Free Writing Prospectus

Filing under Rule 433

Dated March 20, 2009

Registration No. 333-148527

$300,000,000

NORTHWEST NATURAL GAS COMPANY

Secured Medium-Term Notes, Series B

(A Series of First Mortgage Bonds)

and

Unsecured Medium-Term Notes, Series B

Due from One Year to 30 Years from Date of Issue

 

CUSIP No.: 66765RBX3

   Stated interest rate (%): 5.370%

Secured   X      Unsecured         

   Maturity date: February 1, 2020

Principal amount ($): $75,000,000

   Settlement date: March 25, 2009

Issue price (%): 100.000%

 

Net proceeds to Company ($): 74,531,250

 

Repayable at the option of holder: Yes             No    X  

 

    Repayment Date: Not Applicable

 

    Repayment Price: Not Applicable

 

    Election Period: Not Applicable

 

Sole Book-Running Manager: J.P. Morgan Securities Inc.

 

Co-Manager: Banc of America Securities LLC

 

Type of Transaction: Principal Transaction

  

Interest payment dates: February 1 and August 1 commencing August 1, 2009

 

Redeemable: Yes   X      No         

    In whole         

    In whole or in part   X  

 

Fixed redemption price: Yes             No   X  

 

    Initial redemption date: Not Applicable

 

    Initial redemption price: Not Applicable

 

    Reduction Percentage: Not Applicable

 

    Redemption limitation date: Not Applicable

 

    Make-Whole Redemption Price: Yes   X      No         

 

    Make-Whole Spread: 0.500%

 
 
 
 
 

The issuer has filed a registration statement (including a prospectus) with the Securities and Exchange Commission for the offering to which this communication relates. Before you invest, you should read the prospectus in that registration statement and other documents the issuer has filed with the Securities and Exchange Commission for more complete information about the issuer and this offering. You may get these documents for free by visiting EDGAR on the Securities and Exchange Commission’s Web site at www.sec.gov. Alternatively, the issuer, any underwriter or any dealer participating in the offering will arrange to send you the prospectus if you request it by calling J.P. Morgan Securities Inc. collect at 1-212-834-4533.