Workers Credit Union may be moving its headquarters staff to a new, expanded facility in Littleton this summer, but its main operations center will remain in the old head office in downtown Fitchburg.

The $1.6 billion-asset lender announced the finalized plans this morning.

The Main Street Fitchburg facility will continue to be a hub of activity housing Workers’ mortgage division, operations department, training staff and the existing full-service branch. Over the past few years Workers said it has upgraded the building with energy efficiencies, renovations and structural repairs to make it a pleasant and safe environment for its staff.

“Workers Credit Union continues to demonstrate a solid collaborative partnership with the city of Fitchburg and the region,” city Mayor Steven DiNatale said in a statement. “The Fitchburg Operations Center exemplifies the ever changing banking model and Workers’ ability to evolve and meet the needs of its customers.”

Workers Credit Union’s headquarters move is part of an expansion plan intended to build on a wave of growth it has been riding and create space for more. The Fitchburg and Littleton facilities will allow the credit union to consolidate operations, which are now spread across five locations, to just two.

“Our commitment to the Fitchburg community goes beyond our physical location,” Workers CEO Doug Petersen said in a statement. “We will remain steadfast in our support of local organizations, events and nonprofits that improve the quality of life in Fitchburg and the surrounding area. We have many employees and thousands of members who call Fitchburg home so this location will remain an integral part of our operational network.”

The decision keeps a major employer in the heart of a downtown that is receiving significant public and institutional investment in a bid to draw private development.