This is from Imperial Sand Dunes
ORGANIZED GROUP ACTIVITIES AND EVENTS. You may not stage, carry out,participate in, or sponsor an organized event or activity without written authorization from BLM (e.g. customer appreciation days, competitive races, bands, videos, movies, etc.).
http://www.blm.gov/ca/st/en/fo/elcentro/recreation/ohvs/isdra/dunesinfo/lawenforcement/rules_regs.html