The resignation, disclosed Monday, came last month after someone anonymously gave administrators two photos posted on Facebook. Hurd's mother, Rachel, is president of the school board.
"The pictures were taken at a family party on New Year's Eve at my sister-in-law's home," Rachel Hurd said.
The home, outside Grass Valley, has been the gathering spot for the last 10 years for the large extended family.
"My brother-in-law is a big outdoor guy and "My brother-in-law is a big outdoor guy and he makes a humungous bonfire every year," said Hurd.
"Every year (my son) Dan has helped my brother-in-law build the fire up, and this year during the preparation he turned to my husband and said, 'Would it be all right if I have a beer at the party tonight?'" she recalled. "My husband thought about it and said, 'Yes, you can have one.'"
Dan had received a new camera for Christmas, and he took pictures throughout the holidays. Someone picked up the camera and snapped one photo of him holding a beer, with the label showing, and another one of him taking a sip and holding a sparkler. Dan did not realize the photos were taken.
In mid-January, Dan Hurd accompanied friends to a choral group performance at Church of the Valley in San Ramon, where he took more photos.
"He uploaded them to Facebook to show them," said Rachel Hurd, noting that there were more than 50 photos. "He plugged the camera into the computer and uploaded them. He didn't realize he'd done this to himself."
When the choral group members began to look at the photos, they and others noted the one of Dan drinking beer. Someone anonymously turned the photos into school officials.
"On Feb. 5 he was called into the assistant principal's office and confronted with the photos," said Rachel Hurd. "He admitted they were his and what the circumstances were."
Her husband met with Principal Mark Corti, who pointed out that there had been a similar incident three years before with pictures from a teen party and the ASB president at that time had had to resign.
"My husband tried to convey that the circumstances were different," recalled Hurd. But Corti felt nonetheless they had to stick by the decision that Dan should resign.
Hurd, who was elected to the school board in 2006, said she discussed it with the people at the district office and informed the other trustees.
"I came back home and said, 'We need to just go with this. Whether the circumstances were different or not, the pictures were on Facebook,'" she said.
Dan Hurd resigned from his ASB president position in front of his leadership class Feb. 12.
"For the most part, it had been kept under wraps," said Rachel Hurd. "People were surprised."
Earlier this year at Cal High, four varsity cheerleaders were suspended for two weeks after photos of them smoking a hookah were turned in anonymously to the school.
"The policy is a school-by-school thing," said district spokesman Terry Koehne. "Schools often ask students involved in co-curricular activities to sign codes of conduct around things like alcohol and drugs, smoking, those kinds of things."
The Californian, the student newspaper at Cal High, ran a story March 10 about Dan Hurd resigning his elected office, which someone, again anonymously, delivered to a local news source.
Cities in the San Ramon Valley have social drinking ordinances but they only apply to adults supplying alcohol when hosting parties at their homes.
Dan Hurd is an Eagle Scout and has worked at a Boy Scout camp for the last three summers teaching merit badges. He is also on the springboard diving team at Cal High, and he is the student representative to the Cal High Parent Teacher Student Association.
"This was a student who may have made a mistake but he acknowledged it and acted responsibly," Koehne said. "The school dealt with it consistent with their practice and policy - now let's just move on."