Serpentine walls, usually with stone snake heads, are a frequent feature of the ceremonial stone landscapes of eastern North America, as you imply here, bat400. They tend (there are always exceptions in these things, especially since these places were probably built by different groups at different times) to be in low areas and/or places with springs and marshes. Other features are usually found in the same place, but that is the nature of these sites, many different features together.
This construction is almost certainly unrelated, but I'd still be curious to know what the closest body of water is and how far away it is.
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