It was an afterthought that step by step turned into a mission.

In June, Rancho Cucamonga resident Randy Brown, 47, will embark on a journey he has dubbed the Salton Sea Walk, a 116-mile, six-day trek around the entire shoreline of the Salton Sea, California’s largest lake.

In what are expected to be triple-digit temperatures, Brown will trudge through quicksand-like mud and beaches covered with barnacle shells and fish bones, all as a documentary camera crew documents his journey around the 376-square-mile body of water.

He’s hoping to bring attention to the plight of the Salton Sea, which was created more than a century ago when the Colorado River broke through irrigation canals and flowed into the Salton Basin. Now the great lake that straddles Riverside and Imperial counties is at risk of drying up as the toll of falling water levels and reduced agricultural water runoff that has traditionally fed the lake intensifies.

• PHOTOS: Rancho Cucamonga Man to Walk Entire 116 Miles of The Salton Sea

As the lake shrinks, researchers say it will become too small and too salty to remain the ecosystem it has become for the millions of fish and hundreds of migratory bird species that have depended on it.

And with the shrinkage, scientists say dust from the receding shoreline will cause health hazards, from cancer to asthma, and will devastate property values and recreation.

‘Shocked’ by the changes

This is not the place Brown remembered.

When he was a boy, Brown’s family would travel from their home in Monrovia to the Salton Sea every weekend to go camping.

Inspired by the fond memories from those visits — while on a mission to lose weight — he returned for the first time in April and was shocked by what he found.

“It was a ghost town,” Brown said. “The water had receded several yards, the places we used to go to for gas and food are no longer open. I was kind of shocked and surprised.”

By then, Brown had come up with the idea of trying to walk the shoreline. It didn’t take long for him to realize how the body of water impacts people, the economy and the effects of the dust if it does dry.

Creating a public awareness became his motivation.

A self-employed Web designer, with nearly 20 years of experience at GE ­— much of that as a former senior manager — Brown put his tech-savvy skills to work.

His June 9 trek will be for a documentary crew, but he has already well-documented his training walks in the past year by creating a social media campaign, which includes a website.

And, still months before his summer walk, the public has already noticed. His Facebook page has received more than 2,000 likes, and some of his YouTube videos have garnered more than 4,000 views.

“I realized if I was getting the attention that I was already getting then I should mention there’s an issue here,” he said.

• VIDEO: Randy Brown Salton Sea Walk

His training walks are already bringing the awareness he sought, and they’ve only made him more aware of the bittersweet realities of this place.

Brown has seen the towns along the shoreline void of the tourists and celebrities that more than 50 years ago flocked to the region.

In some areas, all that remains are abandoned buildings and salt-covered wooden posts — the only sign where a pier was once.

Brown has had to pull permits just to be able to walk through some portions of the shoreline, such as the Sonny Bono Salton Sea National Wildlife Refuge.

“I get the privilege of walking through areas that no one is allowed to go or nobody does go. You get close enough to the bird and wildlife. They’ll fly away, and then there’s just thousands and (they) almost block out the sky,” he said on a recent training walk.

To this day, Brown said he is still mesmerized by what he encounters.

Striking beauty

“When you are in Salton City in the summertime, as the sun goes down on a clear day, you can see across to the Chocolate Mountains, the water is like glass and you get a mirror reflection,” he described. “The first time I saw that, I thought, ‘It’s amazing. It’s beautiful.’ ”

Brown is not doing this alone. He is getting help from a host of family and friends he’s made along the way, including a young Los Angeles filmmaker who was inspired to produce a documentary about what is happening at the sea and featuring Brown’s journey.

“It’s sort of branched into a whole friendship and adventure that we’re taking together,” said 27-year-old filmmaker Blake Alexander.

• VIDEO: Randy Brown approves shoes

Since he embarked on the journey in April, Brown spent most of last summer making the nearly two-hour drive from his Rancho Cucamonga home on what he called mapping trips. Typically he would walk 10 miles to 12 miles at a time, making notes of river crossings, fencing and obstacles he may encounter.

For the walk in June, he will cover 20-mile segments in six days straight, starting and ending at the North Shore Yacht Club, one of the few new structures around the lake. The club functions more like a community center but was once a premier place to dock boats.

One of the biggest challenges for Brown this summer could be the mud, where in stretches, it is a foot deep, and he’ll only average a mile an hour.

On a relatively warm Friday morning in February, Brown was joined by Alexander and activist Kerry Morrison, executive director of EcoMedia Compass, a nonprofit striving to change the public’s perspective of the sea. The three came together, like they often have in the past year, to prepare for the walk. On a recent morning they met at the North Shore Yacht Club and walked over to a stretch of the shoreline just to the north. There was an understanding among the three, as if they were longtime friends and not strangers who met only nine months ago, as they discussed the mission and things that need to be done.

“When you are together with people in the trenches, working on something that is bigger than yourself, like the Salton Sea, that builds some of the biggest friendships,” said Morrison, who lives in Salton City.

Fear of sinking in mud

The big walk, as they refer to it, is always the topic of conversation, but on this day the trio seemed a bit anxious. On this morning, Brown is testing out mud boots he recently purchased.

As they walked on the black square contraptions, which are placed under the soles of shoes, Brown seemed relieved. He walked, almost glided, over the mud with his hiking shoes sinking in very little. The mini stilt-like boots won’t save him time but they will prevent him from exerting too much energy.

“I no longer fear the mud,” a delighted Brown announced.

Only three months until the walk and Brown has covered almost every single inch of the shoreline. A 20-mile stretch from Niland Marina, south to the sea’s Sonny Bono Salton Sea National Wildlife Refuge, on the east side is left for him to map out.

• VIDEO: Randy Brown tests mud boots

“People — duck hunters — have died in the mud because it’s so deep and so thick. It’s like quicksand in some places,” he said.

Despite all the experience he has racked up in a short period, there are still moments when Brown struggles.

“Sometimes, when you are in the middle, your motivation is, ‘I want to live and I need to keep walking to get back to the car.’ You can’t change your mind because there’s nowhere to go,” he said.

It’s not hard to struggle in stifling heat and exhaustion, like he experienced on an early scouting walk last summer along a 4-mile stretch he called Death Beach.

The heat, the frequent scouting and training trips, even a GoFundme.org campaign to try and raise $2,500 for expenses, are all part of the mission, and well worth it, Morrison said.

What Brown is doing, Morrison said, is desperately needed.

“I’ve traveled all up and down the coast and I’d say a third to even half of the people have never heard of the Salton Sea,” he said. “Even people in Indio — 15 miles away — don’t know that it exists.”

The Salton Sea needs a major positive awareness campaign, Morrison said.

“People need to realize that it is worth saving and that it is beautiful, and not just mud and dead fish. It’s one of the best sunrises and sunsets that you’ll ever see,” he said.

Dinesh Desai can relate. In 2005, he walked 110 miles around the roads that surround the Salton Sea. He completed the summer walk when he was 65.

Brown has a difficult journey ahead, he said.

“Good luck to him,” he said, speaking from his home in Los Altos.

“It’s going to be an interesting adventure,” he said.

Brown is feeling ready for that adventure.

“I’ve gone from thinking this is a suicide mission to thinking ‘I can do this.’ …”