BOULDER — Matt Kelley surveyed the scene at Boulder High’s season-ending lacrosse playoff loss last spring. Players were genuinely hurt by the loss and were leaning on each other for support.

After a decade of building the BHS squad from scratch, something in that moment confirmed to Kelley that he’d finally gotten the squad on a solid foundation.

“They were a true team at that point,” Kelley said Thursday. “They were depending on each other. We’d never seen that at Boulder High with lacrosse.”

Kelley’s pride in the program he’d built only made his decision to resign this week more difficult. Kelley handed in his resignation on Wednesday, having led BHS since the Boulder Valley School District team split into separate squads at Boulder, Fairview and Monarch 10 years ago.

“It was really tough,” Kelley said. “The group that they have right now, they’re extraordinarily talented. Going forward, Boulder really should come on the scene big time.”

Kelley said he’d planned on the coming spring season to be his last so he and his wife could start a family. But with twins due at the end of May — and more likely to arrive in late April or early May — the coach didn’t feel he’d be able to give the team the attention it deserved as he and his wife prepare.

“He’s done a fabulous job of building our lacrosse program here,” BHS athletic director Melissa Warfield said. “He teaches them so many life lessons along the way.”

Warfield is accepting applications for the position immediately.

Assistant coach Kyle Burto had been a sort of coach-in-waiting as Kelley groomed him to take over the program the last few years. But as an hourly paraprofessional with the district, he is not allowed to serve in a paid coaching position unless he were to get a salaried teaching position.

As for Kelley, he said he’s done coaching for awhile. But he said he’d like to get back into it someday, perhaps with his close friend and former Alexander Dawson coach Travis Aldrich.

“Down the road I’ll come back to it,” Kelley said.