Also Glamis Dunes, Imperial Sand Dunes Recreation Area. Roughly 45 mi (72 km) long by 6 mi (10 km) wide. Spanish word algodones translates to the English word cotton. Chocolate Mountains in background. North Algodones Dunes Wilderness; The federal government protected the northern 25,818 acres (104 km²) in the early 1980s and closed them to vehicles as part of the 1994 California Desert Protection Act (Public Law 103-433). Imperial County, CA.