PORTLAND, Maine — With a background in government and nonprofits, the city’s new director of health and human services expects her experience will be a critical tool in running the department.

“All the work I’ve done gives me insight into how government works and connections and contacts that will be helpful,” Dawn Stiles said Monday.

Stiles began work Dec. 1, replacing Doug Gardner, who resigned June 30 to take a private-sector job in Lewiston. She takes over a department with a budget of at least $32.2 million for social services, public health and the Barron Center assisted living facility — or nearly one-fifth of the entire municipal spending outlay of $176 million.

Stiles is a former president and chief operating officer of Spurwink Services, a nonprofit providing mental health and education services for children and families. She was most recently executive director of the Santa Anna Island Community Center in Florida.

She said her work there provided a glimpse of what she will be working with in Portland: providing services for the elderly, and before- and after-school services and care for the children of hospitality-industry workers.

“It was interesting because the island had sort of an ‘invisible poor,’” Stiles said.

She arrives at a challenging time, with Portland facing the loss of state reimbursement for general assistance vouchers given to undocumented immigrants, which could amount to at least $3.6 million.

In a month, the Legislature and Gov. Paul LePage begin work on a new biennial budget to cover fiscal years 2016 and 2017. The last budget reduced social service spending at the state level, while trimming eligibility standards. It threatened municipalities with the loss of revenue sharing derived from income and sales taxes received in Augusta.

Some of the revenue sharing was restored by boosting other taxes, but those increases are set to expire.

Stiles said she will let Mayor Michael Brennan and legislators advocate for the city. But she said her work on the LePage transition team after the 2010 election may provide some useful connections.

“Public health is new to me,” Stiles said, “so this week I have been meeting division directors and learning what they do.”

But with her expertise in Medicaid and Medicare procedures and regulations, she said she expects to be able to ensure the city gets the funding it is eligible for, but she also is ready to explore other funding methods for the department.

She said she does not have any preconceived ideas for operations.

“I never like to come in with my own goals or priorities,” she said. “I like to get to know the issues that are here and what the community wants or needs. I learn better and faster by seeing how things work.”

Stiles said the longevity of department heads will also be critical for her.

“[It is] uplifting in terms of people being in jobs that long without becoming jaded,” she said.