The Golden Gate National Recreation Area posted a photo on Instagram that taken at Fort Mason on Saturday.
This is certainly one of the best spots in the city to take in a beautiful view of the Golden Gate Bridge and enjoy the sunny weekend.
But the mess left behind was so bad, the National Park Service took to a few social media platforms to chastise whomever was responsible.
The Golden Gate Recreation Area took to Twitter to post a photo of all the trash left behind at the park.
Seriously? Why would people treat their public park this way? Who do they think will clean this, at what cost? Sheesh pic.twitter.com/UVOwlCq9x9— Golden Gate NRA (@GoldenGateNPS) March 15, 2015
According to the National Park Service, several volunteers arrived at the Fort Mason park earlier Sunday to clean up the mess.
Regular visitors to the park say people are usually very good about cleaning up their picnic waste.
But a couple people said there was a special event taking place Saturday and that may be why so much trash was left behind.
ABC7 News spoke with people who were shocked at the amount of trash seen in the National Park Service's Twitter picture.
"This is a beautiful park and a big thing that people do in San Francisco is hang out at the parks and to see that people left it in that condition is really disheartening," Jessica Rivas said.
"I understand why, everyone's here trying to have a good time and the weather is nice and people are partying, but it's our city and we should do more to keep it clean," Brendan Joyce said.
Fort Mason isn't the only park in the city that's been left trashed. Garbage is continually cleaned up at Dolores Park in the Mission District.