TACOMA, Wash., July 30 /PRNewswire-FirstCall/ -- Columbia Banking System, Inc. (Nasdaq: COLB) announced today that Melanie J. Dressel, President and Chief Executive Officer, will participate in the Keefe, Bruyette & Woods 8th Annual Community Bank Investor Conference in New York City. Ms. Dressel's presentation at the conference is scheduled for Tuesday afternoon, July 31, 2007 at 3:00 p.m. EDT (12:00 p.m. PDT).

KBW will webcast the presentation; during the conference, the webcast can be viewed at http://www.kbw.com/news/conferenceCommunity.html. All presentations will be archived for 60 days after the event.

Columbia Banking System, Inc. is a 53-branch Tacoma-based bank holding company whose wholly owned banking subsidiaries are Columbia Bank and Bank of Astoria. Columbia Bank is a Washington state-chartered full-service commercial bank. With the July 23, 2007 completion of the acquisitions of Mountain Bank Holding Company and Town Center Bancorp, Columbia Bank has 48 banking offices in Pierce, King, Cowlitz, Kitsap and Thurston counties in Washington State, and Clackamas and Multnomah counties in Oregon. Included in Columbia Bank are former branches of Mt. Rainier National Bank, doing business as Mt. Rainier Bank, with 7 branches in King and Pierce counties. Bank of Astoria, a federally insured commercial bank headquartered in Astoria, Oregon, operates four branches in Clatsop County: Astoria, Warrenton, Seaside and Cannon Beach; and one branch in Manzanita in Tillamook County. More information about Columbia can be found on its website at http://www.columbiabank.com.

Note Regarding Forward Looking Statements

This news release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, which can be identified by words such as "may," "expected," "anticipate," "continue," or other comparable words. In addition, all statements other than statements of historical facts that address activities that Columbia expects or anticipates will or may occur in the future are forward-looking statements. Readers are encouraged to read the SEC reports of Columbia, particularly its form 10-K for the Fiscal Year ended December 31, 2006, for meaningful cautionary language discussing why actual results may vary materially from those anticipated by management.

Contact: Jo Anne Coy; Vice President: Corporate Communications,

             Investor & Community Relations
             253-305-1965

SOURCE Columbia Banking System, Inc.

Contact: Jo Anne Coy, Vice President, Corporate Communications, Investor & Community Relations of Columbia Banking System, Inc., +1-253-305-1965