NORTHWEST NATURAL GAS COMPANY EXECUTIVE DEFERRED COMPENSATION PLAN AMENDED AND RESTATED 2007 RESTATEMENT

Exhibit 10.6

NORTHWEST NATURAL GAS COMPANY

EXECUTIVE DEFERRED COMPENSATION PLAN

AMENDED AND RESTATED 2007 RESTATEMENT

Effective January 1, 1987

Restated as of January 1, 2007

TABLE OF CONTENTS

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TABLE OF CONTENTS

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NORTHWEST NATURAL GAS COMPANY

EXECUTIVE DEFERRED COMPENSATION PLAN

Effective as of January 1, 1987

Restated as of January 1, 2007

ARTICLE I

PURPOSE

1.1 Restatement . Northwest Natural Gas Company adopted an Executive Deferred Compensation Plan (the “Plan”) effective January 1, 1987, which was previously restated effective as of January 1, 2001, January 1, 2003, and December 15, 2005. Effective as of January 1, 2007, the Plan was amended and restated by a 2007 Restatement. The Plan is now amended and restated again by this Amended and Restated 2007 Restatement, effective as of January 1, 2007.

1.2 Purpose . The purpose of this Executive Deferred Compensation Plan is to provide an unfunded deferred compensation plan for a select group of top management personnel.

ARTICLE II

DEFINITIONS

For purposes of this Plan, the following words and phrases shall have the meanings indicated, unless the context clearly indicates otherwise:

2.1 Account . “Account” means the record or records maintained by the Corporation for each Executive in accordance with Article IV with respect to any deferral of Compensation pursuant to this Plan. An Account shall be either a “Stock Account” as described in Section 4.3 or a “Cash Account” as described in Section 4.4.

2.2 Acquiror Stock . “Acquiror Stock” is defined in Section 4.5.

2.3 Base Annual Salary . “Base Annual Salary” means the annual compensation payable to an Executive, excluding bonuses, commissions, LTIP Compensation and other noncash compensation.

2.4 Beneficiary . “Beneficiary” means the person, persons or entity designated under Article VI to receive any Plan Benefits payable after an Executive’s death.

2.5 Board . “Board” means the Board of Directors of Northwest Natural Gas Company or any successor thereto.

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2.6 Bonus . “Bonus” means the compensation derived under the Corporation’s Executive Annual Incentive Plan or other similar incentive plan and payable in any year in a lump sum to an Executive.

2.7 Cash Compensation . “Cash Compensation” means the total Base Annual Salary and Bonus remuneration payable by the Corporation to the Executive for services.

2.8 Change in Control . “Change in Control” means the occurrence of any of the following events:

(a) The consummation of:

(i) any consolidation, merger or plan of share exchange involving the Corporation (a “Merger”) as a result of which the holders of outstanding securities of the Corporation ordinarily having the right to vote for the election of directors (“Voting Securities”) immediately prior to the Merger do not continue to hold at least 50% of the combined voting power of the outstanding Voting Securities of the surviving corporation or a parent corporation of the surviving corporation immediately after the Merger, disregarding any Voting Securities issued to or retained by such holders in respect of securities of any other party to the Merger; or

(ii) any sale, lease, exchange or other transfer (in one transaction or a series of related transactions) of all, or substantially all, the assets of the Corporation;

(b) At any time during a period of two consecutive years, individuals who at the beginning of such period constituted the board of directors of the Corporation (“Incumbent Directors”) shall cease for any reason to constitute at least a majority thereof; provided, however, that the term “Incumbent Director” shall also include each new director elected during such two-year period whose nomination or election was approved by two-thirds of the Incumbent Directors then in office; or

(c) Any person (as such term is used in Section 14(d) of the Securities Exchange Act of 1934, other than the Corporation or any employee benefit plan sponsored by the Corporation) shall, as a result of a tender or exchange offer, open market purchases or privately negotiated purchases from anyone other than the Corporation, have become the beneficial owner (within the meaning of Rule 13d-3 under the Securities Exchange Act of 1934), directly or indirectly, of Voting Securities representing twenty percent (20%) or more of the combined voting power of the then outstanding Voting Securities.

2.9 Committee . “Committee” means the Organization and Executive Compensation Committee, or such other Committee as may be designated by the Board.

2.10 Common Stock . “Common Stock” means common stock of the Corporation.

2.11 Compensation . “Compensation” means Cash Compensation and LTIP Compensation.

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2.12 Corporate Transaction . “Corporate Transaction” means any of the following:

(a) any consolidation, merger or plan of share exchange involving the Corporation pursuant to which shares of Common Stock would be converted into cash, securities or other property; or

(b) any sale, lease, exchange or other transfer (in one transaction or a series of related transactions) of all, or substantially all, the assets of the Corporation.

