– Megan Kalmoe kept saying it, and writing it on her website: There was no reason to obsess over the water quality in Rio, and there was certainly no reason to let potential problems with the water overshadow her sport at the apex of competition.

Turns out the Minneapolis native was right. After all of the doomsday predictions about the water in Rio, it turns out the only objects to worry about were the other boats.

Kalmoe’s U.S. quad sculls rowing team, the defending world champion, failed to medal Thursday, finishing fifth in the finals won by Germany.

Then Kalmoe vanished. Her mother, Mary Martin, had not seen her an hour after the race. A USOC staff member couldn’t locate her. She did not walk through the mix zone to conduct interviews, even though at least two of her teammates did.

At what might have been the end of a successful decade of competing internationally, Kalmoe went out not with a roar but with a couple of tweets.

They read:

• “This is a hard way to go out, because I don’t feel this performance reflects everything our team has gone through together. I am sorry.” She added a blue-heart emoticon.

• “Hurting pretty badly right now because I let my team down. PTC women have been my strength for 10 years — I wanted to win [Thursday] for all of you.”

PTC stands for Princeton Training Center, where Kalmoe has trained for much of the past decade.

Everyone knows what Olympic success looks like for Americans. Medals. Appearances on morning television. Parties. Chants of “U-S-A.”

Everyone knows what high-profile failures look like, too. We see anger. We see tears.

When her scull passed the finish, well out into Rodrigo de Freitas Lagoon, Kalmoe seemed to collapse in exhaustion and sorrow.

There were no TV cameras focused on her face as she recovered, reached shore and headed wherever she was headed.

“We’re very proud of her,” Mary Martin said. “Go, USA!

“They had a good run, and I think today they were beaten by boats that were more effective. That’s rowing.”

Two weeks ago, Kalmoe said her post-Olympic plans were to move to San Diego with her fiancé and relax. She sounded certain she would retire.

“I don’t know,” Martin said. “She has been talking about retiring. I wouldn’t be surprised if she retired, and I wouldn’t be surprised if she decided to row another cycle.”

Kalmoe’s team finished fifth in the double sculls in Beijing in 2008, then her quads team won bronze in London in 2012. Her quads team won the gold at last year’s world championships.

“It was not the result we were hoping for, but we went out there and did our best to just leave everything we could out on the course,” said Tracy Eisser, who teamed with Kalmoe, Adrienne Martelli and Grace Latz. “This is an incredibly talented field. All of these women have a lot of sculling experience, they’re all very fast. I think on any given day any three boats could have medaled. But today just wasn’t our day.”

At times, Eisser had trouble keeping her lower lip from trembling. When four years — or 10 years — of training comes down to one fast race, emotion can range from anger to relief.

“We were just trying to have faith in our training and confidence in our abilities,” Eisser said. “We trained with the fastest women in the world. We know we are just as skilled and just as fit as any of them, so we just tried to rely on all of the training we had done, all the work we’ve put in.”

If there was a consolation, it was the beauty of the setting. The lagoon, north of Copacabana Beach, is picturesque, and was sunny on Thursday.

It was a nice day to have your heart broken.

“It really is beautiful here,” Eissen said, with one last wistful look toward the water.