What are the requirements for the body of water used for tashlich?
For tashlich I'm used to joining a group, and thus somebody else figures out where to do it. But there won't be groups this year. I could of course return to any of the locations we've used in the past, but they're in public parks that are likely to be crowded, so I'd like to understand what my other options are. I know of some smaller bodies of water nearby that aren't suitable for large groups but are just fine for an individual household.
Are there requirements for the body of water, or will any water do? Is there a minimum size for a pond or creek, for example? Does it need to be naturally-occurring, or can one use a man-made pond? Are there other considerations?