Marin County Supervisor Charles McGlashan died of an apparent heart attack Sunday after a two-day ski outing at Lake Tahoe.

McGlashan, a Mill Valley activist who rose to become the county s key environmental visionary, was 49.

Friends said McGlashan was feeling fit and happy after one of the best skiing sessions of his life, but collapsed after loading up the car to return to Marin.

McGlashan s wife, environmental activist Carol Misseldine, called him her "comrade in arms," a man dedicated to making the planet a better place.

"He was the most pure and committed environmentalist I have ever met," she said. "It wasn t about show. It was about his heart. He was deeply concerned about all the beings on this planet."

She added: "He was a leader. I have lost so much, but so has Marin County."

The news stunned friends as well as colleagues at the Marin Civic Center, where flags flew at half-staff. County Administrator Matthew Hymel released a statement saying the county had "lost a visionary environmental leader."

"Supervisor McGlashan leaves a legacy of environmental leadership that was passionate, inspired and pragmatic. His many accomplishments during his short political career include the formation of SMART, the Marin Economic Forum and the Marin Energy Authority," which he headed, Hymel said.

McGlashan, after a day skiing at Northstar-at-Tahoe with friends, collapsed at about 5 p.m. while sitting in a car, ready to leave a friend s home in Tahoe Vista at Lake Tahoe s north shore.

"He had a heart attack in the back of the car and died," said Sgt. Paul Schmidt of the Nevada County Sheriff s Office. "He apparently had heart problems." North Tahoe Fire personnel attempted to revive him, but he was declared dead at Tahoe Forest Hospital in Truckee.

Supervisor Judy Arnold expressed the shock that many felt as news of McGlashan s death circulated. "I can t imagine our board without him," she said. "I admired how passionate Charles was on issues he cared about. His intelligence coupled with that passion enabled him to do amazing things for Marin. I will miss his enthusiasm to jump into issues with me that were far out. "

Supervisor Hal Brown called his colleague s death a "huge loss for the county, a terrible loss" and said he had great admiration for McGlashan. "He was a wonderful, vibrant young man," Brown said.

"Charles brought an undeniable presence to issues he believed in. His education, insight, and passionate advocacy fueled his success in a way that will live on through the shock of losing his leadership," said Supervisor Steve Kinsey.

"The entire county and Marin community has been devastated by the news," said board president Susan Adams, a key political ally. "Charles was a courageous and dedicated leader, fighting for what he believed was right to ensure a sustainable future for everyone. He was spirited, smart and full of energy. "

Mill Valley Mayor Ken Wachtel was among the many expressing profound sorrow. "I have lost a friend and we have all lost a leader in the fight for what is right in our communities. Charles was bright, energetic and always a joy to talk and work with. Charles took on the battles for all of us and usually won. ... We will not soon see his likes again."

Marin Municipal Water District director David Behar said, "Charles drove Marin s leadership in forging a clean energy economy with his vision and hard work in creating the Marin Energy Authority. We will miss that leadership, and benefit from its legacy."

Rep. Lynn Woolsey, D-Petaluma, said she was heartsick. "Charles was a good man and a dedicated, visionary public servant who represented his community with uncommon diligence and decency. He brought to the Board of Supervisors a fierce commitment to environmental causes and an acute sense of right and wrong. He embodied the very best of Marin County s spirit of progressive activism."

McGlashan represented Southern Marin on the county board, and was a relentless advocate for the causes in which he believed, ranging from energy conservation and environmental preservation to prevention of cruelty to animals. He was a cheerleader for county employees whom he said were hard-working and dedicated public servants unfairly targeted by government critics.

McGlashan was born in Hillsborough, the son of an Army colonel, a heroic officer who fired back at the attacking Japanese at Pearl Harbor.

He earned a bachelor s degree in honors English from Yale University and received a master s in business administration from Stanford. He had lived in Marin for two decades, working as an environmental consultant before being appointed to the board of the Marin Municipal Water District in April 2003. While there, he championed plans for a water desalination plant.

He won election as county supervisor in November 2004 and spearheaded environmental causes, including the Marin Energy Authority, and most recently shepherded a plastic bag ban in Marin after winning consensus from consumer and industry groups.

At a Board of Supervisors meting Wednesday, an animated McGlashan vigorously advocated budget priorities; lauded staff work; urged review of a proposal requiring most voters to use mail-in ballots in county elections in order to save $300,000 a year; and supported charging developers more money for county permits.

McGlashan sailed past opponent Andrew Thompson in the 2004 race for the county board, running for the post as a rookie politician after serving just a year and a half on the water board. McGlashan, who campaigned on a platform that a healthy economy and a healthy environment go hand in hand, was backed by the Marin Association of Realtors even though Thompson was a commercial realty broker. He was also endorsed by the Sierra Club and the Marin Builders Association.

McGlashan s grieving widow took a moment from a hectic round of somber phone calls from friends and colleagues to reflect on her life with him, saying they first talked over the phone when both worked for Natural Steps, a sustainability organization, while she was in the Great Lakes office and he consulted with the San Francisco office. They met at a conference in Santa Fe, N.M., but he was married at the time, a 13-year union with Suzy Herrick of Palo Alto that ended in divorce. McGlashan and Misseldine were married in 2002.

"It was definitely our values that brought us together," said Misseldine, a passionate environmentalist. "He was a visionary ... like a compass on true north who never wavered," she said. "He was so clear."

His fervor was tested by those whose slings and arrows he could not fathom, she said. "It broke his heart that he tried so hard and got so much hostility," she added, referring to government critics who ridiculed his progressive beliefs.

Other survivors include two brothers. Plans for a memorial service are pending.

Contact Nels Johnson via e-mail at ij.civiccenter@gmail.com