UNITED STATES DEPARTMENT OF THE INTERIOR 

NATIONAL PARK SERVICE 

FINAL ENVIRONMENTAL IMPACT STATEMENT 

PERSONAL WATERCRAFT RULEMAKING 

GLEN CANYON NATIONAL RECREATION AREA 

Arizona and Utah 

Lead Agency: Department of the Interior, National Park Service, Intermountain Region 

This final environmental impact statement evaluates three alternatives for managing the use of 

personal watercraft at Glen Canyon National Recreation Area. Two alternatives would allow personal 

watercraft use under defined conditions. The third alternative would eliminate personal watercraft use 

within the recreation area. 

Alternative A would allow personal watercraft use identical to that before September 2002 under a 

special regulation. Personal watercraft use would be authorized for all areas of the recreation area 

above Glen Canyon Dam except where prohibited by the Superintendent’s Compendium, 2002. A lake 

management plan that would comprehensively consider all lake uses would be developed to manage 

the effects on resources by all watercraft use. 

Alternative B (modified preferred alternative) would allow personal watercraft use in the recreation 

area under a special regulation with additional management restrictions. Personal watercraft use would 

be prohibited in portions of the Colorado, Escalante, Dirty Devil, and San Juan Rivers to increase 

protection of environmental values and reduce visitor conflict. To further reduce visitor conflict and 

improve visitor experience, speed restrictions would be imposed in a section of the Escalante River. 

Under this alternative, all personal watercraft two-stroke carbureted engines would be prohibited at the 

end 2012. Educational programs and materials would be enhanced to provide more information to 

visitors on watercraft use and safety as well as recreation area resources. Development of a monitoring 

program to evaluate the effects of personal watercraft use on recreation area resources would be 

emphasized. A lake management plan that would comprehensively consider all lake uses would be 

developed to manage the effects on resources by all watercraft use. 

Under Alternative C, the no action alternative, all personal watercraft use within the recreation area 

would be prohibited, based on the year 2000 National Park Service personal watercraft rule. A lake 

management plan would be developed under the no action alternative to address the cumulative effects 

of all watercraft use on Lake Powell. 

The potential environmental consequences of the actions are addressed under each alternative, 

including impacts on natural resources, cultural resources, visitor experience and safety, 

socioeconomic resources, and management and operations. 

Kitty L. Roberts, Superintendent 

Glen Canyon National Recreation Area 

P.O. Box 1507 

Page, Arizona 86040 

For further information about this document, write the above address or call (928) 608-6272 

United States Department of the Interior • National Park Service • Glen Canyon National Recreation Area 

FINAL ENVIRONMENTAL IMPACT STATEMENT v

EXECUTIVE SUMMARY 

FINAL ENVIRONMENTAL IMPACT STATEMENT 

FOR THE PERSONAL WATERCRAFT RULEMAKING 

GLEN CANYON RECREATION AREA 

Glen Canyon National Recreation Area encompasses 1,254,306 acres of land and water in northern 

Arizona and southeastern Utah. Its southern boundary is contiguous with the Navajo Nation. Other 

boundaries adjoin Grand Canyon National Park, Capitol Reef National Park, Canyonlands National 

Park, and Rainbow Bridge National Monument, all managed by the National Park Service (NPS). The 

recreation area also adjoins areas administered by the Bureau of Land Management that include Grand 

Staircase – Escalante National Monument, Vermilion Cliffs National Monument, and Paria Canyon 

Wilderness. 

Lake Powell is the predominant physical feature. At full pool (3,700 feet above sea level), it occupies 

about 163,000 surface acres, stores approximately 27 million acre-feet of water, and has about 

1,960 miles of shoreline. More than 2 million people visit Glen Canyon National Recreation Area each 

year. 

PURPOSE AND SIGNIFICANCE OF GLEN CANYON NATIONAL RECREATION AREA 

National park system units are established by Congress to fulfill specific purposes, based on the unit’s 

unique and “significant” resources. A unit’s purpose, as established by Congress, is the foundation on 

which later management decisions are based to conserve resources while providing “for the enjoyment 

of future generations.” The purpose and significance of Glen Canyon National Recreation Area and its 

broad mission goals are derived from its enabling legislation and are summarized the recreation area’s 

General Management Plan (NPS 1979a) and Strategic Plan (NPS 2000g). 

Glen Canyon National Recreation Area was established in 1972 (PL 92-593) “to provide for public 

outdoor recreation use and enjoyment of Lake Powell and lands adjacent thereto . . . and to preserve 

scenic, scientific, and historic features contributing to public enjoyment of the area.” The recreation 

area’s primary management objective, as established in the General Management Plan (NPS 1979a), 

is “to manage the recreation area so that it provides maximal recreational enjoyment to the American 

public and their guests.” 

The recreation area’s enabling legislation states: 

The secretary shall administer, protect, and develop the recreation area in accordance with the 

provision of the [Organic Act] . . . and with any other statutory authority available to him for 

the conservation and management of natural resources (16 United States Code, Section 459f5(a)). 

This act also specifies that “nothing . . . shall affect or interfere with the authority of the Secretary . . . 

to operate Glen Canyon dam and reservoir” for the purposes of the Colorado River Storage Project 

Act, the achievement of which is the responsibility of the Bureau of Reclamation. 

As stated in the General Management Plan (NPS 1979a) and Strategic Plan (NPS 2000g), Glen 

Canyon National Recreation Area is significant because: 

It offers a tremendous diversity of both water-based and land-based recreational opportunities. 
EXECUTIVE SUMMARY

vi GLEN CANYON NATIONAL RECREATION AREA

It contains Lake Powell, the second largest man-made lake in North America, which provides 

both a unique opportunity for recreation in a natural environment and a transportation corridor to 

remote backcountry areas of Glen Canyon National Recreation Area. 

It is in the heart of the Colorado Plateau region, which offers a unique combination of water and 

desert environments. It offers a natural diversity of rugged water and wind carved canyons, 

buttes, mesas, and other outstanding physiographic features. 

The climate and physical features have created local environments favorable to the preservation 

of scientifically important objects, sites, populations, habitats, or communities that are 

significant in and of themselves or provide opportunities to add to our understanding of past or 

ongoing events. 

It possesses evidence of 10,000 years of human occupation and use of resources, which provides 

a continuing story of the prehistoric, historic, and present-day affiliation of humans and their 

environments. 

It constitutes a significant part of the outstanding public lands of the Colorado Plateau. 

The recreation area offers a diversity of land and water-based recreational opportunities. The area’s 

major recreational resource is Lake Powell, a 186-mile-long reservoir at full pool that was created 

when the Colorado River was dammed. Boating is very popular on the lake, including the use of 

personal watercraft, houseboats, powerboats, tour boats, canoes, kayaks, and sailboats. Other popular 

activities include fishing, camping, waterskiing, hiking, photography, and driving for pleasure. 

PURPOSE AND NEED FOR ACTION 

The purpose of and the need for taking action is to evaluate a range of alternatives and strategies for 

the management of personal watercraft use at Glen Canyon National Recreation Area. The goal is to 

ensure the protection of recreation area resources and values while offering recreational opportunities 

as provided for in the recreation area’s enabling legislation, purpose, mission, and goals. Upon 

completion of this process in accordance with the National Environmental Policy Act, the National 

Park Service may take action to adopt special regulations to manage personal watercraft use at Glen 

Canyon National Recreation Area. Alternately, it may discontinue personal watercraft use at this unit, 

as allowed for in the National Park Service March 21, 2000 personal watercraft rule. 

More than one million personal watercraft are estimated to be in operation today in the United States 

(NMMA 2001b). Sometimes referred to as “jet skis” or “wet bikes,” these vessels use an inboard, 

internal combustion engine powering a water jet pump as its primary source of propulsion. They are 

used for enjoyment and are capable of speeds in the 60-mph range. The Personal Watercraft Industry 

Association believes that through the 2002 model year the output on a limited number of higher rated 

models was around 155 and 165 hp (PWIA 2002b). National personal watercraft ownership increased 

every year between 1991 and 1998; the rate of annual increase peaked in 1994 and dropped slightly in 

1999, 2000 and 2001. While personal watercraft use remains a relatively new recreational activity, it 

has occurred in 32 of 87 national park system units that allow motorized boating. 

Studies in Everglades National Park showed that personal watercraft use resulted in damage to 

emergent and submerged aquatic vegetation, adversely impacted shorebirds, and disturbed the life 
Purpose and Need for Action

FINAL ENVIRONMENTAL IMPACT STATEMENT vii

cycles of other wildlife. As a result, the National Park Service prohibited personal watercraft use by a 

special regulation at Everglades National Park in 1994. 

In recognition of its duties under its Organic Act and NPS management policies, as well as increased 

awareness and public controversy about personal watercraft use, the National Park Service 

subsequently reevaluated its methods of personal watercraft regulation. Historically, the National Park 

Service had grouped personal watercraft with all vessels; thus, personal watercraft use was allowed 

when a unit’s superintendent’s compendium allowed the use of other vessels. Later the National Park 

Service closed seven units to personal watercraft use through the implementation of horsepower 

restrictions, general management plan revisions, and park-specific regulations such as those 

promulgated by Everglades National Park. 

In May 1998 the Bluewater Network filed a petition urging the National Park Service to initiate a 

rulemaking process to prohibit personal watercraft use throughout the national park system. In 

response to the petition, the National Park Service issued an interim management policy requiring 

superintendents of units where personal watercraft use could occur but had not yet occurred to close 

the unit to such use until the rule was finalized. 

The National Park Service envisioned the servicewide regulation as an opportunity to evaluate impacts 

of personal watercraft use before authorizing the use. On March 21, 2000, the National Park Service 

issued a final regulation prohibiting personal watercraft use in most units and required 21 units to 

determine the appropriateness of continued personal watercraft use. Specifically, the regulation 

allowed the National Park Service to designate personal watercraft areas and to continue their use by 

promulgating a special regulation in 11 units and by amending the units’ superintendent’s 

compendium in 10 units, including Glen Canyon National Recreation Area (36 CFR 3.24(b), 2000). 

The National Park Service based the distinction between designation methods on each unit’s degree of 

motorized watercraft use. 

In response to the personal watercraft final regulation, Bluewater Network sued the National Park 

Service, challenging NPS’s decision to allow continued personal watercraft use in 21 units. In 

response to the suit, the National Park Service negotiated a settlement. Each of those units desiring to 

continue long-term personal watercraft use must promulgate a unit-specific special regulation. 

Consistent with this agreement, personal watercraft use at Glen Canyon National Recreation Area 

would have been suspended after September 15, 2002 until a recreation area-specific special 

regulation was completed. 

However, the proposed September 16, 2002, prohibition of personal watercraft at Glen Canyon was 

averted with the execution of a stipulated modification to the settlement agreement. The modified 

settlement agreement was approved by the court on September 9, 2002, and extended unrestricted 

personal watercraft use in selected NPS units until November 6, 2002. Following this date, personal 

watercraft are prohibited in the recreation area until such time the final rule is published. 

On January 17, 2003, the National Park Service published a draft rule for the operation of personal 

watercraft at Glen Canyon National Recreation Area. The draft rule for personal watercraft use is 

based on Alternative B (the preferred alternative) in the Draft Environmental Impact Statement. The 

60-day public comment period on the draft rule ran from January 17 to March 18, 2003. 

The settlement stipulates that the National Park Service must evaluate its decision to issue a unitspecific special regulation to allow personal watercraft use through an environmental analysis 

conducted in accordance with the National Environmental Policy Act. The National Environmental 
EXECUTIVE SUMMARY

viii GLEN CANYON NATIONAL RECREATION AREA

Policy Act analysis at a minimum, according to the settlement, must evaluate personal watercraft 

impacts on water quality, air quality, soundscapes, wildlife, wildlife habitat, shoreline vegetation, 

visitor conflicts, and visitor safety. 

OBJECTIVES AND SCOPE OF ANALYSES 

Objectives were established to determine whether alternatives for managing personal watercraft use at 

Glen Canyon National Recreation Area would be successful. All action alternatives had to 

substantially meet all of the objectives and also had to resolve the purpose of and need for action. 

Objectives for managing personal watercraft use were developed from the Glen Canyon National 

Recreation Area enabling legislation, mandates, and direction in the general management plan, 

strategic plan, and other management documents. All objectives are compatible with the purpose and 

significance statements of Glen Canyon National Recreation Area presented above. 

The scope of the environmental analysis is to examine a range of management alternatives for personal 

watercraft use at Glen Canyon National Recreation Area. 

Motorboats and other watercraft have been used in Glen Canyon National Recreation Area since its 

establishment in 1972. Personal watercraft use has emerged at the recreation area only since the 

introduction of this type of vessel in the 1980s. Prior to 2000, personal watercraft use was allowed 

throughout Glen Canyon National Recreation Area except in areas below Glen Canyon Dam that were 

closed to personal watercraft use in the superintendent’s compendium. In March 2000, the waters 

below the dam were closed by provisions of the NPS personal watercraft rule. Therefore, waters below 

the dam are not considered in this environmental impact statement. 

Those waters of the recreation area above the dam where personal watercraft use could occur in any 

capacity, as identified in the Superintendent’s Compendium (NPS 2002c), are within the scope of this 

analysis. These areas include Lake Powell and the Colorado, San Juan, Dirty Devil, and Escalante 

Rivers from Lake Powell upstream to the boundary of the recreation area. 

The National Park Service acknowledges that other watercraft may affect resources. However, other 

watercraft were not the subject of the March 21, 2000 rule, and were not part of the Bluewater 

Network lawsuit and subsequent settlement agreement. Therefore, other watercraft will not be 

included in any upcoming rule-making, and are not a primary focus of this impact assessment. Nonethe-less, for each impact topic, the effects of other watercraft are evaluated in the cumulative effects 

analysis. 

IMPACT TOPICS REQUIRED UNDER THE SETTLEMENT AGREEMENT 

Under provisions of the settlement agreement, the National Environmental Policy Act analysis at a 

minimum must evaluate personal watercraft impacts on water quality, air quality, soundscapes, 

wildlife, wildlife habitat, shoreline vegetation, visitor conflicts, and visitor safety. The national and 

Glen Canyon National Recreation Area-specific issues relative to each impact topic are summarized 

below. 
Impact Topics Required Under the Settlement Agreement

FINAL ENVIRONMENTAL IMPACT STATEMENT ix

Water Quality 

Water quality issues from the national perspective are that personal watercraft engines (especially the 

widely used, carbureted, two-stroke engines) discharge up to 30% of their fuel as uncombusted 

constituents into surface waters during operation. In sufficient concentrations, these constituents can 

adversely affect human health and aquatic organisms. Chemical constituents of particular concern 

include benzene, ethylbenzene, toluene, xylenes, polycyclic aromatic hydrocarbons, and methyl 

tertiary-butyl ether. 

These concerns are relevant in the recreation area, particularly because of the potential to affect or 

degrade water quality for fish and other aquatic life, agricultural water supply, livestock watering, 

drinking water, and recreation uses. There also is concern that the introduction of human waste into 

Lake Powell by personal watercraft users who do not have access to toilets may contribute to water 

quality degradation. 

Air Quality 

Air quality issues from the national perspective are that personal watercraft engines (especially the 

widely used, carbureted two-stroke engines) discharge large amounts of air pollutants, such as 

nitrogen oxides, carbon monoxide, particulate matter, and volatile organic compounds. All of these 

emissions can adversely affect air quality. In areas with high personal watercraft use, there was 

concern about air quality degradation. 

From the recreation area perspective, issues included visibility effects that may occur from the 

discharge of exhaust smoke into the air, especially at marinas and popular launch facilities. 

Photochemical transformations of the engine emissions that could affect visibility conditions in the 

recreation area also were a concern. 

Soundscape 

Nationally, many recreationists who do not use personal watercraft find the noise from these vessels to 

be annoying. Sounds from personal watercraft are identified as being more disturbing than sounds 

from other watercraft because of numerous changes in pitch associated with frequent turns and 

changes in speed. Other issues are related to the potential for personal watercraft noise to disturb 

wildlife, including waterfowl and nesting birds. 

In the recreation area, there is concern that personal watercraft produce noise that could affect 

recreation area soundscapes and visitor experiences. The maximum noise level allowed in NPS units, 

including Glen Canyon National Recreation Area, is 82 decibels at 82 feet at full acceleration. 

Wildlife and Wildlife Habitat 

Nationally, personal watercraft use has been described as adversely affecting wildlife (principally 

birds) through harassment and disturbing nesting colonies of terns. Disturbance can be deliberate or 

incidental to the use of personal watercraft (such as noise). Impacts on wildlife habitat could occur 

through crushing or uprooting of submerged and near-shore vegetation. 
EXECUTIVE SUMMARY

x GLEN CANYON NATIONAL RECREATION AREA

In the recreation area, concern was expressed that personal watercraft operations may affect wildlife, 

causing alarm or flight, or avoidance of personal watercraft activity areas. Areas indicated as being of 

particular concern include the recreation area’s shallow-water, narrow side-canyons. 

Shoreline Vegetation 

Nationally, the effects of personal watercraft on shoreline and aquatic plant communities have not 

been fully studied, and scientists disagree about whether personal watercraft adversely impact aquatic 

vegetation. Most concern arises from the shallow draft of personal watercraft, allowing them to use 

shallow areas that conventional motorboats cannot reach. Personal watercraft may crush or uproot 

grasses and other submerged aquatic vegetation that occurs in shallow water. 

In the recreation area, there are few areas of submerged aquatic vegetation, which limits the concern 

regarding this impact topic. Many areas of Lake Powell have unsuitable shoreline substrates, steep 

shoreline slopes, high water velocities in tributary river reaches, or large seasonal fluctuations of water 

surface elevations. Together, these factors preclude the development of submerged aquatic and 

shoreline vegetation. 

Visitor Conflicts and Visitor Safety 

Nationally, some data suggest that personal watercraft have higher accident rates than other watercraft. 

Conflicts with other recreationists can arise because of the noise produced by personal watercraft, their 

ability to operate in shallow water, and the inconsiderate or aggressive behavior sometimes exhibited 

by some personal watercraft operators. 

In the recreation area, many concerns about conflicts with personal watercraft use focus on visitors 

who do not use motorboats, such as swimmers, fishermen, and rafters and kayakers. Conflicts also can 

arise with land-based users, such as those who are seeking solitude in the recreation area’s Natural 

Zone. Safety issues include the number and severity of accidents involving personal watercraft. 

ALTERNATIVES 

This environmental impact statement evaluates three alternatives concerning the use of personal 

watercraft at Glen Canyon National Recreation Area. 

Alternative A: Continue Personal Watercraft Use 

as Currently Managed under a Special Regulation 

Alternative A would allow the management and regulation of personal watercraft use, as provided for 

in the recreation area’s Superintendent’s Compendium (NPS 2002c), under a special regulation. This is 

considered the “baseline” condition against which the other management strategies, including closure 

of the recreation area to personal watercraft use, were compared. 

Under alternative A, personal watercraft use would be authorized in all areas of Lake Powell, except 

where specifically prohibited in the Superintendent’s Compendium (NPS 2002c). Location restrictions 

would include: 
Alternatives

FINAL ENVIRONMENTAL IMPACT STATEMENT xi

Upstream travel on the Dirty Devil River from the point where measurable downstream current 

is encountered; 

Upstream travel on the Escalante River upstream from the confluence with Coyote Creek; 

Upstream travel on the San Juan River upstream from the Clay Hills pullout; and 

Upstream travel on the Colorado River upstream from the base of Imperial Rapid. 

Downstream travel through these areas by personal watercraft would be allowed. 

Alternative A would also include a three-year pilot study to identify the techniques and area 

restrictions that would be most effective in reducing conflicts between watercraft and other visitors. 

The pilot study would support the development of a lake management plan which would 

comprehensively consider all lake uses to better protect recreation area resources, improve visitor 

safety, and reduce conflicts. 

Alternative B (NPS Modified Preferred Alternative): Promulgate a Special Regulation 

to Continue Personal Watercraft Use with Additional Management Restrictions 

Alternative B would be similar to alternative A. However, it would include additional geographic 

restrictions on personal watercraft use and would implement additional flat-wake zones. Under this 

alternative all carbureted two-stroke personal watercraft would be prohibited after 2012. In addition,

alternative B also would include strategies to better protect recreation area resources, improve visitor 

safety, and reduce conflicts. Some of these strategies would include preparation of a lake management 

plan and conduct of a three-year pilot study to identify the techniques that would be most effective in 

reducing conflicts. 

Location restrictions would include closing the following river areas to all personal watercraft use, 

including both upstream and downstream travel: 

Dirty Devil River upstream of Utah Highway 95 Bridge; 

Escalante River upstream of the confluence of Coyote Creek; 

San Juan River upstream from the Clay Hills pullout; and 

Colorado River upstream from Sheep Canyon. 

Wake restrictions would be implemented on the: 

Escalante River from the confluence of Cow Canyon to the confluence with Coyote Creek. 

Alternative C: No-Action (Personal Watercraft Use Would Be Eliminated) 

Alternative C is the no-action alternative. The National Park Service would not take action to 

promulgate a special regulation that would allow personal watercraft use. Therefore, under the 

provisions of the March 21, 2000 final rule, all personal watercraft use would be permanently 

eliminated from the recreation area. 
EXECUTIVE SUMMARY

xii GLEN CANYON NATIONAL RECREATION AREA

Preferred and Environmentally Preferred Alternative 

The environmentally preferred alternative is the alternative that will promote the National 

Environmental Policy Act, as expressed in section 101 of the act. The preferred alternative and the 

environmentally preferred alternative is alternative B. This alternative was designed to meet the 

general management objectives of the National Park Service for protecting recreation area resources 

and values, while providing the opportunity for personal watercraft operators to enjoy water-based 

recreation. 

Alternative B would have impacts on recreation area resources and visitor use and experience at Glen 

Canyon National Recreation Area that were very similar to conditions that existed prior to September 

2002. However, it would prohibit the use of carbureted two-stroke personal watercraft after 2012 and

further restrict personal watercraft use within portions of the Dirty Devil, Escalante, San Juan, and 

Colorado Rivers. These restrictions would reduce adverse effects on water quality, air quality, and 

soundscapes relative to alternative A while allowing for a wider range of recreational uses than 

alternative C. This alternative would emphasize recreational opportunities for visitors while enhancing 

protection of sensitive natural and cultural resources. 

ENVIRONMENTAL CONSEQUENCES 

Impacts of the three personal watercraft management alternatives were assessed in accordance with 

Director’s Order 12 and Handbook: Conservation Planning, Environmental Impact Analysis and 

Decision Making. This handbook requires that impacts on park resources be analyzed in terms of their 

context, duration, and intensity. The analysis provides the public and decision-makers with an 

understanding of the implications of personal watercraft management actions in the short and long 

term, cumulatively, and within context, based on an understanding and interpretation by resource 

professionals and specialists. 

For each impact topic, methods were identified to measure the change in recreation area resources that 

would occur with the implementation of each personal watercraft management alternative. Three field 

programs were conducted by Glen Canyon National Recreation Area in the summer of 2001 to collect 

data on water quality, air quality, and noise from high, low, and moderate personal-watercraft-use 

areas. The results were used to evaluate potential impacts of each alternative, using modeling 

techniques. Thresholds were established for each impact topic to help understand the severity and 

magnitude of changes in resource conditions, both adverse and beneficial. 

Each personal watercraft management alternative was compared to a baseline to determine the context, 

duration, and intensity of resource impacts. The baseline is the condition that resulted from 

management of personal watercraft use under the Superintendent’s Compendium (NPS 2002c) and is 

represented by alternative A. 

The table ES-1 summarizes the results of the impact analysis for the impact topics that were assessed. 

The analysis considered a 10-year period from the end of 2002 through 2012. 
FINAL ENVIRONMENTAL MPACT I STATEMENT xiii

TABLE ES-1:

COMPARISON OF IMPACTS OF THE 

ALTERNATIVES

Impact Topic 

Alternative A: 

Continue Personal Watercraft Use as 

Currently Managed under a Special Regulation 

Alternative B (Modified Preferred Alternative): 

Promulgate a Special Regulation to 

Continue Personal Watercraft Use with 

Additional Management Restrictions 

A

(Person

Would 

Water quality Under alternative A, personal watercraft have 

negligible to minor, direct, adverse effects on the water quality of Lake Powell. Effects would be long term because they would recur during each summer heavy-use season. Cumulatively, the lake loadings from all vessels also would have negligible to minor, direct, adverse effects on the water quality of Lake Powell. Alternative A would not result in the impairment of the water quality of Lake Powell or any other waters. 

