"I believe he endangered the lives of his fellow officers," Ferman said.
Attorney Tim Woodward said his client regretted his actions and would work to repay the department.
Nolan had served as the fire company's treasurer for 24 years when he was voted out of office in December. An investigation was triggered after Nolan's successor quickly found "irregularities" in the fire company's books.
An audit and the criminal investigation found "that the defendant stole $249,703.77 of Upper Gwynedd Fire Company funds and used it for his personal expenses between 2006-2012, all while he served as the volunteer treasurer of the organization," Ferman said in the statement.
Investigators will look into records predating 2006 that were not covered by the initial audit to see whether more money is missing, Ferman said.
"I certainly want to know the full extent of the theft," Ferman said at a later news conference.
She said the fire company trusted Nolan and did not have built-in checks and balances to monitor its finances.
Nolan was employed as the township fire marshal.
"We have no reason to believe it went any further than his activities with the fire company," Township Manager Leonard Perrone said. He said Nolan would not have had access to township money.
Authorities believe Nolan took the money two ways - through cash advances totaling $116,000 and two credit cards linked to fire company accounts that he used to pay for personal expenses including vacations to China, Jamaica, Miami, and 15 trips to Las Vegas.
He also allegedly used fire company money to pay for expenses related to his daughter's 2006 wedding in Las Vegas, including airfare for guests. He also used stolen money, according to county detectives, to gamble in Las Vegas.
Nolan was arraigned Friday morning and released after posting bail.
Contact Carolyn Davis at 610-313-8109, firstname.lastname@example.org, or follow @carolyntweets on Twitter.