Peter Douglas, who over the past 40 years did more than any other Californian to preserve the state’s coastline and ensure that its beaches were open to the public, has died.

Douglas, 69, who had struggled with cancer for the past seven years, died Sunday night at the home of his sister, Christina Douglas, in La Quinta, near Palm Springs.

“California has lost a true champion for our world-renowned coast, and I have lost a good friend,” said John Laird, California’s secretary for natural resources. “His vision and leadership over nearly half a century has shaped a coast that is accessible to all and whose beauty has been protected.”

Douglas retired last fall after 34 years on the staff of the California Coastal Commission. He was its executive director from 1985 to 2011.

Famous for his bolo ties, Douglas had an encyclopedic knowledge of the state’s coastline and its often complex development rules. He was co-author of Proposition 20, the landmark Coastal Initiative approved by voters in 1972. The measure set up the powerful Coastal Commission and locked into place the public’s right to access the state’s 1,100-mile coastline.

Hailed by environmentalists, Douglas was often criticized by developers and private-property-rights advocates, who said the commission had too much power and turned the lives of coastal landowners who wanted to build anything into a bureaucratic morass.

“The coast is never saved. It’s always being saved,” Douglas said in August at his final commission meeting, fighting back tears. “Our work, your work, is a labor of love that is never finished.”

As the news of his passing became public Tuesday, supporters said Douglas will rank among the top four or five most influential conservation leaders in California history.

“There’s no doubt Peter will go down in the history books alongside the likes of John Muir and other great champions of our environment,” said Michael Sutton, vice president of the Monterey Bay Aquarium. “His enduring legacy is not what you see when you go to the coast, but what you don’t see — the high-rise development, coastal runoff and pollution, gating off of beaches.”

Douglas’ battles are legendary. In 1998, he persuaded the commission to reject a plan by the Hearst Corporation to build a 650-room hotel and golf course on the San Simeon coast. In 2007, he won a long-running battle with media mogul David Geffen, who wanted to shut off public access to a beach near his Malibu compound.

At the helm of the commission, Douglas fought offshore oil-drilling proposals from Presidents Ronald Reagan and George W. Bush. He blocked the Pebble Beach Company from cutting down thousands of trees to build a new golf course. He pushed for public access to lands that became state parks, including Tomales Bay in Marin County, Garrapata in Big Sur and Crystal Cove in Orange County.

But he lost battles, too. In 1987, the U.S. Supreme Court ruled that the commission could not require landowners to dedicate public pathways to the beach through their property as a condition of granting a building permit — a key defeat.

“The Supreme Court said it was out-and-out extortion,” said attorney Ronald Zumbrun of Arcata, who filed the lawsuit against the commission on behalf of a Ventura family. “He was enthusiastic and committed to his goals, but Peter and the commission lost sight of balance, realism and protecting private property rights as well as balancing them with environmental protection.”

Douglas often shrugged off such criticism, noting that the commission approves 95 percent of the permit applications that come before it. He noted that other states had copied California’s strict coastal laws and insisted that most California voters want even stronger protections.

“It’s natural when you are prevented from exploiting a resource without any constraints, there are people who get very angry about that,” Douglas said in an interview with this newspaper in October.

“They don’t want to be told what to do. But the reality is that the coast belongs to everybody. When you buy coastal property, you have a special responsibility. That means the use of your property has more oversight because it’s necessary to protect the long-term best interest of future generations of Californians.”

There were other controversies. During the early 1990s, coastal Commissioner Mark Nathanson served prison time for a bribery scheme. “I had talked to the FBI about it. But I didn’t have a smoking gun. I was delighted when they nailed him,” Douglas said in October. And three years ago, Douglas came under fire when the commission banned the town of Gualala from shooting off July Fourth fireworks because it would disrupt nesting sea birds.

Without Douglas’ hard-nosed advocacy, even overreaching at times, his supporters say, the California coastline would largely be a place for the wealthy.

“His wisdom and guidance have bestowed upon California’s citizens and visitors a great service,” the Surfrider Foundation said in February when it gave him a “wavemaker” award.

Douglas was born into a Jewish family in 1942 in Berlin. The family eventually fled to live with relatives in Southern California. He grew up surfing and working on tugboats and ferries, graduating from UCLA law school. Working as an aide to former state Assemblyman Alan Sieroty, he tried to pass a coastal protection law in the Legislature in 1971, but it was defeated amid opposition from developers.

Undaunted, Douglas co-wrote Proposition 20 the next year, then helped write the 1976 Coastal Act — which locked in further protections — before being named the commission’s deputy director a year later.

During his final six months, as his lung cancer spread, Douglas left hospice care and drove around the state in his Ford Escape Hybrid.

In January and February, he visited Point Reyes National Seashore; a cabin he owned on the Smith River near Oregon; and Anza Borrego State Park in the Southern California Desert. He even went on a whale-watching trip off Orange County.

“It’s not in my nature to sit and mope or wallow in despair,” Douglas said in October. “I’m going to make the most of every moment I have left. I live every day. When I go out to one of these landscapes, I look at it as if it is the first and last time I’ll ever see it.”

Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045.