We lost a very expensive digital camera there last week. Call the general information number, and they have an option for Lost and Found. They can check both parks, and City Walk. Unfortunately, they didn't have our camera, but they did have a couple of others that had been turned in.
If they don't have the option for L and F, then hit 0 for an operator. They can connect you. I was very familiar with the department after a few calls over several days. Good luck.