Part of what I wrote on another board:
...Joshua Tree National Park is very close to the Los Angeles mega-metropolis which is full of gangs and social deviants. So is particularly vulnerable to graffiti and vandalism. The first thing authorities need to do is make the crime way more financially painful than the usual wimpy penalities given for painting on some urban wall. Confiscate vehicles used to enter parks and then sell em.
An obvious way to clamp down on such graffiti is to record licence plate numbers of every vehicle entering the park which can be done automatically by robots and then creating a database which correllates dates of discovery of such vandalism with entering visitors. There are just 3 park entrances and most climbers enter from the main northwest one. Probably the same cretins are coming back for more because bragging has always been huge in that underworld culture. Once a vehicle is on a refined list and reappears coming into the park, the database could alert a team for immediate undercover survellance. Local vehicles that frequently enter the park for legitimate reasons could quickly be removed from the list. The vandals likely are carrying their paint in daypacks while being disguised in typical hiker bouldering clothing but at some point have to take out their tools and then can be seen at a distance by a team with binoculars. Instead of busting them at their parked vehicles they ought to do so when they leave the park at the gate in order to keep the survellance strategy secret.
Another obvious strategy would be to set up actual cameras using the same trigger tools wildlife biologists use to remotely capture all manner of wildlife goings on. A tagger enters a favored graffiti area through a narrow section breaking through an invisbile infared sensor beam that then starts captures.
Park authorities need to get off their d!@# butts and do something without whining about lack of funding. Get regional politicians involved. Make it happen.