate in such proceeding and shall pay the fees and disbursements of such counsel related to such proceeding. In any such proceeding, any indemnified party

shall have the right to retain its own counsel, but the fees and expenses of such counsel shall be at the expense of such indemnified party unless (i) the indemnifying party and the indemnified party shall have mutually agreed to the retention of such counsel or (ii) the named parties to any such proceeding (including any impleaded parties) include both the indemnifying party and the indemnified party and representation of both parties by the same counsel would be inappropriate due to actual or potential differing interests between them. It is understood that the indemnifying party shall not, in respect of the legal expenses of any indemnified party in connection with any proceeding or related proceedings in the same jurisdiction, be liable for (x) the fees and expenses of more than one separate firm (in addition to any local counsel) for all Underwriters and all persons, if any, who control any Underwriter within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act or who are affiliates of any Underwriter within the meaning of Rule 405 under the Securities Act, or (y) the fees and expenses of more than one separate firm (in addition to any local counsel) for the Company, its directors, its officers who sign the Registration Statement and each person, if any, who controls the Company within the meaning of either such Section, and that all such fees and expenses shall be reimbursed as they are incurred. In the case of any such separate firm for the Underwriters and such control persons and affiliates of any Underwriters, such firm shall be designated in writing by Baird. In the case of any such separate firm for the Company, and such directors, officers and control persons of the Company, such firm shall be designated in writing by the Company. The indemnifying party shall not be liable for any settlement of any proceeding effected without its written consent, but if settled with such consent or if there be a final judgment for the plaintiff, the indemnifying party agrees to indemnify the indemnified party from and against any loss or liability by reason of such settlement or judgment. Notwithstanding the foregoing sentence, if at any time an indemnified party shall have requested an indemnifying party to reimburse the indemnified party for fees and expenses of counsel as contemplated by the second and third sentences of this paragraph, the indemnifying party agrees that it shall be liable for any settlement of any proceeding effected without its written consent if (A) such settlement is entered into more than 30 days after receipt by such indemnifying party of the aforesaid request and (B) such indemnifying party shall not have reimbursed the indemnified party in accordance with such request prior to the date of such settlement. No indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement of any pending or threatened proceeding in respect of which any indemnified party is or could have been a party and indemnity could have been sought hereunder by such indemnified party, unless such settlement includes an unconditional release of such indemnified party from all liability on claims that are the subject matter of such proceeding.

     (d) To the extent the indemnification provided for in 8(a) or 8(b) is unavailable to an indemnified party or insufficient in respect of any losses, claims, damages or liabilities referred to therein, then each indemnifying party under such paragraph, in lieu of indemnifying such indemnified party thereunder, shall contribute to the amount paid or payable by such indemnified party as a result of

such losses, claims, damages or liabilities (i) in such proportion as is appropriate to reflect the relative benefits received by the indemnifying party or parties on the one hand and the indemnified party or parties on the other hand from the offering of the Shares or (ii) if the allocation provided by clause (i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause (i) above but also the relative fault of the indemnifying party or parties on the one hand and of the indemnified party or parties on the other hand in connection with the statements or omissions that resulted in such losses, claims, damages or liabilities, as well as any other relevant equitable considerations. The relative benefits received by the Company on the one hand and the Underwriters on the other hand in connection with the offering of the Shares shall be deemed to be in the same respective proportions as the net proceeds from the offering of the Shares (before deducting expenses) received by the Company and the total underwriting discounts and commissions received by the Underwriters, in each case as set forth in the table on the cover of the Prospectus, bear to the aggregate Public Offering Price of the Shares. The relative fault of the Company on the one hand and the Underwriters on the other hand shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company or by the Underwriters and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The Underwriters’ respective obligations to contribute pursuant to this Section 9 are several in proportion to the respective number of Shares they have purchased hereunder, and not joint.

     (e) The Company and the Underwriters agree that it would not be just or equitable if contribution pursuant to this Section 9 were determined by pro rata allocation (even if the Underwriters were treated as one entity for such purpose) or by any other method of allocation that does not take account of the equitable considerations referred to in Section 9(d). The amount paid or payable by an indemnified party as a result of the losses, claims, damages and liabilities referred to in Section 9(d) shall be deemed to include, subject to the limitations set forth above, any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending any such action or claim. Notwithstanding the provisions of this Section 9, no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Shares underwritten by it and distributed to the public were offered to the public exceeds the amount of any damages that such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The remedies provided for in this Section 9 are not exclusive and shall not limit any rights or remedies which may otherwise be available to any indemnified party at law or in equity.

