Common Threats to The National Parks: Anthropogenic Noise

Anthropogenic noise is one of the least understood and most common threats to National Parks. Energy development, infrastructure expansion, and urbanization create a noise footprint that fragments the acoustical landscape and restricts the natural quiet to brief intervals in most protected natural areas. A group of National Park Service retirees compiled what they considered the Parks most threatened by noise; Mount Rushmore National Monument, Hawaii Volcanoes National Park, Everglades National Park, Mojave National Preserve, and Minute Man National Historical Park. All of these Parks have anthropogenic noise in common, whether from air tours, motorcycles, all-terrain vehicles, power boats, or city traffic. The Parks where they felt visitors could still find quiet and natural sounds were; Great Basin National Park, North Cascades National Park, and Muir Woods National Monument. One reason Muir Woods National Monument is quieter has been the institution of “quiet days” within certain areas of the Park. Merely by posting signs designating quiet areas, visitors respected the call for quiet and resulting in significantly lower overall noise in these areas. Because of this success, Cathedral Grove has been dedicated as a permanent place of peace and quiet. Muir Woods National Monument found their answer to anthropogenic noise was found by changing behavior instead of other strategies such as limiting the number of visitors. In this way, the Muir Woods appealed to visitors to alter their behavior, thereby changing and restoring a more natural soundscape.

A person’s experience in nature affects how they feel and can influence a decision to visit again or support protection programs. The presence of natural sounds enhances the experience and may increase a person’s value of nature. This enjoyment of nature and wildlife can begin a feedback loop that has the ability to increase biodiversity through conservation and policies that protect natural soundscapes. “ The role of natural soundscape conditions for human experience and for processes within ecological communities is not yet fully known, but the weight of evidence suggests that soundscapes play a larger role in regulating ecological communities and human experiences than we would have ever imagined just ten years ago”. For many people, the absence of human sounds provides an opportunity for reflection and introspection. This, in turn, encourages their support of the mission of the National Parks. The National Parks can then be a space to appreciate the beauty and majesty of the wilderness and the illusion of being alone.

Pushing for more research, Dumyahn and Pijanowski focus on the impact of noise on both people and wildlife and to add value to conservation efforts. The study reports the Parks are quieter than urban and suburban communities but that noise is audible for a significant part of the day. While illustrating the parks are quieter, the goal of the National Park Service is natural quiet as outlined in their management policies. “Separation from the sights and noise originating outside wilderness is one of the primary indicators used to gauge success in wilderness preservation.” Using separation as one goal, metrics can be developed to move toward a quieter soundscape.

Dumyahn and Pijanowski propose a soundscape conservation framework for public lands with the following principles: the conservation of soundscapes can benefit by being treated like conservation of biodiversity, managing soundscapes at the landscape level, considering ecological and social values associated with soundscapes, and be consistent with public area soundscape resource management goals being proposed by natural resource agencies, such as the National Park Service. Miller feels it is important to measure both the duration of noise-free intervals and how loud human-produced sounds are relative to the natural sounds as part of soundscape quantification. Additionally, soundscapes must have management goals that recognize both spatial and temporal importance. Migrating species may depend on these visits which are temporal but still must be included in mitigation plans. To set management goals, the soundscape must first be studied, and scientifically quantified, and only then can comprehensive plans be proposed.

