The Federal Reserve has approved Tacoma, Wash.-based Columbia Banking System Inc.'s pending acquisition of Eugene, Ore.-based Pacific Continental Corp.

The merger, valued at $644.1 million when it was announced in January, will push Columbia past the $10 billion regulatory threshold. The combined company will have about $12 billion in assets, with more than 150 branches in Washington, Oregon and Idaho.

In evaluating the potential risks of the merger, the Federal Reserve Board noted that proposals involving an acquisition of less than $10 billion in assets or resulting in an entity with less than $100 billion in total assets are unlikely to pose systemic risks.