WASHINGTON, D.C. — In 1989, years after coming up with a fancy water gun no one seemed to care about, Lonnie Johnson was at a crossroads. The inventor and engineer, who had worked with NASA on the Galileo mission to Jupiter, had been under pressure before. But, awaiting an interview with Larami, a toy company who could make or break him, he was young, gifted, black — and alone.

"Most of my career as an engineer, I was put in environments where I was the only person of color in the room," he later said.

Johnson went in to sell Larami on his strange-looking homemade water cannon. The executives' question: "Does it work?"

Sometimes, a powerful jet of water launched across an office is the best pitch. Johnson let fly. Soon, water covered a conference room wall.

The response: "Wow."

"At that point, I knew I had captured their imagination," Johnson said. "They could see what I had seen in the water gun all along."

Though he's already made millions, founded his own lab and company, been lauded as a historically significant inventor and hailed as a revolutionary toy maker, Johnson is now an official squirt-gun saint. The Super Soaker — that most-powerful squirt weapon, which transformed water battle in the same way the Gatling gun revolutionized warfare — has recently been inducted into the National Toy Hall of Fame.

"Fun with Super Soakers yields several dividends: exercise in the chases and brain-training while calculating vectors to moving targets and improvising tactics on the fly," Chris Bensch — vice president of collections for the Strong National Museum of Play in Rochester, N.Y., which runs the hall of fame — said in a statement. "Getting soaked in the process adds up to good, clean fun."

(The other inductees included the puppet, no particular brand — just the simple puppet — and the game Twister.)

For Johnson, it was just another honor in career that began in the hard-scrabble days of segregated post-World War II Alabama. He was the third child of six; in Mobile, his family struggled constantly to get by. His mother worked in a laundry and as a nurse's aid; his father was handyman and a civilian driver at an air force base. Both picked cotton on Johnson's grandfather's farm. There would be no fancy store-bought toys, so Johnson's father taught him to tinker. The pair shot chinaberries out of bamboo shoots.

In Johnson's all-black high school, the kid called "Professor" found no encouragement. Even when Johnson, part of the only African-American team present, won a science competition with a robot powered by compressed air at the University of Alabama at Tuscaloosa, he was shuffled out the door.

"The only thing anybody from the university said to us during the entire competition," Johnson said, "was "Goodbye" and "Y'all drive safe, now.""

A degree at Tuskegee University, where Johnson sought to follow in the footsteps of famed inventor George Washington Carver, led to a career in the Air Force and a stint at NASA. But even while designing missions to Jupiter and Saturn, Johnson was messing around at home with heat pumps that wouldn't depend on freon, a greenhouse gas.

In 1982, he saw the light. But the light wasn't directly related to notions of environmental sustainability.

"I was working on a heat pump that used water as a working fluid," he once told Popular Mechanics, "and I made some jet pumps for it. I accidentally shot a stream of water across a bathroom where I was doing the experiment and thought to myself, "This would make a great gun.""

Space would have to wait.

"I decided, "Well, why don't I, you know, put the high-tech science stuff on hold for awhile and go work and see if I can develop a toy that's something that anyone could appreciate?" he said.

The design did not come immediately.

"The original one that I first made actually had the pressurized water and the air inside a Plexiglas body," he said. "After a number of iterations, I eventually put the bottle on the top."

Seven years later, Larami signed on. Within two years, the Super Soaker — which, at up to $14, cost about 14 times more than a water gun — brought in $200 million in sales, becoming the No. 1 selling toy in America, even with limited advertising. Soon, even Johnny Carson was wielding one on-air. Sales by 2007: $1 billion.

"I started to see the royalty checks start to ramp up," he said. "... I said, "Wow, this is doing okay."" He added: "My life had changed permanently."

But where the Super Soaker went, trouble followed. There were reports of the water weapons being loaded with bleach. And, in Boston, one was implicated in an altercation that ended in real-life gunfire.

"It got really serious," Johnson said in 2009. "At one point I got a phone call from a news reporter. They said, "Mr. Johnson . . . I understand that Super Soakers are being used in drive-by shootings.""

Johnson wasn't worried.

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Water fight in Vilnius, Lithuania — Photo: Augustas Didžgalvis

Indeed, the Super Soaker survived the controversy. But, before long, Johnson was embroiled in a lawsuit with toy giant Hasbro, who purchased Larami, over unpaid royalties. The suit was settled through arbitration in 2013 — Johnson took home $73 million.

Much of his fortune, however, has been invested back into his company, Johnson Research and Development. Johnson has worked with Nerf dart guns, yes. But he's also on the hunt for more efficient solar power and rechargeable batteries. According to the company's Web site, Johnson is "a technology company that has the creative culture and radically innovative atmosphere of a toy company."

In other words: beyond the Super Soaker, into the unknown. Inventors, after all, must keep chasing wild dreams and crazy notions.

"Persevere," Johnson advised inventors not long after the Super Soaker debuted. "That's what I always say to people. There's no easy route. Nobody's going to step in and dump a lot of money and make it easy. Unless you have a lot of money, you have to pay your dues and make a personal sacrifice."