Localized, long-term benefits to water quality would occur in the four tributaries where personal watercraft use would be restricted. However, because these areas have low rates of use, the intensity would likely be negligible. Prior to the end of 2012, effects to water quality would be the same as those described for alternative A. This is anticipated because boat usage and engine type distribution are assumed to be the same as in alternative A. After implementation of clean technology personal watercraft restrictions, pollutant loadings from personal watercraft would decrease. However, changes in water quality may be difficult to quantify. The continued contribution of personal watercraft to pollutant loading in Lake Powell would result in long-term, adverse effects to water quality of negligible to minor intensity. Cumulative effects from all watercraft would be similar to alternative A until 2005. A decrease in pollutant loading with implementation of personal watercraft engine type restrictions at the end of 2012 and other water quality improvement projects would result in long-term negligible benefits. Alternative B would not result in the impairment of the water quality of Lake Powell or any other waters. 

Alternative C would pollutant loadings in alternatives A and Blong-term. This wouminor, direct, benefwater quality of the would also experienbenefits, but due to use rates, these wowould not result in tquality of Lake Pow

Air quality Personal watercraft management under 

alternative A would have the following effects on air quality. Emission levels of carbon monoxide, hydrocarbons, and volatile organic compounds would decrease between 2004 and 2012. Hydrocarbon plus nitrogen oxide emissions, which are the principal constituents of ozone, would also decrease by 2012. All of this change would be attributable to increased proportions of lowemission engines on the lake. However, these pollutants would continue to be emitted by personal watercraft at volumes exceeding 100 tons per year. As a result, alternative A would 

Effects of alternative B would be similar to those of alternative A in 2004. Conversion of carbureted two-stroke personal watercraft to cleaner engines under the modified alternative would have the following effects on air quality. There would be sizeable reductions in volatile organic compounds, hydrocarbon, and hydrocarbon plus nitrogen oxide emissions. There would also be reduction in particulates (PM10 and 

PM2.5) and carbon monoxide emissions. 

Human health effects would be adverse and moderate for volatile organic compounds, carbon monoxide, hydrocarbons, and hydrocarbons plus 

Under the no-action condition in the recrbe below national aSUM06 ozone meaarea would remain bhour. No change in be expected becausactivity has not resunational air quality sThe no-action alternnegligible to moderaquality related valuewould result from thwatercraft emission
xiv GLEN CANYON NATIONAL RECREATION AREA Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

have moderate, long-term, direct, adverse impacts on human health and air quality related values. Particulate matter emissions from personal watercraft would decrease by 2012 to between 46 to 67 tons per year. These levels of particulate matter would continue to cause locally degraded visibility from personal watercraft exhaust during peak use periods in high-use areas. This would be a direct, long-term, negligible to minor, adverse effect on human health and air quality related values. Air quality in the recreation area would continue to be below national ambient air quality standards (negligible effect). SUM06 ozone measurements in the recreation area would remain between 8 and 15 parts per million per hour (negligible effect). No change in class II airshed status would result from this alternative (negligible effect). The cumulative effect on air quality related values and human health from all motorized vessel would be direct, long-term, adverse, and minor to moderate. This alternative would not result in an impairment of the air quality resource or related values. nitrogen oxides. Some beneficial effects would occur after 2012 from the elimination of carbureted two-stroke personal watercraft engine emissions as hydrocarbon, carbon monoxide, volatile organic hydrocarbons, and particulate matter emissions are reduced. Adverse impacts to air quality-related values would be reduced from minor levels in 2004 to negligible to minor in 2012. Particulate matter reductions would contribute to an improvement in visibility, and the reduced ozone production would contribute to a reduced potential for plant damage. Air quality in the recreation area would continue to be below national ambient air quality standards (negligible effect). SUM06 ozone measurements in the recreation area would remain between 8 and 15 parts per million per hour (negligible effect). No change in class II airshed status would result from this alternative (negligible effect). The cumulative effect on air quality related values and human health from all motorized vessels would be direct, long-term, adverse, and minor to moderate. This alternative would not result in an impairment of the air quality resource or related values. organic compounds

oxide, and particulaarea. In the short-term, towould be reduced abe prohibited from tbe sizeable reductioemissions of carbon compounds, hydrocnitrogen oxide when Particulates (PM10 a

from minor to modeto negligible under talternative. In the long-term viswatercraft with a difvessel and other veThis would offset thelimination of persothat ambient air quato be met, moderateon human health anwould occur from caoxide, hydrocarboncompound emissionmotorized boating aimpacts on human hwith particulate matnegligible to minor. Implementation of tin an impairment of 

Soundscapes During summer days in the Recreation and Resource Utilization and Developed Zones, the existing level and character of noise generated by personal watercraft are acceptable within the expressed purpose of the park to provide the motorized watercraft form of recreation. Given this level of impact, and the amount of use that occurs during peak seasons, mitigation takes the form of education and enforcement of the existing regulations and compendium. Noise-producing behaviors are regulated to the greatest possible Alternative B would have overall noise impacts similar to those described under alternative A. During summer days in the Recreation and Resource Utilization and Developed Zones, the existing level and character of noise generated by personal watercraft are acceptable within the expressed purpose of the park to provide the motorized watercraft form of recreation. During other times of the year, the overall impact of noise within this area decreases. Noise generated in this zone, year-round, affects adjacent areas in Due to the eliminati

in alternative C, impsoundscape would levels produced in arepresents a benefisoundscape – elimijudged as minor to the year. Compared the level of beneficiconsidered as great negligible to minor a
FINAL ENVIRONMENTAL MPACT I STATEMENT xv Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

extent, and use of newer technologies that reduce noise are encouraged. During other times of the year, the overall impact of noise within this area decreases. Noise generated in this zone, year- round, affects adjacent areas in Natural and Cultural Zones. In the Natural and Cultural Zones, alternative A would produce negligible to moderate adverse effects on the soundscape within a mile of the lakeshore, depending on the level of boating use in nearby waters at various times of the year. During high-use periods, areas in which noise is audible would be affected at minor to moderate levels. During low-use periods, areas in which noise is audible would be affected at negligible to minor levels. These areas consist of about 16,000 acres covering 2.3% of the natural and cultural zones. The remainder of the zone area is expected to be unaffected. All of these effects would be adverse, both short and long term, and direct. Alternative A would not result in impairment of the natural soundscape of Glen Canyon National Recreation Area since a major level of impact is not demonstrated. Natural and Cultural Zones. In the Natural and Cultural Zones, under alternative B during high-use periods, areas in which noise is audible would be affected at minor to moderate levels. During low-use periods, areas in which noise is audible would be affected at negligible to minor levels. The area affected would be 2.3% of the natural and cultural zones. The remainder of the zone area is expected to be unaffected. All of these effects would be adverse, both short and long term, and direct. Alternative B would not result in impairment of the natural soundscape of Glen Canyon National Recreation Area since a major level of impact is not demonstrated. would not result in i

soundscape of Glen Area. Wildlife and wildlife habitats Personal and other watercraft uses with alternative A would result in negligible to minor short-term adverse impacts. Under some conditions impacts, from noise, high-speed personal watercraft operations, shoreline habitat disturbances, and the ingestion or absorption of fuel constituents, petroleum hydrocarbon additives and derivatives, could be observable and/or measurable. However, changes resulting from such conditions would not be expected to be outside the range of natural environmental and biological variability. Population numbers, population structure, genetic variability, and other demographic factors for species may experience small, short-term changes, but long-term characteristics of wildlife and wildlife habitat within the area of analysis would remain stable and viable. Impacts on wildlife and wildlife habitats due to alternative B would result in negligible to minor short-term adverse impacts. Under some conditions impacts, from noise, high-speed personal watercraft operations, shoreline habitat disturbances, and the ingestion or absorption of fuel constituents, petroleum hydrocarbon additives and derivatives, could be observable and/or measurable. However, changes resulting from such conditions would not be expected to be outside the range of natural environmental and biological variability. Prohibiting carbureted two- stroke personal watercraft engines at the end of 2012 would indirectly benefit wildlife and wildlife habitat. Alternative B would not contribute to deterioration of the recreation area’s wildlife resource to the extent that the recreation area’s purpose could Alternative C would 

beneficial impact on from a reduction in result from eliminatithe lake. By the end 2012, the number oreturned to levels walternatives A and Bwildlife and wildlife watercraft and othesimilar, the long-terwildlife and wildlife Alternative C would and wildlife species 
xvi GLEN CANYON NATIONAL RECREATION AREA Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

Operations of personal watercraft would not adversely impact special-interest wildlife concentration or high-quality wildlife habitat areas because such resources are not present in the recreation area. Special-interested wildlife features (such as active peregrine falcon nest sites) are present in the recreation area and many occur in areas visited by personal watercraft and other types of motorized watercraft. Alternative A would not contribute to deterioration of the recreation area’s fish or wildlife resources to the extent that the recreation area’s purpose could not be fulfilled as established in its enabling legislation. It would not affect resources key to the recreation area’s natural integrity or opportunities for enjoyment or affect the wildlife or wildlife habitat resource, whose conservation is identified as a goal in the recreation area’s general management plan. Implementing this alternative would not result in an impairment of wildlife, fish, or supporting habitat resources. not be fulfilled as established in its enabling legislation. Implementing this alternative would not result in an impairment of wildlife, fish, or supporting habitat resources. Threatened and endangered species Alternative A would not adversely affect any ecological, biological, or physical processes associated with endangered fish critical habitats. Continuing the location restriction on upstream portions in the Colorado, San Juan, Dirty Devil, and Escalante Rivers would provide some protection of critical habitat for endangered fish. Compared to current conditions, alternative A would have negligible effects on the bald eagle, American peregrine falcon, southwestern willow flycatcher, or yellow-billed cuckoo or their critical habitats within Lake Powell and its tributaries in the recreation area. Cumulative impacts are not likely to adversely affect endangered, threatened, or special-concern species or their designated critical habitats in the recreation area. No impairment to threatened or endangered species or their designated critical habitats would occur from the implementation of alternative A. Restrictions on access and designation of flat- wake speeds along sections of river shorelines would produce short-term, direct, negligible benefits to habitats of endangered fishes in the inflow areas. These would occur because fewer personal watercraft would use these areas, and the remaining vessels would operate at lower speeds, producing less site disturbance. These effects would not change ecological function or structure of critical habitat and would probably be indistinguishable from the range of environmental variation that occurs under natural conditions. The availability, use, and location of suitable endangered fish habitat would be more extensively affected by reservoir operations and annual river runoff patterns than by operation of personal watercraft. Therefore, the impacts on endangered fish species and their designated critical habitat with alternative B would be similar to alternative A. Endangered fish would benefit indirectly with the prohibition of carbureted two- strike personal watercraft engines at the end of Negligible improvem

habitat would be exdirect beneficial imptheir designated critareas. The bald eagsouthwester willow cuckoo might experterm beneficial direcdisturbance incidenyears when the totaexpected to declineunlikely to adversely birds or their critical species or state-sencritical habitats or frand riparian habitatCumulative impacts adversely affect endspecial-concern specritical habitats in thNo impairment wou
FINAL ENVIRONMENTAL MPACT I STATEMENT xvii Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

2012 which would reduce the amount of fuel discharge into the water in subsequent years. There would be no distinguishable adverse effects on the bald eagle, American peregrine falcon, southwestern willow flycatcher, or yellow-billed cuckoo. As a result, this alternative would be unlikely to adversely affect these species in the recreation area. Cumulative impacts are not likely to adversely affect endangered, threatened, or special-concern species or their designated critical habitats in the recreation area. No impairment would be expected to endangered, threatened, or special-concern species or their designated critical habitats with this alternative. threatened, or spec

designated critical h

Shoreline vegetation Personal watercraft use would have negligible, adverse, direct and indirect impacts, for both short and long terms. This would occur because there would be no perceptible changes to shoreline, riparian, aquatic, or wetland community size, integrity, or continuity. Alternative A would not result in any substantial or noticeable physical change of submerged, riparian, or wetland shoreline vegetation. Past, current, and future use of personal watercraft and other motorized watercraft also would not produce any noticeable effect on shoreline vegetation. Therefore, cumulative effects would also be short-term, direct, and negligible. Alternative A would not result in impairment of shoreline vegetation at Glen Canyon National Recreation Area. Restricting access to upper portions of the Colorado, Escalante, Dirty Devil, and San Juan Rivers would provide negligible beneficial protection of riparian shoreline vegetation. Impacts on shoreline vegetation in the vicinity of the four main marinas would be similar to those described for alternative A and would result primarily from minor short-term foot traffic associated with users of personal watercraft and other watercraft when landing on lake shorelines. Limiting personal watercraft operations to flat- wake speeds on a portion of the Escalante River would reduce wave production but because of the lack of existing shoreline vegetation no benefits to shoreline vegetation would be expected. Past, current, and future personal watercraft use would not produce any noticeable effect on submerged aquatic, riparian and wetland vegetation. Therefore, cumulative effects would remain similar to alternative A and would be short-term, direct, and negligible. Alternative B would not result in impairment of shoreline vegetative resources. Alternative C would 

noticeable adverse submerged aquaticlakeshore does not submerged aquatic localized negligible vegetation would be implementing this afuture motorcraft usnoticeable effect on and wetland vegetaeffects would be simbe short-term, direcAlternative C would shoreline vegetative 

Visitor use and experience Alternative A would have negligible effects on visitor use and experience because the number of personal watercraft using Lake Powell and their management would not change. The effect on the Most effects of alternative B would be similar to those described for alternative A. Most effects would be long-term and negligible to minor because of the presence of other motorcraft. An In the short term, vi

watercraft as a primpersonal watercraft their visit would exp
xviii GLEN CANYON NATIONAL RECREATION AREA Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

visitor experience for personal watercraft users would continue to be beneficial, while experiences for visitors seeking quiet and solitude would continue to be adversely affected. Cumulative effects would be either adverse or beneficial, depending on the visitor’s goals. However, in either case impacts would be negligible. additional flat-wake zone and closed areas would produce negligible to minor, long-term, direct effects. Perceptions of individual visitors would determine if the effects were adverse or beneficial. Improvements in visitor education would result in negligible to minor, indirect, long- term, beneficial effects. Cumulative effects on visitor experience would be long-term, indirect, and moderate because there would be detectable change on certain portions of the lake. Perceptions of individual visitors would determine if effects were adverse or beneficial. short- and long-term 

Other users of perswho use them in cowould experience sadverse effects that in the long term. Visitors who did not generally perceive mbenefits from reducnoise. These benefin the long term. Visitor conflicts and visitor safety Alternative A would have negligible impacts on visitor conflicts and visitor safety. Improvements in visitor protection staffing would result in long-term minor beneficial effects on visitor conflicts and safety. Cumulative effects of watercraft use and other visitor activities on visitor conflicts and safety combined with NPS management activities to prevent accidents would be negligible. Compared to alternative A, alternative B would have direct and indirect, long-term, minor, beneficial impacts on both visitor conflicts and visitor safety. Cumulatively, the improved education components of this alternative would have indirect, long-term, beneficial, negligible to minor effects on visitor conflicts and visitor safety. In the short term, al

direct, beneficial, mHowever, as visitors which have higher athan personal watersafety would be advVisitor conflicts wouand improvements would produce both beneficial effects. Cwatercraft use and o

conflicts and safety management activitbe negligible. Cultural resources Effects on cultural resources from the implementation of alternative A would be adverse and mostly long-term. While most personal watercraft users would be conscientious about protecting the recreation area’s cultural resources, a few would engage in destructive actions such as illegal collecting of artifacts or vandalism. The effects of this behavior would be most noticeable in the narrow, steep-walled canyon areas that are inaccessible by most other types of motorcraft, but that can be traveled in a downstream direction by personal watercraft under alternative A. In these areas, impact intensities mostly would be negligible to minor. Impact intensities from personal watercraft users would be of similar magnitude in other areas, but would be Compared to alternative A, alternative B would have direct, long-term, negligible to minor, beneficial effects on archeological and ethnographic sites along the river canyons. Effects on traditional practices would be beneficial and negligible to moderate in intensity. In other areas, the effects of alternative B may be beneficial compared to alternative A, but the intensity would be negligible. Cumulative effects would be similar to alternative A. Alternative B would not result in impairment of the cultural resources of the recreation area. Compared to altern

have direct, long-tebeneficial effects on ethnographic resoumoderate, beneficiapractices in the rivearea. It also would hnegligible to minor, practices that are colake shore. In the short term, thfollow implementatioin a negligible, shordisturbances to cultend by 2012 if visitoincreases due to na
FINAL ENVIRONMENTAL MPACT I STATEMENT xix Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

indistinguishable from the adverse effects caused by the relatively few destructive visitors who used other transport methods to access the sites. Cumulatively, direct, adverse, long-term effects on the cultural resources in the recreation area would vary in intensity from negligible to moderate, depending on individual site vulnerability and accessibility. Negligible to minor, adverse, indirect effects on near-shore cultural sites would continue from the wave action caused both by boats and wind. The contribution of personal watercraft under alternative A to wave-caused effects would be negligible. Overall, the direct effect within the recreation area would be adverse and minor. Regionally, the effect from activities that occur outside of the recreation area would continue to be adverse and moderate. The contribution of alternative A to the regional effects would be negligible. Alternative A would not result in impairment of the cultural resources of Glen Canyon National Recreation Area. visitors finding othe

personal watercraftindividuals who prevarea due to personacumulative effects wA. Alternative C wothe cultural resourceRecreation Area. Socioeconomic environment Alternative A would have a negligible socioeconomic effect by itself and cumulatively with other actions. Alternative B would have a negligible socioeconomic effect by itself and cumulatively with other actions. Alternative C would 

term effect on the ecommunities in the recreation area wouadverse effects. The and indirect as reduservice related to perecreation rippled thCumulative effect obe moderate. In the would recover to prebusinesses that had watercraft sales and term effect on the lomoderate to major. National recreation area management and operations Use of personal watercraft in the recreation area under alternative A would have negligible, short- and long-term effects on operations. Increased funding for visitor protection staff would offset some of the long-term impacts to visitor protection Alternative B primarily would affect the enforcement, interpretation, and facilities maintenance components of recreation area operations. Short-term impacts would be minor, as staff resources were committed to marking Alternative C would 

minor, adverse effeoperations, primarily commitments needeban on personal wa
xx GLEN CANYON NATIONAL RECREATION AREA Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

services. The cumulative effects on management and operations of personal watercraft use in conjunction with other activities at existing levels also would be negligible. newly restricted areas and developing and implementing new educational programs. In the long term, most of these effects would decrease to negligible levels. Increased funding for visitor protection staff would lead to long-term, minor benefits to visitor protection services. Effects on recreation area staff from restrictions on carbureted two-stroke personal watercraft at the end of 2012 would be negligible as most watercraft would already be compliant with EPA emission standards and distribution of education materials would inform users well in advance of the restriction. Without additional funding, staff requirements for additional monitoring could have long-term, negligible to minor, adverse effects on operations of the resource management division. Cumulatively, all recreation area visitors would benefit from the improved education and visitor protection services that would be implemented with alternative B. These could reduce the need to respond to emergencies and improve the ability to focus recreation area services on the protection of resources and the safety of visitors. These would be beneficial, negligible to minor, direct and indirect, long-term effects on recreation area operations. these effects would 

Law enforcement rewould be reduced, adecreased in assocthe long-term effect would be negligible area increases due to visitors finding otpersonal watercraftindividuals who prevarea due to personafunding for visitor prsome of the long-teprotection services. additional cumulativ
FINAL ENVIRONMENTAL IMPACT STATEMENT xxi 

CONTENTS 

PURPOSE OF AND NEED FOR ACTION 

INTRODUCTION ................................................................................................................................................... 3 

PURPOSE OF AND NEED FOR ACTION.......................................................................................................... 10 

SCOPE OF THE ANALYSIS ............................................................................................................................... 11 

PURPOSE AND SIGNIFICANCE OF GLEN CANYON NATIONAL RECREATION AREA ........................ 12 

BACKGROUND ................................................................................................................................................... 14 

ORGANIC ACT AND MANAGEMENT POLICIES ................................................................................... 14 

SUMMARY OF NATIONAL INFORMATION ON THE EFFECTS OF PERSONAL WATERCRAFT... 15 

Water Quality....................................................................................................................................... 16 

Air Quality ........................................................................................................................................... 17 

Soundscapes......................................................................................................................................... 17 

Wildlife and Wildlife Habitat .............................................................................................................. 18 

Shoreline Vegetation............................................................................................................................ 18 

Health and Safety Concerns................................................................................................................. 18 

PERSONAL WATERCRAFT USE AND REGULATION AT GLEN CANYON 

NATIONAL RECREATION AREA.............................................................................................. 20 

OBJECTIVES IN TAKING ACTION .................................................................................................................. 21 

IMPACT TOPICS AND ISSUES RELATED TO PERSONAL WATERCRAFT USE ...................................... 23 

IMPACT TOPICS EVALUATED IN THIS ENVIRONMENTAL IMPACT STATEMENT ...................... 23 

ISSUES RELATED TO PERSONAL WATERCRAFT USE IN GLEN CANYON 

NATIONAL RECREATION AREA.............................................................................................. 23 

Water Quality....................................................................................................................................... 24 

Air Quality ........................................................................................................................................... 24 

Soundscapes......................................................................................................................................... 24 

Wildlife and Wildlife Habitat .............................................................................................................. 24 

Endangered or Threatened Species ...................................................................................................... 24 

Shoreline Vegetation............................................................................................................................ 25 

Visitor Experience and Visitor Conflicts ............................................................................................. 25 

Visitor Safety ....................................................................................................................................... 25 

Cultural Resources............................................................................................................................... 25 

Socioeconomic Effects......................................................................................................................... 25 

Recreation Area Operations................................................................................................................. 25 

IMPACT TOPICS ELIMINATED FROM FURTHER CONSIDERATION ....................................................... 26 

RELATIONSHIPS TO OTHER PLANS, POLICIES, AND ACTIONS .............................................................. 28 
CONTENTS

xxii GLEN CANYON NATIONAL RECREATION AREA

ALTERNATIVES 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY MANAGED 

UNDER A SPECIAL REGULATION ...................................................................................................... 35 

LOCATION RESTRICTIONS....................................................................................................................... 35 

WAKE AND LAUNCH RESTRICTIONS.................................................................................................... 44 

ENFORCEMENT OF FEATURES REGULATED BY THE STATES OF 

ARIZONA AND UTAH................................................................................................................. 44 

EDUCATION................................................................................................................................................. 45 

SANITATION................................................................................................................................................ 45 

MONITORING AND SAMPLING PROGRAMS......................................................................................... 46 

LAKE MANAGEMENT PLAN .................................................................................................................... 46 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE A SPECIAL 

REGULATION TO CONTINUE PERSONAL WATERCRAFT USE WITH ADDITIONAL 

MANAGEMENT RESTRICTIONS.......................................................................................................... 47 

LOCATION RESTRICTIONS....................................................................................................................... 47 

WAKE AND LAUNCH RESTRICTIONS.................................................................................................... 51 

ENFORCEMENT OF FEATURES REGULATED BY THE STATES OF ARIZONA AND UTAH ........ 52 

EDUCATION................................................................................................................................................. 52 

SANITATION................................................................................................................................................ 53 

MONITORING AND SAMPLING PROGRAMS......................................................................................... 53 

LAKE MANAGEMENT PLAN .................................................................................................................... 54 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)........... 55 

LOCATION RESTRICTIONS....................................................................................................................... 55 

WAKE AND LAUNCH RESTRICTIONS.................................................................................................... 55 

ENFORCEMENT OF PERSONAL WATERCRAFT BAN.......................................................................... 55 

EDUCATION................................................................................................................................................. 55 

SANITATION................................................................................................................................................ 56 

MONITORING AND SAMPLING PROGRAMS......................................................................................... 56 

LAKE MANAGEMENT PLAN .................................................................................................................... 56 

ALTERNATIVES ELIMINATED FROM FURTHER CONSIDERATION ....................................................... 57 

ALTERNATIVES SUMMARY............................................................................................................................ 57 

THE ENVIRONMENTALLY PREFERRED ALTERNATIVE........................................................................... 66 

AFFECTED ENVIRONMENT

GENERAL PROJECT SETTING ......................................................................................................................... 71 

WATER QUALITY .............................................................................................................................................. 75 

COLORADO RIVER..................................................................................................................................... 76 
Contents 

FINAL ENVIRONMENTAL IMPACT STATEMENT xxiii

SAN JUAN RIVER........................................................................................................................................ 77 

DIRTY DEVIL RIVER.................................................................................................................................. 77 

ESCALANTE RIVER.................................................................................................................................... 77 

LAKE POWELL ............................................................................................................................................ 78 

Hydrology............................................................................................................................................ 78 

Water Quality....................................................................................................................................... 80 

WATER POLLUTION SOURCES WITHIN GLEN CANYON NATIONAL RECREATION AREA ....... 80 

Untreated Sewage ................................................................................................................................ 80 

Fuel Leaks or Spills at Marinas and Launch Sites ............................................................................... 81 

