UNITY, Maine — When returning students go back to Unity College this coming weekend, they’re going to find a few changes around the campus, including a new president and a just-announced gift of $10 million that will more than triple the endowment for their small school.

The money has been donated by a Maine woman who wishes to remain anonymous and who strongly believes in the mission of Unity College, according to vice president for college advancement Rob Constantine.

“We’re very excited,” a jubilant-sounding Constantine said over the phone on Tuesday afternoon. “For a college like Unity, it is truly an amazing gift.”

Earlier that day, President Stephen Mulkey had announced the gift during his State of the College address at the Unity Centre for the Performing Arts.

“You could hear everybody in the room taking a deep breath,” Constantine said. “Over lunch, that’s all anybody could talk about. It’s a huge recognition of the great work that everybody is doing here.”

The donation is by far the biggest gift that Unity College has ever received and will generate about $500,000 each year in additional operating revenue. That is about 4 percent of the school’s existing operating budget of $14 million, Constantine said.

Mulkey, who began his job in mid-July after outgoing President Mitchell Thomashow left, received a call in the last couple of weeks from the donor’s attorney telling him of the large gift.

“We’ve been working with the donor for a while, building the relationship with the college,” Constantine said. “We’ve received a lot of support in the past from this donor.”

About 20 of the college’s 500 students were present Tuesday when Mulkey made his announcement.

“Most of the students have not met him yet, but they’ll probably like him now,” Constantine joked.

He said the money will do many things for the school, which calls itself “America’s Environmental College.”

The gift will provide “huge leverage” for Unity College, in terms of working with other donors, he said.

“And it elevates the profile of the college for other students and other institutions,” Constantine said. “The profile of the college has an impact on the students in terms of their job possibilities.”

Also, the money will provide Unity College with the resources to implement changes as the school moves forward in the field of sustainability science, according to the president.

“A gift like this allows us to adapt to the latest developments in sustainability science and sustainability studies, and to continually hone our curriculum,” Mulkey said in a press release. “The annual draw from this gift will allow us to move forward strategically to prepare our students for the challenges and opportunities brought on by climate change and resource depletion.”

Before the $10 million gift, the largest gift from a living donor was $400,000, with some bequests approaching $1 million, according to Constantine.

The school was founded in 1965 and has been achieving more of a national presence in recent years. It was one of 18 U.S. colleges and universities named to The Princeton Review’s Green Rating Honor Roll in 2010, when it also was named to the top 30 of the Washington Monthly’s college rankings.

Some majors include agriculture, conservation law enforcement, ecology, environmental writing, forestry, wildlife biology and recreation and ecotourism.

Unity College is a national leader in the sustainability movement, and has worked to reduce its carbon emissions through a program of energy audits and building retrofits.