Water problem? plumbing? Private spring?

[Michaela G.]

So, I've noticed this puddle of water in my front yard and thought it was the main line. But I've dug around today and my water line (left, in the picture) is about 3 feet away from the puddle. 

The line is at least 6" below the puddle surface and there's no wetness around the line. 

The meter is about 4' below the puddle surface and there's no water around it. Since water goes to the lowest point, it would have rather come out near the sidewalk, instead of the top of my yard, I think. 

It's clear water and my dog uses it as a water dish, so, it's not sewer.

I've lived in this house before for 1.5 years (moved out 5 years ago) and didn't notice this, but I also didn't do much yardwork in the front, which I'm doing now. 

What can this be? Private spring that sprung up? ;-). I'm in Atlanta, so, I don't know if we have any here. 

I did take a huge Post oak out of my backyard 2 weeks ago and don't know if that would have had anything to do with this - but don't see a connection. 

Any ideas?