Discharge of Gasoline, Oil, and Other Chemicals by Personal Watercraft Engines............................ 83 

CHEMICAL COMPOSITION OF GASOLINE AND COMBUSTION PRODUCTS WITH 

REGARD TO PERSONAL WATERCRAFT MANAGEMENT................................................... 85 

STATE WATER QUALITY STANDARDS ................................................................................................. 87 

Arizona ................................................................................................................................................ 88 

Utah...................................................................................................................................................... 90 

Environmental Protection Agency Criteria and Recommendations..................................................... 91 

ANTIDEGRADATION POLICIES ............................................................................................................... 91 

Arizona ................................................................................................................................................ 92 

Utah...................................................................................................................................................... 92 

AIR QUALITY...................................................................................................................................................... 93 

NATURAL SOUNDSCAPES............................................................................................................................... 96 

NATURAL SOUNDSCAPES AND VISITOR EXPERIENCE .................................................................... 96 

SOUND VERSUS NOISE ............................................................................................................................. 96 

NATURAL SOUNDSCAPE AT GLEN CANYON NATIONAL RECREATION AREA........................... 97 

HUMAN SOUNDSCAPE: NOISE FROM PERSONAL WATERCRAFT AND OTHER SOURCES........ 99 

Noise within the National Recreation Area’s Management Zones (Noise Context)............................ 99 

Intensity of Noise from Personal Watercraft and Other Sources ....................................................... 101 

Timing of Noise from Personal Watercraft and Other Sources ......................................................... 104 

WILDLIFE AND WILDLIFE HABITAT........................................................................................................... 106 

WILDLIFE GROUPS OF PRIMARY INTEREST...................................................................................... 106 

Mammals ........................................................................................................................................... 106 

Birds................................................................................................................................................... 107 

Fish .................................................................................................................................................... 108 

Reptiles and Amphibians ................................................................................................................... 109 

Aquatic Invertebrates......................................................................................................................... 109 

SEASONAL USE PATTERNS OF WILDLIFE GROUPS OF PRIMARY INTEREST ............................ 109 
CONTENTS

xxiv GLEN CANYON NATIONAL RECREATION AREA

SPECIAL-INTEREST USE AREAS OR HABITAT FEATURES OF CONCERN ................................... 110 

Spawning Areas ................................................................................................................................. 110 

Nesting Areas..................................................................................................................................... 110 

Wetlands/Riparian Areas ................................................................................................................... 111 

Areas of High Waterfowl and Shorebird Concentration.................................................................... 111 

River Refugia..................................................................................................................................... 111 

SPECIAL-INTEREST SPECIES ................................................................................................................. 112 

EXISTING CONFLICTS BETWEEN WILDLIFE AND PERSONAL WATERCRAFT USERS ............. 112 

THREATENED, ENDANGERED, AND SPECIAL-CONCERN SPECIES ..................................................... 113 

SPECIES KNOWN TO OCCUR IN ANALYSIS AREA............................................................................ 113 

PRESENCE OF DESIGNATED CRITICAL HABITATS .......................................................................... 113 

KNOWN CONFLICTS WITH PERSONAL WATERCRAFT USERS ...................................................... 119 

SHORELINE VEGETATION............................................................................................................................. 120 

SUBMERGED AQUATIC VEGETATION ................................................................................................ 120

UPLAND SHORELINE COMMUNITIES.................................................................................................. 121 

RIPARIAN VEGETATION......................................................................................................................... 122 

WETLANDS ................................................................................................................................................ 122 

VISITOR USE AND EXPERIENCE .................................................................................................................. 124 

WATERCRAFT USE AND DISTRIBUTION ............................................................................................ 124 

Use of Tributary Canyons.................................................................................................................. 128 

Tributary Canyon Use Originating from Outside of the Recreation Area ......................................... 129 

WATERCRAFT USER MOTIVATIONS, SATISFACTION, AND CONFLICTS.................................... 130 

Desired Experiences........................................................................................................................... 130 

Trip Satisfaction................................................................................................................................. 130 

Perception of Conflict........................................................................................................................ 130 

PERSONAL WATERCRAFT AND OTHER WATERCRAFT USE TRENDS......................................... 132 

Pattern of Visitation at Glen Canyon National Recreation Area........................................................ 133 

Comparative National Park Visitation Trends ................................................................................... 133 

National and State Boating Trends .................................................................................................... 133 

VISITOR CONFLICTS AND VISITOR SAFETY............................................................................................. 135 

SAFETY REQUIREMENTS ....................................................................................................................... 135 

ACCIDENTS................................................................................................................................................ 136 

Watercraft Accidents at Glen Canyon National Recreation Area...................................................... 136 

National and State Watercraft Accidents ........................................................................................... 137 

Fatalities Involving Carbon Monoxide .............................................................................................. 138 

VISITOR USE SURVEY INFORMATION AND PERCEPTIONS OF USE AND SAFETY ................... 138 
Contents 

FINAL ENVIRONMENTAL IMPACT STATEMENT xxv

EDUCATION............................................................................................................................................... 139 

CULTURAL RESOURCES................................................................................................................................ 140 

ARCHEOLOGICAL RESOURCES ............................................................................................................ 140 

HISTORIC RESOURCES............................................................................................................................ 141 

CULTURAL LANDSCAPES ...................................................................................................................... 141 

ETHNOGRAPHIC RESOURCES ............................................................................................................... 142 

NATIONAL REGISTER OF HISTORIC PLACES AND NATIONAL HISTORIC LANDMARK 

PROPERTIES............................................................................................................................... 142 

PAST CULTURAL RESOURCE INVESTIGATIONS............................................................................... 143 

SOCIOECONOMIC ENVIRONMENT.............................................................................................................. 144 

PERSONAL WATERCRAFT OWNERSHIP AND RENTAL ................................................................... 144 

Annual Rental of Personal Watercraft in Gateway Communities...................................................... 145 

Annual Purchases of Personal Watercraft in Gateway Communities ................................................ 145 

Businesses Supported by Personal Watercraft Use............................................................................ 145 

OTHER EXPENDITURES IN THE PAGE AREA ..................................................................................... 146 

DEMOGRAPHY AND ECONOMY ........................................................................................................... 146 

RECREATION AREA MANAGEMENT AND OPERATIONS ....................................................................... 150 

VISITOR PROTECTION............................................................................................................................. 150 

INTERPRETATION .................................................................................................................................... 151 

MAINTENANCE......................................................................................................................................... 152 

CONCESSIONS........................................................................................................................................... 152 

RESOURCE MANAGEMENT.................................................................................................................... 152 

ENFORCEMENT CASES .................................................................................................................................. 152 

ENVIRONMENTAL CONSEQUENCES 

SUMMARY OF LAWS AND POLICIES .......................................................................................................... 157 

GENERAL METHODOLOGY FOR ESTABLISHING IMPACT THRESHOLDS AND MEASURING 

EFFECTS ................................................................................................................................................. 158 

GENERAL ANALYSIS METHOD............................................................................................................. 158 

ASSUMPTIONS .......................................................................................................................................... 159 

Analysis Period.................................................................................................................................. 159 

Analysis Area..................................................................................................................................... 159 

Level of Use and Distribution by Watercraft Type............................................................................ 159

Engine Emissions............................................................................................................................... 160 

IMPAIRMENT ANALYSIS METHOD ............................................................................................................. 161 

CUMULATIVE EFFECTS ANALYSIS METHOD........................................................................................... 162 

WATER QUALITY ............................................................................................................................................ 163 
CONTENTS

xxvi GLEN CANYON NATIONAL RECREATION AREA

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL WATERCRAFT USE...... 163 

Issues.................................................................................................................................................. 163 

Management Objectives..................................................................................................................... 163 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 163

METHODOLOGY AND ASSUMPTIONS................................................................................................. 164

Summary of Water Quality Evaluation Procedure for Personal Watercraft ...................................... 164 

Estimation of Personal Watercraft Use and Other Boating Use ........................................................ 165 

Calculation of Lake Loading by Carbureted Two-Stroke Personal Watercraft ................................. 166 

Estimation of Personal Watercraft Emissions Changes in Response to Regulatory Requirements ... 167 

Calculation of Lake Loading by Low-Emissions Personal Watercraft.............................................. 168 

Comparison to State Standards or Toxicity Benchmarks................................................................... 169 

Analysis of Cumulative Effects – Calculation of Lake Loading by All Watercraft........................... 169 

Impact Threshold Definitions ............................................................................................................ 170 

Geographic Area Evaluated for Impacts............................................................................................ 170 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY 

MANAGED UNDER A SPECIAL REGULATION.................................................................... 170 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE A SPECIAL 

REGULATION TO CONTINUE PERSONAL WATERCRAFT USE WITH 

ADDITIONAL MANAGEMENT RESTRICTIONS................................................................... 175 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)... 178 

AIR QUALITY.................................................................................................................................................... 180 

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL 

WATERCRAFT USE................................................................................................................... 180 

Issues.................................................................................................................................................. 180 

Management Objectives..................................................................................................................... 181 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 181

METHODOLOGY AND ASSUMPTIONS................................................................................................. 183

Impact Threshold Definitions ............................................................................................................ 186 

Geographic Area Evaluated for Impacts............................................................................................ 188 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY 

MANAGED UNDER A SPECIAL REGULATION.................................................................... 188 

Human Health Impacts from Airborne Pollutants.............................................................................. 189 

Air Quality Related Value Impacts from Airborne Pollutants ........................................................... 190 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE A SPECIAL 

REGULATION TO CONTINUE PERSONAL WATERCRAFT USE WITH 

ADDITIONAL MANAGEMENT RESTRICTIONS................................................................... 192 

Human Health Impacts from Airborne Pollutants.............................................................................. 193 

Air Quality Related Value Impacts from Airborne Pollutants ........................................................... 194 
Contents 

FINAL ENVIRONMENTAL IMPACT STATEMENT xxvii

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)... 196 

Human Health Impacts from Airborne Pollutants.............................................................................. 196 

Air Quality Related Value Impacts from Airborne Pollutants ........................................................... 196 

NATURAL SOUNDSCAPES............................................................................................................................. 199 

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL WATERCRAFT USE...... 199 

Issues.................................................................................................................................................. 199 

General Effects of Noise on the Natural Soundscape ........................................................................ 200 

Management Objectives..................................................................................................................... 201 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 201

METHODOLOGY AND ASSUMPTIONS................................................................................................. 203

Context............................................................................................................................................... 203 

Sound Characteristics Used in the Analysis....................................................................................... 203 

Time Factors ...................................................................................................................................... 204 

Other Methods and Assumptions....................................................................................................... 204 

Impact Threshold Definitions ............................................................................................................ 205 

Geographic Area Evaluated for Impacts............................................................................................ 206 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY 

MANAGED UNDER A SPECIAL REGULATION.................................................................... 206 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE A 

SPECIAL REGULATION TO CONTINUE PERSONAL WATERCRAFT 

USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS ............................................... 210 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE 

ELIMINATED) ............................................................................................................................ 211 

WILDLIFE AND WILDLIFE HABITAT........................................................................................................... 214 

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL WATERCRAFT USE...... 214 

Issues.................................................................................................................................................. 214 

Management Objectives..................................................................................................................... 214 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 214

METHODOLOGY AND ASSUMPTIONS................................................................................................. 217

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY 

MANAGED UNDER A SPECIAL REGULATION.................................................................... 219 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE A SPECIAL 

REGULATION TO CONTINUE PERSONAL WATERCRAFT USE WITH 

ADDITIONAL MANAGEMENT RESTRICTIONS................................................................... 225 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)... 226 

THREATENED AND ENDANGERED SPECIES............................................................................................. 227 

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL WATERCRAFT USE...... 227 

Issues.................................................................................................................................................. 227 
CONTENTS

xxviii GLEN CANYON NATIONAL RECREATION AREA

Management Objectives..................................................................................................................... 227 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 227

METHODOLOGY AND ASSUMPTIONS................................................................................................. 228

Impact Threshold Definitions ............................................................................................................ 230 

Geographic Area Evaluated for Impacts............................................................................................ 231 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY MANAGED 

UNDER A SPECIAL REGULATION ......................................................................................... 231 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE 

A SPECIAL REGULATION TO CONTINUE PERSONAL WATERCRAFT 

USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS ............................................... 235 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)... 237 

SHORELINE VEGETATION............................................................................................................................. 239 

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL 

 WATERCRAFT USE.................................................................................................................. 239 

Issues.................................................................................................................................................. 239 

Management Objectives..................................................................................................................... 239 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 239

METHODOLOGIES AND ASSUMPTIONS.............................................................................................. 240 

Impact Threshold Definitions ............................................................................................................ 240 

Geographic Area Evaluated for Impacts............................................................................................ 241 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY MANAGED 

UNDER A SPECIAL REGULATION ......................................................................................... 241 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE A 

SPECIAL REGULATION TO CONTINUE PERSONAL WATERCRAFT USE 

WITH ADDITIONAL MANAGEMENT RESTRICTIONS........................................................ 243 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)... 244 

VISITOR USE AND EXPERIENCE .................................................................................................................. 246 

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL WATERCRAFT USE...... 246 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 246

METHODOLOGIES AND ASSUMPTIONS.............................................................................................. 247 

Impact Threshold Definitions ............................................................................................................ 247 

Geographic Area Evaluated for Impacts............................................................................................ 248 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY MANAGED 

UNDER A SPECIAL REGULATION ......................................................................................... 248 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE A SPECIAL 

REGULATION TO CONTINUE PERSONAL WATERCRAFT USE WITH 

ADDITIONAL MANAGEMENT RESTRICTIONS................................................................... 250 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)... 251 

VISITOR CONFLICTS AND VISITOR SAFETY............................................................................................. 253 
Contents 

FINAL ENVIRONMENTAL IMPACT STATEMENT xxix

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL WATERCRAFT USE...... 253 

Issues.................................................................................................................................................. 253 

Management Objectives..................................................................................................................... 253 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 253

METHODOLOGY AND ASSUMPTIONS................................................................................................. 254

Impact Threshold Definitions ............................................................................................................ 254 

Geographic Area Evaluated for Impacts............................................................................................ 254 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY MANAGED 

UNDER A SPECIAL REGULATION ......................................................................................... 255 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE A SPECIAL 

REGULATION TO CONTINUE PERSONAL WATERCRAFT USE WITH 

ADDITIONAL MANAGEMENT RESTRICTIONS................................................................... 256 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)... 257 

CULTURAL RESOURCES................................................................................................................................ 259 

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL 

WATERCRAFT USE................................................................................................................... 259 

Issues.................................................................................................................................................. 259 

Management Objectives..................................................................................................................... 259 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 259

METHODOLOGY AND ASSUMPTIONS................................................................................................. 260

General Analysis Method .................................................................................................................. 260 

Impacts on Cultural Resources, and Section 106 of the National Historic 

Preservation Act.......................................................................................................................... 261 

Impact Threshold Definitions ............................................................................................................ 262 

Geographic Area Evaluated for Impacts............................................................................................ 265 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY MANAGED 

UNDER A SPECIAL REGULATION ......................................................................................... 265 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE 

A SPECIAL REGULATION TO CONTINUE PERSONAL WATERCRAFT 

USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS ............................................... 269 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)... 270 

SECTION 106 SUMMARY......................................................................................................................... 271 

SOCIOECONOMIC ENVIRONMENT.............................................................................................................. 273 

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL WATERCRAFT USE...... 273 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 273

METHODOLOGY AND ASSUMPTIONS................................................................................................. 273

Impact Threshold Definitions ............................................................................................................ 274 

Geographic Area Evaluated for Impacts............................................................................................ 274 
CONTENTS

xxx GLEN CANYON NATIONAL RECREATION AREA

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY MANAGED 

UNDER A SPECIAL REGULATION ......................................................................................... 274 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE 

A SPECIAL REGULATION TO CONTINUE PERSONAL WATERCRAFT 

USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS ............................................... 275 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)... 275 

RECREATION AREA MANAGEMENT AND OPERATIONS ....................................................................... 278 

ISSUES AND MANAGEMENT OBJECTIVES RELATED TO PERSONAL 

WATERCRAFT USE................................................................................................................... 278 

Issues.................................................................................................................................................. 278 

Management Objectives..................................................................................................................... 278 

GUIDING REGULATIONS AND POLICIES ............................................................................................ 279

METHODOLOGY AND ASSUMPTIONS................................................................................................. 279

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE AS CURRENTLY 

MANAGED UNDER A SPECIAL REGULATION.................................................................... 280 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): PROMULGATE 

A SPECIAL REGULATION TO CONTINUE PERSONAL WATERCRAFT 

USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS ............................................... 281 

ALTERNATIVE C: NO-ACTION (PERSONAL WATERCRAFT USE WOULD BE ELIMINATED)... 283 

SUSTAINABILITY AND LONG-TERM MANAGEMENT............................................................................. 286 

UNAVOIDABLE ADVERSE IMPACTS.................................................................................................... 286 

RELATIONSHIP BETWEEN LOCAL SHORT-TERM USES OF THE 

ENVIRONMENT AND THE MAINTENANCE AND ENHANCEMENT 

OF LONG-TERM PRODUCTIVITY .......................................................................................... 286 

IRREVERSIBLE OR IRRETRIEVABLE COMMITMENTS OF RESOURCES....................................... 287 

CONSULTATION AND COORDINATION 

HISTORY OF PUBLIC INVOLVEMENT......................................................................................................... 291 

SCOPING PROCESS AND PUBLIC PARTICIPATION ........................................................................... 291 

ENDANGERED OR THREATENED SPECIES CONSULTATIONS....................................................... 293 

CULTURAL RESOURCES CONSULTATIONS....................................................................................... 293 

List of Native American Tribes ......................................................................................................... 294 

LIST OF PREPARERS ....................................................................................................................................... 295 

NATIONAL PARK SERVICE .................................................................................................................... 295 

Glen Canyon National Recreation Area, Planning Team Members................................................... 295 

Washington Office............................................................................................................................. 295 

Intermountain Region Office ............................................................................................................. 295 

Parsons............................................................................................................................................... 295 

RED, Inc. Communications ............................................................................................................... 296 
Contents 

FINAL ENVIRONMENTAL IMPACT STATEMENT xxxi

LIST OF RECIPIENTS ....................................................................................................................................... 297 

FEDERAL AGENCIES ............................................................................................................................... 297 

NATIVE AMERICAN TRIBES .................................................................................................................. 297 

STATE OF ARIZONA................................................................................................................................. 297 

STATE OF NEW MEXICO......................................................................................................................... 297 

STATE OF UTAH........................................................................................................................................ 297 

STATE OF IDAHO...................................................................................................................................... 298 

LIBRARIES ................................................................................................................................................. 298 

PARKS, MONUMENTS AND RECREATION AREAS............................................................................ 298 

BUSINESSES AND ORGANIZATIONS.................................................................................................... 298 

APPENDIXES 

APPENDIX A: PARTS OF THE SUPERINTENDENT’S COMPENDIUM, 2002 APPLICABLE TO 

PERSONAL WATERCRAFT ................................................................................................................. 303 

APPENDIX B: ARIZONA AND UTAH WATERCRAFT REGULATIONS APPLICABLE TO 

PERSONAL WATERCRAFT ................................................................................................................. 306 

APPENDIX C: PROPOSED PILOT STUDY TO RESEARCH SOCIAL CONDITIONS IN SUPPORT 

OF A LAKE MANAGEMENT PLAN .................................................................................................... 310 

APPENDIX D: RESULTS OF SAMPLING AND SURVEYS .......................................................................... 313 

APPENDIX E: METHOD USED TO CALCULATE BOAT USE DAYS......................................................... 328 

APPENDIX F: TEN-YEAR VISITATION CHANGE (1991–2001).................................................................. 332 

APPENDIX G: APPROACH TO EVALUATING SURFACE WATER QUALITY IMPACTS 

FROM THE USE OF PERSONAL WATERCRAFT.............................................................................. 334 

APPENDIX H: CONSULTATION LETTERS................................................................................................... 343 

REFERENCES / INDEX 

REFERENCES .................................................................................................................................................... 367 

INDEX................................................................................................................................................................. 388 

FIGURES 

1: Glen Canyon National Recreation Area Region............................................................................................... 4 

2: Glen Canyon National Recreation Area Vicinity ............................................................................................. 5 

3: Glen Canyon Alternative A (Area 1) — Colorado and Dirty Devil Rivers.................................................... 41 

4: Glen Canyon Alternative A (Area 2) — Escalante River............................................................................... 42 

5: Glen Canyon Alternative A (Area 3) — San Juan River................................................................................ 43 

6: Glen Canyon Alternative B (Area 1) — Colorado and Dirty Devil Rivers .................................................... 48 
CONTENTS

xxxii GLEN CANYON NATIONAL RECREATION AREA

7: Glen Canyon Alternative B (Area 2) — Escalante River ............................................................................... 49 

8: Glen Canyon Alternative B (Area 3) — San Juan River ................................................................................ 50 

9: General Management Zones Map................................................................................................................... 73 

10: Water Levels Variations, as Indicated by Shoreline Formations.................................................................... 79 

11: A-Level Time History .................................................................................................................................. 103 

12: Typical Vegetation along Lake Powell Shorelines....................................................................................... 120 

13: Boating Use in Visitor Use Zones ................................................................................................................ 127 

14: Typical Steep Shoreline................................................................................................................................ 219 

15: Shoreline Access by Motorized Vessels....................................................................................................... 219 

TABLES 

1: National PWC Registration Trenda ................................................................................................................ 15 

2: Nationwide Personal Watercraft Estimates and Accident Statistics ............................................................... 19 

3: Objectives for Recreation Area Management and Personal Watercraft Management.................................... 21 

4: Summary of Alternatives................................................................................................................................ 36 

5: Comparison of Impacts of the Alternatives .................................................................................................... 58 

6: Characteristics of the Rivers Upstream from Lake Powell............................................................................. 76 

7: Hydrologic Characteristics of Lake Powell .................................................................................................... 79 

8: Lake Powell Water Quality, Summer 2001 .................................................................................................... 83 

9: Arizona and Utah Water Quality Standards for Selected Pollutants............................................................... 89 

10: Ecotoxicological and Human Health Benchmarks ......................................................................................... 90 

11: National Ambient Air Quality Standards for Criteria Pollutants.................................................................... 94 

12: Comparison of Air Pollutant Concentrations from 2001 at Glen Canyon National Recreation Area............. 95 

13: Estimates of the Percentages of the Lake Powell Surface Area that Are within General 

Sound Categories............................................................................................................................................ 99 

14: Watercraft Pass-by Sound Levels Measured in Glen Canyon National Recreation Area in August 2001 ... 102 

15: Federal and State-Listed Candidate, Threatened, and Endangered Species Believed to Occur 

in the Personal Watercraft Analysis Area..................................................................................................... 114 
Contents 

FINAL ENVIRONMENTAL IMPACT STATEMENT xxxiii

16: Location of Endangered Fish Species Critical Habitat ................................................................................. 115 

17: Distribution of Engine Types and Average Daily Operating Hours Present on Lake Powell ...................... 125 

18: Types of Watercraft Used in Glen Canyon National Recreation Area ......................................................... 126 

19: Estimates of Personal Watercraft and Other Watercraft Use in Glen Canyon National Recreation 

Area by Month in 2001................................................................................................................................. 127 

20: Estimates of Personal Watercraft and Other Watercraft Use by Zone in 2001............................................. 128 

21: Estimated Numbers of Watercraft Typically Observable on the Tributary Rivers to Lake Powell.............. 129 

22: Boats per Year Entering Glen Canyon National Recreation Area on the Colorado and 

San Juan Rivers, 2000 and 2001................................................................................................................... 129 

23: Perception of Conflict by Users of Personal Watercraft and Other Watercraft ............................................ 131 

24: Support for Possible Management Actions by Personal Watercraft and Other Watercraft Users ................ 132 

25: Boat Registrations by State, 1995 through 1999 .......................................................................................... 134 

26: Summary of Watercraft Accident Records for Glen Canyon National Recreation Area, 

1999 through 2001........................................................................................................................................ 136 

27: Perception of Safety Concerns by Users of Glen Canyon National Recreation Area................................... 139 

28: Ownership and Rental Estimates for Personal Watercraft............................................................................ 145 

29: Demographic and Economic Summary for States and Counties Adjoining Glen Canyon 

National Recreation Area ............................................................................................................................. 147 

30: Summer Distribution of National Park Service Law Enforcement Rangers compared to Lake Use 

Levels ........................................................................................................................................................... 151 

31: Summary of Watercraft Enforcement Cases for Glen Canyon National Recreation Area, 

1999 through 2001........................................................................................................................................ 153 

32: Estimated EPA Reductions in Watercraft Emissions ................................................................................... 160 

33: Estimated Distribution of Use by Engine Type on Lake Powell in June and July 2001............................... 166 

34: Estimated Daily Loadings to Lake Powell by Carbureted, Two-Stroke Engines during a High-Use 

Period in 2001, under Alternative A............................................................................................................. 171 

35: Estimated Daily Loadings to Lake Powell by Carbureted, Two-Stroke Engines during a High-Use 

Period in 2005 and 2012, under Alternative A ............................................................................................. 171 

36: Acre-Feet of Water Needed to Meet State Standards or Toxicological Criteria........................................... 172 

37: Pollution Contribution Relative to Engine Type under Alternative A.......................................................... 173 

38: Estimated Daily Loadings to Lake Powell with EPA 2006 Compliant Technology Restrictions 

During a High Use Period............................................................................................................................. 176 
CONTENTS

xxxiv GLEN CANYON NATIONAL RECREATION AREA

39: Pollution Contribution Relative to Engine Type Under Alternative C ......................................................... 178 

40: Alternative A Personal Watercraft Emissions and Ambient Air Quality Levels.......................................... 189 

41: Alternative A Cumulative Emissions from Personal Watercraft and Other Motorized Boat Use 

and Ambient Air Quality Levels................................................................................................................... 191 

42: Modified Preferred Alternative B Personal Watercraft Emissions and Ambient Air Quality Levels........... 193 

43: Alternative B Cumulative Emissions from Personal Watercraft and Other Motorized Boat Use and 

Ambient Air Quality Levels ......................................................................................................................... 195 

44: No Action Cumulative Emissions from Personal Watercraft and Other Motorized Boat Use and 

Ambient Air Quality Levels ......................................................................................................................... 197 

45: Computed Watercraft plus Background Noise at Various Distances from the Shoreline............................. 208 

46: Watercraft Noise Percent Time Audible at Various Distances from the Shoreline ...................................... 208 

47: Laws and National Park Service Policies Relating to Wildlife and Wildlife Habitat................................... 215 

48: Definitions of Intensity Levels for Cultural Resources ................................................................................ 263
1

PURPOSE OF AND NEED FOR ACTION 

DIVIDER 

THIS PAGE TO BE REMOVED
2 

THIS PAGE TO BE REMOVED 

Back of Divider 
FINAL ENVIRONMENTAL IMPACT STATEMENT 3

INTRODUCTION 

Glen Canyon National Recreation Area encompasses 1,254,306 acres in northern Arizona and 

southeastern Utah (see figure 1, the Glen Canyon National Recreation Area Region). It includes parts 

of four counties in Utah and one county in Arizona. As shown in figure 2, Glen Canyon National 

Recreation Area Vicinity, its southern boundary is contiguous with the Navajo Nation. Other 

boundaries adjoin Grand Canyon National Park, Capitol Reef National Park, Canyonlands National 

Park, and Rainbow Bridge National Monument, all managed by the National Park Service (NPS). The 

recreation area also adjoins areas administered by the Bureau of Land Management that include Grand 

Staircase – Escalante National Monument, Vermilion Cliffs National Monument, and Paria Canyon 

Wilderness. 

