AMENDED AND RESTATED COLUMBIA BANKING SYSTEM, INC. 401 Plus Plan Recitals

Exhibit 10.1

AMENDED AND RESTATED

COLUMBIA BANKING SYSTEM, INC.

401 Plus Plan

Recitals

The Company wishes to memorialize in a written plan document the terms of such arrangement.

Plan

The Columbia Banking System, Inc. Deferred Compensation Plan (“Plan”) is intended to provide deferred compensation for the directors and a select group of senior management or highly compensated employees of the Company.

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The Plan Administrator (defined in Section XIV), in its sole and absolute discretion, shall select the individuals who are permitted to participate in the Plan (“Participants”). The Plan Administrator may only select Participants from among the directors and the senior management or highly compensated employees of the Company. No individual shall have a right (whether because of his position with the Company, his level of compensation or any other reason whatsoever) to be selected as a Participant.

A. Amount Deferred. A Participant may elect to defer a fixed dollar amount of Covered Compensation (defined in paragraph IV) earned by him for services performed in a year, which deferred amount shall not exceed fifty percent (50 %) of base salary and shall not be less than $5,000/year. Notwithstanding anything in the immediately preceding sentence to the contrary, a Participant may elect to defer up to one hundred percent (100%) of any bonus awarded for services performed in a year and up to one hundred percent (100%) of his fees for services performed in a year as a director of the Company. An election to defer Covered Compensation earned for services performed in a year shall be irrevocable, except to the extent provided in the Plan.

B. Deferral Agreement and Notice. An election to defer Covered Compensation earned by a Participant for services performed in a year shall be made by delivering to the Company a “Deferral Agreement and Notice” (see Attachment A) duly signed by the Participant. Such “Deferral Agreement and Notice” shall set forth the percentage or fixed dollar amount of Covered Compensation that the Participant wishes to defer. A Participant may only defer Covered Compensation earned by him for services performed in a year if he delivers to the Company a “Deferral Agreement and Notice” electing to defer such Covered Compensation in December of the year immediately preceding the year. In the case of the first year in which an individual is selected to be a Participant, he may make an initial election to defer Covered Compensation paid for services performed after the election in the year by delivering to the Company a “Deferral Agreement and Notice” at least thirty (30) after being selected.

As used herein, “Covered Compensation” means all cash compensation (including, but not limited to annual salary, bonuses, fees or retainers) earned by an employee or director of the Company for services performed, in such capacity, for the Company.

A. Deferred Compensation Account. The Company shall credit amounts deferred by a Participant under Section III of this Plan by an entry to an account that shall be maintained for such Participant on its books and records. Such account shall be called the “Deferred Compensation Account” (“DCA”). In addition, the Company shall credit interest to the DCA, as provided in Section VI.

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B. Plan Un-funded. The Plan is intended to be un-funded for federal income tax purposes and for purposes of Title I of the Employee Retirement Income Security Act of 1974, as amended from time to time. All monies used to pay amounts credited to the DCA maintained for a Participant shall come from the general funds of the Company. A Participant is an unsecured general creditor of the Company with respect to a DCA maintained for the Participant and shall have no interest, rights or priority in any specific assets of the Company by reason of this Plan. The Company shall not be required to transfer monies to a separate account, create a separate fund, purchase life insurance or annuity contracts, or make other arrangements to fund its liabilities with respect to a DCA maintained for a Participant or any other obligations it may have under the Plan.

C. Informal Funding. If the Company, in its sole and absolute discretion, chooses to transfer monies to a separate account, create a separate fund, purchase life insurance or annuity contracts, or make other arrangements to fund its liabilities with respect to a DCA maintained for a Participant or any other obligations it may have under the Plan, then any such separate account, separate fund, life insurance or annuity contracts, or other arrangements shall remain solely the asset of the Company, subject to the claims of its unsecured general creditors; and a Participant shall have no interest, rights or priority therein, except as an unsecured general creditor of the Company.

