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Volume 26
Number 3
Winter 2009-2010
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Organ Pipe Cactus National Monument, Arizona. NPS Photo/Katy Warner. Generator noise along the U.S.-Mexico border

By Jeff Selleck
Published: 4 Sep 2015 (online)  •  14 Sep 2015 (in print)
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Organ Pipe Cactus National Monument, Arizona.

NPS/Katy Warner

Organ Pipe Cactus National Monument, Arizona.

OVER THE LAST DECADE THE UNITED STATES has emphasized the importance of securing its borders. The Secure Border Initiative (SBI) has provided for an increase in the number of Border Patrol agents and construction of border infrastructure such as pedestrian fences. The most recent addition to this infrastructure is surveillance towers that can detect, classify, and track human activity along the border. The Department of Homeland Security is planning for the construction of a network of these towers in and around Organ Pipe Cactus National Monument, Arizona, with the potential for additional towers at or near other national park units in the future.

The National Park Service is concerned about the impacts that construction, maintenance, and operation of the towers may have on natural and cultural resources, including the wilderness character of Organ Pipe Cactus National Monument and Sonoran pronghorn antelope, a federally designated endangered species that is sensitive to noise. The primary source of power for many of the planned surveillance towers will be gas-powered generators, which have been recorded at 70 dB(A) from a distance of 4 meters (13 ft). In anticipation of this project, the National Park Service documented the condition of the existing soundscape in April 2009—before construction—when staff from the Natural Sounds Program monitored ambient sound levels at several proposed tower sites and at an existing surveillance tower at an off-site location.

The results from the monitoring effort were shared with park staff in November 2009 and included an inventory of sounds recorded at each site along with their loudness, frequency, and duration. Not surprisingly, these data revealed that the sites were already impacted, to varying degrees, by border surveillance activities. National monument and Natural Sounds Program staff used this information in conference with the Department of Homeland Security to try to reduce the noise footprint of the generators. Additionally, once the towers are constructed, national monument staff will engage in long-term sound monitoring in order to document and mitigate impacts to the greatest extent possible, for the protection of wilderness values and sensitive Sonoran pronghorn.

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This page updated:  7 January 2010

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At Your Service
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Science Notes
Field Moment
Meetings of Interest
Masthead Information
From landscapes to soundscapes: Introduction to the special issue
Measuring and monitoring soundscapes in the national parks
Integrating soundscapes into National Park Service planning
Excerpt from Governors Island General Management Plan
Conserving the wild life therein--Protecting park fauna from anthropogenic noise
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Soundscape management at Grand Canyon National Park
Tools of the trade: An example of using spectrograms to count fixed-wing aircraft
Visually impaired students help collect acoustic data in Grand Canyon National Park
Protecting the acoustic conditions at Great Sand Dunes National Park and Preserve
  Generator noise along the U.S.-Mexico border
Airport expansion adjacent to San Antonio Missions
A program of research to support management of visitor-caused noise at Muir Woods National Monument
Modeling and mapping hikers’ exposure to transportation noise in Rocky Mountain National Park
Aircraft overflights at national parks: Conflict and its potential resolution
Managing the natural soundscape: The National Park Service as a learning organization
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