Glen Canyon National Recreation Area was established in 1972 “to provide for public outdoor 

recreation use and enjoyment of Lake Powell and adjacent lands, and to preserve and protect the 

scenic, scientific, and historic features contributing to public enjoyment of the area.” The recreation 

area’s primary management objective, as established in the General Management Plan (NPS 1979a), 

is “to manage the recreation area so that it provides maximal recreational enjoyment to the American 

public and their guests.” 

More than two million people visit Glen Canyon National Recreation Area each year. The recreation 

area offers a tremendous diversity of land and water-based recreational opportunities. The area’s major 

recreational resource is Lake Powell, a 186-mile-long reservoir at full pool that was created when the 

Colorado River was dammed. Boating is very popular on the lake, including the use of personal 

watercraft, houseboats, powerboats, tour boats, canoes, kayaks, and sailboats. Other popular activities 

in the recreation area include fishing, camping, waterskiing, hiking, photography, and driving for 

pleasure. 

More than one million personal watercraft1

 are estimated to be in operation today in the United States 

(National Marine Manufacturers Association [NMMA] 2001b). Sometimes referred to as “jet skis” or 

“wet bikes,” these vessels have inboard, internal combustion engine powering a water jet pump as its 

primary source of propulsion. 

Personal watercraft are used for enjoyment, particularly for touring and maneuvers such as wave 

jumping, and they are capable of speeds in the 60-mph range. National personal watercraft ownership 

increased every year between 1991 and 1998; the rate of annual increase peaked in 1994 at 32% and 

dropped slightly in 1999, 2000, and 2001.

 

1. Personal watercraft, as defined in 36 CFR §1.4(a) (2000), refers to a vessel, usually less than 16 feet in length, which uses 

an inboard, internal combustion engine powering a water jet pump as its primary source of propulsion. The vessel is intended 

to be operated by a person or persons sitting, standing, or kneeling on the vessel, rather than within the confines of the hull. 

The length is measured from end to end over the deck excluding sheer, meaning a straight line measurement of the overall 

length from the foremost part of the vessel to the aftermost part of the vessel, measured parallel to the centerline. Bow sprits, 

bumpkins, rudders, outboard motor brackets, and similar fittings or attachments, are not included in the measurement. Length 

is stated in feet and inches. 
PURPOSE OF AND NEED FOR ACTION

4 GLEN CANYON NATIONAL RECREATION AREA

FIGURE 1: GLEN CANYON NATIONAL RECREATION AREA REGION
Introduction

FINAL ENVIRONMENTAL IMPACT STATEMENT 5

This page to be removed 

11 x 17 Map 

forced odd blank page behind

FIGURE 2: GLEN CANYON NATIONAL RECREATION AREA VICINITY
PURPOSE OF AND NEED FOR ACTION

6 GLEN CANYON NATIONAL RECREATION AREA

This page to be removed 

Back of Figure 2 
Introduction

FINAL ENVIRONMENTAL IMPACT STATEMENT 7

Personal watercraft emerged and gained popularity in park units before the National Park Service 

could initiate and complete “a full evaluation of the possible impacts and ramifications.” Although 

personal watercraft use remains a relatively new recreational activity, it has occurred in 32 of 87 park 

units that allow motorized boating (NPS 2000e). 

The National Park Service first began to study personal watercraft in Everglades National Park. The 

studies showed that personal watercraft use over emergent vegetation, shallow grass flats, and mud 

flats commonly used by feeding shore birds damaged the vegetation, adversely impacted the shore 

birds, and disturbed the life cycles of other wildlife. Consequently, managers at Everglades National 

Park determined that personal watercraft use was inconsistent with the resources, values, and purposes 

for which the park was established. In 1994, the National Park Service prohibited personal watercraft 

at Everglades National Park by a special regulation (59 Federal Register [FR] 58781). 

Other public entities have taken steps to limit, and even to ban, personal watercraft use in certain 

waterways as national researchers study more about the effects of personal watercraft use. At least 

34 states have either implemented regulations or considered regulating the use and operation of 

personal watercraft (63 FR 49314). Several federal agencies, including the U.S. Fish and Wildlife 

Service and the National Oceanic and Atmospheric Administration, have managed personal watercraft 

differently than other classes of motorized watercraft. 

When the National Oceanic and Atmospheric Administration regulated the use of personal watercraft 

in most national marine sanctuaries, it was sued by the Personal Watercraft Industry Association 

(PWIA). As a result, the Court of Appeals for the District of Columbia declared such personal 

watercraft-specific management to be valid. In Personal Watercraft Industry Association v. 

Department of Commerce, 48 F.3d 540 (D.C. Cir. 1995), the court ruled that an agency can 

discriminate and manage one type of vessel (specifically, personal watercraft) differently than other 

vessels if the agency explains its reasons for the differentiation. 

In February 1997, the Tahoe Regional Planning Agency, the governing body charged with ensuring no 

derogation of Lake Tahoe’s water quality, voted unanimously to ban all vessels using two-stroke, 

internal combustion engines, including personal watercraft, because of their adverse effects on water 

quality. Lake Tahoe’s ban began in 2000. 

In 1998, San Juan County, Washington became the first local government in the country to 

successfully ban the use of personal watercraft in its waters. In January 1996, the county passed an 

ordinance placing a two-year ban on personal watercraft while studies of their effects were conducted. 

Personal watercraft proponents sued, and late that year the Superior Court found the ordinance to be 

unconstitutional. The basis was the distinction made between personal watercraft and other vessels 

while no such distinction is made in the state's boat licensing rules. The county appealed, and in July 

1998 the Washington Supreme Court reversed the trial court and upheld the county's authority. Based 

on this ruling and the results of the studies, the county made the ban permanent. Since then, other 

jurisdictions have banned personal watercraft with ordinances based on San Juan County’s. 

Historically, the National Park Service grouped personal watercraft with all other vessels. Thus, 

people could use personal watercraft within a park service unit when the unit’s superintendent’s 

compendium allowed the use of other vessels. However, by 1998 the National Park Service had closed 

seven units to personal watercraft use through the implementation of horsepower restrictions, general 

management plan revisions, and park-specific regulations such as those promulgated by Everglades 

National Park. At that time, the National Park Service was reevaluating its methods of personal 
PURPOSE OF AND NEED FOR ACTION

8 GLEN CANYON NATIONAL RECREATION AREA

watercraft regulation, based on its responsibilities under the NPS Organic Act of 1916 and increased 

public awareness and controversy. 

In May 1998, the Bluewater Network, a private, independent, non-profit organization, filed a petition 

urging the National Park Service to initiate a rule-making process to prohibit personal watercraft use 

throughout the national park system. In response to the petition, the National Park Service issued an 

interim management policy requiring superintendents of units where personal watercraft use can 

occur, but where they have not been used, to close the unit to personal watercraft until the rule was 

finalized. In addition, the National Park Service proposed a specific personal watercraft regulation 

premised on the notion that personal watercraft differ from conventional watercraft in terms of design, 

use, safety record, controversy, visitor impacts, resource impacts, horsepower-to-vessel ratio, and 

thrust capacity (63 FR 49312-49317, September 15, 1998). 

The National Park Service envisioned the servicewide regulation as an opportunity to evaluate impacts 

of personal watercraft use before authorizing their use. The preamble to the servicewide regulation 

calls the regulation a “conservative approach to managing personal watercraft use” that considered 

resource concerns, visitor conflicts, visitor enjoyment, and visitor safety. During a 60-day public 

comment period, the National Park Service received nearly 20,000 comments on the proposed 

regulation. 

As a result of public comments and further review, the National Park Service promulgated an amended 

regulation (36 CFR 3.24(a), 2000; 64 FR 15077-15090, March 21, 2000). It prohibited personal 

watercraft use in most park units and required the remaining units to determine personal watercraft 

appropriateness for continued use. Specifically, the regulation allowed the National Park Service to 

designate personal watercraft areas and to continue their use by promulgating a special regulation in 

11 units and by amending the units’ superintendent’s compendium in 10 units, including Glen Canyon 

National Recreation Area (36 CFR 3.24(b), 2000). The National Park Service based the distinction 

between designation methods on the units’ degree of motorized watercraft use. 

In response to the personal watercraft final regulation, Bluewater Network sued the National Park 

Service under the Administrative Procedures Act and the Organic Act. The organization challenged 

the NPS’s decision to allow continued personal watercraft use in 21 units while prohibiting personal 

watercraft use in other units. In addition, the organization disputed the NPS decision to allow 10 units 

to continue personal watercraft use after 2002 by making entries in superintendent’s compendiums, 

which would not require the opportunity for public input through a notice and a comment rule-making 

process. Further, the Bluewater Network claimed that because personal watercraft cause water and air 

pollution, increase noise levels, and pose public safety threats, the National Park Service acted 

arbitrarily and capriciously when making the challenged decisions. 

In response to the suit, the National Park Service and the Bluewater Network negotiated a settlement. 

The settlement agreement, signed by the judge on April 12, 2001, changed portions of the NPS rule. 

While the 21 units could continue personal watercraft use in the short term, each of those parks 

desiring to continue long-term personal watercraft use had to promulgate a park-specific special 

regulation. In addition, the settlement stipulated that the National Park Service must base each 

decision to issue a park-specific special regulation to continue personal watercraft use on an 

environmental impact analysis conducted in accordance with the National Environmental Policy Act. 

Each environmental analysis must, at a minimum, according to the settlement, evaluate personal 

watercraft impacts on water quality, air quality, soundscapes, wildlife, wildlife habitat, shoreline 

vegetation, visitor conflicts, and visitor safety. 
Introduction

FINAL ENVIRONMENTAL IMPACT STATEMENT 9

In 2001, the National Park Service adopted its new servicewide policy for personal watercraft. As 

stated in section 8.2.3.3 of Management Policies 2001 (NPS 2000d), “personal watercraft use is 

prohibited unless it has been identified as appropriate for a specific park.” Personal watercraft use can 

only be authorized based on “an evaluation of the park’s enabling legislation, resources and values, 

other visitor uses, and overall management objectives [that] confirms that personal watercraft use is 

appropriate and consistent” with other NPS management goals and objectives. 

As the settlement deadline approached and the park units were preparing to prohibit personal 

watercraft use, the National Park Service, Congress, and personal watercraft user groups sought legal 

methods to keep the parks open to this activity. However, no method was successful. On April 22, 

2002, the following units closed for personal watercraft use: Assateague Island National Seashore; Big 

Thicket National Preserve; Pictured Rocks National Lakeshore; Fire Island National Seashore; and 

Gateway National Recreation Area. On September 15, 2002, eight other park units scheduled to close 

to personal watercraft. Park units that prepare an environmental assessment to analyze personal 

watercraft use alternatives and then select an alternative to continue such use will have to draft a 

special regulation to authorize that use in the future.

The proposed September 16, 2002 prohibition of personal watercraft was averted with the execution of 

a stipulated modification to the settlement agreement. The modified settlement agreement was 

approved by the court on September 9, 2002, and extended unrestricted personal watercraft use in 

some selected National Park Service units until November 6, 2002. 
10 GLEN CANYON NATIONAL RECREATION AREA

PURPOSE OF AND NEED FOR ACTION 

The purpose of and the need for taking action is to evaluate a range of alternatives and strategies to 

manage personal watercraft use at Glen Canyon National Recreation Area. The goal is to ensure the 

protection of recreation area resources and values while offering recreation opportunities as provided 

for in the recreation area’s enabling legislation, purpose, mission, and goals. Upon completion of the 

National Environmental Policy Act process, the National Park Service may either adopt a special 

regulation to manage personal watercraft use at the recreation area, or continue the current ban on 

personal watercraft use at this national park unit that went into effect in September 2002, in 

accordance with the National Park Service March 21, 2000 rule. 

This environmental impact statement evaluates three alternatives for managing the use of personal 

watercraft at Glen Canyon National Recreation Area. Two of the alternatives would allow personal 

watercraft use under specified conditions. 

Alternative A would allow personal watercraft use, consistent with the Superintendent’s 

Compendium (NPS 2002c), under a special regulation. 

Alternative B, the modified preferred alternative, would promulgate a special regulation to allow 

personal watercraft use with additional management restrictions. 

In accordance with the requirements of the National Environmental Policy Act, the alternative of no 

federal action also was evaluated. All personal watercraft use in the recreation area would be

eliminated after November 6, 2002. Alternative C would make this condition permanent. This would 

occur because the National Park Service would not promulgate a special regulation allowing for 

continued personal watercraft use. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 11

SCOPE OF THE ANALYSIS 

Motorboats and other watercraft have been used in Glen Canyon National Recreation Area since its 

establishment in 1972. Personal watercraft use has emerged at the recreation area only since the 

introduction of this type of vessel in the 1980s. 

The scope of this analysis is to examine a range of management alternatives for personal watercraft 

use at Glen Canyon National Recreation Area in support of possible personal watercraft rule-making 

for this unit. 

Prior to 2000, personal watercraft use was allowed throughout Glen Canyon National Recreation Area 

except in areas below Glen Canyon Dam that were closed to personal watercraft use in the 

superintendent’s compendium. In March 2000, the waters below the dam were closed by provisions of 

the NPS personal watercraft rule. Therefore, waters below the dam are not considered in this draft 

environmental impact statement and the rule-making it supports. 

Those waters of the recreation area above the dam where personal watercraft use could occur in any 

capacity, as identified in the Superintendent’s Compendium (NPS 2002c), are within the scope of this 

analysis. (A copy of the parts of the Superintendent’s Compendium (NPS 2002c), that are applicable to 

personal watercraft is provided in appendix A.) These areas include Lake Powell within Glen Canyon 

National Recreation Area and the Colorado, San Juan, Dirty Devil, and Escalante Rivers from Lake 

Powell upstream to the boundaries of the recreation area. 

The National Park Service acknowledges that other watercraft may affect resources. However, other 

watercraft were not the subject of the March 21, 2000 rule, and were not part of the Bluewater 

Network lawsuit and subsequent settlement agreement. Therefore, other watercraft will not be 

included in the upcoming rule-making, and are not a primary focus of this impact assessment. Nonethe-less, for each impact topic, the effects of other watercraft are evaluated in the cumulative effects 

analysis. 

Glen Canyon National Recreation Area recognizes the need for a comprehensive lake management 

plan to more thoroughly explore all water-based recreation. The objectives of the lake management 

plan would be to determine the management of Lake Powell and provide for the long-term protection 

of lake resources while allowing a range of visitor recreational opportunities. The implementation of a 

lake management plan would allow the recreation area to take any additional affirmative action to 

reduce effects on recreation area resources by all types of watercraft users. This would enhance the 

protection and preservation of the recreation area for use by future generations. 
12 GLEN CANYON NATIONAL RECREATION AREA

PURPOSE AND SIGNIFICANCE OF GLEN CANYON NATIONAL RECREATION AREA 

National park system units are established by Congress to fulfill specific purposes, based on the unit’s 

unique and “significant” resources. A unit’s purpose, as established by Congress, is the foundation on 

which later management decisions are based to conserve resources while providing “for the enjoyment 

of future generations.” 

The purpose and significance of Glen Canyon National Recreation Area and its broad mission goals 

are derived from its enabling legislation and are summarized in the recreation area’s proposed General 

Management Plan (NPS 1979a) and Strategic Plan (NPS 2000g). Excerpts that are relevant to 

personal watercraft management in the recreation area are provided below. 

Establishment: Congress established Glen Canyon National Recreation Area in 1972 (PL 92-593). 

The enabling legislation states: 

In order to provide for public outdoor recreation use and enjoyment of Lake Powell and lands 

adjacent thereto . . . and to preserve scenic, scientific, and historic features contributing to the 

public enjoyment of the area, there is established the Glen Canyon National Recreation Area ” 

(Title 16 U.S.C., section 460dd 1972). 

Administration: The recreation area’s enabling legislation states: 

The secretary shall administer, protect, and develop the recreation area in accordance with the 

provision of the [Organic Act] . . . and with any other statutory authority available to him for 

the conservation and management of natural resources (16 U.S.C., section 459f-5(a)). 

This act also specifies that “nothing . . . shall affect or interfere with the authority of the Secretary . . . 

to operate Glen Canyon dam and reservoir” for the purposes of the Colorado River Storage Project 

Act, the achievement of which is the responsibility of the Bureau of Reclamation. 

Purpose of Glen Canyon National Recreation Area: As stated in the recreation area’s enabling 

legislation and restated in the General Management Plan (NPS 1979a) and Strategic Plan (NPS 

2000g), the purpose of the recreation area is “to provide for public outdoor recreation use and 

enjoyment of Lake Powell and lands adjacent thereto . . . and to preserve scenic, scientific, and historic 

features contributing to public enjoyment of the area.” 

Significance: As stated in the General Management Plan (NPS 1979a) and Strategic Plan (NPS 

2000g), Glen Canyon National Recreation Area is significant because: 

It offers a tremendous diversity of both water-based and land-based recreational opportunities. 

It contains Lake Powell, the second largest man-made lake in North America, which provides 

both a unique opportunity for recreation in a natural environment and a transportation corridor to 

remote backcountry areas of Glen Canyon National Recreation Area. 

It is in the heart of the Colorado Plateau region, which offers a unique combination of water and 

desert environments. It offers a natural diversity of rugged water and wind carved canyons, 

buttes, mesas, and other outstanding physiographic features. 
Purpose and Significance of Glen Canyon National Recreation Area

FINAL ENVIRONMENTAL IMPACT STATEMENT 13

The climate and physical features have created local environments favorable to the preservation 

of scientifically important objects, sites, populations, habitats, or communities that are 

significant in and of themselves or provide opportunities to add to our understanding of past or 

ongoing events. 

It possesses evidence of 10,000 years of human occupation and use of resources, which provides 

a continuing story of the prehistoric, historic, and present-day affiliation of humans and their 

environments. 

It constitutes a significant part of the outstanding public lands of the Colorado Plateau. 

The recreation area’s purpose and significance are linked to the concept of impairment, which is 

discussed in section 1.4.5 of Management Policies 2001 (NPS 2000d). That section defines what 

constitutes impairment of park resources and values, and establishes guidelines for recognizing 

impairment. Those guidelines have been incorporated into the analysis methods for each impact topic 

evaluated in this environmental impact statement. Additional information on impairment is included in 

section entitled “Organic Act and Management Policies.” 
14 GLEN CANYON NATIONAL RECREATION AREA

BACKGROUND 

ORGANIC ACT AND MANAGEMENT POLICIES 

In the NPS Organic Act of 1916, Congress directed the Department of the Interior and the National 

Park Service to manage units “to conserve the scenery and the natural 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” (Title 16 U.S.C., section 1 1972). 

Congress reiterated this mandate in the Redwood National Park Expansion Act of 1978 by stating that 

the National Park Service must conduct its actions in a manner that will ensure no “derogation of the 

values and purposes for which these various areas have been established, except as may have been or 

shall be directly and specifically directed by Congress” (Title 16 U.S.C., section 1a-1 1972). 

Within these mandates, the Organic Act and its amendments afford the National Park Service latitude 

when making resource decisions that balance visitor recreation and resource preservation. By these 

acts, Congress “empowered [the National Park Service] with the authority to determine what uses of 

park resources are proper and what proportion of the parks resources are available for each use” 

(Bicycle Trails Council of Marin v. Babbitt, 82 F.3d 1445, 1453 [9th Cir. 1996]). 

Courts have consistently interpreted the Organic Act and its amendments to elevate resource 

conservation above visitor recreation. For example: 

Michigan United Conservation Clubs v. Lujan, 949 F.2d 202, 206 (6th Cir. 1991) states, 

“Congress placed specific emphasis on conservation.” 

The National Rifle Ass’n of America v. Potter, 628 F. Supp. 903, 909 (D.D.C. 1986) states, “In 

the Organic Act Congress speaks of but a single purpose, namely, conservation.” 

In Management Policies 2001 (NPS 2000d), the National Park Service recognizes that resource 

conservation takes precedence over visitor recreation. Section 1.4.3 states “when there is a conflict 

between conserving resources and values and providing for enjoyment of them, conservation is to be 

predominant.” 

Because conservation is predominant, the National Park Service seeks to avoid or to minimize adverse 

impacts on park resources and values. In addition, section 1.4.3 of Management Policies 2001 (NPS 

2000d) recognizes that the National Park Service has discretion to allow negative impacts when 

necessary. However, as discussed further in section 1.4.3, the National Park Service cannot allow an 

adverse impact that constitutes resource impairment. 

The Organic Act prohibits actions that permanently impair park resources unless a law directly and 

specifically allows for such actions (Title 16 U.S.C., section 1a-1 1972). According to section 1.4.5 of 

Management Policies 2001 (NPS 2000d), an action constitutes an impairment when its impacts “harm 

the integrity of park resources or values, including the opportunities that otherwise would be present 

for the enjoyment of those resources or values.” To determine impairment, the National Park Service 

must evaluate “the particular resources and values that would be affected; the severity, duration, and 

timing of the impact; the direct and indirect effects of the impact; and the cumulative effects of the 

impact in question and other impacts.” 
Background

FINAL ENVIRONMENTAL IMPACT STATEMENT 15

Park units vary based on their enabling legislation, missions, and natural and cultural resources. 

Therefore, the recreational activities appropriate for each unit and for areas within each unit vary. An 

action appropriate in one unit could impair resources in another unit. Thus, this environmental impact 

statement analyzes the context, duration, and intensity of impacts related to personal watercraft use at 

Glen Canyon National Recreation Area, as well as the potential for resources impairment. The 

environmental impact statement conforms with the guidelines presented in Director’s Order 12 and 

Handbook: Conservation Planning, Environmental Impact Analysis and Decision-Making (NPS 

2001b). 

SUMMARY OF NATIONAL INFORMATION 

ON THE EFFECTS OF PERSONAL WATERCRAFT 

National personal watercraft ownership increased every year between 1991 and 1998. The rate of 

annual increase peaked in 1994 at 32% and dropped slightly in 1999, 2000, and 2001 (see table 1). 