     (f) The indemnity and contribution provisions contained in this Section 9 shall remain operative and in full force and effect regardless of (i) any termination of this Agreement, (ii) any investigation made by or on behalf of any Underwriter, any person controlling any Underwriter or any affiliate of any Underwriter, or the Company, its officers or directors or any person controlling the Company and (iii) acceptance of and payment for any of the Shares.

     10. Termination. The Underwriters may terminate this Agreement by notice given by the Managers to the Company, if after the execution and delivery of this Agreement and prior to the Closing Date (a) trading generally shall have been suspended or materially limited or minimum prices shall have been established on, or by, as the case may be, any of the New York Stock Exchange, the American Stock Exchange, or the NASDAQ Global Market, (b) trading of any securities in the Company or materially limited on any exchange or in any over-the-counter market, (c) a material disruption in securities settlement, payment or clearance services in the United States shall have occurred, (d) any moratorium on commercial banking activities shall have been declared by federal, Wisconsin or New York state authorities, (e) there shall have occurred any outbreak or escalation of hostilities, act of terrorism involving the United States or declaration by the United States of a national emergency or war, or (f) any other calamity or crisis or any change in financial, political or economic conditions in the United States or elsewhere, if the effect of any such event specified in clause (e) or (f), in the Managers’ judgment, is material and adverse and makes it, in the Managers’ good faith judgment, impracticable or inadvisable to proceed with the offer, sale or delivery of the Shares on the terms and in the manner contemplated in the Time of Sale Prospectus or the Prospectus (exclusive of any supplement thereto).

     11. Effectiveness; Defaulting Underwriters. This Agreement shall become effective upon the execution and delivery hereof by the parties hereto.

     If, on the Closing Date or an Option Closing Date, as the case may be, any one or more of the Underwriters shall fail or refuse to purchase Shares that it has or they have agreed to purchase hereunder on such date, and the aggregate number of Shares which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase is not more than one-tenth of the aggregate number of the Shares to be purchased on such date, the other Underwriters shall be obligated severally in the proportions that the number of Firm Shares set forth opposite their respective names in Schedule I bears to the aggregate number of Firm Shares set forth opposite the names of all such non-defaulting Underwriters, or in such other proportions as the Managers may specify, to purchase the Shares which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase on such date; provided that in no event shall the number of Shares that any Underwriter has agreed to purchase pursuant to this Agreement be increased pursuant to this Section 11 by an amount in excess of one-ninth of such number of Shares without the written consent of such Underwriter. If, on the Closing Date, any Underwriter or Underwriters shall fail or refuse to purchase Firm Shares and the aggregate

number of Firm Shares with respect to which such default occurs is more than one-tenth of the aggregate number of Firm Shares to be purchased on such date, and arrangements satisfactory to the Managers and the Company for the purchase of such Firm Shares are not made within 36 hours after such default, this Agreement shall terminate without liability on the part of any non-defaulting Underwriter or the Company. In any such case either the Managers or the Company shall have the right to postpone the Closing Date, but in no event for longer than seven days, in order that the required changes, if any, in the Registration Statement, in the Time of Sale Prospectus, in the Prospectus or in any other documents or arrangements may be effected. If, on an Option Closing Date, any Underwriter or Underwriters shall fail or refuse to purchase Additional Shares and the aggregate number of Additional Shares with respect to which such default occurs is more than one-tenth of the aggregate number of Additional Shares to be purchased on such Option Closing Date, the non-defaulting Underwriters shall have the option to (i) terminate their obligation hereunder to purchase the Additional Shares to be sold on such Option Closing Date or (ii) purchase not less than the number of Additional Shares that such non-defaulting Underwriters would have been obligated to purchase in the absence of such default. Any action taken under this paragraph shall not relieve any defaulting Underwriter from liability in respect of any default of such Underwriter under this Agreement.

