X0306 4 2018-02-21 0 0000073020 NORTHWEST NATURAL GAS CO NWN 0001571275 WILSON BRODY J 220 NW SECOND AVENUE PORTLAND OR 97209 0 1 0 0 VP, Treas., CAO & Controller Common Stock 2018-02-21 4 A 0 450 0 A 3033 D Common Stock 2018-02-21 4 A 0 255 0 A 440.578 I See Footnote Common Stock 2018-02-21 4 A 0 886 0 A 3919 D Common Stock 151.865 I See Footnote Shares are issuable as a result of satisfaction of the performance threshold for 2017 under restricted stock unit awards. Organization and Executive Compensation Committee certification of the satisfaction of the performance threshold occurred on the transaction date. Shares are issuable as a result of satisfaction of the performance threshold for 2017 under restricted stock unit awards, and credited to reporting person's account under the issuer's Deferred Compensation Plan for Directors and Executives pursuant to a prior election. Organization and Executive Compensation Committee certification of the satisfaction of the performance threshold occurred on the transaction date. Reflects shares that have been credited to reporting person's account under the issuer's Deferred Compensation Plan for Directors and Executives. Shares are issuable as a result of satisfaction of performance goals for 2015-2017 under a performance share award. Organization and Executive Compensation Committee certification of the award payout level occurred on the transaction date. Shares held in the reporting person's account under issuer's Retirement K Savings Plan as of January 31, 2018. Shawn M. Filippi, Attorney-in-Fact 2018-02-23