Environmental groups, personal watercraft users and manufacturers, and land managers express 

differing opinions about the environmental consequences of personal watercraft use, and about the 

need to manage or to limit this recreational activity. The following section is a summary of national 

research conducted over two decades on the effects of personal watercraft use on natural resources and 

human health and safety. Results of studies on personal watercraft use related to water quality, air 

quality and soundscapes conducted at Glen Canyon National Recreation Area are presented in the 

“Affected Environment” chapter of this environmental impact statement. 

TABLE 1: NATIONAL PWC REGISTRATION TRENDa

Year 

No. of 

Boats Owned 

No. of Personal 

Watercraft Owned 

Boat Ownership Trend 

(percentage change) 

Personal Watercraft 

Ownership Trend 

(percentage change) 

1991 16,262,000 305,915 — — 

1992 16,262,000 372,283 0 21.7 

1993 16,212,000 454,545 0 22.1 

1994 16,239,000 600,000 0 32.0 

1995 15,375,000 760,000 -5 26.7 

1996 15,830,000 900,000 3 18.4 

1997 16,230,000 1,000,000 3 11.1 

1998 16,657,000 1,100,000 3 10.0 

1999 16,773,000 1,096,000 1 -0.4 

2000 16,965,000 1,078,400 1 -1.6 

2001 1,053,560 -2.4 

 

Source: M. Schmidt, USCG, email comm., September 4, 2001; National Marine Manufacturers Association (NMMA) 2002. 

a. Estimates provided by the National Marine Manufacturers Association (M. Schmidt, USCG, pers. comm., Sept. 4, 2001).
PURPOSE OF AND NEED FOR ACTION

16 GLEN CANYON NATIONAL RECREATION AREA

Water Quality 

The majority of personal watercraft in use today are powered by conventional two-stroke carbureted 

engines, which discharge as much as 30% of their fuel directly into the water (California 

Environmental Protection Agency, Air Resources Board [CARB] 1999a, NPS 1999c). Hydrocarbons, 

including benzene, ethylbenzene, toluene, and xylenes, are released as part of this uncombusted fuel 

mixture along with gasoline additives, such as methyl tertiary-butyl ether. Some polycyclic aromatic 

hydrocarbons are released as part of the uncombusted fuel mixture, but the combusted fraction of 

emissions releases larger amounts of polycyclic aromatic hydrocarbons. 

In 1996, the U.S. Environmental Protection Agency (EPA) promulgated a rule to reduce exhaust 

emissions from new marine engines, including outboards and personal watercraft. Emission controls 

provided for increasingly strict standards beginning in model year 1998 (61 FR 52087-52106, 

October 4, 1996a). As stated in the rule-making, the agency expects a 52% reduction in hydrocarbon 

emissions from marine engines from present levels by 2010 and a 75% reduction in hydrocarbon 

emissions by 2030, based on phasing out polluting machines. The 1997 EPA rule delayed 

implementation by one year (EPA 1996a, 1997a). 

A typical conventional (i.e., carbureted) two-stroke personal watercraft engine discharges as much as 

30% of its fuel unburned directly into the water (NPS 1999c; CARB 1999a). At common fuel 

consumption rates, an average two-hour ride on a personal watercraft may discharge 3 gallons of fuel 

into the water (NPS 1999c). According to data from the California Air Resources Board, two-stroke 

personal watercraft engines may consume 5 to 10 gallons of fuel per hour, of which up to 3.3 gallons 

per hour may be discharged unburned (CARB 1998b). (As described in appendix C, an estimated 

discharge rate of 3 gallons per hour is used in the water quality impact calculations.) The Personal 

Watercraft Industry Association notes that direct-injection engines have been available in personal 

watercraft for four years; and three personal watercraft manufacturers introduced four-stroke engines 

for the 2002 model year (PWIA 2002a). The Environmental Protection Agency assumes that the 

existing two-stroke engine models would not be completely replaced by newer personal watercraft 

technology until 2050 (40 CFR 89, 90, 91). 

The average operating life of a personal watercraft is 5 to 10 years, depending upon the source. The 

formula for determining the operating life of personal watercraft was published in the Federal Register

on October 4, 1996 (EPA 1996a). Based on this formula, the National Park Service expects that by 

2012, most boat owners will already be in compliance with the 2006 EPA marine engine standards. 

The Personal Watercraft Industry Association believes the typical operating life of a personal 

watercraft rental is three years and approximately five to seven years for a privately owned vessel 

(PWIA 2002a).

The amount of pollution attributable to personal watercraft compared to other motorboats and the 

degree to which personal watercraft affect water quality are uncertain. Data from one study of personal 

watercraft and outboard motorboats show that personal watercraft represented one third of the 

watercraft but emitted 80% of the hydrocarbons (CARB 1998a). Other factors that affect pollutants’ 

impacts are intrinsic to each water body, and include water temperature, air temperature, water mixing, 

motorboating use, and winds (ODEQ 1999). 

Discharges of methyl tertiary-butyl ether and polycyclic aromatic hydrocarbons are particularly of 

concern because of their potential to adversely affect the health of people and aquatic organisms. 

Additional studies are needed to determine the distribution of polycyclic aromatic hydrocarbons and 

their ecotoxicity on a variety of biota (Allen et al. 1998). Long-term studies are required on the effect 
Background

FINAL ENVIRONMENTAL IMPACT STATEMENT 17

on organisms or human health of repeated exposure to low levels of polycyclic aromatic hydrocarbons 

and methyl tertiary-butyl ether (Asplund 2000). 

The sources, fates, and effects of hydrocarbon contaminants in aquatic systems are examined in the Oil 

in the Sea report (Ocean Studies Board, Marine Board, and Transportation Research Board 2002), 

which was first produced in 1985. This report focuses primarily on marine ecosystems, but also 

includes information on freshwater systems. It identifies petroleum consumption as the source of the 

overwhelming majority of the petroleum that enters marine systems, and names carbureted, two-stroke 

engines as an important source of water pollutants. 

Air Quality 

Personal watercraft emit various compounds that pollute the air. In the two-stroke engines commonly 

used in personal watercraft, the lubricating oil is used once and is expelled as part of the exhaust; and 

the combustion process results in emissions of air pollutants such as volatile organic compounds 

(VOC), nitrogen oxides (NOx), particulate matter (PM), and carbon monoxide (CO). 

In August 2002, the Environmental Protection Agency proposed additional rules that would further 

reduce boating emissions. The proposal includes evaporative emission standards for all boats and 

would reduce emissions from fuel tanks by 80% (67 FR 157, August 14, 2002, pp. 53049-53115). 

It is assumed that the 1996 EPA rule concerning marine engines will reduce air emissions from 

personal watercraft in the future. 

Soundscapes 

Personal watercraft generated noise varies from vessel to vessel. No literature was found that 

definitively described scientific measurements of personal watercraft noise. Some literature stated that 

all recently manufactured watercraft emit fewer than 80 decibels at 50 feet from the vessel, while other 

sources attributed levels as high as 102 decibels without specifying distance. None of this literature 

fully described the method used to collect noise data. 

The National Park Service contracted for noise measurements of personal watercraft and other 

motorized vessels in 2001 at Glen Canyon National Recreation Area (Harris Miller Miller & Hanson, 

Inc. 2002). The results show that maximum personal watercraft noise levels at 82 feet ranged between 

68 to 76 decibels on the A-weighted scale. Noise levels for other motorboat types measured during 

that study ranged from 65 to 86 decibels at 82 feet. 

Noise limits established by the National Park Service require vessels to operate at less than 82 dB at 

82 feet from the vessel. Personal watercraft may be more disturbing than other motorized vessels 

because of rapid changes in acceleration and direction of noise. More detail on this study is provided 

in the “Affected Environment” chapter under “Soundscapes.” 

Personal watercraft users tend to operate close to shore or in confined areas, and often travel in groups. 

These factors make noise more noticeable to other recreationists. Motorboats speeding back and forth 

in one area or spinning around in small inlets also generate noise complaints. However, most 

motorboats tend to operate away from shore and to navigate in a straight line, which reduces the 

perception of noise (Vlasich 1998). The Personal Watercraft Industry Association (PWIA) believes 
PURPOSE OF AND NEED FOR ACTION

18 GLEN CANYON NATIONAL RECREATION AREA

that through the 2002 model year, the personal watercraft output on a limited number of higher rated 

models was around 155 and 165 horsepower (PWIA email to NPS dated September 23, 2002b).

Most studies on the effects of noise on soundscapes and human receptors have focused on highway 

and airport noise. Komanoff and Shaw (2000) used the analytical approaches of these studies to 

perform a noise-cost analysis of personal watercraft. They concluded that the cost to beachgoers from 

personal watercraft noise was more than $900 million per year. The cost per personal watercraft was 

estimated to be about $700 per vessel each year or $47 for each 3-hour “personal watercraft day.” 

They concluded that the cost per beachgoer was highest at secluded lake sites, where beachgoers had a 

higher expectation of experiencing natural quiet and usually invested a larger amount of time and 

personal energy in reaching the area. However, because there are many more visitors available to be 

affected at popular beaches, noise costs per personal watercraft were highest at crowded sites 

(Drowning in Noise: Noise Costs of Jet Skis in America [Komanoff and Shaw 2000]). 

Wildlife and Wildlife Habitat 

Few studies have examined personal watercraft effects on wildlife. Based on observations, some 

wildlife disturbance and harassment likely occurs. It can be deliberate (such as attempts to run over 

shorebirds or birds resting on the water) or incidental to the use of the craft (such as noise). Nesting 

colonial birds appear to be particularly susceptible to disturbance (Burger 1998). However, the extent, 

duration, and magnitude of biological impacts because of personal watercraft operations versus other 

motorboats remain unknown. 

Burger (2000) examined the behavior of common terns in relation to personal watercraft use and other 

boats and noted that personal watercraft users traveled faster and came closer to banks, resulting in 

more flight response in terns and contributing to lower reproductive success. 

Shoreline Vegetation 

The effects of personal watercraft on aquatic communities have not been fully studied, and scientists 

disagree about whether personal watercraft adversely impact aquatic vegetation. Most concern arises 

from the shallow draft of personal watercraft, allowing them access to shallow areas that conventional 

motorboats cannot reach. Like other vessels, personal watercraft may crush or uproot grasses that 

occur in shallow water (Stevenson and Dennison 2000; Asplund 2000). 

Anderson (2000) studied the effect of personal watercraft wave-wash on shallow salt marsh vegetation 

and found that although the waves from personal watercraft are not different from those generated by 

other boats, personal watercraft can enter marsh channels and create sediment suspension problems in 

these areas. 

Health and Safety Concerns 

Personal watercraft industry representatives report that personal watercraft accidents decreased in 

some states in the late 1990s, but other research does not support their contention. Two national 

studies of personal watercraft accidents and injuries report that personal watercraft pose a health and 

safety risk, primarily to operators (Branche et al. 1997; National Transportation Safety Board [NTSB] 

1998). Industry representatives report that personal watercraft accidents decreased in some states in 
Background

FINAL ENVIRONMENTAL IMPACT STATEMENT 19

the late 1990s. The National Transportation Safety Board reported that in 1996 personal watercraft 

represented 7.5% of state-registered recreational boats but accounted for 36% of recreational boating 

accidents. In the same year personal watercraft operators accounted for more than 41% of people 

injured in boating accidents. Personal watercraft operators accounted for approximately 85% of the 

persons injured in accidents studied in 1997 (NTSB 1998). 

Increased personal watercraft use in recent years has resulted in more concern about the health and 

safety of operators, swimmers, snorkelers, divers, and other boaters. A 1998 National Transportation 

Safety Board study revealed that while recreational boating fatalities have been declining in recent 

years, personal watercraft-related fatalities have increased (NTSB 1998). Nationwide personal 

watercraft accident statistics provided by the U.S. Coast Guard (USCG) supports the increase in 

personal watercraft-related fatalities however, since a peak of 84 personal watercraft-related fatalities 

in 1997, accidents, injuries, and fatalities involving personal watercraft have decreased (see table 2) 

(M. Schmidt, USCG, pers. comm., Sept. 4, 2001). The U.S. Coast Guard’s Office of Boating Safety 

studied exposure data to assess boating risks. This method allows for a comparison between boat types 

based on comparable time in the water. Personal watercraft use ranked second in boat type for 

fatalities per million hours of exposure in 1998, with a 0.24 death rate per million exposure hours. 

TABLE 2: NATIONWIDE PERSONAL WATERCRAFT ESTIMATES AND ACCIDENT STATISTICS

Year 

Recreational 

Boats 

Owned* 

Personal 

Watercraft 

Owneda

No. of 

Personal 

Watercraft in 

Accidents 

No. of 

Personal 

Watercraft 

Injuries 

No. of 

Personal 

Watercraft 

Fatalities 

No. of All 

Boats 

Involved in 

Accidents 

Percentage of 

Personal 

Watercraft 

Involved in 

Accidents 

1987 14,515,000 N/A 376 156 5 9,020 4.2 

1988 15,093,000 N/A 650 254 20 8,981 7.2 

1989 15,658,000 N/A 844 402 20 8,020 10.5 

1990 15,987,000 N/A 1,162 532 28 8,591 13.5 

1991 16,262,000 305,915 1,513 708 26 8,821 17.2 

1992 16,262,000 372,283 1,650 730 34 8,206 20.1 

1993 16,212,000 454,545 2,236 915 35 8,689 25.7 

1994 16,239,000 600,000 3,002 1,338 56 9,722 30.9 

1995 15,375,000 760,000 3,986 1,617 68 11,534 34.6 

1996 15,830,000 900,000 4,099 1,837 57 11,306 36.3 

1997 16,230,000 1,000,000 4,070 1,812 84 11,399 35.7 

1998 16,657,000 1,100,000 3,607 1,743 78 11,368 31.7 

1999 16,773,000 1,096,000 3,374 1,614 66 11,190 30.2 

2000 16,965,000 1,078,400 3,282 1,580 68 11,079 29.6 

Total 33,851 15,238 645 

Source: M. Schmidt, USCG, e-mail comm., Sept. 4, 2001. 

a. Estimates provided by the National Marine Manufacturers Association (M. Schmidt, USCG, pers. comm., Sept. 4, 2001).
PURPOSE OF AND NEED FOR ACTION

20 GLEN CANYON NATIONAL RECREATION AREA

PERSONAL WATERCRAFT USE AND 

REGULATION AT GLEN CANYON NATIONAL RECREATION AREA 

Glen Canyon National Recreation Area was established for recreation and conservation purposes in 

1972. Its major recreational resource is Lake Powell, which was created when the Colorado River was 

dammed in 1963. Use of motorboats occurred shortly after as Lake Powell began to fill. Personal 

watercraft use at the recreation area is thought to have begun in the late 1980s when the machines 

were first manufactured, although their use initially was limited. Data have not been collected in the 

recreation area to determine changes in personal watercraft use over time. 

Glen Canyon National Recreation Area is managed according to resource zones that were established 

in the recreation area’s proposed General Management Plan (NPS 1979a). Lake Powell, which 

constitutes 186,000 acres (13%) of the 1,254,306 acres in the recreation area, is part of the Recreation 

and Resource Utilization Zone. Within this zone, recreational activity such as personal watercraft use 

is permitted. 

In the year 2001, use of all types of watercraft in Glen Canyon National Recreation Area totaled 

831,079 boat days and the watercraft operating hours totaled 3,121,114. A boat day equals one 

watercraft on the lake during a 24-hour period and operating hours are the average number of hours a 

vessel is underway during a 24-hour period. Use of Lake Powell by personal watercraft and all other 

types of vessels is highest in the summer months, from June through September. 

In 2001, personal watercraft accounted for 26% of all boat days, or about 229,377 boat days, and 18% 

of all operating hours (559,480 hours). Based on national and state trends in personal watercraft sales 

and registration, as well as eight-year trends in recreation area visitation, the proportion of personal 

watercraft boat days and operating hours in the total watercraft population is expected to remain 

constant through 2012.

Personal watercraft are more maneuverable and can access more areas than most other types of 

motorized watercraft. However, they are intended to be short-distance recreational vehicles and are 

generally used within localized areas. Personal watercraft use on Lake Powell is concentrated in areas 

associated with entry ports and marinas such as Bullfrog, Wahweap, Hite, and Halls Crossing; and 

launch ramps such as Antelope Point and Stateline. 

In Glen Canyon National Recreation Area, personal watercraft are often used in conjunction with 

houseboats and other powerboats. Fueling stations enable these larger boats to access any location on 

the lake. As a result, personal watercraft are used throughout the lake, including remote areas well 

away from launch points or other developed facilities. 

The Superintendent’s Compendium (NPS 2002c), for Glen Canyon National Recreation Area (36 CFR 

1.7 (b), 3.6) permits the use of personal watercraft in Glen Canyon National Recreation Area on Lake 

Powell and in the upper Colorado, Escalante, Dirty Devil, and San Juan Rivers. Personal watercraft 

users in the recreation area must comply with regulations set forth by Arizona and laws and rules set 

forth by Utah while operating on the waters within these states. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 21

OBJECTIVES IN TAKING ACTION 

Objectives were established to determine whether alternatives for managing personal watercraft use at 

Glen Canyon National Recreation Area would be successful. All action alternatives selected for 

detailed analysis had to substantially meet all of the objectives and also had to resolve the purpose of 

and need for action. 

Objectives for managing personal watercraft use were developed from the Glen Canyon National 

Recreation Area enabling legislation, mandates and direction in the general management plan and 

strategic plan, and other management documents. All objectives are compatible with the purpose and 

significance statements of Glen Canyon National Recreation Area presented above. For each impact 

topic, the recreation area objectives as defined in the general resource management plans (NPS 1979a, 

1986) and the objectives for management of personal watercraft are presented in table 3. 

TABLE 3: OBJECTIVES FOR RECREATION AREA MANAGEMENT

AND PERSONAL WATERCRAFT MANAGEMENT

Impact Topic 

Recreation Area 

Management Objective Personal Watercraft Management Objective 

Water quality Encourage the maintenance of high 

water quality in all bodies and sources 

of water and perpetuate the natural flow 

of free water. 

Manage personal watercraft emissions that enter the water in 

accordance with water quality protection policies and goals. 

Protect aquatic organisms from personal watercraft effects, 

including those related to emissions and sediment. 

Manage human wastes associated with personal watercraft 

use in accordance with water quality protection policies and 

goals. 

Air quality No objective identified. Manage personal watercraft activity so that exhaust 

emissions do not appreciably degrade ambient air quality. 

Soundscapes No objective identified. Manage the effects of personal watercraft on soundscapes in 

a manner consistent with recreation area management 

zones. 

Wildlife and 

wildlife habitat 

No objective identified. Protect fish and wildlife (including endangered or threatened 

species) and their habitats from personal watercraft 

disturbances. 

Protect fish and wildlife from the potential adverse effects that 

result from the bioaccumulation of contaminants emitted from 

personal watercraft. 

Threatened and 

endangered 

species 

Protect all known populations of 

endangered fish species from impacts 

of human activities in the Glen Canyon 

National Recreation Area. 

Protect river inflow as native species 

habitat. 

Protect endangered or threatened species (both fauna and 

flora) and their habitats from personal watercraft 

disturbances. 

Shoreline 

vegetation 

No objective identified. Manage personal watercraft use to protect native vegetation 

at or near the shoreline from personal watercraft user activity 

and access. 

Visitor 

experience 

and conflict 

Manage the recreation area so that it 

provides maximal recreational 

enjoyment to the American public and 

their guests. 

Manage personal watercraft use to enhance the quality of the 

visitor experience. 

Reduce potential conflicts associated with personal watercraft 

use and other uses of Glen Canyon National Recreation 

Area. 

Visitor safety No objective identified. Reduce the potential for personal watercraft user accidents. 

Cultural 

resources 

Interpret historical and archeological 

resources and the culture of aboriginal 

societies while centering interpretive 

themes around outdoor recreation. 

Manage personal watercraft use and access to enhance 

protection of cultural resources. 
PURPOSE OF AND NEED FOR ACTION

22 GLEN CANYON NATIONAL RECREATION AREA

Impact Topic 

Recreation Area 

Management Objective Personal Watercraft Management Objective 

Socioeconomic 

environment 

No objective identified. Minimize adverse effects of personal watercraft-related 

management policies within the recreation area on waterrecreation-based businesses. 

Federal/state 

cooperation and 

recreation area 

operations 

Maximize the efficiency and 

effectiveness of the management of the 

recreation area and adjacent lands. 

Cooperate with the Bureau of 

Reclamation in their management of the 

reservoir. 

Cooperate with the Navajo Tribe in 

managing and developing the southern 

shoreline of Lake Powell for 

recreational use. 

Maintain cooperation with state entities that regulate personal 

watercraft use and protect quality of air and water. 

Provide sufficient staffing levels as funding allows to 

adequately manage personal watercraft use and to resolve 

personal watercraft user-related conflicts. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 23

IMPACT TOPICS AND ISSUES RELATED TO PERSONAL WATERCRAFT USE 

IMPACT TOPICS EVALUATED IN THIS ENVIRONMENTAL IMPACT STATEMENT 

Many of the impact topics associated with personal watercraft use at Glen Canyon National Recreation 

Area were identified in the settlement agreement with the Bluewater Network. The settlement requires 

that, at a minimum, the effects of personal watercraft use be analyzed for: 

Water quality; 

Air quality; 

Soundscapes; 

Wildlife and wildlife habitat; 

Shoreline vegetation; 

Visitor conflicts; and 

Visitor safety. 

Impact topics and issues within each impact topic also were identified during scoping meetings with 

NPS staff, through consultation with other federal and state agencies, and as a result of public 

comments. Impact topics beyond those required by the settlement agreement that were considered in 

this environmental impact statement included: 

Endangered or threatened species; 

Wetlands and submerged aquatic vegetation, which were combined with the consideration of 

shoreline vegetation; 

Visitor use and experience; 

Cultural resources; 

Socioeconomic effects; and 

National recreation area operations. 

ISSUES RELATED TO PERSONAL WATERCRAFT 

USE IN GLEN CANYON NATIONAL RECREATION AREA 

Personal watercraft issues specific to Glen Canyon National Recreation Area are briefly summarized 

below. The relevant current conditions of impact topics are discussed in detail in the “Affected 

Environment” chapter. Impacts associated with each of the personal watercraft management 

alternatives are described in the “Environmental Consequences” chapter. 
PURPOSE OF AND NEED FOR ACTION

24 GLEN CANYON NATIONAL RECREATION AREA

Water Quality 

As described earlier in the section entitled “Summary of National Information on the Effects of 

Personal Watercraft,” two-stroke, carbureted personal watercraft engines discharge as much as 30% of 

their fuel directly into the water. Release of these chemical compounds into surface waters may 

degrade water quality for multiple uses, including aquatic life, drinking water, and agricultural water 

supplies. 

Some research shows that polycyclic aromatic hydrocarbons, including those from personal watercraft 

emissions, adversely affect water quality via harmful phototoxic effects on ecologically sensitive 

plankton and other small water organisms (EPA 1998; Oris et al. 1998; Landrum et al. 1987; 

Mekenyan et al. 1994; Arfsten et al. 1996). Phytoplankton and zooplankton are important components 

of the aquatic food chain. 

Personal watercraft do not have portable toilets on-board. This condition may contribute to water 

quality degradation as a result of the introduction of human waste into the lake. 

Air Quality 

Personal watercraft emit nitrogen oxides, volatile organics, and other compounds that may adversely 

affect air quality. Visibility effects may occur from the discharge of exhaust smoke into the air. 

Photochemical transformations of the engine emissions may affect visibility conditions in the 

recreation area.

Soundscapes 

The noise from personal watercraft may be more disturbing than sounds from other watercraft because 

of numerous changes in pitch associated with frequent changes in speed. 

Wildlife and Wildlife Habitat 

Personal watercraft uses may affect fish and wildlife, which could include alarm or flight, avoidance 

of disturbed areas, degradation of habitat, and effects on reproductive success. Wildlife effects may be 

caused by personal watercraft noise and their ability to access shallow water areas and riparian 

habitats. 

Endangered or Threatened Species 

Concerns about personal watercraft effects on endangered or threatened wildlife would be similar to 

those described above for other wildlife in the recreation area. Personal watercraft use represents a 

concern to endangered or threatened plant species because the craft can go ashore on beaches and side 

canyons, providing access to plant habitats. 
Impact Topics and Issues Related to Personal Watercraft Use

FINAL ENVIRONMENTAL IMPACT STATEMENT 25

Shoreline Vegetation 

Personal watercraft users may go ashore on beaches and side canyons, allowing visitors to access 

shoreline areas where they may trample vegetation. Effect on submerged aquatic vegetation would be 

limited because in most areas, unsuitable shoreline substrates, steep shoreline slopes, or large seasonal 

fluctuations of water surface elevations would preclude development of submerged aquatic vegetation. 

