The Valles Caldera National Preserve is a national preserve located in northeastern Sandoval County and southern Rio Arriba County, just west of Los Alamos. It protects a large portion of the Valles Caldera, an area of significant geological, ecological and cultural interest. It has a land area of and until 2015 was administered by the Valles Caldera Trust with offices in Jemez Springs. In 2014 legislation attached to the Defense Authorization Act authorized the transfer of the preserve to the National Park Service and dissolution of the Valles Caldera Trust. The transfer to NPS management took place on October 10, 2015.