     12. Representations and Indemnities to Survive. The respective agreements, representations, warranties, indemnities and other statements of the Company and the Underwriters set forth or made pursuant to this Agreement will remain in full force and effect, regardless of any investigation made by or on behalf of any Underwriter or the Company or any of the officers, directors, employees, agents or controlling persons referred to in Section 9 hereof, and will survive delivery of and payment for the Shares. The provisions of Sections 8 and 9 hereof shall survive the termination or cancellation of this Agreement.

     13. Entire Agreement. (a) This Agreement, together with any contemporaneous written agreements and any prior written agreements (to the extent not superseded by this Agreement) that relate to the offering of the Shares, represents the entire agreement between the Company, on the one hand, and the Underwriters, on the other, with respect to the preparation of any Preliminary Prospectus, the Time of Sale Prospectus, the Prospectus, the conduct of the offering, and the purchase and sale of the Shares.

     (b) The Company acknowledges that in connection with the offering of the Shares: (i) the Underwriters have acted at arm’s length, are not agents of, and owe no fiduciary duties to, the Company or any other person; (ii) the Underwriters owe the Company only those duties and obligations set forth in this Agreement and prior written agreements (to the extent not superseded by this Agreement), if any; and (iii) the Underwriters may have interests that differ from those of the Company.

The Company waives to the full extent permitted by applicable law any claims it may have against the Underwriters arising from an alleged breach of fiduciary duty in connection with the offering of the Shares.

     14. Counterparts. This Agreement may be signed in any number of counterparts, each of which shall be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument.

     15. Applicable Law. This Agreement shall be governed by and construed in accordance with the internal laws of the State of Delaware.

     16. Headings. The headings of the sections of this Agreement have been inserted for convenience of reference only and shall not be deemed a part of this Agreement.

     17. Notices. All communications hereunder shall be in writing and effective only upon receipt and if to the Underwriters shall be delivered, mailed, faxed or sent to the Managers in care of Robert W. Baird & Co. Incorporated, 777 East Wisconsin Avenue, Milwaukee, Wisconsin 53202, Fax: (414) 298-7800, Attention: John Lanza, with a copy to the Legal Department, Robert W. Baird & Co. Incorporated, 777 East Wisconsin Avenue, Milwaukee, Wisconsin 53202, Fax: (414)298-7800; and if to the Company shall be delivered, mailed, faxed or sent to California Water Service Group, 1720 North First Street, San Jose, California 95112, Attention: Marty Kropelnicki (Fax: (408) 367-8430), with a copy to Peter Nelson (Fax: (408) 367-8430) and Calvin Breed (Fax: (408) 367-8425).

Accepted as of the date hereof

ROBERT W. BAIRD & CO. INCORPORATED
A.G. Edwards & Sons, Inc.
Edward D. Jones & Co., L.P.
J.J.B. Hilliard, W.C. Lyons, Inc.
Stifel, Nicolaus & Company Incorporated
     As Representatives of the Several Underwriters

     Identified in Schedule I Annexed Hereto
Acting severally on behalf of themselves and
      the several Underwriters named in
      Schedule I hereto

By: Robert W. Baird & Co. Incorporated

SCHEDULE I

						Maximum Number of
		Number of Firm Shares				Additional Shares To Be
Underwriter		To Be Purchased				Purchased
Robert W. Baird & Co. Incorporated			830,000				124,500
A.G. Edwards & Sons, Inc.			780,000				117,000
Edward D. Jones & Co., L.P.			130,000				19,500
J.J.B. Hilliard, W.C. Lyons, Inc.			130,000				19,500
Stifel, Nicolaus & Company Incorporated			130,000				19,500
Total:			2,000,000				300,000

SCHEDULE II

Time of Sale Prospectus

1.		Preliminary Prospectus, including Preliminary Prospectus Supplement dated September 27, 2006, and Base Prospectus dated September 27, 2006
2.		Issuer Free Writing Prospectus, dated October 5, 2006 with the final terms of the offering and filed by the Company under Rule 433(d) of the Securities Act

EXHIBIT A

[FORM OF LOCK-UP LETTER TO BE SIGNED BY OFFICERS,
DIRECTORS AND CERTAIN STOCKHOLDERS]