Visitor Experience and Visitor Conflicts 

Personal watercraft characteristics such as noise, odors, safety hazards, and operational style may 

affect the experience for some other recreation area visitors. Personal watercraft speed, operator 

behavior, and proximity to other lake users can pose conflicts and safety hazards. Inexperience in 

launching personal watercraft, combined with congestion in the launch ramp area, may result in 

conflicts between personal watercraft users and other motorcraft users. 

Visitor Safety 

Surveys conducted in 2001 to characterize boating use in Glen Canyon National Recreation Area 

indicated that personal watercraft comprised about 26% of the total vessel use (NPS unpublished data 

2001d). In 2001, personal watercraft were involved in approximately 13% of all boating accidents 

(NPS unpublished data 2001e). Health and safety risks to personal watercraft operators and passengers 

could also occur because of the vessels’ emissions of carbon monoxide. 

Cultural Resources 

Personal watercraft use may provide visitors with access to the sites of historic and archeological 

resources, and traditional cultural properties that are listed on or are eligible for listing on the National 

Register of Historic Places. However, many of these sites are located at considerable distances from 

areas that are easily accessible via personal watercraft, which may limit the potential for adverse 

effects. 

Socioeconomic Effects 

Personal watercraft sales and rentals and other expenditures by personal watercraft users represent an 

important segment of the local and regional recreation-based economy. Some businesses may be 

affected by actions related to a change in personal watercraft management. 

Recreation Area Operations 

Personal watercraft operating regulations, laws, and rules are different between Arizona and Utah, 

leading to some visitor confusion, and making enforcement difficult on occasion. Concern has been 

expressed that current recreation area staffing levels may not be adequate to manage personal 

watercraft-related issues or to enforce new personal watercraft management actions. 
26 GLEN CANYON NATIONAL RECREATION AREA

IMPACT TOPICS ELIMINATED FROM FURTHER CONSIDERATION 

Director’s Order 12 and Handbook: Conservation Planning, Environmental Impact Analysis, and 

Decision Making (NPS 2001b) lists 13 impact topics that must be considered in an environmental 

impact statement. If any are judged to be not applicable to the federal action being evaluated, they 

should be identified as being dismissed from detailed evaluation. The reason should be provided. 

The impact topics identified below have been dismissed from further consideration because the range 

of personal watercraft management alternatives would have no effect on these resources or because the 

impacts have been evaluated within another impact topic. 

Possible Conflicts with Land Use Plans, Policies, or Controls — Plans and policies associated with 

lands adjacent to Lake Powell or the recreation area were reviewed. It was determined that the 

alternatives to manage personal watercraft use in the recreation area would not involve actions that 

would affect these lands. Therefore, the management of personal watercraft within the recreation area 

would not conflict with any land use plans, policies, or controls. 

Urban Quality, Historic and Cultural Resources, and Design of the Built Environment — 

Historic and cultural resources were included as an impact topic that was considered in detail in this 

environmental impact statement. Urban quality and design of the built environment were eliminated 

from further consideration because the recreation area is not in an urban setting and there is little or no 

development that would be affected by personal watercraft management actions. 

Socially or Economically Disadvantaged Populations — Executive Order 12898, “General Actions 

to Address Environmental Justice in Minority and Low-Income Populations,” directs agencies to 

address environmental and human health conditions in minority and low-income communities so as to 

avoid the disproportionate placement of any adverse effects from federal policies and actions on these 

populations. This topic was dismissed from further analysis because NPS actions to manage personal 

watercraft use at the recreation area would not displace personal watercraft use to minority or lowincome communities. Local residents may include low-income populations; however, these 

populations would not be disproportionately affected by any of the proposed alternatives. The decision 

to dismiss was supported by notification received from the Navajo Nation Historic Preservation 

Department, Traditional Cultural Program that the Navajo Nation does not currently have any 

concerns with the proposed project. 

Floodplains — The alternatives do not involve development that would change water surface 

elevations or cause flooding that would affect human safety, health, or welfare. None of the personal 

watercraft or related activities identified in the alternatives would cause effect on floodplains. 

Prime and Unique Agricultural Lands — There are no prime or unique agricultural lands located 

within areas of Glen Canyon National Recreation Area that would be affected by personal watercraft 

management. 

Ecologically Critical Areas, Wild and Scenic Rivers, or Other Unique Natural Resources — The 

areas of Glen Canyon National Recreation Area that would be affected by management of personal 

watercraft use do not contain ecologically critical areas, wild and scenic rivers, or other unique natural 

resources, as referenced in 40 CFR 1508.27. 
Impact Topics Eliminated from Further Consideration

FINAL ENVIRONMENTAL IMPACT STATEMENT 27

Indian Trust Resources — Indian trust assets are assets that the United States holds and administers 

for Indian tribes. The federal Indian trust responsibility is a legally enforceable fiduciary obligation on 

the part of the United States to protect tribal lands, assets, resources, and treaty rights, and it represents 

a duty to carry out the mandates of federal law with respect to American Indian and Alaska Native 

tribes. Indian trust resources would not be affected by personal watercraft management. Therefore, this 

impact topic was eliminated from further consideration. 
28 GLEN CANYON NATIONAL RECREATION AREA

RELATIONSHIPS TO OTHER PLANS, POLICIES, AND ACTIONS 

Numerous National Park Service, federal, and state plans, policies, and actions could affect the 

alternatives or cumulative impacts analysis for personal watercraft management. These plans and 

policies are also considered in the analyses of cumulative effects. From newest to oldest, the most 

relevant include the following. 

Bureau of Reclamation Reservoir Operations Plan, Updated Annually. The Bureau of 

Reclamation is required by section 602 of the Colorado River Basin Project Act to prepare an 

operations plan each year. The plan establishes: 

The operation of reservoirs on the Colorado River under the year’s anticipated hydrologic and 

climatic conditions; 

The quantity of water requiring storage; 

The water available for delivery and whether water consumptive users will be normal, surplus or 

shortage; and 

Whether water apportionments not used could be allocated to other downstream beneficial users. 

Glen Canyon Dam is managed primarily to meet statutory water delivery obligations, with 

consideration to maintaining or improving instream flow for aquatic resources. Within these 

obligations, release restrictions for maximum and minimum flows are established. 

Antelope Point Marina and Ramp Development Plan, 2002. This plan would increase visitor use 

by adding up to 300 boat slips, a marina, hotel, and boat launch. Although the marina would not 

provide personal watercraft rentals, a portion of the increased visitor use would come from personal 

watercraft operations. 

Strategic Plan for Glen Canyon National Recreation Area and Rainbow Bridge National 

Monument, October 1, 2000 – September 30, 2005. This plan translated servicewide mission goals 

into objectives with specific targets to be accomplished at Glen Canyon National Recreation Area. 

Some of the objectives that could be relevant to personal watercraft management include: 

Protecting water quality by ensuring that all discharge permit requirements are met and that the 

recreation area would not be subject to any notices of violations; 

Improving the protection of at least two endangered or threatened fish species; 

Protecting and improving the condition of archeological resources so that at least 30% of the 

non-inundated sites would meet the classification for good condition; 

Ensuring a 95% visitor satisfaction rate; and 

Protecting visitor safety with an accident rate that does not exceed the level in the early 1990s. 

Grazing Management Plan, Glen Canyon National Recreation Area, 1999. This plan described the 

resource protection and grazing administrative responsibilities of the National Park Service and 
Relationships to Other Plans, Policies, and Actions

FINAL ENVIRONMENTAL IMPACT STATEMENT 29

Bureau of Land Management; assessed range conditions; established the goals, objectives, and 

recommendations for grazing practices and management actions; and established the maximum 

grazing intensities to ensure compatibility with the recreation area. The plan included establishment of 

a monitoring plan for the protection of water resources, vegetation (including riparian resources), and 

cultural resources. 

Glen Canyon National Recreation Area Fish Management Plan, 1996. This plan provided longrange planning and management for endangered and native fish species within the recreation area. It 

included coordination of inter-agency efforts for habitat protection and management, and for providing 

adequate inflow. Policies were established that would maintain or enhance forage conditions to allow 

adequate nutrition of all fish in Lake Powell, and to improve nursery habitat by providing adequate 

vegetative cover. Another goal of the plan was to understand and minimize the impacts of dam 

operation on native and sport fish population. 

Environmental Assessment and Management/Development Concept Plans for Lake Powell’s 

Accessible Shorelines, 1988. These plans provided management strategies for all shoreline areas and 

site-specific strategies to resolve specific problems. Goals included reducing resource impacts and 

visitor conflicts, and improving shorelines for recreation use. It included monitoring actions to 

evaluate the effectiveness of management strategies. 

Water Resource Management Plan, 1987. This document provided a 10-year water resource 

management plan for Glen Canyon National Recreation Area. Its goal was to provide adequate 

management to ensure public use and recreation enjoyment. It covered Lake Powell, its tributaries, and 

the waters of adjoining lands, including springs, seeps, ephemeral streams, and groundwater. 

Glen Canyon Natural Resource Management Plan, 1986. This plan addressed research, monitoring, 

and actions to manage the natural resources of the recreation area. The plan specified eight resource 

areas and ranked the management areas for inventory and analysis. It also set a recommended course 

of action for protection of resources from impacts of human activities. 

Development Concept Plan for Hite Marina, 1982. This plan established guidelines for 

development of facility infrastructure for the next 10 years. It included improved parking and traffic 

circulation, housing, camping, boating, and day use facilities. 

Glen Canyon National Recreation Area General Management Plan, 1979. The most recent 

General Management Plan for the recreation area, including Lake Powell, was completed in 1979 and 

reprinted in 1991. Much has changed since this document was written, including visitor use patterns 

and the emergence of personal watercraft as a popular recreation vessel. The plan established 

management zones, including the Recreation and Resource Utilization Zone on the lake surface, and 

the land-based Natural, Cultural, and Development Zones. The plan recognized that the shoreline of 

Lake Powell fluctuates with the water level and established that the boundaries between the Recreation 

and Resource Utilization Zone and the land-based zones would change with the shoreline. This action 

was important because it defined the limits of the Recreation and Resource Utilization Zone within 

which watercraft could be used. 

Glen Canyon National Recreation Area Act of 1972 (PL 92-593 Appendix 1). Congress 

established Glen Canyon National Recreation Area for public outdoor recreation use and enjoyment of 

the lake and lands adjacent to it and to preserve scenic, scientific, and historic features for public 

enjoyment. The act specifies that there shall be no effect or interference with the authority of the 
PURPOSE OF AND NEED FOR ACTION

30 GLEN CANYON NATIONAL RECREATION AREA

Secretary of the Interior to operate Glen Canyon Dam and Lake Powell for the Colorado River 

Storage Project Act as administered by the Bureau of Reclamation. 

Section 6 of the Enabling Legislation Public Law 92-593. Grazing is administered by the Bureau of 

Land Management. The National Park Service and the Bureau of Land Management coordinate and 

promote the effective management of livestock grazing with other resource management. 

Memorandum of Agreement, September 17, 1965 between the Bureau of Reclamation and the 

National Park Service. This document related to the administration and development of lands and 

facilities at the Glen Canyon Unit of the Colorado River Storage Project. It specified the transfer of the 

Glen Canyon reservoir area to the National Park Service, which would develop and manage the area 

for recreational purposes. It established cooperative management procedures, objectives, and activities 

for using the structures, lands, and water resources. It had several attachments, including: 

Memorandum of Understanding between the National Park Service and Bureau of Land 

Management in Utah. This joint agreement covers the portion of the recreation area in Utah. It 

delineates geographic areas of common concern, including development, maintenance, planning, 

annual operations, and approval plans. To promote efficiency of operations and service to the 

public, land use management plans are jointly reviewed for any adjustments in boundaries or 

management responsibility. This joint analysis and review includes cooperation on all National 

Environmental Policy Act, wildlife, grazing, mineral leasing, and watershed management 

compliance. 

Memorandum of Understanding between the National Park Service and the Bureau of Land 

Management in Arizona. This joint agreement covers the portion of the recreation area in 

Arizona. It provides a joint agreement to determine grazing zones and procedures for grazing 

permits, developments, and improvements. 

Memorandum of Agreement between the National Park Service and the Navajo Tribe. This 

agreement involves joint administration for “Parcel “B” lands, including lands below elevation 

3,720 feet northeast of Antelope Creek and within the recreation area contiguous to the Navajo 

Indian Reservation. The agreement covers the construction of all recreation facilities and utilities 

in accordance with a long-range management and development plan for the recreation area. 

Exchange Act of September 2, 1958 (72 Stat. 1686). Under this act, “Parcel B” lands were 

transferred to the federal government. Such lands are not to be used for public recreational facilities 

without the approval of the Navajo Tribal Council. 

Colorado River Storage Project Act of April 11, 1956 (PL 84-485). This act authorized the 

construction of Glen Canyon Dam. It directs the purposes and policies for using Lake Powell for river 

regulation, irrigation, flood control, and generation of hydroelectric power. 

Arizona Statute Title 3, Chapter 7 (Article 1, Section 3-903). This law authorizes the director of the 

Arizona Department of Agriculture to establish and maintain a list of state-protected native plants. The 

statute provides for protection of native plants on both publicly and privately owned lands. It also 

defines the terms and conditions for investigations of native plants and authorizes the state to 

determine where protected species occur. 

The Utah State Lands Endangered and Threatened Plant Species Statute (Title 65A-2-3). This 

state law defines the terms and conditions of the state status of endangered or threatened plant species. 
Relationships to Other Plans, Policies, and Actions

FINAL ENVIRONMENTAL IMPACT STATEMENT 31

The State Lands Division may make determinations concerning the management, protection, and 

conservation of plant species officially designated as endangered or threatened under the federal 

Endangered Species Act of 1973, as amended, on state lands. 

Federal, Arizona, and Utah Boating Laws. The boating laws of all three jurisdictions apply to all or 

part of the waters of Lake Powell. Regulations, laws, and rules are enforced by several agencies, 

including the National Park Service, U.S. Coast Guard, Utah State Parks and Recreation, Utah 

Department of Natural Resources, and Arizona Game and Fish Department. 

EPA Final Rule for Gasoline Spark-Ignition Marine Engines. As directed under section 213 of the 

Clean Air Act, as amended in 1990 (CAA 1990), the Environmental Protection Agency passed a 

regulation on December 3, 1996 (EPA 1996b), to regulate exhaust emissions from new spark-ignition 

gasoline marine engines (including outboard engines, personal watercraft engines, and jet boat 

engines) because exhaust emissions from spark-ignition gasoline marine engines cause or contribute to 

ozone in more than one ozone nonattainment area (an area that does not meet the national ambient air 

quality standards for ozone). Once the program is fully implemented, the manufacturers of these 

engines must demonstrate to the Environmental Protection Agency that hydrocarbon emissions are 

reduced by 75% from present levels through testing engines representative of the product line before 

sale and after use. The result of these regulations will be a new generation of cleaner gasoline marine 

engines that will be available to boaters. 

The emission standards were phased in beginning with the 1998 model year and will be fully 

implemented in the 2006 model year. The emission standard is being phased in to provide time to 

develop new technology.
PURPOSE OF AND NEED FOR ACTION

32 GLEN CANYON NATIONAL RECREATION AREA
Relationships to Other Plans, Policies, and Actions

FINAL ENVIRONMENTAL IMPACT STATEMENT 33

ALTERNATIVES 

Divider 

This page to be removed 

(needs to be an odd page) 
PURPOSE OF AND NEED FOR ACTION

34 GLEN CANYON NATIONAL RECREATION AREA

This page to be removed 

Back of divider
FINAL ENVIRONMENTAL IMPACT STATEMENT 35

Three alternatives were evaluated for the management of personal watercraft at Glen Canyon National 

Recreation Area. At a minimum, all three alternatives satisfied the need for the project, described in 

the “Purpose of and Need for Action” chapter, met most of the project objectives that were presented 

in table 3, and were judged to be implementable. Proposed alternatives or actions that did not meet 

these criteria are described at the end of this section under the heading “Alternatives Eliminated from 

Further Consideration.” 

The alternatives analyzed in this document in accordance with the National Environmental Policy Act

are the result of agency and public scoping input. The action alternatives (alternative A and 

alternative B) would provide for use of personal watercraft under a special regulation. The no-action 

alternative (alternative C) would make permanent the ban on personal watercraft use that took effect in 

November 2002. 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT USE 

AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Alternative A would involve issuing a special regulation that specifically authorized the use of 

personal watercraft in Glen Canyon National Recreation Area. The use would be identical to that 

occurring before September 15, 2002 without further modifications, mitigations, or restrictions. A 

summary of the features of alternative A is provided in table 4. Key components are illustrated on the 

alternative A maps (figures 3, 4, and 5). 

Alternative A recognizes that market and regulatory factors outside of NPS control will change 

personal watercraft use within the recreation area. This includes a 1996 EPA regulation for the 

manufacture of cleaner-technology engines. On October 4, 1996, the Environmental Protection 

Agency published a final rule that established emission standards for new spark ignition marine 

engines (EPA 1996a). The applicable emission standards are being phased-in, beginning in the 1998 

model year, and will be fully implemented in the 2006 model year. This rule requires each 

manufacturer of personal watercraft and other spark ignition boat engines to meet a corporate fleet 

average emission level that reduces hydrocarbon emissions by 75%, compared to their corporate fleet 

average emissions prior to the rule (EPA 1996a). 

The EPA action is expected to produce lower levels of hydrocarbon emissions, smoke, fumes, and 

noise compared to engines currently in use (EPA 1996b). Implementation of the new regulation will, 

over time, change the types of personal watercraft used in the recreation area, as personal watercraft 

users replace old engines with new, cleaner models. 

LOCATION RESTRICTIONS 

Personal watercraft use would be authorized in all areas, except where specifically prohibited in the 

Superintendent’s Compendium (NPS 2002c) (36 CFR 1.7 (b)). 

Under alternative A, personal watercraft would be prohibited from traveling upstream along portions 

of the Escalante, San Juan, Colorado, and Dirty Devil Rivers, as stated in the Superintendent’s 

Compendium (NPS 2002c) (36 CFR 1.7 (b), section 3.6) and summarized below. Downstream travel 

through the areas identified below would be allowed. 
36 GLEN CANYON NATIONAL RECREATION AREA

TABLE 4: SUMMARY OF 

ALTERNATIVES

Features 

Alternative A: Continue Personal 

Watercraft Use as Currently Managed 

under a Special Regulation 

Alternative B Modified Preferred 

Alternative: Promulgate a 

Special Regulation to Continue 

Personal Watercraft Use with 

Additional Management Restrictions 

Alternative C: 

Watercraft Use 

Personal watercraft engine technology 

Glen Canyon National Recreation Area would not institute any restrictions on personal watercraft engine technology. 

Personal watercraft would need to meet the 2006 EPA marine engine emission standards by the end of 2012 and in subsequent years. Personal watercraft not meeting the standards would no longer be permitted to operate within Glen Canyon National Recreation Area beginning in 2013. 

Personal watercraft uGlen Canyon Nation

Location restrictions Personal watercraft travel upstream on the 

Dirty Devil River would be prohibited upstream from the point where measurable downstream current is encountered (about 9 miles). 

Personal watercraft use in either direction on the Dirty Devil River would be prohibited upstream from the Utah Highway 95 Bridge(about 19 river miles). 

Personal watercraft uGlen Canyon Nation

 Personal watercraft travel upstream on the 

Escalante River would be prohibited upstream from the confluence with Coyote Creek (about 41 miles). 

Personal watercraft use in either direction on the Escalante River would be prohibited upstream from the confluence with Coyote Creek (about 41 river miles). 

Personal watercraft uGlen Canyon Nation

 Personal watercraft travel upstream on the 

San Juan River would be prohibited upstream from the Clay Hills pullout (about 38 miles). 

Personal watercraft use in either direction on the San Juan River would be prohibited upstream from the Clay Hills pullout (about 38 river miles). 

Personal watercraft uGlen Canyon Nation

 Personal watercraft travel upstream on the 

Colorado River would be prohibited upstream from the base of Imperial Rapid (about 2 miles). 

Personal watercraft use in either direction on the Colorado River would be prohibited upstream from Sheep Canyon (about 25 river miles). 

Personal watercraft uGlen Canyon Nation

Wake restrictions Flat-wake speed or speeds below 5 miles per 

hour would be required at harbors, mooring areas, flat-wake areas, and other “flat-wake” buoyed areas. 

Same as alternative A. In addition: Flat-wake speed would be required from Cow Canyon upstream to the confluence of Coyote Creek on the Escalante River (about 7 river miles). 

Not applicable – persbe prohibited in Glen Recreation Area. 
FINAL 

ENVIRONMENTAL MPACT ISTATEMENT 37

Features 

Alternative A: Continue Personal 

Watercraft Use as Currently Managed 

under a Special Regulation 

Alternative B Modified Preferred 

Alternative: Promulgate a 

Special Regulation to Continue 

Personal Watercraft Use with 

Additional Management Restrictions 

Alternative C: 

Watercraft Use 

Launch restrictions Personal watercraft could be launched and 

retrieved in the following locations only: 

• Public launch ramps • Beach areas in Lone Rock off-road use area • Beach areas at Stanton Creek, Upper 

Bullfrog North, and Upper Bullfrog South primitive camping areas that are legally accessible by motor vehicles 

• Take-out area on the San Juan River at 

Clay Hills Crossing 

• Red Canyon area • Paiute Farms area • Hite from 300 feet upstream of the public 

launch ramp to 300 feet upstream of the marina houseboat loading dock 

• Farley Canyon area • White Canyon area. 

Same as alternative A. Not applicable – pers

be prohibited in Glen Recreation Area. 

Age restrictions and certification requirements 

• Personal watercraft users would have to 

comply with state regulations, laws, and rules. 

• Arizona regulations state that children 

younger than 12 can operate personal watercraft when accompanied by an adult and that children older than 12 can operate personal watercraft alone. 

• Utah laws and rules state that children aged 

12 to 15 can operate personal watercraft after completing a mandatory boating education course if they remain within visual parental supervision, and that children ages 16 and 17 must complete a mandatory boating education course and carry the certificate to operate without supervision. 

