PORTLAND – The U.S. Postal Service is consolidating its operations in northern New England, transferring mail processing from a facility in Portsmouth, N.H., to processing and distribution centers in Scarborough and Manchester, N.H.

The agency said in a news release Wednesday that the changes are aimed at boosting the efficiency and productivity of the service, which has seen mail volume drop by 20 percent since 2007.

Tom Rizzo, Postal Service spokesman for the northern New England district, said the change will not require the agency to add jobs in Scarborough. That plant, he said, has enough employees and equipment to handle extra processing.

“We have such excess capacity these days in our system,” said Rizzo. “We have more capacity than we have mail to process”

Rizzo said the Postal Service will work with employees in Portsmouth, and their union, to fill positions that are now vacant in Scarborough.

He said 70 to 75 Portsmouth staffers will be affected by the consolidation, which is expected to be complete by January.

After the consolidation, the Scarborough plant will process nearly all of the mail that flows into and out of Maine.

Tim Doughty, president of the American Postal Workers Union in the Portland area, acknowledged the troubles facing the Postal Service, which lost $3.1 billion in the quarter ending June 30. In the fiscal year that ended in September 2010, the agency lost $8.5 billion.

Doughty said the problems are largely the fault of Congress, which requires the Postal Service to pay $5 billion each year to pre-fund retirees’ health benefits.

He said the Postal Service also has overpaid for retirement benefits by $50 billion to $75 billion over the years.

“No other federal agency is obligated to pay these exorbitant fees, and the requirement is simply an extortion ploy by Congress to balance their books,” Doughty wrote in an email to The Portland Press Herald.

“These efforts will result in lower standards of customer service and less revenue. The impact will be a self-induced downward spiral of death for the Postal Service,” Doughty said.

In addition to consolidating processing centers, the Postal Service recently proposed cutting 120,000 jobs — about 20 percent of its work force — and is looking to close as many as 3,700 branches nationwide, including 34 in Maine.

Most of the locations under review are in rural Maine, except for Postal Station A at 622 Congress St. in Portland’s West End.

Staff Writer Jonathan Hemmerdinger can be reached at 791-6316 or at:

[email protected]