That joyful scream you heard?

’Twas me — responding to news that the sand castles are back at Minneapolis’ Thomas Beach.

It hasn’t felt fully like summer to me since 2015. That’s when the sand castle contest got axed by the Minneapolis Aquatennial, which shortened its festivities and focused on the Mississippi instead.

I wish them well. But on July 16, I’ll be at Lake Calhoun (also known as Bde Maka Ska) celebrating the poetry and magic of a unique form of art:

The ephemeral kind.

Charlie Casserly has worked for two years to make me happy, although he has no idea this was his mission. Casserly is executive director of Twin Cities Beach Blast, a new nonprofit that has breathed life into the sand castles and the beloved, goofy milk carton boat races.

Casserly secured a corporate sponsor (thank you, Spire Credit Union!) and now hopes the floodgates open, so to speak, with sand castle builders and milk carton magnates.

“We’re thrilled,” he said of their return, adding that the Aquatennial committee has been generous with logistical information to make this independent event happen.

Casserly has been building milk carton boats since college (“my roommates drank a lot of beer; I drank a lot of milk”) and has won his share of prizes.

“It’s really fun to do, and part of the charm is doing it in Minneapolis, in the summer,” he said.

As he watches the boats float, I’ll be nearby with my toes in the sand.

I once wasn’t sure why I was so moved by the act of seemingly ordinary sand-sculpting. Was it the teams in T-shirts, shorts and flip-flops working industriously under a hot sun with buckets and trowels for hours?

Some teams were made up of professional architects or engineers; others were families or groups of friends.

What they created with sand and water ranged from charming to knock-your-socks-off.

So I kept coming back.

I remember one summer Sunday, anxiously rushing my family home from a friend’s cabin, then riding my bike to the beach, alone. It was dinnertime, largely quiet.

Nearby, a few parents gathered up their children and wrapped them in towels, as water lapped the shore. But the sound of DJs blaring loud music, and of excited, competitive voices shouting commands (“more water here!”) were long gone.

I strolled past exquisitely detailed castles with turrets, Rubenesque mermaids, lovable Shreks and creepy sea creatures.

The rain came later that night, relentlessly.

By morning, Thomas was just a beach again.

Shawn McCann has a theory about my weird romance with sand and water.

“Do we enjoy things, take them in more, because we know they’re not going to be there for long?” he wondered.

He doesn’t just wonder. McCann is a master of ephemeral beauty. He was the artist-in-residence at Chalkfest at Arbor Lakes in Maple Grove.

In its second year, the event drew 34 sidewalk chalk artists from around the world in early June, most of them McCann’s friends, who produced stunning and whimsical 2-D and 3-D creations.

A street artist and world traveler, McCann guesses that he’s created upward of 300 chalk pieces. Some take two hours and 50 sticks of chalk. Others require a week of his labor and 2,000 sticks of chalk.

All are quickly washed away by rain or, in McCann’s case at Chalkfest, a power washer at the end of the festival so that businesses could return to normal on Monday morning.

“People love it, but they’re like, ‘I can’t believe you’re doing all this work and then it’s going to disappear,’ ” McCann said.

“But when you think of something being gone, you naturally soak it in. Sand castles offer the same kind of magic,” he said.

“You create something stunning, and let it go.”

Casserly has accepted the same fate for his passion project.

“I build my [milk carton] boats for weeks,” he said. “And they have a boating life of maybe five minutes. You race it and then you see it in the garbage truck.

“It’s kind of strange how it’s over so fast.”

Events like these offer us an opportunity to embrace fleeting beauty, if we’re willing to try.

Just once this summer, while watching fireworks over a lake, or a child’s dance recital, or a grown man building a castle, leave your cellphone in your pocket. Don’t take a picture.

Just soak it in. Commit the magic to memory.

We can do this, because we do this already.

“It’s like summertime,” Casserly said. “It doesn’t last long, either.

“We enjoy it while the moment is here.”