Same as alternative A. Not applicable – pers

be prohibited in Glen Recreation Area. 
38 GLEN CANYON NATIONAL RECREATION AREA Features Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B Modified Preferred Alternative: Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions Alternative C: 

Watercraft Use 

Safety restrictions Flotation devices Personal watercraft operators would have to wear personal floatation devices. Same as alternative A. Not applicable – pers

be prohibited in Glen Recreation Area. Lanyard cut-off In Arizona, personal watercraft operators would have to fasten a lanyard cut-off device to the rider if the personal watercraft has one installed. Same as alternative A. Not applicable – pers

be prohibited in Glen Recreation Area. Daylight restrictions Personal watercraft users would have to comply with state regulations, laws, and rules. • In Arizona, riders can operate a personal watercraft between sunset and sunrise only if the personal watercraft has lights installed. • In Utah, riders cannot operate personal watercraft between sunset and sunrise. Same as alternative A. Not applicable – pers

be prohibited in Glen Recreation Area. Speed restrictions Personal watercraft users would have to comply with state regulations, laws, and rules. • Based on Arizona regulations, a rider could not operate a personal watercraft at a speed that was unreasonable for existing conditions or above flat-wake speed within 60 feet of another vessel. • Utah laws and rules state that a person cannot operate above flat-wake speed when within 150 feet of another vessel, a person in or floating on the water, a waterskier, a shore fisherman, a launching ramp, a dock, or a designated swimming area. Same as alternative A. Not applicable – pers

be prohibited in Glen Recreation Area. Operating restrictions Personal watercraft users would have to comply with state regulations, laws, and rules. In Arizona, a personal watercraft operator who commits two or more of the following acts simultaneously is considered reckless or negligent: • Operating closer than 60 feet to another vessel unless both are flat-wake; • Obstructing the visibility of another vessel Same as alternative A. Not applicable – pers

be prohibited in Glen Recreation Area. 
FINAL ENVIRONMENTAL MPACT I STATEMENT 39 Features Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B Modified Preferred Alternative: Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions Alternative C: 

Watercraft Use 

operator; • Jumping wake within 60 feet of a vessel and causing half of the personal watercraft to leave the water; and/or • Maneuvering quickly, turning sharply, or swerving within 60 feet of a vessel unless to avoid a collision. In Utah, a person who operates in a reckless manner with regard to injury or property commits a misdemeanor. Alcohol and drugs To comply with Arizona and Utah law, it would be illegal to operate a personal watercraft with a blood alcohol content of 0.08% or more, while impaired, or while under the influence of drugs. Same as alternative A. Not applicable – pers

be prohibited in Glen Recreation Area. Carrying capacity Under Arizona regulations, a personal watercraft operator could not carry more passengers or cargo than recommended by manufacturer. Same as alternative A. Not applicable – persbe prohibited in Glen Recreation Area. Noise In Arizona, no personal watercraft may be operated in a manner that causes it to emit a sound level in excess of 86 decibels when measured from a distance of 50 feet or more. In Utah, a personal watercraft may not be operated in a manner that will cause it to emit more than 75 decibels of noise at the shoreline. Same as alternative A. Not applicable – persbe prohibited in Glen Recreation Area. Insurance requirements In Utah, personal watercraft owners or operators would have to carry evidence of insurance with them while operating a personal watercraft. Same as alternative A. Not applicable – persbe prohibited in Glen Recreation Area. Enforcement Personal watercraft would be permitted on Lake Powell. Personal watercraft would have to comply with all applicable provisions of 36 CFR as well as regulations, laws, and rules pertaining to personal watercraft prescribed by the states of Arizona and Utah while operating on their respective waters. Enforce federal and state regulations, laws, and rules, similar to alternative A. Seek additional funding to increase enforcement capability, and enhance visitor contact to reduce visitor conflicts. Work cooperatively with Arizona and Utah in an attempt to develop unified laws for personal Enforcement would f

recreation area. Seek additional fundenforcement capabil
40 GLEN CANYON NATIONAL RECREATION AREA Features Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B Modified Preferred Alternative: Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions Alternative C: 

Watercraft Use 

Seek additional funding to increase enforcement capability. watercraft operations within the recreation area boundaries. Education No education enhancements would be included in this alternative. Improve and enhance materials to educate visitors on personal watercraft regulations and safe operating procedures. Provide materials that highlight areas of the lake where visitors can experience natural quiet and solitude. Educate visitors on t

at the recreation area

Sanitation Continue to evaluate locations for additional portable toilets. Same as alternative A. Same as alternative Monitoring and sampling Continue current monitoring program for bacteriological contamination near beaches. Continue bacteriological contamination monitoring. Implement new air and water monitoring and sampling program for hydrocarbon contamination. Implement a program to monitor noise related to personal watercraft use, as funds allow. Not applicable – pers

be prohibited in Glen Recreation Area. Lake management plan A lake management plan would be prepared, as funds allow. A three-year pilot study would be conducted to support lake management planning. The study would test whether selected management actions could mitigate conflicts between watercraft users. Same as alternative A. Same as alternative 
Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation 

FINAL ENVIRONMENTAL IMPACT STATEMENT 41

FIGURE 3: GLEN CANYON ALTERNATIVE A (AREA 1) — COLORADO AND DIRTY DEVIL RIVERS
ALTERNATIVES 

42 GLEN CANYON NATIONAL RECREATION AREA

FIGURE 4: GLEN CANYON ALTERNATIVE A (AREA 2) — ESCALANTE RIVER
Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation 

FINAL ENVIRONMENTAL IMPACT STATEMENT 43

FIGURE 5: GLEN CANYON ALTERNATIVE A (AREA 3) — SAN JUAN RIVER

On the Escalante River, personal watercraft would be prohibited from upstream travel upstream 

from the confluence of Coyote Creek. Allowing personal watercraft to be operated as far as the 

Coyote Creek confluence would provide personal watercraft users reasonable access to view 

Stevens Arch, a popular geological landmark and sightseeing attraction, as well as to hike 

nearby canyons, including Coyote Gulch. Prohibiting upstream travel by personal watercraft 

upstream of the confluence with Coyote Creek would maintain an atmosphere of quiet and 

solitude, qualities that backpackers and other backcountry hikers desire while visiting the area. 

Upstream travel on the Dirty Devil River would be prohibited upstream from the point where 

measurable downstream current was encountered. 

Personal watercraft would be prohibited from upstream travel on the Colorado River upstream 

from the base of Imperial Rapids. Upstream motorized running of rapids is an advanced boating 

skill that most visitors to the recreation area do not possess. Restricting personal watercraft users 

to areas below these rapids would prevent visitors from endangering themselves. 

Upstream travel by personal watercraft on the San Juan River upstream of Clay Hills would be 

prohibited. Clay Hills is the traditional termination and pullout retrieval point for rafting parties 
ALTERNATIVES 

44 GLEN CANYON NATIONAL RECREATION AREA

on the San Juan River. Prohibiting personal watercraft upstream use above this point would 

prevent recreational use conflicts. 

WAKE AND LAUNCH RESTRICTIONS 

Visitor safety would be protected through the implementation of wake and launch area restrictions. All 

of the restrictions contained in the Superintendent’s Compendium (NPS 2002c) would be in the special 

regulation and would remain in effect for both the short and long term. These would include the 

following. 

A personal watercraft operator cannot operate at speeds in excess of 5 miles per hour or create a 

wake when operating within harbors, mooring areas, flat-wake areas, and other “flat-wake” 

buoyed areas (36 CFR 1.7 (b), section 3.6). 

Operators could launch and retrieve personal watercraft only in areas designated by the 

Superintendent’s Compendium (NPS 2002c). These sites are listed in table 4. During periods of low 

water, a dock may be placed in Glen Canyon National Recreation Area at the boundary with Rainbow 

Bridge National Monument to facilitate visitor access to the monument. 

ENFORCEMENT OF FEATURES 

REGULATED BY THE STATES OF ARIZONA AND UTAH 

Arizona and Utah regulate several aspects of personal watercraft use that are not included in the 

superintendent’s compendium. These include, but may not be limited to: 

Age restrictions and certification requirements; 

Use of a lanyard cutoff; 

Operation of a personal watercraft during the period between sunset and sunrise; 

Speed restrictions; 

Operational restrictions, including such factors as alcohol, drugs, distance from other vessels, 

number of passengers, and noise levels; and 

Proof of insurance requirements. 

Under alternative A, personal watercraft users would continue to comply with regulations, laws, and 

rules set forth by the states of Arizona and Utah while operating on the waters within these states. 

Summaries of the applicable regulations within each of these categories are provided in table 4. The 

state watercraft regulations are included in appendix B. 

Glen Canyon National Recreation Area is proprietary jurisdiction, which mean that the states have 

primary law enforcement jurisdiction and authority. Within the recreation area, personal watercraft 

users are required to comply with all federal (36 CFR, Part 3; 36 CFR 7.70; 33 CFR, United States 

Coast Guard) and state boating laws and regulations. Alternative A would maintain the requirement to 

enforce both Arizona and Utah watercraft regulations, laws, and rules. 
Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation 

FINAL ENVIRONMENTAL IMPACT STATEMENT 45

During summer high-use periods, the recreation area employs up to 38 law enforcement officers. 

Water patrols and enforcement would occur on a regular basis. During high-use periods, land-based 

users within the recreation area often place heavy demands on enforcement personnel, which limits 

their ability to effectively patrol the lake (Mayer 2002). To provide additional enforcement of the 

existing watercraft regulations on the lake, the superintendent would vigorously seek funding to 

increase the law enforcement capability on Lake Powell, particularly during high-visitation periods. 

Enhanced boat patrols would have the added advantage of increasing the number of visitor contacts on 

the lake to prevent unsafe actions that could result in injuries and visitor use conflicts.

EDUCATION 

Personal watercraft users visiting Glen Canyon National Recreation Area would be informed of the 

watercraft regulations that apply on Lake Powell and would be provided with general safety 

information. Literature containing information about watercraft safety would be provided to visitors at 

the entrance gates, visitor centers, and recreation area headquarters in the form of the recreation area’s 

newspaper and brochure, in displays, and on the recreation area website. 

It would continue to be the responsibility of the watercraft user to know the applicable state and 

federal regulations that apply on Lake Powell. These regulations would be available to the personal 

watercraft user at the recreation area headquarters, in the recreation area newspaper and brochure, in 

displays, as launch ramp information, and through personal contacts made on the lake. This 

information could also be obtained prior to arrival at the recreation area on the recreation area’s 

website. 

Visitors would continue to be provided with information regarding the different types of resources that 

can be experienced at Glen Canyon National Recreation Area. This information would be available at 

the recreation area visitor centers and headquarters, and on the recreation area website, and would be 

provided during contacts with or presentation by interpretive rangers. 

No written information is currently provided to the visitor that specifically identifies areas on the lake 

that can be accessed to experience natural quiet and solitude (NPS, Gossard, pers. com., April 2002f). 

This situation would continue under alternative A. 

SANITATION 

Sanitation would continue to be addressed by continuing to operate and maintain both portable and 

permanent toilets and pump-out stations. The recreation area currently has eight floating restrooms 

with pump-out facilities for use by boaters. Land-based sanitary facilities are available at marinas. 

Personal watercraft users that are associated with powerboats and houseboats in general have access to 

facilities on the larger vessel. The recreation area would continue to evaluate areas to install new 

portable facilities for recreational users, including personal watercraft users. The goal would be to 

reduce adverse water quality effects from human waste and reduce the risk of transmission of waterborne diseases. 
ALTERNATIVES 

46 GLEN CANYON NATIONAL RECREATION AREA

MONITORING AND SAMPLING PROGRAMS 

Under alternative A, the National Park Service would continue its participation in the program to 

monitor water quality. This program is being conducted in conformance with the “Strategic Plan to 

Protect Water Quality at Lake Powell” that was entered into in 1996 by the National Park Service and 

the Arizona and Utah Departments of Environmental Quality. The goal of this program is to protect 

human health and prevent water-borne diseases by improving and protecting the water quality of Lake 

Powell. Under this program, water samples are collected to monitor bacteriological contamination near 

beaches. Federal and state water quality standards would remain in place and annual monitoring would 

be conducted. No additional sampling or monitoring efforts would be implemented with alternative A. 

LAKE MANAGEMENT PLAN 

Under all alternatives including alternative A, the superintendent would seek funding for the 

development of a lake management plan to address the overall use of the recreation area. The 

objectives of this plan would be to improve the management of Lake Powell and to provide for the 

long-term protection of lake resources while allowing a range of visitor recreational opportunities. 

Even though the plan is proposed as part of alternative A, a separate National Environmental Policy 

Act assessment would be prepared to evaluate its effects. 

The lake management plan would comprehensively consider all uses on the lake. It would also address 

management issues that are not being adequately addressed or resolved in other planning efforts. 

These issues relate to recreational use of the lake, visitor conflicts and safety, and potential impacts on 

recreation area resources from water-related recreation. 

A soundscape management study would also be a component of the lake management plan. The sound 

analysis would (1) describe the baseline natural ambient sound environment in qualitative and 

quantitative terms; (2) identify sound sources and sound levels consistent with park legislation and 

purposes; (3) identify the level, nature, and origin of internal and external noise sources; (4) articulate 

desired future soundscape conditions; and (5) recommend the approaches or actions to achieve those 

conditions or otherwise mitigate noise impacts. 

The lake management plan would consider visitor use patterns and management options. It would 

provide guidance on future infrastructure improvements, concessions and commercial services (such 

as watercraft rentals), recreation area operations, and educational or informational services. 

To support preparation of the lake management plan, a three-year pilot study would be conducted. The 

study would test whether selected management actions could mitigate conflicts between watercraft 

users and other visitors. A description of the pilot study is provided in appendix C.
FINAL ENVIRONMENTAL IMPACT STATEMENT 47

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

Alternative B is the NPS modified preferred alternative. Under alternative B, the National Park 

Service would issue a special regulation to specifically authorize the use of personal watercraft in Glen 

Canyon National Recreation Area. 

As shown in table 4, many of the management features of alternative B would be identical to those of 

alternative A. However, this alternative would implement additional geographic restrictions on 

personal watercraft use and define an additional flat-wake zone. It also would include strategies to 

better protect recreation area resources, improve visitor safety, and reduce recreational use conflicts. 

Features of alternative B are described below and summarized in table 4. Key components are 

illustrated on the alternative B maps (figures 6, 7, and 8). 

In addition, personal watercraft in the recreation area would be required to meet the 2006 EPA marine 

engine emission standards by the end of 2012 and in subsequent years. Under this alternative, 

carbureted two-stroke engines would be phased out over the next 10 years. This 10-year timeframe 

takes into consideration the typical life span of personal watercraft. The formula for determining the 

operating life of personal watercraft was published in the Federal Register on October 4, 1996 (EPA 

1996a). Based on this formula, the National Park Service expects that by 2012, most personal 

watercraft owners will already be in compliance with the 2006 EPA marine engine standards. The 

Personal Watercraft Industry Association believes the typical operating life of a personal watercraft 

rental is three years and approximately five to seven years for a privately owned vessel (PWIA 2002a). 

Therefore, the average operating life of a personal watercraft is 5 to 10 years, depending upon the 

source. The 10-year phase-out period for the carbureted two-stroke engine provides a reasonable 

timeframe for personal watercraft users to comply with the management objectives. If, in 2013, park 

visitors have personal watercraft that do not meet these strict emission standards, they would not be 

able to operate that personal watercraft on Lake Powell. 

LOCATION RESTRICTIONS 

Under alternative B, about 25 miles of the Colorado River upstream from Sheep Canyon would be 

closed to all personal watercraft use. In addition, those portions of the Escalante, San Juan, and Dirty 

Devil Rivers that currently are closed to upstream personal watercraft travel, as described under 

alternative A, would be closed to personal watercraft use in either direction, upstream or downstream. 

Specifically, alternative B would prohibit personal watercraft use on the: 

Dirty Devil River upstream of Utah Highway 95 Bridge (alternative B, figure 6). 

Escalante River above the confluence of Coyote Creek (alternative B, figure 7). 

San Juan River above the Clay Hills pullout (alternative B, figure 8). 

All of these closures would increase the protection of environmental values and reduce conflict among 

visitor use activities. At all of these sites, the recreation area would install new buoys or other markers 

to delineate the boundaries above which no personal watercraft use would be permitted. 
ALTERNATIVES 

48 GLEN CANYON NATIONAL RECREATION AREA

FIGURE 6: GLEN CANYON ALTERNATIVE B (AREA 1) — COLORADO AND DIRTY DEVIL RIVERS
Alternative B (Modified Preferred Alternative) 

FINAL ENVIRONMENTAL IMPACT STATEMENT 49

FIGURE 7: GLEN CANYON ALTERNATIVE B (AREA 2) — ESCALANTE RIVER
ALTERNATIVES 

50 GLEN CANYON NATIONAL RECREATION AREA

FIGURE 8: GLEN CANYON ALTERNATIVE B (AREA 3) — SAN JUAN RIVER

The intent of the personal watercraft closure on the San Juan River would be to provide an opportunity 

for visitors to enjoy quiet and solitude. Establishing the closure at the Clay Hills pullout would allow 

continued opportunity to access the lake from this remote site when the lake level is above an 

elevation of 3,675 feet. At the same time, it would protect a rare visitor experience for San Juan River 

travelers above this point. 

Personal watercraft use would be prohibited on the Dirty Devil River above Utah Highway 95 Bridge 

(alternative B, figure 6). This requirement would have two benefits. 

Because of the transition from lake to river conditions, personal watercraft operation upstream 

from the bridge is significantly different than operation below this point. The Dirty Devil 

Canyon is very narrow with tight, blind bends, and becomes increasingly hazardous upstream 

because of shallow and murky water, floating debris, uncertain currents, and shifting sandbars. 

Restricting this area to personal watercraft use would help protect the safety of visitors. 

The Dirty Devil River is a popular destination for fishing, including both trolling and fishing 

from stationary boats. High-speed maneuvering with personal watercraft is disruptive to this 
Alternative B (Modified Preferred Alternative) 

FINAL ENVIRONMENTAL IMPACT STATEMENT 51

traditional visitor activity. Visitor conflicts would be eliminated with closure of this area to 

personal watercraft. 

Alternative B would prohibit personal watercraft use on the Colorado River upstream from Sheep 

Canyon (alternative B, figure 6). This action would have two benefits. 

Cataract Canyon upstream of Sheep Canyon is a popular white-water rafting destination that 

provides a recreational experience that is not available in other parts of Glen Canyon National 

Recreation Area. Closure of the Colorado River upstream from Sheep Canyon would preserve 

this locally unique visitor experience for Colorado River white-water river runners. 

Because of the transition from lake to river conditions, personal watercraft operation upstream 

from Sheep Canyon is substantially different than operation below this point. Beginning in 

Cataract Canyon, conditions become increasingly hazardous because of conflicts between 

traditional rafting uses and use of personal watercraft. The river’s uncertain currents and shifting 

sandbars can force both groups to use a common river channel. The presence of standing waves 

also produces a high potential for collision. Closing this area to personal watercraft use would 

help protect the safety of visitors. 

Implementing these closures to all personal watercraft use would strengthen the NPS intent to 

maintain areas of quiet and solitude on portions of the rivers; to reduce the potential for conflict 

between motorized and traditional nonmotorized users; and to promote visitor enjoyment in those 

areas. In addition, prohibiting personal watercraft use on portions of the rivers where the operation of 

such a craft is made hazardous by natural features such as rapids and narrow, confined canyons would 

help to ensure visitor safety. 

The recreation area may consider other location restrictions, which would be implemented as part of a 

lake management plan that is described under alternative A and is common to all alternatives. To 

support the decision to implement other restrictions, a three-year pilot study would be conducted. The 

study would examine the effectiveness of location restrictions and other management actions in 

reducing visitor conflicts associated with motorized vessels, including personal watercraft, in the 

recreation area. Details of the pilot study are provided in appendix C. The pilot study could be 

implemented after the record of decision for this personal watercraft rule-making was completed and 

after appropriate compliance and public participation had taken place. 

WAKE AND LAUNCH RESTRICTIONS 

Launch restrictions under alternative B would be the same as those for alternative A (see table 4). 

However, the visitor experience would be improved through the implementation of additional wake 

restrictions under alternative B. 

All of the wake restrictions pertaining to personal watercraft use contained in the Superintendent’s 

Compendium (NPS 2002c) (36 CFR 1.7 (b), section 3.6) would be in the alternative B special 

regulation. These would include requirements that a personal watercraft operator cannot operate at 

speeds in excess of 5 miles per hour or create a wake when operating within harbors, mooring areas, 

flat-wake areas, and other “flat-wake” buoyed areas. To further reduce visitor conflict, enhance visitor 

safety and experience, and protect soundscapes, alternative B would prohibit operation of personal 

watercraft above flat-wake speed on portions of the Escalante River. 
ALTERNATIVES 

52 GLEN CANYON NATIONAL RECREATION AREA

The 4.4-river-mile stretch of the Escalante River between Cow Canyon and the confluence of Coyote 

Creek (alternative B, figure 7) would be designated as flat-wake for personal watercraft. This stretch 

of the Escalante River is a popular float stream and hiking area. In most years, travel upstream by 

personal watercraft from Cow Canyon is precluded by low water levels and insufficient stream flow. 

However, when lake levels are sufficiently high, the natural quiet of this area is often disturbed by 

noise from personal watercraft. Limiting personal watercraft use to flat-wake speeds above Cow 

Canyon would help maintain a more natural sound quality in this portion of the Escalante River and 

Coyote Gulch area. 

ENFORCEMENT OF FEATURES 

REGULATED BY THE STATES OF ARIZONA AND UTAH 

As in alternative A, boating regulations, laws, and rules for both Arizona and Utah, as well as 

applicable federal regulations (36 CFR, Part 3; 36 CFR 7.70; 33 CFR, United States Coast Guard), 

would continue to be enforced. A summary of the state regulations is included in table 4. Appendix B 

includes the full text of the Arizona and Utah regulations, laws, and rules that apply to personal 

watercraft use. 

Glen Canyon National Recreation Area is proprietary jurisdiction, which means that the states have 

primary law enforcement jurisdiction and authority. Like current conditions, users would have to 

comply with the regulations, laws, and rules pertaining to personal watercraft prescribed by the states 

of Arizona and Utah while operating on their respective waters. However, under alternative B, the 

National Park Service would work cooperatively with both states in an attempt to develop unified laws 

for personal watercraft operations within the boundaries of the recreation area. 

The level of law enforcement at the recreation area is insufficient to adequately patrol activities on the 

land and on Lake Powell during peak-use seasons. To provide additional enforcement of the existing 

watercraft regulations on the lake, the superintendent would vigorously seek funding to increase the 

law enforcement capability on Lake Powell, particularly during high-visitation periods. Enhanced boat 

patrols would have the added advantage of increasing the number of visitor contacts on the lake to 

prevent unsafe actions that could result in injuries and visitor use conflicts. 

EDUCATION 

Alternative B would improve education to provide more information to visitors regarding regulations 

pertaining to personal watercraft use and safety. The goal would be to avoid or reduce accidents, 

visitor conflicts, and adverse effects on recreation area resources. Features of the improved education 

program could include the following. 

The National Park Service would improve interpretive contacts and programs to incorporate 

relevant personal watercraft safety information. Coordination with local and regional media 

could be used to convey information to users. 

The recreation area would provide literature to visitors at entrance stations on personal 

watercraft safety and regulations. This literature would highlight the regulations that are most 

commonly violated by personal watercraft users, such as speed and proximity, underage 

operator, and wake speed, that result in the issuance of citations or warnings. 
Alternative B (Modified Preferred Alternative) 

FINAL ENVIRONMENTAL IMPACT STATEMENT 53

The National Park Service would coordinate with concessioner and other Lake Powell Water 

Safety Council members to disseminate information to recreation area visitors about the safe use 

of personal watercraft. 

Conflicts sometimes occur between personal watercraft users and those visitors who come to the 

recreation area to experience natural quiet and solitude. To reduce these conflicts, alternative B would 

include enhanced educational materials and interpretive programs to emphasize areas of the recreation 

area that offer this experience. 

SANITATION 

The sanitation features of alternative B would be the same as that described under alternative A. The 

recreation area would continue to evaluate areas to install new portable facilities for recreational users, 

including personal watercraft users. The goal would be to reduce adverse water quality effects from 

human waste and reduce the risk of transmission of water-borne diseases. 

MONITORING AND SAMPLING PROGRAMS 

The alternative B monitoring and sampling program for contamination by human waste would include 

all of the features described for alternative A. In addition, alternative B would include new air and 

water quality monitoring and sampling programs for hydrocarbon contamination. The recreation area 

would also conduct noise monitoring in association with personal watercraft use, as funds allow. 

An important element of this alternative would be protecting water quality and air quality from 

chemical pollutants emitted from personal watercraft, and protecting natural soundscapes from 

personal watercraft noise. An adequate baseline description of noise and chemical pollution produced 

by personal watercraft engines has not been established within Glen Canyon National Recreation 

Area. Under this alternative, water quality, air quality, and noise sampling and monitoring would be 

conducted to establish baseline conditions and resource trends from which to detect changes and 

develop a management and protection program. These efforts would allow recreation area staff to 

make management decisions based on recreation area-specific data and would improve protection of 

recreation area resources, as funds allow. 

A lakewide monitoring program for gasoline constituents, including hydrocarbons in Lake Powell 

water and sediments, would be developed based on data and methods of studies that are currently 

taking place or planned in the recreation area. These studies are focused on determining the chemical 

content of sediment at the main inflow areas of selected rivers and examining the dynamics of 

sediment resuspension and reworking at selected river inflows. The monitoring program would 

consider the most likely places for contamination, such as marinas and areas downstream from major 

sediment depositional zones. The monitoring plan development would be guided by the Technical 

Advisory Committee that was formed in 1996 by the National Park Service and the Utah and Arizona 

Departments of Environmental Quality Water Quality Divisions and other interested organizations and 

agencies (including the Environmental Protection Agency) to protect Lake Powell water quality. The 

Technical Advisory Committee provides an excellent vehicle for establishing standards and protocols 

for Lake Powell that are acceptable to Utah and Arizona, congruous with their regulations, and 

developed under authority of the Clean Water Act. Benthic population sampling and bioassay may be 

included in the monitoring plan as determined to be appropriate by the Technical Advisory 

Committee. 
ALTERNATIVES 

54 GLEN CANYON NATIONAL RECREATION AREA

All monitoring programs would be based on approved monitoring plans that would identify, describe 

in detail, and provide the procedural steps required for major work elements. The plans would be 

reviewed and approved by the National Park Service, State of Utah Department of Environmental 

Quality, and State of Arizona Department of Environmental Quality. 

LAKE MANAGEMENT PLAN 

The features of the lake management plan would be the same as those described under alternative A. 

In addition, a three-year pilot study would be conducted to support preparation of the lake 

management plan. The study would test whether selected management actions could mitigate conflicts 

between watercraft users and other visitors. A description of the pilot study is provided in appendix C. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 55

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

Under alternative C, the National Park Service would not take any rule-making action to authorize 

personal watercraft use in Glen Canyon National Recreation Area. Based on the NPS rule that was 

published on March 21, 2000, personal watercraft use would have been prohibited after September 15, 

2002; however, a stipulated modification to the settlement agreement approved by the court extended 

the closure date until November 6, 2002. Alternative C would make the ban permanent. This 

alternative allows for the comparison of impacts of the rule-making actions with conditions that would 

occur in the absence of a rule that allowed for personal watercraft use. 

