NPS Photo

Figure 1. Technicians deployed acoustical monitoring equipment at Lake Mead National Recreation Area, this setup at site LAME009. The anemometer on the left is used to determine wind speeds. The microphone on the right is topped with a metal spike to prevent birds from landing on the foam windscreen. This equipment was used to document the extraordinary quiet of the wilderness areas at Lake Mead.

Wilderness plays a significant role in the lives of wildlife and people, whose activities in wilderness may benefit from its solitude and associated quiet. For example, sounds can have a profound effect on the perceived quality of an image or visual landscape (Benfield et al. 2010). Lake Mead National Recreation Area (NRA), particularly its nine designated wilderness areas, is home to many animals of special concern. Most animal species rely on a quiet environment for life-sustaining activities such as locating prey, finding mates, predator detection, and basic communication. Animals such as the Sonoran pronghorn (Antilocapra americana sonoriensis) avoid loud areas, which reduces their range and often fragments their habitat (Landon et al. 2003). Increased human activity is reducing suitable habitat for animals throughout the United States therefore it is important to preserve and protect wilderness resources.

Beyond providing habitat for wildlife, wilderness areas also contain many cultural resources and meanings important to people. The Spirit Mountain Wilderness in Nevada is significant and sacred to the Yuman-speaking tribes, used in ways according to their traditions. Modern sounds can have an impact on the traditional ceremonies and aesthetics of what is considered sacred land.

Lake Mead NRA, on the Nevada-Arizona border, comprises 607,028 ha (1,499,966 ac), including nine wilderness areas totaling approximately 75,187 ha (185,787 ac). Adjacent and potential wilderness-designated lands bring the total wilderness to more than 291,575 ha (720,482 ac) in size. Despite these designations, the western border of Lake Mead NRA lies only 9.7 km (6.0 mi) from Las Vegas, and its eastern boundary abuts Grand Canyon National Park.