October           , 2006

ROBERT W. BAIRD & CO. INCORPORATED
A.G. EDWARDS & SONS, INC.
EDWARD D. JONES & CO., L.P.
J.J.B. HILLIARD, W.L. LYONS, INC.
NICOLAUS & COMPANY, INCORPORATED]
c/o Robert W. Baird & Co. Incorporated
777 East Wisconsin Avenue
Milwaukee, Wisconsin 53202

Ladies and Gentlemen:

     The undersigned understands that Robert W. Baird & Co. Incorporated (“Baird”), A.G. Edwards & Sons, Inc., Edward D. Jones & Co., L.P., J.J.B. Hilliard, W.L. Lyons, Inc. and Nicolaus & Company, Incorporated (together, the “Managers”) propose to enter into an Underwriting Agreement (the "Underwriting Agreement”) with California Water Service Group, a Delaware corporation (the "Company”), providing for the public offering (the “Public Offering”) by the several underwriters, including the Managers (the “Underwriters”), of ___shares (the “Shares”) of the Common Stock, $0.01 par value per share of the Company (the “Common Stock”).

     To induce the Underwriters that may participate in the Public Offering to continue their efforts in connection with the Public Offering, the undersigned hereby agrees that, without the prior written consent of Baird on behalf of the Underwriters, it will not, during the period commencing on the date hereof and ending 90 days after the date of the final prospectus relating to the Public Offering (the “Restricted Period”), (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock, (2) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Common Stock, whether any such transaction described in clause (1) or (2) above is to be settled by delivery of Common Stock or such other securities, in cash or otherwise, (3) file any registration statement with the Commission relating to the offering of any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock, or (4)

publicly announce an intention to effect any transaction specified in clause (1), (2) or (3). The foregoing sentence shall not apply to:

     (a) transactions relating to shares of Common Stock or other securities acquired in open market transactions after the completion of the Public Offering, provided that no filing under Section 16(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) shall be required or shall be voluntarily made in connection with subsequent sales of Common Stock or other securities acquired in such open market transactions;

     (b) transfers of shares of Common Stock or any security convertible into Common Stock as a bona fide gift and any transfers by will or intestate; or

     (c) distributions or transfers of shares of Common Stock or any security convertible into Common Stock to any trust, limited partners, limited liability companies or stockholders of the undersigned for the direct or indirect benefit of the undersigned and/or the immediate family of the undersigned for estate planning purposes;

provided that in the case of any transfer or distribution pursuant to clause (b) or (c), (i) each donee or distributee shall sign and deliver a lock-up letter substantially in the form of this letter and (ii) no filing under Section 16(a) of the Exchange Act, reporting a reduction in beneficial ownership of shares of Common Stock, shall be required or shall be voluntarily made during the restricted period referred to in the foregoing sentence. In addition, the undersigned agrees that, without the prior written consent of Baird on behalf of the Underwriters, it will not, during the Restricted Period, make any demand for or exercise any right with respect to, the registration of any shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock. The undersigned also agrees and consents to the entry of stop transfer instructions with the Company’s transfer agent and registrar against the transfer of the undersigned’s shares of Common Stock except in compliance with the foregoing restrictions.

     If:

     (1) during the last 17 days of the Restricted Period the Company issues an earnings release or material news or a material event relating to the Company occurs; or

     (2) prior to the expiration of the Restricted Period, the Company announces that it will release earnings results during the 16-day period beginning on the last day of the Restricted Period;

then the restrictions imposed by this agreement shall continue to apply until the expiration of the 18-day period beginning on the issuance of the earnings release or the occurrence of the material news or material event.

     The undersigned understands that the Company and the Underwriters are relying upon this agreement in proceeding toward consummation of the Public Offering. The undersigned further understands that this agreement is irrevocable and shall be binding upon the undersigned’s heirs, legal representatives, successors and assigns.

     Whether or not the Public Offering actually occurs depends on a number of factors, including market conditions. Any Public Offering will only be made pursuant to an Underwriting Agreement, the terms of which are subject to negotiation between the Company and the Underwriters. Notwithstanding anything herein to the contrary, this agreement shall automatically terminate if the purchase of the Firm Shares (as defined in the Underwriting Agreement) pursuant to the Underwriting Agreement has not occurred by October 31, 2006.

		Very truly yours,
		(Name)
		(Address)