The Santa Rosa Wilderness is a 72,259-acre (292.42 km2) wilderness area in Southern California, in the Santa Rosa Mountains of Riverside and San Diego counties, California. It is in the Colorado Desert section of the Sonoran Desert, above the Coachella Valley and Lower Colorado River Valley regions in a Peninsular Range, between La Quinta to the north and Anza Borrego Desert State Park to the south. The United States Congress established the wilderness in 1984 with the passage of the California Wilderness Act, managed by both the US Forest Service and the Bureau of Land Management. In 2009, the Omnibus Public Land Management Act was signed into law which added more than 2,000 acres (8.1 km2). Most of the Santa Rosa Wilderness is within the Santa Rosa and San Jacinto Mountains National Monument.