Sharraxaadda

I'm so tired of seeing the Walnut Creek Trail being used for dirt biking. I find it disrespectful, as these illegal users create ruts in the grass next to the trail because they don't stay on the asphalt, throw mud and gravel onto the trail when they take shortcuts, and do this all without fear of consequences. What is the most that can be done to these habitual offenders if they're apprehended?