Noise and its Effects

'Calling noise a nuisance is like calling smog an inconvenience. Noise must be considered a hazard to the health of people everywhere.' Dr. William H. Stewart, former U.S. Surgeon General in his keynote address to the 1968 Conference on “Noise as a Public Health Hazard”. The Noise Control Act of 1972 worked to make an environment free from noise that puts health or welfare in danger but the funding was ended in 1981 by the Reagan administration and the regulations and the protections were allowed to lapse. Since that time, nothing has replaced the Noise Control Act, and therefore, no incentives to control noise. Anthropogenic noise impacts human health in many insidious ways. Increased sound decibel levels have a clear association with hearing loss but other health factors are affected. Short-term effects include increased blood pressure and heart rate. Chronic noise exposure can increase stress, and annoyance, raise blood pressure, disturb sleep, and decrease task performance. Noise-related studies point to decreases in memory, poor mood, stress recovery, and cognitive restoration. Noise interferes with workers’ ability to concentrate on difficult tasks and reduces worker efficiency. Even children are affected by chronic noise, illustrated by a greater likelihood of reading deficits and falling behind in other academic areas. Examples of common sounds and amplitude or loudness measured in decibels (dB) are breathing which is at the lower threshold of hearing at 0-10 dB, a conversation indoors is approximately 50 dB, annoyance begins at 70dB, and the usual sound level of freeway traffic, vacuum cleaner or loud party. Hearing damage begins at 100 dB and human pain at 120 dB, the level of chain saws, sirens, and thunderclaps. Daniel Fink has called noise “the new secondhand smoke” due to its well-documented effects on human health. In addition to pollution, chronic noise exposure has environmental justice implications and is an area for further study. With the multiple health deficits and possible injuries caused by noise, the desire to leave it behind and escape to the quiet of the National Park becomes clear.

Noise and Regulation

The Environmental Protection Agency (EPA) is responsible for the regulations concerning noise pollution in the United States. The National Environmental Policy Act of 1969 (NEPA) requires federal agencies to disclose an accurate description of the potential environmental impacts of proposed federal actions. The Government imposes regulations during the planning of federally-funded projects or projects on federal land utilizing NEPA. “NEPA requirements are invoked when airports, buildings, military complexes, highways, parkland purchases, and other federal activities are proposed. Environmental Assessments (EA) and Environmental Impact Statements (EIS), which are assessments of the likelihood of impacts from new projects, are required from all Federal agencies and are the most visible NEPA requirements”. NEPA does not require Federal Agencies to prepare an EIS to avoid or mitigate impacts even if mitigation is feasible.

The State of California utilizes a similar program, the California Environmental Quality Act (CEQA) governing projects that are carried out by a state agency or that require state approval or funding. CEQA is similar to NEPA but projects must additionally provide an Environment Impact Review (EIR) and attempt to mitigate environmental impacts and monitor results. The EIR must contain the environmental impact of the project, any adverse environmental effects that cannot be avoided, proposed mitigation to minimize the impact, alternatives to the project or action, and any irreversible environmental change. It requires that all stakeholders be informed of potential environmental impacts and it gives the public an opportunity to not only read the EIR, but the ability to submit a public comment before the agency acts.

Controlling anthropogenic noise is a complicated issue. Other than the National Park Service, there are no policies that govern monitoring or managing anthropogenic noise in natural areas. Oil and gas exploration, wind energy, logging, mining, and other manufacturing businesses, unless it is a government-funded projects, are not required to study or limit noise. This gap is a missed mitigation opportunity that could improve habitats and ecosystems. There are currently no incentives for private companies to curb industrial or transportation noise in natural areas and without enforced regulations, change is unlikely.

A unique way to look at soundscapes is as a common-pool resource that must be managed to the benefit of all stakeholders. Natural quiet is an example of a common property resource that is owned by all but is subject to overuse and degradation by the few if not managed in the public’s interest. In the classic paper, “The Tragedy of the Commons,” Garrett Hardin postulates that what is needed to manage a common property resource; “mutual coercion, mutually agreed upon by the majority of the people affected”. Soundscapes have key features of common-pool resources; they have multiple users, it is difficult to exclude users, it can be degraded by overuse and one user can subtract the benefits from another user. Utilizing this framework, an air tour could be impacting people on the ground and subtracting their resource of natural quiet without recognizing their impact on others on the ground. Possible common-pool resource soundscape solutions could be allocating use, limiting access, and aligning incentives. “Using common pool resource theory, it can be recognized that the soundscape has a flow of benefits to many resource users; natural sounds, ecosystem function, cultural and historical heritage, silence or natural quiet, ability to communicate with one another, and even creating a sense of place”. While limits are never desirable, the preservation of the natural soundscape may require changes in behaviors if voluntary alternatives fail. “Plainly, we must soon cease to treat the parks as commons or they will be of no value to anyone” (Hardin 1968, 1245). Government agencies must establish regulations and enforce agreed-upon rules for the benefit of all stakeholders.

