X0306 4 2018-03-01 0 0000073020 NORTHWEST NATURAL GAS CO NWN 0001445672 Saathoff MardiLyn 220 NW SECOND AVENUE PORTLAND OR 97209 0 1 0 0 SVP, General Counsel & Reg. Common Stock 2018-03-01 4 F 0 318 52.15 D 4871.5268 D Common Stock 7546.044 I See Footnote Common Stock 1079.627 I See Footnote Shares were withheld by the issuer to cover withholding taxes on issuance of shares due to vesting of restricted stock units. Organization and Executive Compensation Committee certification of satisfaction of the performance threshold and vesting for these restricted stock units was reported on Form 4 filed on February 23, 2018. Includes 1,549 of 3,100 restricted stock units (RSUs) granted under issuer's Long Term Incentive Plan. The 3,100 RSUs vest in three installments: 775 shares on each March 1, 2019 and 2020, and 1,550 shares on March 1, 2021. Pursuant to reporting person's previous election, only 50% of the shares received upon vesting of the RSUs, or an aggregate of 1,549 shares, will be directly issued to the reporting person, with the balance being credited to the reporting person's account under the issuer's Deferred Compensation Plan for Directors and Executives. Includes 1,551 of 3,100 RSUs granted under issuer's Long Term Incentive Plan. The 3,100 RSUs vest in three installments: 775 shares on each March 1, 2019 and 2020, and 1,550 shares on March 1, 2021. Reporting person has previously elected that 50% of shares received on vesting of RSUs, or an aggregate of 1,551 shares, will be deferred under the issuer's Deferred Compensation Plan for Directors and Executives. Shares have been credited to reporting person's account under the issuer's Deferred Compensation Plan for Directors and Executives. Shares held in reporting person's account under issuer's Retirement K Savings Plan as of February 28, 2018. Shawn M. Filippi, Attorney-in-Fact 2018-03-05