NORTHWEST NATURAL GAS COMPANY EXECUTIVE SUPPLEMENTAL RETIREMENT INCOME PLAN (2007 Restatement)

Exhibit 10b.

NORTHWEST NATURAL GAS COMPANY

EXECUTIVE SUPPLEMENTAL RETIREMENT INCOME PLAN

(2007 Restatement)

NORTHWEST NATURAL GAS COMPANY

EXECUTIVE SUPPLEMENTAL RETIREMENT INCOME PLAN

(2007 RESTATEMENT)

TABLE OF CONTENTS

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NORTHWEST NATURAL GAS COMPANY

EXECUTIVE SUPPLEMENTAL RETIREMENT INCOME PLAN

(2007 RESTATEMENT)

PURPOSE; EFFECTIVE DATE

This Executive Supplemental Retirement Income Plan (“Plan”) was established effective January 1, 1981, and was later amended, to promote the best interests of the Company by enabling the Company (a) to attract to its key management positions persons of outstanding ability, and (b) to retain in its employ those persons of outstanding competence who occupy key executive positions and who in the past contributed and who continue in the future to contribute materially to the success of the business by their ability, ingenuity and industry. Participation in the Plan is limited to a select group of management and highly compensated employees. Effective September 1, 2004, participation is limited to Participants in the Plan as of September 1, 2004, and no new Participants will be added to the Plan after September 1, 2004. In order to comply with changes in applicable law and to clarify existing provisions, the Company adopts this 2007 Restatement on December 20, 2007 with a retroactive effective date of January 1, 2005; provided, however, that the amendments made in this 2007 Restatement shall not apply to any Participant whose Separation from Service occurred prior to January 1, 2005 and the benefits for those Participants shall be governed by the terms of the Plan in effect immediately prior to this 2007 Restatement.

ARTICLE I. DEFINITIONS

The following words and phrases as used herein shall, for the purpose of this Plan and any subsequent amendment thereof, have the following meanings, unless a different meaning is plainly required by the context:

1.01 Benefit Commencement Date means the first day of the month in which Plan benefits are required to commence as provided under 3.02.

1.02 Board of Directors means the Board of Directors of the Company as constituted from time to time.

1.03 Change in Control Severance Benefit means, for any Participant who is party to a Change in Control Severance Agreement with the Company, the severance benefit provided for in such agreement; provided, however, that such severance benefit is a “Change in Control Severance Benefit” for purposes of this Plan only if, under the terms of the Participant’s Change in Control Severance Agreement, the Participant becomes entitled to the severance benefit (a) after a change in control of the Company has occurred, (b) because the Participant’s employment with the Company has been terminated by the Participant for good reason in accordance with the terms and conditions of the Change in Control Severance Agreement or by the Company other than for cause or disability, and (c) because the Participant has satisfied any other conditions or requirements specified in the Change in Control Severance Agreement and

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necessary for the Participant to become entitled to receive the severance benefit. Under no circumstances will a Participant who is not party to a Change in Control Severance Agreement be deemed to become entitled to a Change in Control Severance Benefit for purposes of this Plan. For purposes of 1.03, the terms “change in control,” “good reason,” “cause” and “disability” shall have the meanings as may be set forth in the Participant’s Change in Control Severance Agreement, if any.

1.04 Committee means the Organization and Executive Compensation Committee of the Board of Directors, previously known as the Compensation Committee.

1.05 Company means Northwest Natural Gas Company and its subsidiaries.

1.06 Effective Date means January 1, 1981, subject to any later effective date of any specific section provided in any amendment hereto.

1.07 Final Annual Compensation means the annual average determined by taking the sum of the Participant’s Total Compensation for the three (3) consecutive Compensation Years out of the Participant’s final ten (10) Compensation Years with the Company which produce the highest three (3) year total amount, and dividing such sum by three (3).

1.07-1 Total Compensation for any Compensation Year means the sum of (a) plus (b):

(a) The annual salary approved by the Board of Directors and in effect during the Compensation Year; provided, however, that if a Participant’s salary is changed during a Compensation Year, the salary amount included in Total Compensation for that Compensation Year shall be the total amount of salary the Participant earned for services during that Compensation Year or would have earned for services during that Compensation Year if employment had continued at his or her final salary level for the full Compensation Year.

(b) The annual performance award for the prior calendar year approved by the Board of Directors by the beginning of the Compensation Year; provided, however, that if a Participant has a Separation from Service during the last 61 days of any Compensation Year, Total Compensation for each of the Participant’s final ten (10) Compensation Years shall also be calculated as the sum of the salary in effect for such Compensation Year as determined under (a) plus the annual performance award for the calendar year that ended during such Compensation Year, and these alternate Total Compensation calculations shall be used if the resulting Final Average Compensation is higher.

1.07-2 Compensation Year means the twelve (12) month period from March 1 to February 28/29, including any partial portion of such period preceding a Separation from Service.

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1.08 Normal Retirement Date means the first day of the month next following the Participant’s 65th birthday.

1.09 Participant means an employee specifically designated by the Committee to be covered under this Plan and who continues to fulfill all requirements for participation. The initial designation of Participants shall be all executive officers of the Company elected by the Board of Directors (not including “assistant” officer positions). A list of Participants as of September 1, 2004 who were employed by the Company as of that date is included in the 2004 ESRIP Appendix. No new Participants shall enter the Plan after September 1, 2004.

1.10 Plan means the Executive Supplemental Retirement Income Plan herein set forth, as amended from time to time.

1.11 Retirement Plan means the Company’s Retirement Plan for Non-Bargaining Unit Employees, as amended from time to time.

