Summary of COLUMBIA BANKING SYSTEM INC

Item 8.01. Other Events.

Beginning in the first quarter of 2009, Columbia Banking System, Inc. (the "Company"), changed its segment reporting to include an allocation of the provision for loan and lease losses, previously reported as part of the Other segment, to the Commercial and Retail Banking segments, as described more fully in Note 5 to the unaudited consolidated condensed financial statements included in the Company's Form 10-Q for the period ended March 31, 2009. This segment reporting change did not have a material impact on the Company's consolidated financial statements.

This segment reporting change did impact the segment disclosures required to be reported in the Company's consolidated financial statements in accordance with Statement of Financial Accounting Standards No. 131, Disclosures about Segments of an Enterprise and Related Information. The principal effect on the prior segment disclosures was to allocate the provision for loan and lease losses, which were previously reported as part of the Other segment, to the Commercial and Retail Banking segments, based upon factors including average loan balances and credit quality metrics.

As a result of this segment reporting change, the Company will reflect the change in presentation and disclosure for all periods presented in future filings.

The segment reporting reflecting the change for the years ended December 31, 2008, 2007 and 2006 is summarized as follows:

                                                                       Year Ended December 31, 2008
                                                       Commercial
                                                        Banking         Retail Banking        Other          Total
                                                                              (in thousands)
Net interest income                                   $     47,461     $         55,411     $  16,641     $   119,513
Provision for loan and lease losses                        (27,824 )            (13,352 )           -         (41,176 )
Net interest income after provision for loan and
lease losses                                                19,637               42,059        16,641          78,337
Noninterest income                                           3,624                9,089         2,137          14,850
Noninterest expense                                        (11,055 )            (28,205 )     (52,865 )       (92,125 )
Income (loss) before income taxes                           12,206               22,943       (34,087 )         1,062
Income tax benefit                                                                                              4,906
Net income                                                                                                $     5,968
Total assets                                          $  1,443,029     $      1,000,209     $ 653,841     $ 3,097,079

                                                                       Year Ended December 31, 2007
                                                       Commercial
                                                        Banking         Retail Banking        Other          Total
                                                                              (in thousands)
Net interest income                                   $     30,062     $         82,306     $  (3,548 )   $   108,820
Provision for loan and lease losses                         (2,441 )             (1,164 )           -          (3,605 )
Net interest income after provision for loan and
lease losses                                                27,621               81,142        (3,548 )       105,215
Noninterest income                                           3,192                8,571        15,985          27,748
Noninterest expense                                        (11,054 )            (28,221 )     (49,554 )       (88,829 )
Income (loss) before income taxes                           19,759               61,492       (37,117 )        44,134
Income tax provision                                                                                          (11,753 )
Net income                                                                                                $    32,381
Total assets                                          $  1,474,678     $      1,068,282     $ 635,753     $ 3,178,713

                                                                       Year Ended December 31, 2006
                                                       Commercial
                                                        Banking         Retail Banking        Other          Total
                                                                              (in thousands)
Net interest income                                   $     22,870     $         79,366     $  (4,473 )   $    97,763
Provision for loan and lease losses                         (1,424 )               (641 )           -          (2,065 )
Net interest income after provision for loan and
lease losses                                                21,446               78,725        (4,473 )        95,698
Noninterest income                                           2,076                7,700        14,896          24,672
Noninterest expense                                         (9,073 )            (24,036 )     (43,025 )       (76,134 )
Income (loss) before income taxes                           14,449               62,389       (32,602 )        44,236
Income tax provision                                                                                          (12,133 )
Net income                                                                                                $    32,103
Total assets                                          $  1,204,269     $        682,029     $ 666,833     $ 2,553,131

Although the change in segment reporting is not material to the Company's consolidated financial statements for the periods presented above, the Company is filing this Current Report on Form 8-K for the purpose of updating segment reporting disclosure for the periods presented in its Annual Report on Form 10-K for the year ended December 31, 2008 (the "2008 Form 10-K") to be consistent with the Company's current segment reporting and for incorporation by reference into the Company's existing and future registration statements filed under the Securities Act of 1933, as amended, including but not limited to the registration statement on Form S-3 filed with the Securities and Exchange Commission on October 17, 2008.

The information in this report should be read in conjunction with the 2008 Form 10-K. For developments since December 31, 2008, please refer to the Company's Quarterly Reports on Form 10-Q for the quarters ended March 31, 2009 and June 30, 2009 as well as other Current Reports on Form 8-K the Company has filed since December 31, 2008.