Kudos to Santa Rosa Police, who stayed up late on Wednesday to stake out the Prince Memorial Greenway, where gang-related graffiti has been spreading like a bad rash in recent weeks.

According to Mary Callahan's brief report in today's paper, city crews painted over the markings early Wednesday, and police then put the area under surveillance Wednesday night. Officers were watching around 11:30 p.m. when they saw two men spray-painting new graffiti onto the walls, authorities said.

Police arrested Joseph R. Spratling, 21, and Felix Fernando Carreon III, 18, for suspected vandalism with a gang enhancement that would earn them stiffer penalties with a conviction.

To which I say: Keep up the good work.

And I mean that literally. Graffiti, and increasingly gang graffiti, is a constant problem along the Greenway. Allowing it to proliferate is an embarrassment and a disgrace to our city.

We've spent $25 million to create the Greenway, which is often called a "crown jewel" of Santa Rosa. Stretching from the front door of City Hall to the West End neighborhood, it is a linear park, a transportation corridor, an urban waterway, a tourist attraction.

It is usually a pleasant oasis in the middle of the city, but sometimes it can be scary. Then-City Councilwoman Veronica Jacobi was mugged on the Greenway several Fourth of Julys ago while riding her bike home at dusk. Knots of youngsters sometimes gather in the shadows on weekday afternoons to smoke pot. Homeless people sleep in the weeds alongside the trail west of Third Street.

Still, the majority of Greenway denizens are people out enjoying themselves — strolling, running, walking, biking and playing in and around the creek. As a regular user of the trail, I consider it safe.

But that can change very quickly and easily, and that change can start with the kind of graffiti that popped up in the past few weeks.

The pictures of graffiti at left were taken on Thursday, after Wednesday night's arrests. This is not the kind of welcome mat that Santa Rosa wants to lay out for tourists. When this kind of stuff is spray-painted at the entrance to shadowy tunnels running underneath Highway 101, it discourages ordinary citizens from using the Greenway for recreation or transportation. Smart people might choose instead to take their chances playing or walking in the streets.

Portions of the Greenway have been turned into artists' canvas, including large murals painted on bridge supports, a colorful mosaic tile mural (see photo at left) and a lovely and creative series of wall paintings with an anti-littering message along the walkway connecting the Greenway with the Joe Rodota Trail. These art pieces are, for the most part, graffiti-free.

The challenge is to keep the rest of the Greenway as clean and welcoming as the portions that the taggers leave alone. There doesn't appear to be a simple solution; a mural that was painted under the freeway became a target for graffiti and, when the graffiti was painted over, the blank walls became a canvas for the gang messages that led to Wednesday's stakeout.

More stakeouts, and more arrests, may be what it takes to keep our "crown jewel" polished. Particularly when we offer blank walls such as the one in this picture, which seems to be calling out to every idiot with a can of spray paint. How long do you think this will stay graffiti-free?