Police say too many drink-drivers caught leaving the Rhythm and Vines music festival let everyone down and put others in danger unnecessarily.
It was the 21st year the popular music festival was held, with up to 30,000 people at Gisborne's Waiohika Estate from 29 December, to the morning of New Year's Day.
Thousands of drivers were breath-tested as they left the event on the morning of 1 January, and 45 were caught over the legal breath alcohol limit, police area commander Danny Kirk said.
"No driver has the right to put other people's lives at risk; every person in and around your vehicle relies on you being in full control of it," Kirk said.
"That's 45 people who shouldn't be anywhere near the controls, operating a vehicle on the same roads we all drive.
"There is no argument that can justify driving after a night on the beers."
After the festival, police ran three checkpoints on the roads leading away the site. They also found many people not wearing seatbelts, acting Inspector Kirk said - a mix of people from the area and from out of town.
"In a crash, you risk being catapulted through the windscreen, and your excuse for not wearing a belt isn't going to save your life," he said.
Police working inside the site during the festival had made no arrests in the three days, but had been able to "mingle with the crowds and soak up the positive, fun-filled atmosphere," Kirk said.
Most festival-goers had "partied responsibly and made the weekend so enjoyable".
He said officers would continue to have a visible presence on the roads and in and around the towns in the coming days.
"Wear your belt, drive sober, and expect to see us."
This year's New Year's Eve Highlife Festival at Matakana faced seas of mud resulting from long spells of rain, while the Love Your Ways music festival in Auckland had been cancelled.
Drivers were earlier warned to leave extra time for travel and to be careful on Tai Rāwhiti roads and State Highway 2 in the region, some of which were still showing signs of damage from Cyclone Gabrielle.