Central Sierra Bank & Western Sierra Bancorp Agree to Join Forces.

Business Editors

SAN ANDREAS, Calif.--(BUSINESS WIRE)--March 13, 2003

Central Sierra Bank (OTCBB:CESR), headquartered in San Andreas and Western Sierra Bancorp (Nasdaq:WSBA), a multi-bank holding company headquartered in Cameron Park have signed a definitive agreement whereby Central Sierra Bank will join Western Sierra's Alliance of Community Banks and will merge with Central California Bank, a Western Sierra subsidiary. The agreement, which is valued at approximately $21.5 million in stock and cash, is expected to be completed by this July.

Central Sierra Bank, with $137 million in assets, presently has seven locations in the Northern California communities running along the Mother Lode and into the central valley. Branches are located in Calaveras, Amador, Tuolumne and San Joaquin counties. Clarence Hartley, President & CEO, will remain with the bank continuing to lead his team of professional bankers.

"This is an extremely positive event for Central Sierra Bank customers, shareholders and employees," stated Hartley. "The increased capacity, enhanced financial services and expanded resources that accrue from this partnership will make us an even more formidable competitor in our local markets. Western Sierra's strong emphasis on responsive customer service closely mirrors our own business philosophy and adds great synergy to this combination."

Gary D. Gall, President & CEO of Western Sierra Bancorp stated, "Central Sierra Bank is a key part of our strategic plan, filling in the gap between Cameron Park and Sonora along Highway 49 while initiating a new presence in the affluent Lodi market. Our similar business philosophy of community service and building personal relationships can now be enhanced with an expanded line of financial services, and the convenience of expanded branch locations."

This will be the fifth acquisition for Western Sierra Bancorp since 1999. When completed, the Western Sierra alliance of financial institutions will serve its customers with 26 branch locations and 4 loan production offices in 15 northern and central California counties. Total assets of the combined group will exceed $830 million including Western Sierra Bank, Lake Community Bank and Central California Bank. Central Sierra Bank and Central California Bank will have combined assets exceeding $300 million. It is expected that this transaction will be accretive to earnings in the second full quarter of operation together.

Central Sierra Bank security holders will be receiving approximately $21.5 million in stock and cash on a fully diluted basis. The transaction will need regulatory as well as Central Sierra Bank shareholder approval, which is expected in the second quarter of this year.

More information about this bank can be found on its website at www.centralsierrabank.com

This press release contains statements which constitute forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934 that involve risk and uncertainties. Actual results may differ materially from the results in these forward-looking statements. Factors that might cause such a difference include, among other things, fluctuations in interest rates, changes in economic conditions or governmental regulation, credit quality and other factors discussed in the Central Sierra Bank's Annual Report on form 10-K for the year ended December 31, 2001.

Additional Information and Where to Find It: It is expected that Western Sierra Bancorp will file a Registration Statement on SEC Form S-4, and Central Sierra Bank and Western Sierra Bancorp will file a Proxy Statement/Prospectus with the SEC and FDIC in connection with the merger, and that Central Sierra Bank and Western Sierra Bancorp will mail a Proxy Statement/Prospectus to stockholders of Central Sierra Bank containing information about the merger. Central Sierra Bank investors and security holders are urged to read the Registration Statement and the Proxy Statement/Prospectus carefully when they are available. The Registration Statement and the Proxy Statement/Prospectus will contain important information about Central Sierra Bank, Western Sierra Bancorp, the merger, the persons soliciting proxies relating to the merger, their interests in the merger, and related matters.

Investors and security holders will be able to obtain free copies of these documents through the website maintained by the SEC. When available, free copies of the Proxy Statement/Prospectus and these other documents may also be obtained from Central Sierra Bank by mail to Central Sierra Bank, P.O. Box 729, San Andreas, CA 95249, attention: Investor Relations, telephone, [phone].

In addition to the Registration Statement and the Proxy Statement/Prospectus, Central Sierra Bank and Western Sierra Bancorp file annual, quarterly, and special reports, proxy statements and other information with the FDIC and the SEC respectively. You may read and copy any reports, statement, or other information filed by Central Sierra Bank at the FDIC, 550 17th Street N.W., Washington, D.C., or by Western Sierra Bancorp at the SEC public reference rooms in New York, New York, and Chicago, Illinois. Please call the FDIC at (877) ASKFDIC or the SEC at (800) SEC-0330 for further information on the public reference rooms. Western Sierra Bancorp's filings with the SEC are also available to the public from commercial document-retrieval services and at the website maintained by the SEC at http://www.sec.gov.

Participants in Solicitation: Central Sierra Bank, its directors, and certain other members of management and employees may be soliciting proxies from Central Sierra Bank stockholders in favor of the merger. The directors' beneficial owner shares of Central Sierra Bank are as follows: Clarence E. Hartley 54,577; Glen C. Croshaw 30,188; Rosemary Faulkner 12,073; Wilbur W. Fullaway 27,534; Kenneth L. James 6,118; Sarah Platt 3,745; Robert J. Manassero 11,978; and Forrest A. Turner, Jr. 20,597.