Noise and Air Traffic

One source of noise in Yosemite National Park is from high-altitude commercial jets, military jets, and small aircraft used for sightseeing impacting the soundscape in Yosemite National Park. The origination and destination of the greatest number of high-altitude jets are the Bay Area airports. The Federal Aviation Administration (FAA) has organized these bay area airports into the NorCal Metroplex to create an “Optimization of Airspace and Procedures” project. The NorCal Metroplex is San Francisco International, Oakland International, Norman Y. Mineta San Jose International, Hayward Executive Airport, Palo Alto Airport, and Sacramento International Airport. These six airports account for over 2000 scheduled flights in 2017 with the number of flights going up each year.

The stated aim of the Metroplex plan is to improve the efficiency of air travel, in part, by concentrating planes on more direct routes using consistent, repeatable approaches to airports. Whereas in the past, before the implementation of the Metroplex, planes spread out across a large region with flight paths dictated by weather and pilot knowledge, planes are now directed onto specific pathways using satellite technology. Yosemite National Park is bisected by a straight line from San Francisco and other NorCal Metroplex towards airports to the east. At issue is that the Federal Aviation Administration does not consider how noise impacts quiet, natural habitats. For areas with soundscapes of less than 45 dB, the baseline for very quiet, the FAA does not consider any need to study noise impacts. It argues “it’s pointless to analyze plane noise impacts when an area is already so quiet and thus easily disturbed by minor noise increases”. In his book, “One Square Inch author Gordon Hempton perfectly describes the issue of air traffic over national parks; “The problem is that the jet noise is so much louder than the quiet ambiance: for every 3-dBA increase there is twice as much energy; for every 10-dBA increase an event will sound twice as loud.” In a January 2014 letter to the FAA, Christine Lehnertz, the NPS Pacific West regional director, specifically requested that the FAA include Yosemite National Park in its environmental assessment, noting that a significant amount of east-west air traffic in the NorCal Metroplex flies over the park and that the NPS has the extensive documentation about the frequent, negative impacts on wildlife and visitors”. The FAA responded that Yosemite National Park was outside the geographic bounds of the NorCal Metroplex and that flights were more than 18,000 feet above the ground and that it had no reason to analyze noise in Yosemite National Park. “The NPS found that aircraft were audible fifty-five percent of the day at Granite Lake near Tioga Pass; fifty-eight percent of the time at Tuolumne Meadows; and between forty-one percent and forty-nine percent at locations along the Tioga Road corridor”. Additionally, after repeated requests from the National Park Service, the FAA refused to disclose how many commercial jets fly over the national parks in the Metroplex area. While not all air travel into the NorCal Metroplex originates in the east, approximately forty-four percent of San Francisco arrivals use the Mod Star (Modesto standard terminal arrival), twenty-nine percent of Oakland arrivals, and thirty-five percent of San Jose arrivals (FAA, NorCal OAPM EA) use these route that accounts for the majority of flights that pass over Yosemite National Park. The majority of the information concerning the NorCal Metroplex routes is for the three Bay Area airports with little route information for Hayward Executive Airport, Palo Alto, and Sacramento International Airport. Therefore, the figures below do not account for all air traffic into the NorCal Metroplex that flies over Yosemite National Park. The figures below illustrate the volume of air traffic into three of the NorCal Metroplex airports in the Bay Area; San Francisco International, Oakland International Airport, and Norman Y. Mineta San Jose International Airport.