PORTSMOUTH — The Portsmouth Naval Shipyard pumped more than $600 million into the region’s economy last year, according to a report presented Friday by the Seacoast Shipyard Association.

The shipyard’s 5,474 civilian employees earned about $414 million last year, while the military payroll on the base reached nearly $42 million, the report shows. The base spent another $168 million on base supplies and contracted services, which includes construction and utility expenses.

“The budget aside, the unknowns aside, our shipyard is thriving,” said Paul O’Connor, president of the Metal Trades Council, one of four shipyard unions.

“We have 10 years of work ahead of us … our drydocks are full. We have hundreds of millions of dollars of construction ongoing right now. We’re hiring. We have a robust young workforce that’s eager to learn, and our future, in my opinion, is bright.”

But the future also holds uncertainty. Last month, U.S. Defense Secretary Chuck Hagel called for another round of base closures to reduce military spending. The Portsmouth shipyard was targeted for closure in 2005 but later was removed from the final closure list amid strong support from residents and the Seacoast Shipyard Association.

“Anytime the Secretary of Defense wants to close bases, it’s a threat to the shipyard,” O’Connor said Friday.

He said there is little the facility can to do avoid being placed on a new BRAC (base realignment and closure) list, but if it winds up there the base and its workers will once again demonstrate its strategic value to the military — as it did in 2005. He believes it can do that by maintaining its strong track record of efficiency, quality workmanship and by meeting aggressive repair timetables.

Another thing the Portsmouth shipyard has going for it is that other U.S. bases that perform similar submarine maintenance and repairs appear to have plenty to do.

“That provides them with work, so they are not looking for our work,” said Capt. William McDonough, a former Portsmouth shipyard commander and a leader of the Save Our Shipyard effort.

The economic impact study released Friday shows that dozens of communities across three states directly benefit from the shipyard’s presence.

Roughly 3,300 civilian shipyard employees living in Maine earned nearly $237 million last year, and 2,173 workers living in New Hampshire earned about $151 million. An additional 150 employees live in Massachusetts and earned more than $11 million.

Another 197 employees, many of whom work in San Diego, earned about $16 million.

Civilian payrolls at the base fell by about $6.5 million last year, driven largely by the furloughs that were mandated by the federal sequestration budget cuts, O’Connor said. Total base employment actually increased in 2013 by around 160.

That hiring trend will continue for some time, according to O’Connor.