PORTLAND — In this “big political year,” Tony Donovan, head of the Sierra Club of Maine, said the organization will use its “respected and effective” voice to urge action on a broad array of environmental issues.

The Sierra Club of Maine is celebrating its 25th anniversary and Donovan said now, more than ever, grassroots environmental advocacy is essential to upholding a wide range of protections that are currently being undermined, especially on the federal level.

“Clean air and water are critical to human health and overall food production. Everything we do impacts the environment and that’s why it’s critical to work every day to sustain our natural resources,” he said.

Donovan joined the Sierra Club about a decade ago and said in the past couple years the organization has grown steadily. Interest in the club is so strong these days, he said, that 100 new members were added to the rolls in June alone.

The Sierra Club was founded nationally in 1892, and calls itself  “the oldest and largest environmental advocacy organization in North America,” according to its website.

The club boasts 64 chapters around the country, with each local chapter being run almost entirely by volunteers.

The Maine chapter was formed in 1993 after it broke off from a more regional group that also included Massachusetts, New Hampshire, Rhode Island and Vermont.

Today the goals of the Maine chapter include fighting global warming, promoting smart growth and energy efficiency and supporting pro-environment candidates for public office, among other initiatives.

Donovan said the overall mission of Sierra Club Maine is to get people outside and into nature, while encouraging them to “enjoy, explore and protect,” the natural environment.

He compared the Sierra Club to a “big tent” that welcomes members who are interested in everything from promoting better public transportation options to alternative energy production to climate change solutions.

In Maine, he said the club has been particularly active in working with municipalities to ban single-use plastic bags, create community garden opportunities and encourage weatherization of older homes.

The local chapter has also working closely with Portland and South Portland to develop municipally operated solar arrays, Donovan said.

Donations to the Sierra Club of Maine generally fall into two categories, he said. One pot of money is specifically used for political advocacy and the other is for education, outreach and special events.

One such event is a new, two-day environmental film festival being held this weekend at SPACE Gallery on Congress Street in downtown Portland.

On Friday, Aug. 10, at 7 p.m. the Sierra Club will screen the documentary, “SEED: The Untold Story.” Then on Sunday, Aug. 12, it will show “Albatross” at 1 p.m. and “Reluctant Radical” at 7 p.m.

Both of Sunday’s screenings will be preceded by a short film. The 1 p.m. show includes “The Refuge,” while the 7 p.m. show includes “The Accidental Environmentalist.”

Donovan said film screenings are one of the Sierra Club’s best outreach tools and he hopes this new summer festival will become an annual event.

Another way the club is observing its 25th anniversary, he said, is with an expanded annual meeting, being planned for November after the General Election.

“Hopefully we’ll have a lot to celebrate,” Donovan said.

In 1993 it was issues such as the emergence of global warming, unsustainable forestry practices and concerns about large tracts of land being sold off for development that led to the creation of an independent Maine chapter of the Sierra Club, according to a history of the organization written by longtime member Jim Frick.

Those leading the effort to create a Maine chapter were Joan Saxe, Ken Cline and John Boomer. “We started thinking that we could be more visible … and more effective … if we were our own chapter,” Saxe told Frick.

“Becoming independent was a bit scary,” Cline added. “But it was the right decision. It really pushed us into taking even greater ownership of the environmental issues in the state.”

Frick said the Sierra Club of Maine been successful by developing planning strategies, doing community and grassroots level organizing and building partnerships.

Some of the chapter’s most important efforts, he said, included assisting in the establishment of the 100-Mile Wilderness in 2010, which protects more than 150,000 acres of land along the Appalachian Trail.

In addition, in 1999 the local Sierra Club co-sponsored the first Global Climate Change Conference in Maine, which has anchored its commitment to action on climate change ever since, Frick said.

“We deserve to take some time to celebrate, but not too long (because) there are daunting challenges ahead,” he said.

Among those challenges are the “current government’s denial of science and climate change” and “growing threats such as water extraction, ocean acidification, and mining,” Frick said.

“What I like about the Sierra Club is that we’re all in this together and we’re committed to helping people and the environment,” Donovan said. “Twenty-five years ago we saw the importance of having our own voice, now we’re a force in the state.”

Kate Irish Collins can be reached at 710-2336 or kcollins@theforecaster.net. Follow Kate on Twitter: @KIrishCollins.