The southernmost boundary of the sand dunes in the Buttercup area shares an international border with Mexico. The construction of the "border fence" by the U.S. Border Patrol makes this boundary quite apparent. Please try to remain at least 100' away from the fence, as this will make patrol of the fence by border agents easier, and help to ensure your safety.
Despite the fence, illegal activity remains prevalent along the border. Report any suspicious or illegal activity to the BLM Dispatch Center at 909-383-5651, but never make any encounter. Suspicious activity may be an indication of drug smuggling. Smugglers are dangerous, and your safety is at risk. Always be aware of your surroundings when you are recreating in this area.
Direct reports of illegal aliens to the U.S. Border Patrol at 1-800-901-2003.