A. Interest Crediting Rate. At the time of adoption of the Plan, the agreed upon interest rate shall be equal to the three month LIBOR rate plus 3.58%. The Plan Administrator shall annually review the calculation of the rate of interest that will be applied to DCAs (the “Interest Crediting Rate”) for appropriateness. The Interest Crediting Rate shall be adjusted quarterly for fluctuations in the three-month LIBOR rate. Plan participants will be notified of any adjustments to the Interest Crediting Rate.

B. Crediting Interest to DCA. On the last date of each month, the DCA maintained for each Participant shall be credited with an amount equal to the product of (i) one-twelfth (1/12th) of the Interest Crediting Rate for the quarter in which such month occurs, times (ii) the average balance in the DCA for that month. The amount so credited shall be treated as a part of the credit balance of the DCA for all purposes of this Plan. As used herein, the average balance in a DCA for a month shall be equal to the quotient determined by dividing (i) the sum of the credit balance in the DCA at the close of business each day in the calendar month, by (ii) the number of days in such month.

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A. Definitions. As used herein, the following capitalized terms shall have the meanings given below:

1. “Designated Beneficiary” means (i) a person that Participant designates on the “Designated Beneficiary Notice” (see Attachment B) as the person entitled to receive, upon Participant’s death, the distributions that would otherwise be made under the Plan to Participant, or (ii) in the absence of a person so designated by Participant, Participant’s estate.

2. “Disabled” means that (i) Participant is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment that can be expected to result in death or can be expected to last for a continuous period of not less than twelve (12) months; or (ii) Participant is, by reason of any medically determinable physical or mental impairment that can be expected to last for a continuous period of not less than twelve (12) months, receiving income replacement benefits for a period of not less than three (3) months under an accident and health plan covering employees of the Company.

3. “Retire” means Participant’s Separation from Service with the Company, but only if, at the time of such separation, Participant has satisfied all of the following conditions: (i) Participant has attained the age of fifty-five (55), and (ii) Participant has completed ten (10) years of service as a director and/or employee of the Company. For purposes of the immediately preceding sentence, a Participant shall be credited with one (1) year of service for each twelve (12) month period of continuous service as a director and/or employee of the Company.

4. “Separation from Service” shall have the meaning given to such term in Treas. Reg. 1.409A-1(h).

B. Distribution Election Notice. At the time a Participant first makes an election to defer Covered Compensation, he shall deliver to the Company a signed “Distribution Election Notice” (see Attachment C) in which he shall elect to receive distributions of the credit balance in his DCA in the form of either a single lump-sum payment or monthly installment payments over a period not to exceed one hundred twenty (120) months. A Participant may change such election from time to time, subject to satisfaction of each and every one of the following conditions:

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C. Distributions Upon Retirement or Disability. The Company shall distribute the credit balance in a DCA maintained for a Participant at the time he Retires or becomes Disabled as either a single lump-sum or monthly installment payments, as elected by the Participant. If the Participant has elected a single lump-sum distribution, such distribution shall be made within ninety (90) days after the date that he Retires or becomes Disabled. If the Participant has elected monthly installment payments, such distribution shall be made on the first day of each month, beginning with the first day of the third month following the month in which he Retires or becomes Disabled and continuing until the full amount of the DCA maintained for him has been distributed. Until such DCA has been distributed in full, interest shall continue to be credited to the DCA, as provided in Section VI. The monthly installment payments shall be in as nearly equal amounts as possible. Notwithstanding any contrary provisions of the Plan, if Participant dies after monthly installment payments of the credit balance in the DCA maintained for him have begun, then the remaining credit balance in the DCA shall be distributed to his Designated Beneficiary in a single lump-sum within thirty (30) days after the Participant’s death.

