Walk by the ever-changing graffiti wall on Portland’s eastern waterfront, and you can see what people mean when they say graffiti is an art form.

It’s bold, it’s creative, and it’s the product of obvious skill. It’s also done for the pure love of expression — no image lasts for long, no one gets paid and, aside from the other artists, there is no fame attached.

Walking around the rest of the city, however, the “tags” painted on walls, mailboxes and street signs are something else altogether. They are a form of theft, where an individual claims ownership of someone else’s property (or public property) by putting his mark on it. Artists can talk about the culture of graffiti, but really, very little of it is anything more than vandalism.

The city is considering an anti-graffiti ordinance that would penalize graffiti writers and property owners who don’t quickly remove the markings. That has drawn protests from building owners who say they are the victims of a crime, not the responsible parties.

A solution may be found in an ongoing project of LearningWorks, which puts teams of teens out on the streets removing offensive graffiti. With a little support from property owners and the city, the anti-graffiti teams could be beefed up, keeping the walls clean.

Graffiti sends a message, and when it’s allowed to stay up, the message is that this is a neighborhood where no one cares what you do.

A community effort to wipe it out should begin by treating this nuisance as what it is — criminal activity, not art.