Columbia Banking System, Inc. (Nasdaq: COLB) expects to report third quarter 2009 financial results on Thursday, October 29, 2009 at 6:15 a.m. PDT. Management will discuss these results on a conference call scheduled for that afternoon at 1:00 p.m. PDT (4:00 p.m. EDT). Interested parties may listen to this discussion by calling 1-888-318-7969; Conference ID code #34709998.

A conference call replay will be available from approximately 4:00 p.m. PDT on October 29, 2009 through midnight PST on Thursday, November 5, 2009. The conference call replay can be accessed by dialing 1-800-642-1687 and entering Conference ID code #34709998.

About Columbia

Headquartered in Tacoma, Washington, Columbia Banking System, Inc. is the holding company of Columbia Bank, a Washington state-chartered full-service commercial bank which was awarded second place in the large employer category by Seattle Business Magazine's 100 Best Companies to Work For 2009. With the 2007 acquisitions of Mountain Bank Holding Company and Town Center Bancorp and the 2008 internal merger of its subsidiary, Bank of Astoria, into Columbia Bank, Columbia Banking System has 51 banking offices in Pierce, King, Cowlitz, Kitsap, Thurston and Whatcom counties in Washington State, and Clackamas, Clatsop, Tillamook and Multnomah counties in Oregon. Included in Columbia Bank are former branches of Mt. Rainier National Bank, doing business as Mt. Rainier Bank, with 5 branches in King and Pierce counties. Columbia Bank does business under the Bank of Astoria name at the Bank of Astoria's former branches located in Astoria, Warrenton, Seaside and Cannon Beach in Clatsop County and in Manzanita and Tillamook in Tillamook County. More information about Columbia can be found on its website at www.columbiabank.com.

Contacts: JoAnne Coy, Vice President, Corporate Communications 253-305-1965; jcoy@columbiabank.com

SOURCE Columbia Banking System, Inc.

http://www.columbiabank.com