1.12 Separation from Service shall have the meaning ascribed to such term in Treasury Regulations §1.409A-1(h).

1.13 Service depends on the context:

(a) Benefit Accrual . Service for benefit accrual under 2.01 means years of actual participation, including service credited under 1.13(c), after becoming a Participant under this Plan, plus any additional years of benefit accrual credit earned or awarded under 2.01-2(b)(2) and/or (3).

(b) Vesting Service . Service for vesting means all service with the Company from commencement of employment, including service credited under 1.13(c), plus any additional grant under 2.05-5.

(c) Other Service . To the extent “service” is not addressed by (a) or (b) above, Service includes all accredited years of service with the Company credited under the Retirement Plan and includes all periods of Company paid disability and long-term disability leave.

1.14 Surviving Beneficiary means the beneficiary or beneficiaries designated by the Participant on the form provided by the Company. Such beneficiary designation may be changed by the Participant at any time by written notice to the Committee. If no Surviving Beneficiary is designated, or if the designated Surviving Beneficiary dies before the Benefit Commencement Date, the Surviving Beneficiary shall be the Participant’s surviving spouse or, if none, the Participant’s estate.

1.15 Total and Permanent Disability means that the 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 12 months.

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ARTICLE II. AMOUNT OF BENEFITS; RIGHT TO RECEIVE BENEFITS

Each Participant or the Participant’s Surviving Beneficiary shall have the right to receive, and the Company shall pay, supplemental benefits as provided in this Article II, in the form and at the time provided in Article III:

2.01 Normal Retirement Supplemental Income . Upon Separation from Service at or after the Normal Retirement Date with at least ten (10) years of Service for vesting under 1.13(b), a Participant shall be entitled to receive, subject to 2.07, monthly supplemental retirement payments determined under 2.01-1 through 2.01-4:

2.01-1 Determining ESRIP Benefit Amount . The amount to be paid at the Normal Retirement Date under this Plan shall be determined by a three step process under the following (a), (b) and (c):

(a) Determine Target Benefit . The sum of the Participant’s accrued target percentage credits under 2.01-2 is multiplied by Final Annual Compensation.

(b) Determine Offset Amount . The amount to be paid at Normal Retirement Date from three other sources of retirement benefits shall be determined under 2.01-3.

(c) Determine Net Benefit . If the target benefit amount under (a) exceeds the total payments from the other three sources under (b), the excess shall be paid under 2.01-4.

2.01-2 Accrued Target Percentage . Participant’s accrued target percentage shall be the sum of the accruals at the rate specified below in (a) for each Year of Participation (defined below in (b)) credited under this Plan.

(a) Yearly Accrual Percentage Schedule :

(1) Years 1-15 . The yearly target percentage accrual for all Participants shall be:

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(2) Years 16-25 . In addition, each of the Participants who had at least six (6) Years of Participation as of September 1, 2004 as shown in the attached 2004 ESRIP Appendix shall be entitled to additional accruals for Years of Participation 16-25 as follows:

(b) Year of Participation means the sum of (1), (2) and (3):

(1) Each consecutive twelve (12) month period (including fractions calculated to the nearest hundredth of a year) of Service measured by each anniversary of the date of first becoming a Participant under this Plan.

(2) Any additional Years of Participation awarded to a Participant by the Committee in the exercise of its discretion, specifically including any additional Years of Participation reflected in the attached 2004 ESRIP Appendix as of September 1, 2004.

(3) Three (3) additional Years of Participation credit shall be awarded to any Participant who becomes entitled to a Change in Control Severance Benefit.

2.01-3 Payments From Other Sources . The total annual payments from the three sources listed below in (a), (b) and (c) shall be determined, all calculated as a single life annuity.

(a) the Retirement Plan.

(b) Social Security (as determined under 2.01-4(b)(2)).

(c) Supplemental retirement payments under Section 5.7 of the Company’s Executive Deferred Compensation Plan and Section 8 of the Company’s Deferred Compensation Plan for Directors and Executives.

2.01-4 Benefit Payable Under This Plan . The monthly payment under this Plan shall be determined under the formula of (a) minus (b) as follows:

(a) The target monthly benefit shall be one-twelfth (1/12) times Final Annual Compensation times the accrued target percentage determined under 2.01-2 above;

MINUS

(b) The sum of (1) plus (2) plus (3):

(1) The Participant’s monthly retirement benefit under the Retirement Plan assuming commencement of benefits in the month following Separation from Service and calculated as if the Participant had elected to have the entire benefit paid as a single life annuity;

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PLUS

(2) One-twelfth (1/12) of the Participant’s annual primary Social Security benefit assuming commencement of benefits in the month following Separation from Service and determined in the same manner and based on the same earnings as are used to compute the actual Social Security benefit;

PLUS

(3) The Participant’s monthly supplemental retirement benefit under Section 5.7 of the Company’s Executive Deferred Compensation Plan and/or Section 8 of the Company’s Deferred Compensation Plan for Directors and Executives, calculated in each case as if the Participant had elected to have the benefit paid as a single life annuity.

2.02 Early Retirement Supplemental Income . Upon Separation from Service at or after age fifty-five (55) with at least ten (10) years of Service for vesting under 1.13(b), a Participant shall be entitled to receive, subject to 2.07, the reduced monthly supplemental retirement payments determined as follows:

2.02-1 First, the target monthly early retirement benefit shall be equal to one-twelfth (1/12) times the Participant’s Final Annual Compensation times the accrued target percentage determined under 2.01-2 based on the Participant’s Years of Participation at the time of Separation from Service.

2.02-2 Second, the unreduced monthly supplemental payment under this Plan shall be determined under the formula in 2.01-4, using in 2.01-4(b)