Since I've spent my fair share of time complaining about Googa Mooga's presence and damage to the park, I think it only fair to mention that others also treat it like crap. I just wanted to point out that the park takes a lot of abuse.
After a holiday weekend with nice weather, the park is COVERED in trash. The main official picnic areas (like the Picnic House and 9th St grill areas) were cleaned up pretty well of bagged trash by 7:30am today, but the meadows and many other areas were a huge mess. As soon as I got into Long Meadow off leash with the dog he started finding plenty of bones and meat packaging just tossed in the grass. The dog beach was loaded with floating trash (lots of drink bottles) and who knows what was at the bottom.
The Nethermead was particularly trashed--tons of food and packaging scattered all around and huge piles of trash (not all bagged). The Peninsula was probably the cleanest spot but bad enough that after a couple of minutes there, I just took the dog back in the woods to get away from the worst of the trash.
Even as the park adds more garbage cans and dumpsters, many people just throw everything down on the ground around them or don't securely bag the trash. Even bagged trash frequently gets opened by raccoons at night, who then spread it around more.
It's far from pretty in the park after nice weekends in the summer, not just holiday weekends. I don't think there's one solution but I wish people who come out to enjoy the park would do a better job of leaving it as they found it.