San Luis Obispo High swimmer Alan Peterson was in an unfamiliar setting.

As he was about to dive in for the 100-yard freestyle, he knew it wasn’t his best event.

Well, it sure looked like it was.

Peterson was trailing Righetti’s Devon Tomooka until the last few yards, when he reached out to touch the finish line in 47.78 seconds to break a four-year record at the PAC 7 championships on Wednesday at Arroyo Grande High.

After the race, one of Peterson’s teammates shouted, “And that’s from a distance swimmer!”

“I’m not a natural sprinter,” said Peterson, who also won the 100 backstroke in 55.08, “so I’m usually out a little slower than the other swimmers and I try to come back a lot faster.”

He competed in the sprint event to help the Tigers earn points. The move worked, as San Luis Obispo won the boys title by edging runner-up Righetti 577-549.5 and winning three events, including having the 4x400 relay team of Peterson, Eric Erbstoesser, Nolan Morgan and Graham Johnson break its own one-year old league record in 3 minutes, 14.82 seconds.

The Tigers’ other win came in the 100 butterfly, in which Graham Johnson came in 52.78.

Arroyo Grande (426), Paso Robles (270.5) and Atascadero (175) rounded out the top five. As for the Tigers, they’ve captured 30 league titles and 12 straight under coach Rick Ernstrom.

“The guys did a great job all day long,” Ernstrom said. “Righetti gave us one heck of a fight. One heck of a fight. I couldn’t be any prouder.”

In the girls competition, Arroyo Grande claimed its seventh consecutive league title and 12th overall with 555 points — just 27.5 more than runner-up San Luis Obispo, which was followed by Righetti (347), Paso Robles (306) and Atascadero (253).

For Arroyo Grande, it all started with the Eagles’ B team of Molliann Jones, Emma Vogan, Regan Jensen and Hannah Wadlow finishing its medley relay heat in 2:01.44, enough for a CIF consideration.

But the Eagles are allowed one relay team to next week’s CIF Southern Section Championships in Riverside.

“The varsity A was up next, and they crushed their time by seconds,” Arroyo Grande coach Claudia Souder said. “And it just went from that. Every single event, we had incredible swims and it was like everyone was feeding off the excitement.”

The Eagles won after the 200 medley relay of Corryn Haynes, Kelsey Docouto, Amelia Schachter and Ashley Danell finished in 1:53.44, and the 400 freestyle relay of Schachter, Haynes, Claren Ruth and Morgan Clark came in 3:41.62.

Schachter, who’s signed with Tulane, attempted to break the PAC 7 record in the 200 medley but fell short in 2:09.85; the record is 2:08.98.

“I was aiming at the league record, but my shoulder gave out or something in the race,” she said, adding that her shoulder has been a nuisance since her freshman season. “I just deal with it. You have to stretch through practices and stuff. Occasionally, it twinges during races but it’s not too big of an obstacle.”

Six league records were set Wednesday, and all but one belonged to county swimmers.

Atascadero senior Dustin Bolt, broke his own PAC 7 records in the boys 200 and 500 freestyles in 1:43.11 and 4:35.79, respectively.

“I just wanted to swim fast, hit my goal times and paces,” he said. “I had good races with the other guys” in the competitions.

Other county record setters were San Luis Obispo’s Teagan Griffith and Paso Robles’ Ryan Springer, who both eclipsed a five-year-old mark of 54.61 in the girls 100 freestyle. Griffith won in 53.49 and Springer had a 54.28.

And the San Luis Obispo boys finished off the league championship by winning the 4x400 relay, breaking the previous mark by 1.17 seconds.

“We were safe with our starts,” Ernstrom said. “We didn’t push the starts at all. We waited on our starts. We didn’t want to risk a false start. We were very careful. I was very pleased by how it ended.”

Arroyo Grande’s Zach Stevens was a multi-event winner, as he captured the boys 200 medley in 1:59.29 and 100 breaststroke in 58.04.

Springer also won the girls 50 freestyle in 24.92, and San Luis Obispo’s Gabrielle Penvenne captured the 100 backstroke in 1:00. And the Tigers’ 200 freestyle relay team of Griffith, Penvenne, Julia Donath and Ariana Shakibnia won in 1:43.53.

Atascadero’s Claire Leong won the girls 100 breaststroke in 1:09.69.