When you call in you can do so as to remain anonymous. Sometimes that can still be a problem, for obvious situations, but like you say it wasn't even your house you noticed it at. Of course the only obligation here is a moral one but I mostly don't want people scared off from calling just for being identified in situations they don't have to worry.
noted, but it was next door, so I think I'd be a prime suspect.
Report anonymously saying you were driving by and saw it?
Trust me your local utilities want to know about this before it becomes an accident.