D. Lump Sum Distributions Upon Separation From Service Other Than Because of Retirement, Upon Death or if DCA is Less Than Specified Amount. Notwithstanding a Participant’s election to receive a distribution of the credit balance in the DCA maintained for him in the form of monthly installment payments, such credit balance shall be distributed to the Participant or, in the case of clause (ii) below, his Designated Beneficiary, in a single lump-sum within ninety (90) days after the occurrence of any of the following events:

(i) Participant experiences a Separation from Service the Company for any reason other than because he Retires or is Disabled;

(ii) Participant dies; or

(iii) After Participant monthly installment payments have begun or are required to begin hereunder, the credit balance of the DCA maintained for him does not exceed the “applicable dollar amount” (as defined in Code § 402(g)(1)(B)) then in effect, provided that such distribution results in the termination and liquidation of the entirety of the Participant’s interest under the Plan, including all agreements, methods, programs or other arrangements with respect to which deferrals of compensation are treated as having been deferred under single nonqualified deferred compensation plan under Treas Reg. § 1.409A-1(c)(2).

E. Required Delay in Payments to Specified Employees. If Participant is a “specified employee” within the meaning of Treas. Reg.§ 1.409A-1(i), then notwithstanding any contrary provisions of the Plan, any amounts payable to the Participant under the Plan on account of a Separation from Service for any reason that could cause the Participant to be subject to the gross income inclusion, interest and additional tax provisions of Code § 409A(a)(1) shall not be paid until after the end of the sixth calendar month beginning after such Separation from Service (the “Suspension Period”). Within fourteen (14) calendar days after the end of the Suspension Period, the

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Company shall pay Participant a lump sum payment in cash equal to any payments delayed because of the preceding sentence. Thereafter, Participant shall receive any remaining payments under the Plan as if this paragraph E of Section VIII were a not a part of the Plan.

In the event of a “change in control” of the Company, the Company may, in its sole discretion, establish, on or before the effective date of such change in control, a trust or trusts (“Trust”) to which the Company shall transfer assets in an amount sufficient to satisfy its obligations under the Plan. Such Trust shall comply with applicable Treasury regulations and rulings in order to qualify as a “rabbi trust.” The principal of the Trust, and any earnings thereon, shall be held separate and apart from the other assets of the Company and used to discharge of the Company’s obligations under the Plan; provided, however, that such principal and earnings shall continue to be subject to, and may also be used to satisfy, the claims of the unsecured general creditors of the Company. The term “change in control” shall mean the occurrence of (i) a merger or consolidation in which the Company is not the continuing or surviving entity or pursuant to which the issued and outstanding shares of common stock of the Company are converted into cash, securities or other property, other than a merger of the Company in which the holders of issued and outstanding shares of the common stock of the Company immediately prior to the merger have substantially the same proportionate ownership of common stock of the surviving corporation immediately after the merger, (ii) the acquisition of shares of the Company’s issued and outstanding common stock in a single or a series of related transactions, if immediately thereafter persons who owned shares of such common stock immediately before such acquisition do not own more than fifty percent (50%) of the combined voting power of the Company immediately after such acquisition, or (iii) the sale, transfer or other disposition of all or substantially all of the assets of the Company.

Nothing contained in this Agreement shall affect the right of a Participant to participate in or, be covered by, any other qualified or nonqualified pension, profit sharing, bonus, supplemental compensation or fringe benefit plans maintained by the Company.

Except to the extent required by law, a Participant’s rights to any amounts credited to a DCA maintained for the Participant, or to receive any payments under the Plan (i) may not be sold, exchanged, transferred, assigned, pledged, hypothecated, encumbered or otherwise conveyed by the Participant, (ii) shall not be subject to levy or seizure for the payments of any debts, liabilities or obligations of the Participant (including, without limitation, judgments against, and child support, alimony or separate maintenance obligations of, the Participant), and (iii) shall not be transferable in the event of the bankruptcy or insolvency of the Participant, to the fullest extent permitted by law.

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This Plan shall not (i) expand or restrict any rights or obligations created under an employment agreement by and between the Company and a Participant, (ii) create specific employment rights in a Participant, (iii) limit the right of the Company to terminate a Participant’s services or employment with the Company at any time and for any reason whatsoever, or (iv) limit the right of a Participant to terminate his services or employment with the Company at any time and for any reason whatsoever.

