Tourism helped to boost interest in recreation and conservation in the area as early as 1929, when the Lenox Garden Club established the Pleasant Valley Wildlife Sanctuary on Lenox Mountain, now owned by the Massachusetts Audubon Society. The Bousquet Ski Area opened in 1932 on the north side of the ridge at Mahanna Cobble. The New York Philharmonic gave a series of summer concerts in 1934 at the Hanna Estate, located on the lower east side of West Stockbridge Mountain. Two years later, the Boston Symphony began its longstanding seasonal residency at nearby Tanglewood, the former Brooks Estate. Beginning in the 1970s, the Berkshire Natural Resources Council and others helped to further highlight the area's recreational and scenic potential, in part by offering the invented name "Yokun Ridge" to emphasize its then relatively unrecognized continuity. Portions of Yokun Ridge are owned by the non-profit Berkshire Natural Resources Council (BNRC), the Massachusetts Audubon Society (MAS), and the towns of Lenox, Stockbridge, and West Stockbridge. The ridge and certain outlying features were designated as part of a conservation planning area in 1993 by the U.S. Forest Service under its Forest Legacy Program. Called the "Stockbridge-Yokun Ridge Reserve," it consists of 6,300 acres and is among at least five in Massachusetts authorized in 1993 by the program, which enables federal purchases of conservation easements. About in the Stockbridge-Yokun Ridge Reserve, or about 6 percent of the area, had been conserved using the Forest Legacy Program as of 2000. The northern boundary of the Stockbridge-Yokun Ridge Reserve conservation zone includes Mud Pond and its surrounding wetlands, and the outlying summit of South Mountain . Both are located in Pittsfield. In December 2010, the Berkshire Natural Resources Council closed on the purchase of 80 acres of land around Mahanna Cobble from the Bousquet Ski Area after two years of negotiation. The BNRC maintains trails through its Olivia's Lookout property on West Stockbridge and Lenox Mountain; they also manage a roadside scenic vista along Lenox Road at the Stockbridge/ Lenox border, as well as Steven's Glen, a waterfall on Lenox Mountain Brook. The Massachusetts Audubon Society (MAS) maintains a network of hiking trails at their Pleasant Valley Wildlife Sanctuary in Lenox. Cooperative agreements with towns, private landholders, and MAS and BNRC have resulted in the marking of a ridgeline trail extending from the southern end of West Stockbridge Mountain to the Bousquet Ski Area.