A field at Sunset Beach Park will be closed for up to five weeks because of damage caused by attendees at the 420 cannabis culture event Thursday, according to the Vancouver Park Board.

"The field is in rough shape and muddy with lots of rutting, holes and dips so staff will need to aerate, overseed and top dress it before it can be used again," said a statement from Vancouver Park Board chair Michael Wiebe.

The annual 420 event began as a protest of the criminalization of marijuana, but in recent years has had thousands congregate to smoke pot, eat pot edibles and listen to performances.

Vancouver's director of parks said the damage at Sunset Beach Park is not as bad as it has been in the past.

"Generally it's looking pretty good this year compared to last year," said Howard Normann. "I'm quite pleased with the lack of garbage."

Vancouver park board director Howard Normann holds up some of the litter cleanup crews found the morning after the 420 event. (Gian-Paolo Mendoza/CBC News)

The Vancouver Park Board said organizers helped put a lot of garbage away and city crews came and helped overnight.

"Obviously, the organizer put a lot of their garbage away and our crews came and picked up all throughout the night," said Normann.

"Now we have a final pick to do. It's not as bad as I thought it would be for garbage."

Normann, who found roaches and drug paraphernalia littered on the beach, said a crew will finish picking up the garbage Friday morning.

"People with pets who are out here — we don't want them ingesting these kind of things."

Have a look as crews clean up following the event:

Volunteers, city workers and event organizers clean-up Sunset Beach Park after the marjiuana rally. 0:38

Rain damage

While overall the park was in decent shape, Normann said the field at the park was worse than last year, in large part because of the rain.

"We didn't have to do much on the field last year because the field was very dry. It's just the way it was with the weather," he said.

But event organizer Dana Larsen said, overall, the event went well and he heard positive feedback from city officials.

"I think it was a big success," Larsen said.

As for the damage to the field, Larsen said any big celebration like the Pride Parade, which also ends at Sunset Beach, would have had a similar effect on a rainy day.

"We certainly didn't make the rain happen. We didn't try to hurt the park in any way and in a couple of weeks it will look good again," he said.

Attendees at the 420 event walk through a muddy vendor area. (David Horemans/CBC)

Normann said cleanup for the event, which had no permit, will cost thousands of dollars.

Larsen said event organizers will wait for details before determining how much they will contribute towards those costs.

"We're certainly willing to talk about that and to look at covering some or all of the costs," Larsen said.

Wiebe said it could be weeks before the bill comes in for the final cost of the cleanup, but when it does, the board will be sending it to organizers.

"Last year we didn't try to get back any of our funds, but this year we have been putting the cost together from the park board and we'll be bringing an invoice forward to the organizers."

​New location next year?

Wiebe said his staff had asked organizers to help prevent damage to the park.

"They could have put plywood down to help protect the field, but organizers didn't do that ... the fact that organizers didn't do that, it doesn't look good for us."

But Larsen said event organizers had been working with park and city officials for weeks leading up to the event, and plywood never came up as a requirement.

He said rows of wet, uneven plywood would have likely made the event unsafe for attendees.

Wiebe said the board is trying to help organizers find a new location for next year.

"People are already working on finding other locations," he said.

Sunset Beach after the cleanup crews had done their work. (Gian-Paolo Mendoza/CBC)

Hospital visits

According to Providence Health Care, St. Paul's emergency department treated 66 patients with issues related to 420.

"Patients mostly had edibles that brought on complaints of nausea, vomiting, anxiety and dizziness," wrote Ann Gibbon, a spokesperson for Providence Health Care, in an email to CBC News.

Ten of the patients were under the age of 20, with the youngest person being 14 years old.