"Following the major challenges experienced during the Great Recession, some of which still linger, Visterra's board began exploring opportunities and ideas that would ensure Visterra's long-term survival in a changed marketplace," Barbara Purvis, Visterra's board chair, wrote in a letter to members. "A merger with Altura quickly emerged as the best option for maintaining and improving our range of products and the level of member service that you expect and deserve."

Robert Cameron, Visterra's president/CEO, will retire and Mark Hawkins, Altura's president/CEO, will assume the reins of the combined cooperatives that will serve more than 116,000 members.

Additionally, Visterra's management team will join Altura's management team, and all seven members of Visterra's board will join Altura's board to ensure representative governance for all members, according to the joint statement.

While most Visterra's employees are expected to continue working Altura CU after the merger, some positions may be eliminated because of branch/department consolidations and other changes, according to a prepared statement on Visterra's website.

In her letter to Visterra members, Purvis also announced the credit union plans to close two of its branches in Riverside and Murrieta, Calif. She added these plans have been in the works for some time.

"As you may know, we sold the Riverside branch last year and have been leasing it back from the new owner. Our intention at that time was to downsize and relocate to another Riverside location before the lease expires in May 2016," Purvis wrote. "Murrieta will be closed this spring. We want to stress that despite these closures, the impact to Visterra members will be minimal because of the merger. Altura has five Riverside branch locations and one in Murrieta, very close to ours."

Altura's Operations and Technology Center in Riverside will serve as the merged institution's headquarters.