WATERVILLE -- While some of Maine's cities and towns might wait until they are pushed into action on environmental issues, Waterville, Winslow, Oakland, and Fairfield aren't wasting any time.

As part of the Sustain Mid-Maine regional group, some 50 citizens in those towns are volunteering their time to promote sustainability, efficiency, and a healthier environment.

Local town governments are on board, too. Waterville City Manager Mike Roy is on the group's steering committee, and he said that addressing issues like energy use and efficiency is part of his job.

On Wednesday, the group is sponsoring the Green Living Expo in Waterville, at which local residents can learn more about ways to save energy and money. The Expo will take place from noon to 5 p.m. at the old CVS building at 88 Main St.

According to organizer Jamie Nemecek, the event is geared toward homeowners, and will feature presentations by five speakers on topics ranging from wood boilers to local foods. A number of area businesses and organizations will also be at the expo providing information and advice on efficiency and sustainability.

"People can go to learn more about sustainability, what they can do in their homes, and how it can save them money in the end," Nemecek said.

The Expo is one of a number of initiatives that have arisen from Sustain Mid-Maine.

Roy said the group's genesis began three years ago, when the city of Waterville formed a sustainability committee. Then, in 2007, an anonymous local donor provided funding for a summer intern to further examine issues of sustainability, which Roy said "allowed us to look beyond the bounds of just the city of Waterville and our own municipal needs."

That intern, Colby College student Steve Erario, worked for the summers of 2007 and 2008 on a number of projects related to sustainability and efficiency, including a greenhouse gas inventory -- a rough measure of the contribution of a given city or town to global climate change.

Starting in 2008, Erario's work moved beyond the borders of Waterville to consider Fairfield, Oakland, and Winslow.

Then, this last January, Sustain Mid-Maine was officially formed after a three-day workshop at which area residents, business owners, and nonprofit and town employees, and others discussed sustainability and the environment. They decided on five key issues to tackle: energy, transportation, waste and recycling, education, and local foods.

Erario, who is still an intern with the group, said that while there is no desire to replace the organization's volunteers with paid staff, there is a need for "somebody on top of what's going on at all points in time."

Aside from the Expo, Sustain Mid-Maine has opened a community garden in Waterville, and has completed energy audits of municipal buildings, Roy said.

While the group arose from Waterville's sustainability committee, Roy said that its focus quickly expanded into a regional initiative, and that it could serve as a model for other areas.

"I think it should be groupings of communities working together," Roy said. "We're connected in so many ways, energy-wise, that it doesn't make sense for communities to do some of these kinds of things individually."