Officials said Saturday's event, an unsanctioned annual celebration of marijuana smoking in the eastern part of the park, drew a larger-than-usual crowd of 10,000-15,000 and it cost the city more than $10,000 to have crews pick up the mess left behind, the San Francisco Chronicle reported Monday.
Officials said there were likely a number of reasons for the large turnout.
"The nice weather and fact it [fell] on a weekend worsened the situation," said Connie Chan, a spokeswoman with the San Francisco Recreation and Park Department.
The city said extra garbage cans and toilets aren't provided for the annual April 20 event because it is unsanctioned but extra police and ambulances are kept on hand for emergencies.
"It's almost completely unmanageable. There are no officials you can contact to deal with things so that's a frustration for us," said Lt. Simon Silverman of the San Francisco Police Department. "The people paying for all of this are going to be the taxpayers, so it's not without cost."