You are not mistaken, there is dog poop on the beach. But the majority of the waste is from the geese that hang out there.
This year there have been alot of dogs loose on the beach, thier owners letting them swim. There is a dog beach just down the park for them. The enforcement is concentrated in that area. None of that area has dog poop left on the ground.
Hopefully just making the Park aware will help the problem.
Note: some of the dogs that are running loose are from SSP users, if you see it happening, please remind them to pick up after thier dog.