U.S. Postal Service’s announcement Wednesday it plans to end Saturday mail delivery the week of Aug. 5 “shouldn’t be a complete shock to anybody because it’s been talked about for so long,” Dowagiac Postmaster Leah Sovine said.

Under the proposal, the Postal Service would continue to deliver packages six days a week and mail to street addresses Monday through Friday.

The Postal Service expects to save approximately $2 billion annually once the plan is fully implemented, but it’s unclear if the service can eliminate Saturday mail delivery without congressional approval.

“The Postal Service is advancing an important new approach to delivery that reflects the strong growth of our package business and responds to the financial realities resulting from Americans’ changing mailing habits,” Postmaster General and CEO Patrick R. Donahoe said. “We developed this approach by working with our customers to understand their delivery needs and by identifying creative ways to generate significant cost savings.”

Over the past several years, the Postal Service advocated shifting to a five-day delivery schedule for mail and packages.

However, recent strong growth in package delivery — a 14-percent volume increase since 2010 — and projections of continued strong package growth throughout the coming decade led to the revised approach to maintain package delivery six days per week.

“Our customers see strong value in the national delivery platform we provide and maintaining a six-day deliver schedule for packages is an important part of that platform,” Donohoe said. “As consumers increasingly use and rely on delivery services — especially due to the rise of e-commerce, we can play an increasingly vital role as a delivery provider of choice and as a driver of growth opportunities for America’s businesses.”

Sovine, whose customers particularly rely on package delivery for pharmacy prescriptions, said Dowagiac post office would still be open for retail service from 10 a.m. to noon and sorting mail into the P.O. box section.

“Carriers going door to door is about the only change,” Sovine said. Dowagiac has 12 routes.

“It will affect our substitute employees,” she said. “We have a swing carrier for every five routes which we wouldn’t need. Another important fact is that blue boxes will not be collected on Saturday,” so mail posted on that date would need to be dropped at the post office between 10 and noon.

Market research conducted by the Postal Service and independent research by major news organizations indicate nearly seven out of 10 Americans — 70 percent — support the switch to five-day delivery as a way for the Postal Service to reduce costs in its effort to restore financial stability.

The Postal Service made the announcement Feb. 6, more than six months in advance of implementing five-day mail delivery, to give residential and business customers time to plan and adjust. It plans to publish specific guidance in the near future for residential and business customers about its new delivery schedule.

“The Postal Service faces a number of tough choices in order to remain fiscally solvent and continue providing the many services that its rate payers depend upon,” said U.S. Rep. Fred Upton, R-St. Joseph. “As they explore these cost-saving measures, I will continue to work hard to insure that families and businesses across southwest Michigan have access to the important products and mail delivery services they require.”

Upton said since the 1980s, Congress mandated six-day delivery via an appropriations rider.

That mandate has been extended under the current Continuing Resolution, which provides for federal funding through March 27.

Postal officials contend the mandate does not apply, giving them authority to make the transition without explicit congressional approval.

Fredric Rolando, president of the National Association of Letter Carriers, said move “flouts the will of Congress.”

“Postmaster General Patrick Donahoe’s plan to end Saturday delivery is a disastrous idea that would have a profoundly negative effect on the Postal Service and on millions of customers,” Rolando said in a statement. “It would be particularly harmful to small businesses, rural communities, the elderly, the disabled and others who depend on Saturday delivery for commerce and communication.”

Donahoe said the law governing the agency’s operations expires at the end of March, and if there’s any disagreement it can be resolved by then.

The Postal Service lost $15.9 billion last year.

“By any measure, that is unsustainable and it’s unacceptable,” Donohoe said.

Since 2006, the Postal Service has reduced its annual cost base by about $15 billion, reduced the size of its career workforce by 193,000, or 28 percent, and consolidated more than 200 mail processing locations.

The Postal Service receives no tax dollars for operating expenses, relying on sale of postage, products and services to fund operations.

It is the only delivery service that reaches every address in the nation — 151 million residences, businesses and post office boxes.