Yes, you can! The water bottle is supposed to be sealed and the food in a gallon ziplock bag, according to their guidelines (though they just did a really quick check of my bag last time I was there and didn't ask questions about anything).
You can bring in 1 un opened gal of water, 1 blanket, 1 lawn chair/ beach chair, NO FOOD!!!!
You can bring in water bottles but I don't think food is allowed.
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