I surveyed the location in person and have no conclusive answer. There's nothing here that would suggest a natural spring is present except a small puddle in the street right at the node.

Now, a puddle is not unusual to see in Seattle, but the area around here at this moment is otherwise completely dry.

Given that the node seems to have been added by a geology student at UW, and a local resident passing by that I talked to said that there is a reservoir near or under a nearby park and that the area around the node does tend to be more wet than the other streets nearby - I wouldn't remove the node without more information from the creator.

Or, maybe I'm chasing down the details of a puddle or a leaky pipe added as a joke. Either way, there is some water here!