That could be a pond. The shape of it in Google Earth certainly suggests so.

One thing I did notice that looking at the terrain from the below screenshot, from the road to the "pond" there is a very possible and distinct appearance of a track/path up to it (follow left of the yellow line and pay attention to where north is this time...see in top right corner) Being so close to the road, it somewhat makes senses, however it is hard to tell as the resolution is not that great so people can draw their own conclusions...

Link to a larger screenshot