Reference Manual (RM #47) Appendix B: Authorities

DRAFT: Preliminary internal document in review/ Do not cite

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Organic Act
The Organic Act establishes and authorizes the National Park Service "to conserve the scenery and the national and historic objects and the wildlife therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations." For NPS, the acoustic environment or soundscape of park units is considered a park resource requiring the same level of protection as any other resource (air, water, wildlife, cultural resources, etc).

Redwoods Act of 1978

The Redwoods Act of 1978, affirms and clarifies the NPS mission and authority. It states: "The authorization of activities shall be construed, and the protection, management and administration of these areas shall be conducted in light of the high public value and integrity of the National Park system and shall not be exercised in derogation of the values and purposes for which these various areas have been established."

Wilderness Act of 1964 [PDF]

The Wilderness Act establishes the following definition of wilderness:
A wilderness, in contrast with those areas where man and his own works dominate the landscape, is hereby recognized as an area where the earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain. An area of wilderness is further defined to mean in this Act an area of undeveloped Federal land retaining its primeval character and influence, without permanent improvements or human habitation, which is protected and managed so as to preserve its natural conditions and which (1) generally appears to have been affected primarily by the forces of nature, with the imprint of man's work substantially unnoticeable; (2) has outstanding opportunities for solitude or a primitive and unconfined type of recreation; (3) has at least five thousand acres of land or is of sufficient size as to make practicable its preservation and use in an unimpaired condition; and (4) may also contain ecological, geological, or other features of scientific, educational, scenic, or historical value.

National Parks Overflight Act of 1987 [PDF]
In 1987, Congress enacted Public Law 100-91, commonly known as the National Parks Overflights Act. The Act mandated a number of studies related to the effects of overflights on parks and directed the National Park Service to report to Congress its results. In July, 1995, NPS Published Report to Congress on Effects of Aircraft Overflights on the National Park System. This statute attempted to deal with the noise problem from aircraft overflights in Grand Canyon National Park and is often referred to as the Grand Canyon Overflights Act. It mandated the "substantial restoration of natural quiet" in Grand Canyon National Park.

National Parks Air Tour Management Act of 2000, as amended
The National Park Air Tour Management Act was signed into law on April 5, 2000. The Act requires the Federal Aviation Administration (FAA), in cooperation with the National Park Service (NPS), to develop an Air Tour Management Plan (ATMP) for each unit of the National Park System to provide acceptable and effective measures to mitigate or prevent the significant adverse impacts, if any, of commercial air tour operations upon natural and cultural resources and visitor experiences. The plans must also cover tribal lands that are within or abutting a unit of the National Park System, or any area within ½ mile outside of a park. As amended, the act introduces an exemption for national parks with 50 or fewer flights each year, and allows for voluntary agreements between NPS and commercial air tour operators to occur as an alternative to air tour management plans.

Management Policies
4.9 Soundscape Management - The National Park Service will preserve, to the greatest extent possible, the natural soundscapes of parks. Natural soundscapes exist in the absence of human- caused sound. The natural soundscape is the aggregate of all the natural sounds that occur in parks, together with the physical capacity for transmitting natural sounds. Natural sounds occur within and beyond the range of sounds that humans can perceive, and can be transmitted through air, water, or solid materials.

The service will restore degraded soundscapes to the natural condition wherever possible, and will protect natural soundscapes from degradation due to noise (undesirable human-caused sound).

Using appropriate management planning, superintendents will identify what levels of human- caused sound can be accepted within the management purposes of parks. The frequencies, magnitudes, and durations of human-caused sound considered acceptable will vary throughout the park, being generally greater in developed areas and generally lesser in undeveloped areas. In and adjacent to parks, the Service will monitor human activities that generate noise that adversely affects park soundscapes, including noise caused by mechanical or electronic devices. The Service will take action to prevent or minimize all noise that, through frequency, magnitude, or duration, adversely affects the natural soundscape or other park resources or values, or that exceeds levels that have been identified as being acceptable to, or appropriate for, visitor uses at the sites being monitored. Cultural Soundscapes - Culturally appropriate sounds are important elements of the national park experience in many parks.The Service will preserve soundscape resources and values of the parks to the greatest extent possible to protect opportunities for appropriate transmission of cultural and historic sounds that are fundamental components of the purposes and values for which the parks were established.Examples of appropriate cultural and historic sounds include native drumming (at Yosemite National Park, for example), music (at New Orleans Jazz National Historical Park, for example), and bands, marching, cannon fire, or other military demonstrations at some national battlefield parks.The Service will prevent inappropriate or excessive types and levels of sound (noise) from unacceptably impacting the ability of the soundscape to transmit the cultural and historic resource sounds associated with park purposes.

8.2 Visitor Use - For the purposes of these policies, unacceptable impacts are impacts that, individually or cumulatively, would be inconsistent with a park's purposes or values, or
  • impede the attainment of a park's desired conditions for natural and cultural resources as identified through the park's planning process, or
  • create an unsafe or unhealthy environment for visitors or employees, or
  • diminish opportunities for current or future generations to enjoy, learn about, or be inspired by park resources or values, or
  • unreasonably interfere with park programs or activities, or an appropriate use, or the atmosphere of peace and tranquility, or the natural soundscape maintained in wilderness and natural, historic, or commemorative locations within the park, or NPS concessioner or contractor operations or services.

