Milk carton boat racing is back.

When Minneapolis Aquatennial discontinued its Beach Bash event on Lake Calhoun in 2015, that meant the loss of the summer festival's sand castle contest and milk carton boat race, which had been a tradition since 1971.

Aquatennial officials said the milk carton race was cut because of a decision to shorten the festival from 10 to four days and to focus on activities on the Mississippi riverfront.

But a group of a dozen lactose-tolerant skippers weren't willing to give up the milk carton ship.

For the past couple years, they've continued to hold small, informal milk carton boat races on Lake Calhoun with just a handful of boats.

Now, they've formed a nonprofit, found a corporate sponsor with Spire Credit Union and are putting on an open-to-all milk carton boat race and sand castle competition this summer.

The Twin Cities Beach Blast will be held on Thomas Beach at Lake Calhoun starting at 9 a.m. on July 16, the Sunday before the start of the Aquatennial, which will run July 19-22.

The Beach Blast event will have boat race categories for kids, teenagers, adults and Big Boats as well as a new category for stand up paddleboards made out of milk cartons.

There will also be a showdown race between the fastest milk carton boat and other types of boats including a dragon boat, a rowing shell and possibly a solar powered boat, according to Charlie Casserly, executive director of the Twin Cities Beach Blast.

The resurrection of the race is good news to Denny Marquardt, a 65-year-old Minneapolis IT consultant. A winning milk carton boat captain for the past 15 to 20 years, he was left with a cache of as many as 10,000 empty milk cartons in his basement and a storage unit when the Aquatennial decided the race had reached its expiration date.

"I was a little disappointed to say the least," Marquardt said. "It's a nice event for family and kids."

Casserly, 55, of Minneapolis, said he got into milk carton boat racing when he was in getting his MBA at the University of St. Thomas and ended up winning the Aquatennial competition for speed and creativity in the big boat category four years in a row.

"My first boat was a milk carton boat," he said. "It was a terrific time in my life."

He said his organization, which is securing a stockpile of milk cartons to give out to aspiring boat builders, also is sponsoring seminars on boat building and sand castle construction to encourage participation.

He hopes to attract 50 boats to the competition, which will boast a top prize of $1,000 for the team that makes the most creative craft in the big boat category. The event also will have space for 30 four-person sand castle building teams.

Casserly maintains that the Twin Cities Beach Blast isn't trying to compete with the Aquatennial.

"We like the Aquatennial," he said. "We just want the race to continue."

The idea for a milk carton boat race at the Aquatennial originally was floated in 1971 by a local advertising agency, Campbell Mithun, which was trying to increase sales for its client, a milk distributor, according to Aquatennial Festival Director Leah Wong.

Wong, who is also vice president of external relations for the Minneapolis Downtown Council, said she doesn't have a problem with another organization relaunching the boat race.

"It's fun that it will continue to happen," she said.

Richard Chin • 612-673-1775