The Imperial Sand Dunes Recreation Area (ISDRA) is a large sand dune field located in the southeastern portion of California near the border with Arizona and the Mexican state of Baja California. The field is approximately 45 miles long by 6 miles wide and extends along a northwest-southeast line that correlates to the prevailing northerly and westerly wind directions. Also known by the name of the "Algodones Dunes" refers to the entire geographic feature, while the administrative designation for that portion managed by the Bureau of Land Management is the Imperial Sand Dunes Recreation Area (sometimes called the Glamis Dunes). The ISDRA is split into many different sections. These sections include Gordon's Well, Buttercup, Midway, and Patton's Valley.
Because the Colorado River flowed through very flat terrain, the course of the river varied over a wide area, being periodically diverted in one direction or another by silt deposits remaining after floods. Sometimes the river flowed into the Gulf of California, as it does today; other times it turned westward toward the Salton Sink. Each time the Salton Sink received the river flow, a large freshwater lake called Lake Cahuilla formed. The last Lake Cahuilla covered much of the Imperial, Coachella and Mexicali Valleys as late as 1450. The most popular theory holds that the Algodones Dunes were formed from windblown beach sands of Lake Cahuilla. The prevailing westerly and northwesterly winds carried the sand eastward from the old lake shore to their present location which continues to migrate southeast by approximately one foot per year.
The ISDRA offers a world-class recreation experience and is one of the largest off-road recreation areas of its kind in the United States.