San Juan National Forest
The San Juan National Forest is a 7200 km² national forest in the counties Archuleta , Conejos , Dolores , Hinsdale , La Plata , Mineral , Montezuma , Rio Grande , San Miguel and San Juan in the west of the US state Colorado . In the north it borders on the Uucompaghne National Forest and in the east on the Rio Grande National Forest . The forest occupies the southern part of the San Juan Mountains and lies west of the continental divide . In the forest are also the two wilderness areas Weminuche Wilderness and South San Juan Wilderness as well as the Piedra Area . Larger lakes are Electra Lake and Haviland Lake . The largest river is the Animas River . The Durango and Silverton Narrow Gauge Railroad , headquartered in Durango , runs through the forest . The San Juan National Forest was declared a National Forest on June 3, 1905 by Theodore Roosevelt . Cascade Creek rises in the San Juan National Forest . Part of the San Juan National Forest is also part of the Chimney Rock National Monument .