This Plan shall be construed and interpreted in accordance with the laws of the State of Washington

A. General. The Company shall have the right, in its sole and absolute discretion, to amend or to terminate the Plan at any time; provided, however, that any such amendment or termination shall not reduce the credit balance in a Participant’s DCA at the time of the amendment or termination or affect the Company’s obligation to distribute to Participant the amount of such credit balance under the terms of the Plan in effect immediately before such amendment or termination. In the event the Plan is terminated, no additional Covered Compensation shall be deferred.

B. Election to Distribute on Termination. Notwithstanding any contrary provisions contained herein, at any time after the Company terminates the Plan, it may, in its sole and absolute discretion, distribute the credit balance in a Participant’s DCA, provided that

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A. Plan Administrator. The Plan shall be administered by the board of directors of the Company (“Board”) or a committee appointed by the Board that shall consist of at least three (3), but less than all, members of the Board. In its sole and absolute discretion, the Board may, from time to time, change the composition of a committee appointed by it to administer the Plan or dismiss such committee and assume sole responsibility for administering the Plan. The person administering the Plan, as provided in this Section XIV, shall be referred to as the “Plan Administrator.” The Plan Administrator may employ such advisors and delegate to other persons such responsibilities relating to the Plan as it deems necessary or advisable.

B. Interpretation of Plan. The Plan Administrator shall have the sole and absolute discretion to interpret the Plan and any agreements entered into in connection therewith, and its interpretation shall be final and binding on all persons. In addition, the Plan Administrator may supply such missing terms to the Plan as it deems reasonably necessary to carry out is purpose.

C. Relationship of Participant, Plan and Company. Nothing contained in this Plan shall be deemed to create a trust relationship between or among a Participant, the Company and the Plan.

D. Statements. Statements detailing a participant’s contributions to the 401 Plus Plan will be provided on a yearly basis beginning after the first quarter subsequent to implementation of this Plan.

E. Unforeseeable Emergency. The Plan is intended to help Participant’s put aside money for their retirement. However, a distribution may be made to a Participant from his DCA if he experiences an Unforeseeable Emergency. As used herein, the term “Unforeseeable Emergency” means (i) a severe financial hardship resulting from an illness or accident suffered by him, his spouse, his Designated Beneficiary or his dependent (as defined in Code § 152, but without regard to Code §§ 152(b)(1), (b)2) and (d)(1)(B)); (ii) loss of his property due to casualty; or (iii) other similar extraordinary and unforeseeable circumstances arising as a result of events beyond his control. Distributions hereunder because of an Unforeseeable Emergency shall be limited to the amount reasonably necessary to satisfy the emergency need (and may include amounts necessary to pay any Federal, state, local or foreign income taxes or penalties reasonably anticipated to result from the distribution). Determination of the amount reasonably

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necessary to satisfy the emergency need must take into account any additional compensation that is available from the cancellation of the Participant’s deferral election under the Plan because of a payment due to an Unforeseeable Emergency. The Plan Administrator shall have the absolute right and discretion to determine whether or not to make a distribution to a Participant because of an Unforeseeable Emergency, and its determination in this regard shall be final and binding on all parties. Upon a determination by the Plan Administrator that a distribution should be made to a Participant hereunder because of an Unforeseeable Emergency, the Participant’s deferral election hereunder shall be cancelled, and not merely postponed or otherwise delayed, for such period of time as the Plan Administrator determines is reasonably necessary to meet the emergency need and any later deferral election will be subject to the provisions governing an initial deferral election under Treas. Reg. § 1.409A-2(a). This paragraph E of Section XIV is intended to comply with the provisions of Treas. Reg. §§ 1.409A-3(i)(3) and (j)(4)(viii) and shall be interpreted accordingly.

F. Use of Certain Terms. As required by the context, (i) masculine, feminine and neuter nouns used in the Plan may be substituted for nouns of another gender, and (ii) singular and plural nouns and verbs used in the Plan may be substituted for nouns or verbs of another number. All references in the Plan to “year” shall be deemed a reference to the calendar year, except for purposes of paragraph A.3 of Section VII or as otherwise required by the context.

