Phelps, 28, has not competed since the 2012 London Olympics, where he won four gold and six total medals, giving him Olympic career records for both (18 and 22.)
USA Swimming announced Monday that he was expected to compete in Mesa. Phelps intends to swim the 50- and 100-meter freestyles and 100 butterfly, according to Drew Johnson, part of Phelps' management team at Octagon.
Phelps' coach, Bob Bowman, had told the Tribune March 25 the swimmer was likely going to get into a meet "sometime soon."
"We have discussed a long-term plan in general terms, but until he swims in a meet we're not going to know," Bowman said via telephone Monday. "Will he be eighth? Second? Sixteenth?
"I think he certainly won't be embarrassed swimming in the meet, and I think he will be competitive. The difference is he is doing half the training he used to."
The swimming community welcomed the news.
"Michael is the greatest swimmer of all time. His return to competition will drive excitement and interest not only for fans and media but also his fellow swimmers," Conor Dwyer of Winnetka, who trains with Phelps in Baltimore and swam with him on the winning 4 x 200 free relay in London, said in a text message.
Kevin Cordes of Naperville, a five-time NCAA breaststroke champion and 2013 world team member, and Matt Grevers of Lake Forest, winner of four Olympic golds, expressed similar sentiments in text messages.
"He brings a level of excitement and recognition that no one else can," Cordes said.
Rowdy Gaines, NBC commentator and Olympic triple gold medalist, compared the impact of Phelps' return to that of another famous comeback.
"Think Michael Jordan in 1995!" Gaines exclaimed in a text. "It will mean so much to our sport. He changed it more dramatically than anyone in history, and it will be a big boost again regardless of how he does."
Bowman reiterated that it was “too early to tell” whether Phelps would try to earn a place on the U.S. team for the 2015 World Championships. The 2014 U.S. Championships this August in Irvine, Calif. is the selection meet for the 2015 world team.
"We haven't thought past this meet," Bowman said.
Bowman had said Phelps intended to concentrate on relays and shorter events, including the 100 freestyle and 100 butterfly. He has won individual event Olympic gold medals in the 100 and 200 butterfly, 200 and 400 individual medley and 200 freestyle.
If Phelps is inclined to try to swim several of those shorter events at upcoming major meets, he would have to increase the volume and intensity of his training, Bowman said Monday.
"This season, I'd guess he'll jump right back on top of the world rankings," Grevers said. "Since it's still a tune-up season, I don't think we should expect any new world records."
Backstroker Grevers, a Northwestern grad, spoke with pride in London of having led off the victorious medley relay that was billed as Phelps' final race.
"He is my swimming idol," Grevers said.
Quadruple Olympic gold medalist Janet Evans, a three-time Olympian and the greatest distance swimmer in U.S. history, wrote in a text message that Phelps' return will lead other swimmers to feel that way.
"It is great for our sport, of course," she said. "Another generation of athletes for him to inspire and influence and a lot of attention to the sport heading into Rio."