A triple bogey on No. 17 (two balls plopped in the water) and a double on No. 18 ate him up inside.
"I play to win tournaments; that's always my main goal," the Osseo senior said. "I wasn't getting through the ball. My gloves were wet. But that's no excuse. I should have prepared better."
Yet as he pondered, there were hints of optimism.
A player who lets one foul round -- heck, one botched shot, for that matter -- affect his mood isn't long for the game of golf. It's why Charboneau later hit golf balls into a home practice net Saturday evening, was back out on the golf course Sunday and quickly turned conversation about the Tri-State Invitational toward this week's two scheduled matches and beyond.
"There's always the chance to hit a few birdies and get right back in there," he said.
Lately, that's sure been the case.
Charboneau was medalist at the 20-team Blaine Invitational at TPC Twin Cities on April 16. He backed it up three days later by winning the 27-hole Bunker Invitational at Bunker Hills in Coon Rapids, site of the Class 3A tournament.
"He has very high aspirations to be one of the best, if not the best, high school golfer in the state," Osseo coach Tim Theisen said. "I know he'll take the mistakes he put himself through and move on. He's probably one of the hardest workers I've coached in any sport. That's what you want out of your best player."
After two years of a de facto apprenticeship with Osseo's varsity golf program as a middle schooler -- "He was just a little rascal, but he hit the ball straight," Theisen said -- Charboneau advanced to state in 2009 as a freshman. He used a second-day, 4-over 76 to land in a tie for 37th in the 88-player field.
He failed to qualify a year later. During the offseason he went through a swing change with his personal instructor.
"My wrists are more up at the start of the swing rather than being stuck inside," Charboneau explained. "I've really started to get that down. I don't even have to think about it anymore. It's all muscle memory."
He was comfortable enough with the adjustment to use it in competition and get back to state last spring, finishing in a tie for 20th. Last summer Charboneau finished in a four-way tie (1-over 143 after 36 holes) atop the leaderboard at the Minnesota Junior PGA Championship at Marshall Golf Club.
He lost in a playoff, but the overall prowess led to his dream -- a scholarship offer from Southern Illinois University Edwardsville, a Division I school just outside of St. Louis.
"I knew that's where I wanted to go before I left" the official visit, Charboneau said. "I'm feeling so confident right now. I'm just really excited for competitive golf. I used to be happy with a 75. Now I'm to the point if I shoot 75, I wonder what I could have done better."