G. Code § 409A. This Plan is intended to comply with, and shall be interpreted and administered in a manner consistent with, Code § 409A and regulations issued thereunder.

XV. 401(k) Make-up Contributions.

A. General. At such times as the Company makes nonelective contributions and/or matching contributions with respect to a year (“Plan Year”) of the qualified 401(k) plan adopted, sponsored or maintained by it for the benefit of its employees, it shall credit to the DCA of each Participant an amount equal to the excess of (i) the amount that it would have contributed on behalf of the Participant to the qualified 401(k) plan as a non-elective contribution and/or matching contribution for such Plan Year, if the Participant had not elected to defer compensation under the Plan (“Maximum Contribution”), over (ii) the amount that it in fact contributes on behalf of the Participant to the qualified 401(k) plan as a non-elective contribution and/or matching contribution for such Plan Year.

B. Maximum Contribution. For purposes of this Section XV, the Maximum Contribution shall be determined by assuming that:

(i) The Participant does not elect to defer compensation under the Plan;

(ii) The compensation that the Participant in fact defers under the Plan is instead paid to Participant in the Plan Year; and

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(iii) After giving effect to clauses (i) and (ii) above, Participant elects to make the maximum elective deferrals that he or she is permitted to make under the Plan for the Plan Year (including “catch-up” contributions under Code § 414(v)).

C. Limitation. Paragraph A of this Section XV shall not apply in the case of matching contributions, unless Participant makes the maximum elective deferrals that he or she is in fact permitted to make under the Plan for the Plan Year.

D. Application of Other Provisions. Amounts credited to the DCA of a Participant under paragraph A of this Section XV shall be treated as, and subject to the provisions of the Plan in the same manner as, amounts credited to the DCA of a Participant under paragraph A of Section V (including, without limitation, for purposes of crediting interest at the Interest Crediting Rate).

A. Claim for Benefits. Each person claiming a benefit under the Plan who has been denied such benefit may file a claim (“Claim”) with the Plan Administrator on a form prescribed by the Plan Administrator. If no such form has been so prescribed, a Claim shall be made in writing to the Plan Administrator setting forth the basis for the claim. The person making the Claim shall provide the Plan Administrator with such documents, evidence, data, or information in support of the Claim as the Plan Administrator considers reasonably necessary or desirable.

B. Notice of Determination. The Plan Administrator shall provide the claimant with written notice of its determination of the Claims. If the Claim is denied, either in whole or in part, the written notice shall set forth the following:

The Plan Administrator’s written notice of its determination of the Claim shall be provided to the claimant within a reasonable period of time, but not more than ninety (90) days after receipt of the Claim by the Plan Administrator, unless special circumstances require an extension of time for processing the Claim, in which case the Plan

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Administrator shall provide a written notice of such extension to the claimant before the expiration of the initial ninety (90) day period. In no event shall such extension exceed ninety (90) days from the end of such initial period. So long as the claimant’s request for review is pending (i.e., prior to the time the Plan Administrator provides the claimant with a written notice of its determination of the Claim), the claimant or his or her duly authorized representative may review pertinent Plan documents (and any pertinent related documents) and may submit issues and comments in writing to the Plan Administrator.

C. Right to Reconsideration. If a claimant has received an adverse determination on its Claim, as described in Paragraph B of this Section XVI, then within sixty (60) days after receipt of the written notice of determination, the claimant shall, if he or she desires further review, file a written request for reconsideration with the Plan Administrator.

D. Reconsideration. After the Plan Administrator has reconsidered its initial decision, pursuant to a written request for reconsideration under Paragraph C of this Section XVI, the Plan Administrator shall issue a final and binding decision within sixty (60) days after receipt from the claimant of the written request for reconsideration; provided, however, that if the Plan Administrator, in its discretion, determines that special circumstances require an extension of time for processing the Claim, the Plan Administrator shall provide a written notice of such extension to the claimant before the expiration of the initial sixty (60) day period. In no event shall the extension exceed sixty (60) days from the end of such initial period.