2.13 Corporation . “Corporation” means Northwest Natural Gas Company, an Oregon corporation, or any successor thereto, and any corporations or other entities affiliated with or subsidiary to it that may be selected by the Board from time to time and which take action to adopt and implement this Plan.

2.14 Deferral Commitment . “Deferral Commitment” means a Deferral Commitment made by an Executive pursuant to Article III and for which a Participation Agreement has been submitted by the Executive to the Committee.

2.15 Deferral Deadline . “Deferral Deadline” means, for any Compensation payable to an Executive, the last day on which the Executive can submit a Participation Agreement to make a Deferral Commitment with respect to such Compensation. The Deferral Deadlines for various forms of Compensation shall be as follows:

(a) For Base Annual Salary payable in any calendar year, the Deferral Deadline shall be the last day of the previous calendar year; provided, however, that for a person who becomes an eligible Executive during a year, the Deferral Deadline for Base Annual Salary payable for the remainder of the year shall be 30 days after the person becomes an Executive and the Deferral Commitment shall only apply to Base Annual Salary payable after the Participation Agreement is submitted.

(b) For Bonus payable in any calendar year, including Bonus payable with respect to the Executive’s or the Corporation’s performance in the previous calendar year, the Deferral Deadline shall be the last day of the previous calendar year.

(c) For LTIP Compensation payable at any time, the Deferral Deadline shall be the date one year prior to the vesting date for time-based awards and the date one year prior to the last day of the award period for performance-based awards; provided, however, that the Deferral Deadline for any LTIP Compensation that becomes payable in any calendar year on an accelerated basis as a result of a Change in Control shall be the last day of the previous calendar year.

2.16 Deferred Cash Compensation . “Deferred Cash Compensation” means the amount of Cash Compensation that the Executive elects to defer pursuant to a Deferral Commitment.

2.17 Deferred Compensation Account Benefit . “Deferred Compensation Account Benefit” means the benefit payable to an Executive as calculated pursuant to Article IV and payable under Sections 5.1 through 5.6.

2.18 Determination Date . “Determination Date” means the last day of each calendar quarter.

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2.19 Disability . “Disability” means a physical or mental condition that, in the opinion of the Committee, prevents the Executive from satisfactorily performing the Executive’s usual duties for the Corporation. The Committee’s decision as to Disability will be based upon medical reports and/or other evidence satisfactory to the Committee.

2.20 Executive . “Executive” means one of a select group of management or highly compensated employees of the Corporation, which shall consist of all executive officers of the Corporation and any other employee of the Corporation designated in writing by the Chief Executive Officer of the Corporation for participation in the benefits of the Plan.

2.21 Financial Hardship . “Financial Hardship” means a severe financial hardship to the Executive resulting from a sudden and unexpected illness or accident of the Executive or of a dependent of the Executive, loss of the Executive’s property due to casualty, or other similar extraordinary and unforeseeable circumstances arising as a result of events beyond the control of the Executive. Financial Hardship shall be determined by the Committee on the basis of information supplied by the Executive in accordance with uniform guidelines promulgated from time to time by the Committee.

2.22 Interest . “Interest” is credited to Cash Accounts under the Plan and means the quarterly equivalent of an annual yield that is two percentage points (2%) higher than the annual yield on Moody’s Average Corporate Bond Yield for the preceding quarter, as published by Moody’s Investors Service, Inc. (or any successor thereto), or, if such index is no longer published, a substantially similar index selected by the Board. At no time shall such Interest rate be less than six percent (6%) annually.

Notwithstanding the foregoing provisions of this Section 2.22, effective as of January 1, 2017, the Interest rate shall equal the rate of interest for interest credited to cash accounts under the Corporation’s Deferred Compensation Plan for Directors and Executives, as such plan may be amended from time to time (the “DCPDE”), regardless of whether or not such rate of interest shall be more or less than six percent (6%) annually; provided, however, that if at any time on or after January 1, 2017 there is no interest credited to cash accounts under the DCPDE because the DCPDE shall have ceased to operate or for any other reason, then, at such time on or after January 1, 2017, the Interest rate shall equal the quarterly equivalent of an annual yield that is equal to the annual yield on Moody’s Average Corporate Bond Yield for the preceding quarter, as published by Moody’s Investors Service, Inc. (or any successor thereto), or, if such index is no longer published, a substantially similar index selected by the Board, regardless of whether or not such Interest rate shall be more or less than six percent (6%) annually. Any change in the Interest rate that occurs on January 1, 2017 or thereafter pursuant to the provisions of this paragraph shall not constitute a “change in the definition of Interest” within the meaning of Section 9.1(b) below.