8.2.2 Recreational Activities - Sounds that visitors encounter affect their recreational and/or educational experience. Many park visitors have certain expectations regarding the sounds they will hear as part of their experience. The type of park unit (for example, national battlefield, national seashore, national recreation area, national park) and its specific features often help shape those expectations. In addition to expectations of muted to loud sounds associated with nature (such as wind rustling leaves, elk bugling, waves crashing on a beach), park visitors also expect sounds reflecting our cultural heritage (such as cannons firing, native drumming, music) and sounds associated with people visiting their parks (such as children laughing, park interpretive talks, motors in cars and motorboats).

Park managers will (1) identify what levels and types of sounds contribute to or hinder visitor enjoyment, and (2) monitor, in and adjacent to parks, noise-generating human activities—including noise caused by mechanical or electronic devices—that adversely affect visitor opportunities to enjoy park soundscapes. Based on this information, the Service will take action to prevent or minimize those noises that adversely affect the visitor experience or that exceed levels that are acceptable to or appropriate for visitor uses of parks.

8.2.3 Use of Motorized Equipment- The variety of motorized equipment—including visitor vehicles, concessioner equipment, and NPS administrative or staff vehicles and equipment—that operates in national parks could adversely impact park resources, including the park's natural soundscape and the flow of natural chemical information and odors that are important to many living organisms. In addition to their natural values, natural sounds (such as waves breaking on the shore, the roar of a river, and the call of a loon), form a valued part of the visitor experience. Conversely, the sounds of motor vehicle traffic, an electric generator, or loud music can greatly diminish the solemnity of a visit to a national memorial, the effectiveness of a park interpretive program, or the ability of a visitor to hear a bird singing its territorial song. Many parks that appear as they did in historical context no longer sound the way they once did.

The Service will strive to preserve or restore the natural quiet and natural sounds associated with the physical and biological resources of parks. To do this, superintendents will carefully evaluate and manage how, when, and where motorized equipment is used by all who operate equipment in the parks, including park staff. Uses and impacts associated with the use of motorized equipment will be addressed in park planning processes. Where such use is necessary and appropriate, the least impacting equipment, vehicles, and transportation systems should be used, consistent with public and employee safety. The natural ambient sound level—that is, the environment of sound that exists in the absence of human-caused noise—is the baseline condition, and the standard against which current conditions in a soundscape will be measured and evaluated.

8.4 Overflights and Aviation Uses

A variety of aircraft, including military, commercial, general aviation, and aircraft used for NPS administrative purposes, fly in the airspace over national parks. Although there are many legitimate aviation uses, overflights can adversely affect park resources and values and interfere with visitor enjoyment. The Service will take all necessary steps to avoid or mitigate unacceptable impacts from aircraft overflights. Because the nation's airspace is managed by the Federal Aviation Administration (FAA), the Service will work constructively and cooperatively with the Federal Aviation Administration and national defense and other agencies to ensure that authorized aviation activities aff ecting units of the national park system occur in a safe manner and do not cause unacceptable impacts on park resources and values and visitor experiences.

8.4.3 –General Aviation

8.4.4 Administrative Use

8.4.5 –Military Aviation

8.4.6 –Commercial Air Tour Management

8.4.7 –Permitted Overflights

8.4.8 –Airports and Landing Sites

NPS Director's Orders

NPS Director's Order #47: Soundscape Preservation and Noise Management
DO 47 directs park managers to (1) measure baseline acoustic conditions, (2) determine which existing or proposed human-made sounds are consistent with park purposes, (3) set acoustic management goals and objectives based on those purposes, and (4) determine which noise sources are impacting the park and need to be addressed by management. DO 47 also directs Superintendents to identify and minimize noise from park operations and consider protection of the acoustic environment in park planning and NEPA documents.The DO also outlines responsibilities and delegations, and provides direction for interpretation, education, civic engagement, and outreach.

NPS Director's Order #100: Resource Stewardship for the 21st Century
The National Park System and related areas face environmental and social changes that are increasingly widespread, complex, accelerating, and uncertain. Addressing these challenges requires updates of National Park Service (NPS) policy to reflect the complexity of decisions needed for resource stewardship. This Director’s Order is intended to guide the Service in taking the necessary actions to support resource stewardship to fulfill its mission in the 21st century.


NPATMA Implementing Regulations
This rule finalizes a 5,000-ft. above ground level (AGL) altitude that completes the definition of "commercial air tour operation" as required by the Act.

36 CFR Section 2.12 Audio Disturbance

Under this section the following is prohibited: Operating motorized equipment or machinery that exceeds a noise level of 60 decibels measured on the A-weighted scale at 50 feet or, if below that level, nevertheless, makes noise that is unreasonable.

36 CFR Section 2.18 Snowmobiles
Under this section the following is prohibited: Operating a snowmobile that makes excessive noise. Excessive noise for snowmobiles manufactured after July 1, 1975 is a level of total snowmobile noise that exceeds 78 decibels measured on the A-weighted scale at 50 feet.

36 CFR Section 3.15 Maximum Noise Level for Operation of Boats
A person may not operate a moving vessel at a noise level exceeding 75dB(A) measured using the test procedures in this section.

Last updated: November 19, 2021