Christina Lethlean, president/CEO of the $1.2 billion Gesa Credit Union in Richland, Wash., since 2007, will resign from her post July 5.

A statement released by Gesa's board of directors Tuesday afternoon said “her decision to leave Gesa is centered around her desire to seek new challenges.”

Effective immediately, the board has appointed Don Miller, chief sales officer, as interim CEO. He joined Gesa in 1987 and has served in a variety of executive roles throughout his career. 

“The board of directors thanks Christina for her years of service and for navigating Gesa through the growth that our credit union has experienced over the last several years,” the statement said.

“Christina's foresight led to an augmentation of Gesa's products and services which helped to attract new business and resulted in growth in the number of members choosing Gesa as their primary financial institution. During her tenure, financial performance improved and the credit union achieved significant strategic milestones. The board of directors wishes Christina success in her future endeavors.”

Under Lethlean's leadership, Gesa has grown its assets from $802 million in 2008 to $1.2 billion in 2012. The credit union's net income also has soared from $1.6 million to $15.8 million in the same years, according to NCUA financial performance reports. Gesa's membership also has increased from 74,499 in 2008 to 113,079, as of March 31.