2.23 LTIP Compensation . “LTIP Compensation” means compensation paid to an Executive pursuant to an award under the Corporation’s Long Term Incentive Plan. LTIP Compensation may be payable to the Executive either in Common Stock (“Stock LTIP Compensation”) or in cash (“Cash LTIP Compensation”).

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2.24 Matching Contribution . “Matching Contribution” means the contribution made by the Corporation and credited to the Executive’s Account under Section 4.2.

2.25 Participation Agreement . “Participation Agreement” means the agreement submitted by an Executive to the Committee no later than the applicable Deferral Deadline with respect to one or more Deferral Commitments.

2.26 Plan Benefits . “Plan Benefits” mean the Deferred Compensation Account Benefit and the Supplemental Retirement Benefit.

2.27 Retirement . “Retirement” means either early retirement, normal retirement, or disability retirement under the Retirement Plan.

2.28 Retirement Plan . “Retirement Plan” means the Corporation’s Retirement Plan for Non-Bargaining Unit Employees.

2.29 Supplemental Retirement Benefit . “Supplemental Retirement Benefit” means the benefit payable to an Executive under Section 5.7.

2.30 Trust . “Trust” means the Northwest Natural Gas Company Umbrella Trust™ For Executives established by the Corporation in connection with this Plan.

ARTICLE III

DEFERRAL COMMITMENTS

3.1 Participation . An eligible Executive may elect to participate in the Plan by submitting a Participation Agreement to the Committee no later than the applicable Deferral Deadline. An election to defer Compensation by the Executive shall continue from year to year and shall be irrevocable with respect to Compensation once the Deferral Deadline for that Compensation has passed, but may be modified or terminated by written notice from the Executive at any time on or prior to the Deferral Deadline for that Compensation.

3.2 Deferral Election .

(a) Election to Defer Cash Compensation . An Executive may, no later than the applicable Deferral Deadline, elect to defer receipt of a certain whole percentage, up to fifty percent (50%), of the Base Annual Salary and a certain whole percentage, up to one hundred percent (100%), of any Bonus payable to the Executive as an employee of the Corporation.

(b) Election to Defer LTIP Compensation . An Executive may, no later than the applicable Deferral Deadline, elect to defer receipt of a certain whole percentage, up to one hundred percent (100%), of any Stock LTIP Compensation and a certain whole percentage, up to one hundred percent (100%), of any Cash LTIP Compensation that becomes payable to the Executive.

(c) FICA Withholding . Under current law, all Compensation and Matching Contributions credited to an Executive’s Accounts will be treated as wages subject to FICA tax,

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and the Corporation will be required to withhold FICA tax from the Executive. The amount required to be withheld for FICA tax with respect to any amount of deferred Compensation or related Matching Contribution shall be withheld from the non-deferred portion, if any, of the same Compensation; provided, however, that if the non-deferred portion of the Compensation is insufficient to cover the full required withholding, the Corporation shall withhold the remaining amount from other non-deferred Compensation payable to the Executive unless the Executive otherwise pays such remaining amount to the Corporation.

(d) Financial Hardship . Termination of the Executive’s election to defer may, solely in the Committee’s discretion, become applicable as soon as practicable after the Committee’s determination that the Executive has incurred Financial Hardship, as evidenced by the Executive to the Committee.

ARTICLE IV

DEFERRED COMPENSATION ACCOUNTS

4.1 Accounts . The Corporation shall establish on its books one or two separate Accounts for each Executive who elects to defer Compensation under the Plan: a Cash Account and/or a Stock Account. Compensation deferred by an Executive shall be credited to the Stock Account or the Cash Account as elected by the Executive at the time the Executive elects to defer Compensation. Such election may be divided between the two Accounts in increments of twenty-five percent (25%) of the deferred Compensation covered by the election. An Executive may change the allocation of new deferrals of Compensation between the Stock Account and the Cash Account, but such change shall apply to new deferrals only if it is submitted on or prior to the Deferral Deadline for such new deferrals. Once Compensation has been credited to the Stock Account or the Cash Account, no transfers between the Stock Account and the Cash Account shall be permitted except as otherwise provided in Section 4.5(d). The credit for deferred Compensation shall be entered on the Corporation’s books of account at the time that Compensation not deferred is paid or payable to the Executive.

4.2 Matching Contribution . The Corporation shall credit a Matching Contribution to an Executive’s Account based on the amount of Deferred Cash Compensation elected by the Executive; provided, however, that no Matching Contributions shall be made to the Account of any Executive who is not eligible to participate in the Corporation’s Retirement K Savings Plan until such time of eligibility. The amount of the Matching Contribution shall be equal to the excess of (a) the lesser of (i) sixty percent (60%) of the Executive’s Deferr