The organiser of a rain-drenched Northland music festival says the event will be back at the end of the year but with lessons learned from this summer's three-day mud bath.

Northern Bass was held near Mangawhai from 29 to 31 December and was hit by 114 millimetres of rain, leaving 10,000 revellers in a quagmire.

Some festival-goers vented their frustration on social media, complaining of camping in ankle-deep mud, cars stuck in swamped paddocks, overflowing loos and a lack of drinking of water.

Director Gareth Popham said the festival was by far the most challenging one he had run, due to what he described as unprecedented amounts of rain.

However, he said some of the claims made on social media were not accurate, and customers who had been in touch directly appreciated efforts to keep the event going despite days of rain.

"A lot of them seemed to understand they were coming to a three-day festival that was predicted to have bad weather, and they decided to come," Popham said.

"Some of them prepared for it and some didn't, and we did our best to make it safe as possible for those people that did decide to come and enjoy it."

Popham said the Settlement Road site had also copped a huge amount of rain in February - that deluge wiped out a bridge at nearby Langs Beach - but at that time there weren't 10,000 festival-goers and 700 staff on site.

Popham said the crowd was slightly smaller than usual because he cut off ticket sales early, due to concerns about how many people the site could handle given the forecast weather.

Once he knew the rain was coming he had extra gravel brought in for vehicle access, but that could not be done in the parking paddock because it was a working farm for the rest of the year.

He also brought in large quantities of mulch for the paths around the campground.

"But that only does so much if the rain just keeps coming. It's fine to mulch at the start of the festival, then in the morning after it's rained, but when it keeps raining every hour on the hour, or consistently for five or six hours at a time, mulch only handles so much - especially with so much foot traffic."

Early on 31 December staff brought in two truck-loads of pallets and used them to build raised walkways, then covered them with astroturf so they weren't slippery.

"I know a lot of media's picked on the complaints .. but we've had a lot of love from our customers saying, 'we can't imagine what you guys are going through' and 'we really appreciate waking up in the morning and seeing you've got diggers on site and you're building bridges and walkways'."

Popham acknowledged there were problems with the water supply, but said claims there was no drinking water on site were not accurate.

He said there were many outlets across the festival site, some of which ran out at times.

That was compounded by problems with the Wellsford town water supply, which meant it took longer to get water onto the site.

Some injuries were reported but nothing out of the ordinary for a festival of its size.

Popham said it had been a tough few years with Covid cancellations and Welcome to the Jungle - another festival that had been planned to use the same site - cancelled in January due to Cyclone Gabrielle.

However, the 13th Northern Bass festival would "definitely" go ahead in December 2024, he said.

"This was the first time we've gone through something like this on this site, so there's lots of learnings from that. We know now, if that amount of rain comes in, where that water goes, and what effect that has.

"There's lots of things we can do with pre-warning."

All festival-goers managed to leave the site by Monday afternoon, with diggers and all-terrain vehicles used to tow festival-goers' cars out of the mire.

About 90 staff remained on site working on the pack-down, with that number set to drop to five in two weeks' time.

Headline acts at the 2023 festival included drum 'n' bass heavyweights Goldie, Sub Focus, Lee Mvtthews, Netsky and Dillinja.

This story was originally published by RNZ