E. Notice of Determination After Reconsideration. The Plan Administrator shall provide the claimant with written notice of its determination of the Claim after reconsideration. If the Claim is once again denied after such reconsideration, either in whole or in part, the written notice shall set forth the following:

So long as the claimant’s request for reconsideration is pending, (i.e., prior to the time the Plan Administrator provides the claimant with a written notice of its determination of the Claim after reconsideration), the claimant or his or her duly authorized representative may review pertinent Plan documents (and any pertinent related documents) and may submit issues and comments in writing to the Plan Administrator.

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Date: December 15, 2010

By:                                     , Corporate Secretary

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ATTACHMENT A

COLUMBIA BANKING SYSTEM, INC.

401K PLUS PLAN

DEFERRAL AGREEMENT AND NOTICE

FOR CALENDAR YEAR 2011

The undersigned, a Participant in the Columbia Banking System, Inc. 401k Plus Plan (“Plan”), hereby irrevocably elects to defer the following Covered Compensation for the calendar year 2011 under the terms and conditions of the Plan:

$           per pay period (not to exceed 50% of my 2011 salary or to be less than $5,000 per year)

    %    (up to 100%) of my bonus earned for services rendered in 2011 that is paid in 2012

    %    (up to 100%) of my fees earned for services performed in 2011 as a director of the Company

The Participant agrees to be bound by all terms and conditions of the Plan. The Participant acknowledges that he has been provided a copy of the Plan. The Participant should seek advice from his own tax and legal advisors concerning any provisions of the Plan that he does not understand and concerning the tax and other consequences of his participation in the Plan. Company does not guarantee a particular tax results to the Participant from participation in the Plan.

Capitalized terms not otherwise defined herein have the meaning given to those terms in the Plan.

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ATTACHMENT B

COLUMBIA BANKING SYSTEM, INC.

401 PLUS PLAN

BENEFICIARY DESIGNATION

(Please indicate the percentage for each beneficiary.)

The primary designated beneficiary is my estate..

Name of the Trust:                                                                                                                                                                        

Execution Date of the Trust:             /             /             

Name of the Trustee:                                                                                                                                                                        

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(Please indicate the percentage for each beneficiary.)

The secondary (contingent) designated beneficiary is my estate.

Name of the Trust: _________________________________________________________

Execution Date of the Trust:          /          /             

Name of the Trustee:                     ¶______________________________________________

All sums payable under this Beneficiary Designation by reason of my death shall be paid to the Primary Designated Beneficiary(ies) if he survives me, and if he does not survive me, then such sums shall be paid to the Secondary (Contingent) Beneficiary(ies). Notwithstanding the immediately preceding sentence, if there is more than one Primary Designated Beneficiary and one or more of them survive me, then the share of such sums that would otherwise be paid to a Primary Designated Beneficiary who does not survive me shall instead be paid in equal shares to the Primary Designated Beneficiary(ies) who do survive me, and not to the Secondary (Contingent) Beneficiary(ies).

This Beneficiary Designation is valid until the Participant notifies the Company in writing of a change.

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ATTACHMENT C

COLUMBIA BANKING SYSTEM, INC.

401 PLUS PLAN

DISTRIBUTION ELECTION NOTICE

A PARTICIPANT MUST SUBMIT A DISTRIBUTION ELECTION NOTICE WHEN HE FIRST BECOMES A PARTICIPANT IN THE PLAN, AND DOES NOT NEED TO RESUBMIT A NEW DISTRIBUTION ELECTION NOTICE UNLESS HE WISHES TO CHANGE A PRIOR DISTRIBUTION ELECTION.

This is an:

Pursuant to the provisions of the Columbia Banking System, Inc. 401k Plus Plan, I hereby elect to have any amounts credited to my Deferred Compensation Account distributed to me as designated below:

This distribution election applies to both prior and future deferrals of compensation by me, and to all other amounts credited to my Deferred Compensation Account.

I understand that I cannot change my distribution election under the Plan unless all of the following conditions are satisfied:

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Subject to the foregoing, the last dated Distribution Election Notice shall supersede all prior Distribution Election Notices.

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