LOCATION RESTRICTIONS 

No unit-specific rule would be developed to allow the use of personal watercraft in the recreation area. 

Therefore, the ban on personal watercraft use in Glen Canyon National Recreation Area that went into 

effect in November 2002 would be permanent. 

WAKE AND LAUNCH RESTRICTIONS 

With a ban on personal watercraft under this alternative, speed restrictions on personal watercraft 

would not be applicable. Prohibition of personal watercraft use under this alternative would preclude 

the launching of personal watercraft anywhere in the recreation area. However, current speed and 

launch restrictions for other types of watercraft would remain in effect. 

ENFORCEMENT OF PERSONAL WATERCRAFT BAN 

Under this alternative, law enforcement personnel would be responsible for enforcing the ban on 

personal watercraft. Initially, increased enforcement staff time may be needed at marinas and launch 

sites to restrict personal watercraft use of Lake Powell and the tributaries. However, this need would 

decrease as visitors became familiar with the elimination of personal watercraft use. 

In addition, the superintendent would vigorously seek funding to increase the law enforcement 

capability on Lake Powell, particularly during high-visitation periods, to provide additional 

enforcement of the existing watercraft regulations on the lake. 

EDUCATION 

Alternative C would require the preparation and distribution of materials informing the public of the 

ban on personal watercraft use in the recreation area. This would involve developing information for 

new recreation area exhibits, hand-outs, community outreach and special programs, and updates to the 

recreation area website. 

Initially, increased interpretive staff time would be needed to educate visitors of the ban on personal 

watercraft use, particularly at launch ramps and marinas. However, this need would decrease as 

visitors became familiar with the elimination of personal watercraft use. 
ALTERNATIVES 

56 GLEN CANYON NATIONAL RECREATION AREA

Education to enhance watercraft safety or to highlight areas of the lake where visitors can experience 

natural quiet and solitude would occur only as part of the recreation area’s ongoing education 

program. 

SANITATION 

Sanitation facilities around the recreation area would continue to be used by other boating and landbased recreation users. Sanitation would be addressed by continuing to operate and maintain both 

portable and permanent toilets and pump-out stations. The recreation area would continue to evaluate 

areas to install new portable facilities for recreational users. The goal would be to reduce adverse 

water quality effects from human waste and reduce the risk of transmission of water-borne diseases. 

MONITORING AND SAMPLING PROGRAMS 

Monitoring and sampling programs would be the same as those described for alternative A. This 

would include continued water quality monitoring to conform with the “Strategic Plan to Protect 

Water Quality at Lake Powell” that was entered into in 1996 by the National Park Service and the 

Arizona and Utah Departments of Environmental Quality. No additional sampling or monitoring 

efforts would be implemented with alternative C. 

LAKE MANAGEMENT PLAN 

Under alternative C, the superintendent would seek funding for the development of a lake management 

plan to address the overall use of the recreation area. The lake management plan would be similar to 

that described for alternative A and B, except that it would not include personal watercraft, since their 

use would not be allowed in the recreation area. A pilot study to support lake management planning 

would be conducted to test whether selected management actions could mitigate conflicts between 

watercraft use and other visitors. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 57

ALTERNATIVES ELIMINATED FROM FURTHER CONSIDERATION 

During the planning process, several actions or mitigation techniques were considered but eliminated 

as alternatives or components of alternatives to managing personal watercraft in Glen Canyon National 

Recreation Area. This section explains why these alternatives or actions were not considered further. 

Limit personal watercraft use to the main channel of Lake Powell. This action would be 

inconsistent with the objectives of the recreation area as defined in its enabling legislation. The 

objectives of the recreation area are to manage the area so that it provides maximum recreational 

enjoyment to the American public and its guests, maximizes the number of opportunities for enjoying 

the recreation area, and accommodates many varieties of use with an emphasis on water-oriented 

recreation. Lake Powell is managed according to resources and appropriate visitor use, as part of the 

Recreation and Resource Utilization Zone. Motorized watercraft use, including the use of personal 

watercraft, is a designated activity throughout this zone. Limiting use only to the main channel would 

not provide the full recreational benefit of this zone. 

Establish special-use areas or zones to accommodate high-density personal watercraft use, 

designate special play areas, or increase watercraft support services. These alternatives were 

dismissed because of concerns over visitor safety and conflicts. Confining high numbers of users to 

smaller areas would potentially increase the number of visitor accidents and conflicts. 

Implement a permit system or allow only four-stroke engines. The immediate restriction on 

carbureted two-stroke personal watercraft was eliminated from further consideration in this document. 

However, alternative B would phase out carbureted two-stroke personal watercraft over the next 

10 years. By the end of 2012 and in subsequent years, all personal watercraft operating in the 

recreation area would be compliant with the EPA marine engine emission standards. The lake 

management plan could allow the recreation area to implement a more comprehensive permit system 

directed at all vessels and engine types, not just personal watercraft. 

ALTERNATIVES SUMMARY 

Table 5 provides a brief summary of the effects of each of the alternatives on the impact topics that 

were retained for analysis. More detailed information on the effects of the alternatives is provided in 

the “Environmental Consequences” chapter. 
58 GLEN CANYON NATIONAL RECREATION AREA

TABLE 5: COMPARISON OF IMPACTS OF THE 

ALTERNATIVES

Impact Topic 

Alternative A: 

Continue Personal Watercraft Use as 

Currently Managed under a Special Regulation 

Alternative B (Modified Preferred Alternative): 

Promulgate a Special Regulation to 

Continue Personal Watercraft Use with 

Additional Management Restrictions 

A

(Person

Would 

Water quality Under alternative A, personal watercraft have 

negligible to minor, direct, adverse effects on the water quality of Lake Powell. Effects would be long term because they would recur during each summer heavy-use season. Cumulatively, the lake loadings from all vessels also would have negligible to minor, direct, adverse effects on the water quality of Lake Powell. Alternative A would not result in the impairment of the water quality of Lake Powell or any other waters. 

Localized, long-term benefits to water quality would occur in the four tributaries where personal watercraft use would be restricted. However, because these areas have low rates of use, the intensity would likely be negligible. Prior to the end of 2012, effects to water quality would be the same as those described for alternative A. This is anticipated because boat usage and engine type distribution are assumed to be the same as in alternative A. After implementation of clean technology personal watercraft restrictions, pollutant loadings from personal watercraft would decrease. However, changes in water quality may be difficult to quantify. The continued contribution of personal watercraft to pollutant loading in Lake Powell would result in long-term, adverse effects to water quality of negligible to minor intensity. Cumulative effects from all watercraft would be similar to alternative A until 2005. A decrease in pollutant loading with implementation of personal watercraft engine type restrictions at the end of 2012 and other water quality improvement projects would result in long-term negligible benefits. Alternative B would not result in the impairment of the water quality of Lake Powell or any other waters. 

Alternative C would pollutant loadings in alternatives A and Blong-term. This wouminor, direct, benefwater quality of the would also experienbenefits, but due to use rates, these wowould not result in tquality of Lake Pow

Air quality Personal watercraft management under 

alternative A would have the following effects on air quality. Emission levels of carbon monoxide, hydrocarbons, and volatile organic compounds would decrease between 2004 and 2012. Hydrocarbon plus nitrogen oxide emissions, which are the principal constituents of ozone, would also decrease by 2012. All of this change would be attributable to increased proportions of lowemission engines on the lake. However, these pollutants would continue to be emitted by personal watercraft at volumes exceeding 100 tons per year. As a result, alternative A would 

Effects of alternative B would be similar to those of alternative A in 2004. Conversion of carbureted two-stroke personal watercraft to cleaner engines under the modified alternative would have the following effects on air quality. There would be sizeable reductions in volatile organic compounds, hydrocarbon, and hydrocarbon plus nitrogen oxide emissions. There would also be reduction in particulates (PM10 and 

PM2.5) and carbon monoxide emissions. 

Human health effects would be adverse and moderate for volatile organic compounds, carbon monoxide, hydrocarbons, and hydrocarbons plus 

Under the no-action condition in the recrbe below national aSUM06 ozone meaarea would remain bhour. No change in be expected becausactivity has not resunational air quality sThe no-action alternnegligible to moderaquality related valuewould result from thwatercraft emission
FINAL ENVIRONMENTAL MPACT I STATEMENT 59 Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

have moderate, long-term, direct, adverse impacts on human health and air quality related values. Particulate matter emissions from personal watercraft would decrease by 2012 to between 46 to 67 tons per year. These levels of particulate matter would continue to cause locally degraded visibility from personal watercraft exhaust during peak use periods in high-use areas. This would be a direct, long-term, negligible to minor, adverse effect on human health and air quality related values. Air quality in the recreation area would continue to be below national ambient air quality standards (negligible effect). SUM06 ozone measurements in the recreation area would remain between 8 and 15 parts per million per hour (negligible effect). No change in class II airshed status would result from this alternative (negligible effect). The cumulative effect on air quality related values and human health from all motorized vessel would be direct, long-term, adverse, and minor to moderate. This alternative would not result in an impairment of the air quality resource or related values. nitrogen oxides. Some beneficial effects would occur after 2012 from the elimination of carbureted two-stroke personal watercraft engine emissions as hydrocarbon, carbon monoxide, volatile organic hydrocarbons, and particulate matter emissions are reduced. Adverse impacts to air quality-related values would be reduced from minor levels in 2004 to negligible to minor in 2012. Particulate matter reductions would contribute to an improvement in visibility, and the reduced ozone production would contribute to a reduced potential for plant damage. Air quality in the recreation area would continue to be below national ambient air quality standards (negligible effect). SUM06 ozone measurements in the recreation area would remain between 8 and 15 parts per million per hour (negligible effect). No change in class II airshed status would result from this alternative (negligible effect). The cumulative effect on air quality related values and human health from all motorized vessels would be direct, long-term, adverse, and minor to moderate. This alternative would not result in an impairment of the air quality resource or related values. organic compounds

oxide, and particulaarea. In the short-term, towould be reduced abe prohibited from tbe sizeable reductioemissions of carbon compounds, hydrocnitrogen oxide when Particulates (PM10 a

from minor to modeto negligible under talternative. In the long-term viswatercraft with a difvessel and other veThis would offset thelimination of persothat ambient air quato be met, moderateon human health anwould occur from caoxide, hydrocarboncompound emissionmotorized boating aimpacts on human hwith particulate matnegligible to minor. Implementation of tin an impairment of 

Soundscapes During summer days in the Recreation and Resource Utilization and Developed Zones, the existing level and character of noise generated by personal watercraft are acceptable within the expressed purpose of the park to provide the motorized watercraft form of recreation. Given this level of impact, and the amount of use that occurs during peak seasons, mitigation takes the form of education and enforcement of the existing regulations and compendium. Noise-producing behaviors are regulated to the greatest possible Alternative B would have overall noise impacts similar to those described under alternative A. During summer days in the Recreation and Resource Utilization and Developed Zones, the existing level and character of noise generated by personal watercraft are acceptable within the expressed purpose of the park to provide the motorized watercraft form of recreation. During other times of the year, the overall impact of noise within this area decreases. Noise generated in this zone, year-round, affects adjacent areas in Due to the eliminati

in alternative C, impsoundscape would levels produced in arepresents a benefisoundscape – elimijudged as minor to the year. Compared the level of beneficiconsidered as great negligible to minor a
60 GLEN CANYON NATIONAL RECREATION AREA Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

extent, and use of newer technologies that reduce noise are encouraged. During other times of the year, the overall impact of noise within this area decreases. Noise generated in this zone, year- round, affects adjacent areas in Natural and Cultural Zones. In the Natural and Cultural Zones, alternative A would produce negligible to moderate adverse effects on the soundscape within a mile of the lakeshore, depending on the level of boating use in nearby waters at various times of the year. During high-use periods, areas in which noise is audible would be affected at minor to moderate levels. During low-use periods, areas in which noise is audible would be affected at negligible to minor levels. These areas consist of about 16,000 acres covering 2.3% of the natural and cultural zones. The remainder of the zone area is expected to be unaffected. All of these effects would be adverse, both short and long term, and direct. Alternative A would not result in impairment of the natural soundscape of Glen Canyon National Recreation Area since a major level of impact is not demonstrated. Natural and Cultural Zones. In the Natural and Cultural Zones, under alternative B during high-use periods, areas in which noise is audible would be affected at minor to moderate levels. During low-use periods, areas in which noise is audible would be affected at negligible to minor levels. The area affected would be 2.3% of the natural and cultural zones. The remainder of the zone area is expected to be unaffected. All of these effects would be adverse, both short and long term, and direct. Alternative B would not result in impairment of the natural soundscape of Glen Canyon National Recreation Area since a major level of impact is not demonstrated. would not result in i

soundscape of Glen Area. Wildlife and wildlife habitats Personal and other watercraft uses with alternative A would result in negligible to minor short-term adverse impacts. Under some conditions impacts, from noise, high-speed personal watercraft operations, shoreline habitat disturbances, and the ingestion or absorption of fuel constituents, petroleum hydrocarbon additives and derivatives, could be observable and/or measurable. However, changes resulting from such conditions would not be expected to be outside the range of natural environmental and biological variability. Population numbers, population structure, genetic variability, and other demographic factors for species may experience small, short-term changes, but long-term characteristics of wildlife and wildlife habitat within the area of analysis would remain stable and viable. Impacts on wildlife and wildlife habitats due to alternative B would result in negligible to minor short-term adverse impacts. Under some conditions impacts, from noise, high-speed personal watercraft operations, shoreline habitat disturbances, and the ingestion or absorption of fuel constituents, petroleum hydrocarbon additives and derivatives, could be observable and/or measurable. However, changes resulting from such conditions would not be expected to be outside the range of natural environmental and biological variability. Prohibiting carbureted two- stroke personal watercraft engines at the end of 2012 would indirectly benefit wildlife and wildlife habitat. Alternative B would not contribute to deterioration of the recreation area’s wildlife resource to the extent that the recreation area’s purpose could Alternative C would 

beneficial impact on from a reduction in result from eliminatithe lake. By the end 2012, the number oreturned to levels walternatives A and Bwildlife and wildlife watercraft and othesimilar, the long-terwildlife and wildlife Alternative C would and wildlife species 
FINAL ENVIRONMENTAL MPACT I STATEMENT 61 Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

Operations of personal watercraft would not adversely impact special-interest wildlife concentration or high-quality wildlife habitat areas because such resources are not present in the recreation area. Special-interested wildlife features (such as active peregrine falcon nest sites) are present in the recreation area and many occur in areas visited by personal watercraft and other types of motorized watercraft. Alternative A would not contribute to deterioration of the recreation area’s fish or wildlife resources to the extent that the recreation area’s purpose could not be fulfilled as established in its enabling legislation. It would not affect resources key to the recreation area’s natural integrity or opportunities for enjoyment or affect the wildlife or wildlife habitat resource, whose conservation is identified as a goal in the recreation area’s general management plan. Implementing this alternative would not result in an impairment of wildlife, fish, or supporting habitat resources. not be fulfilled as established in its enabling legislation. Implementing this alternative would not result in an impairment of wildlife, fish, or supporting habitat resources. Threatened and endangered species Alternative A would not adversely affect any ecological, biological, or physical processes associated with endangered fish critical habitats. Continuing the location restriction on upstream portions in the Colorado, San Juan, Dirty Devil, and Escalante Rivers would provide some protection of critical habitat for endangered fish. Compared to current conditions, alternative A would have negligible effects on the bald eagle, American peregrine falcon, southwestern willow flycatcher, or yellow-billed cuckoo or their critical habitats within Lake Powell and its tributaries in the recreation area. Cumulative impacts are not likely to adversely affect endangered, threatened, or special-concern species or their designated critical habitats in the recreation area. No impairment to threatened or endangered species or their designated critical habitats would occur from the implementation of alternative A. Restrictions on access and designation of flat- wake speeds along sections of river shorelines would produce short-term, direct, negligible benefits to habitats of endangered fishes in the inflow areas. These would occur because fewer personal watercraft would use these areas, and the remaining vessels would operate at lower speeds, producing less site disturbance. These effects would not change ecological function or structure of critical habitat and would probably be indistinguishable from the range of environmental variation that occurs under natural conditions. The availability, use, and location of suitable endangered fish habitat would be more extensively affected by reservoir operations and annual river runoff patterns than by operation of personal watercraft. Therefore, the impacts on endangered fish species and their designated critical habitat with alternative B would be similar to alternative A. Endangered fish would benefit indirectly with the prohibition of carbureted two- strike personal watercraft engines at the end of Negligible improvem

habitat would be exdirect beneficial imptheir designated critareas. The bald eagsouthwester willow cuckoo might experterm beneficial direcdisturbance incidenyears when the totaexpected to declineunlikely to adversely birds or their critical species or state-sencritical habitats or frand riparian habitatCumulative impacts adversely affect endspecial-concern specritical habitats in thNo impairment wou
62 GLEN CANYON NATIONAL RECREATION AREA Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

2012 which would reduce the amount of fuel discharge into the water in subsequent years. There would be no distinguishable adverse effects on the bald eagle, American peregrine falcon, southwestern willow flycatcher, or yellow-billed cuckoo. As a result, this alternative would be unlikely to adversely affect these species in the recreation area. Cumulative impacts are not likely to adversely affect endangered, threatened, or special-concern species or their designated critical habitats in the recreation area. No impairment would be expected to endangered, threatened, or special-concern species or their designated critical habitats with this alternative. threatened, or spec

designated critical h

Shoreline vegetation Personal watercraft use would have negligible, adverse, direct and indirect impacts, for both short and long terms. This would occur because there would be no perceptible changes to shoreline, riparian, aquatic, or wetland community size, integrity, or continuity. Alternative A would not result in any substantial or noticeable physical change of submerged, riparian, or wetland shoreline vegetation. Past, current, and future use of personal watercraft and other motorized watercraft also would not produce any noticeable effect on shoreline vegetation. Therefore, cumulative effects would also be short-term, direct, and negligible. Alternative A would not result in impairment of shoreline vegetation at Glen Canyon National Recreation Area. Restricting access to upper portions of the Colorado, Escalante, Dirty Devil, and San Juan Rivers would provide negligible beneficial protection of riparian shoreline vegetation. Impacts on shoreline vegetation in the vicinity of the four main marinas would be similar to those described for alternative A and would result primarily from minor short-term foot traffic associated with users of personal watercraft and other watercraft when landing on lake shorelines. Limiting personal watercraft operations to flat- wake speeds on a portion of the Escalante River would reduce wave production but because of the lack of existing shoreline vegetation no benefits to shoreline vegetation would be expected. Past, current, and future personal watercraft use would not produce any noticeable effect on submerged aquatic, riparian and wetland vegetation. Therefore, cumulative effects would remain similar to alternative A and would be short-term, direct, and negligible. Alternative B would not result in impairment of shoreline vegetative resources. Alternative C would 

noticeable adverse submerged aquaticlakeshore does not submerged aquatic localized negligible vegetation would be implementing this afuture motorcraft usnoticeable effect on and wetland vegetaeffects would be simbe short-term, direcAlternative C would shoreline vegetative 

Visitor use and experience Alternative A would have negligible effects on visitor use and experience because the number of personal watercraft using Lake Powell and their management would not change. The effect on the Most effects of alternative B would be similar to those described for alternative A. Most effects would be long-term and negligible to minor because of the presence of other motorcraft. An In the short term, vi

watercraft as a primpersonal watercraft their visit would exp
FINAL ENVIRONMENTAL MPACT I STATEMENT 63 Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

visitor experience for personal watercraft users would continue to be beneficial, while experiences for visitors seeking quiet and solitude would continue to be adversely affected. Cumulative effects would be either adverse or beneficial, depending on the visitor’s goals. However, in either case impacts would be negligible. additional flat-wake zone and closed areas would produce negligible to minor, long-term, direct effects. Perceptions of individual visitors would determine if the effects were adverse or beneficial. Improvements in visitor education would result in negligible to minor, indirect, long- term, beneficial effects. Cumulative effects on visitor experience would be long-term, indirect, and moderate because there would be detectable change on certain portions of the lake. Perceptions of individual visitors would determine if effects were adverse or beneficial. short- and long-term 

Other users of perswho use them in cowould experience sadverse effects that in the long term. Visitors who did not generally perceive mbenefits from reducnoise. These benefin the long term. Visitor conflicts and visitor safety Alternative A would have negligible impacts on visitor conflicts and visitor safety. Improvements in visitor protection staffing would result in long-term minor beneficial effects on visitor conflicts and safety. Cumulative effects of watercraft use and other visitor activities on visitor conflicts and safety combined with NPS management activities to prevent accidents would be negligible. Compared to alternative A, alternative B would have direct and indirect, long-term, minor, beneficial impacts on both visitor conflicts and visitor safety. Cumulatively, the improved education components of this alternative would have indirect, long-term, beneficial, negligible to minor effects on visitor conflicts and visitor safety. In the short term, al

direct, beneficial, mHowever, as visitors which have higher athan personal watersafety would be advVisitor conflicts wouand improvements would produce both beneficial effects. Cwatercraft use and o

conflicts and safety management activitbe negligible. Cultural resources Effects on cultural resources from the implementation of alternative A would be adverse and mostly long-term. While most personal watercraft users would be conscientious about protecting the recreation area’s cultural resources, a few would engage in destructive actions such as illegal collecting of artifacts or vandalism. The effects of this behavior would be most noticeable in the narrow, steep-walled canyon areas that are inaccessible by most other types of motorcraft, but that can be traveled in a downstream direction by personal watercraft under alternative A. In these areas, impact intensities mostly would be negligible to minor. Impact intensities from personal watercraft users would be of similar magnitude in other areas, but would be Compared to alternative A, alternative B would have direct, long-term, negligible to minor, beneficial effects on archeological and ethnographic sites along the river canyons. Effects on traditional practices would be beneficial and negligible to moderate in intensity. In other areas, the effects of alternative B may be beneficial compared to alternative A, but the intensity would be negligible. Cumulative effects would be similar to alternative A. Alternative B would not result in impairment of the cultural resources of the recreation area. Compared to altern

have direct, long-tebeneficial effects on ethnographic resoumoderate, beneficiapractices in the rivearea. It also would hnegligible to minor, practices that are colake shore. In the short term, thfollow implementatioin a negligible, shordisturbances to cultend by 2012 if visitoincreases due to na
64 GLEN CANYON NATIONAL RECREATION AREA Impact Topic Alternative A: Continue Personal Watercraft Use as Currently Managed under a Special Regulation Alternative B (Modified Preferred Alternative): Promulgate a Special Regulation to Continue Personal Watercraft Use with Additional Management Restrictions A

(Person

Would 

indistinguishable from the adverse effects caused by the relatively few destructive visitors who used other transport methods to access the sites. Cumulatively, direct, adverse, long-term effects on the cultural resources in the recreation area would vary in intensity from negligible to moderate, depending on individual site vulnerability and accessibility. Negligible to minor, adverse, indirect effects on near-shore cultural sites would continue from the wave action caused both by boats and wind. The contribution of personal watercraft under alternative A to wave-caused effects would be negligible. Overall, the direct effect within the recreation area would be adverse and minor. Regionally, the effect from activities that occur outside of the recreation area would continue to be adverse and moderate. The contribution of alternative A to the regional effects would be negligible. Alternative A would not result in impairment of the cultural resources of Glen Canyon National Recreation Area. visitors finding othe

personal watercraftindividuals who prevarea due to personacumulative effects wA. Alternative C wothe cultural resourceRecreation Area. Socioeconomic environment Alternative A would have a negligible socioeconomic effect by itself and cumulatively with other actions. Alternative B would have a negligible socioeconomic effect by itself and cumulatively with other actions. Alternative C would 

term effect on the ecommunities in the recreation area wouadverse effects. The and indirect as reduservice related to perecreation rippled thCumulative effect obe moderate. In the would recover to prebusinesses that had watercraft sales and term effect on the lomoderate to major. National recreation area management and operations Use of personal watercraft in the recreation area under alternative A would have negligible, short- and long-term effects on operations. Increased funding for visitor protection staff would offset some of the long-term impacts to visitor protection Alternative B primarily would affect the enforcement, interpretation, and facilities maintenance components of recreation area operations. Short-term impacts would be minor, as staff resources were committed to marking Alternative C would 

minor, adverse effeoperations, primarily commitments needeban on personal wa
FINAL 

ENVIRONMENTAL MPACT ISTATEMENT 65

Impact Topic 

Alternative A: 

Continue Personal Watercraft Use as 

Currently Managed under a Special Regulation 

Alternative B (Modified Preferred Alternative): 

Promulgate a Special Regulation to 

Continue Personal Watercraft Use with 

Additional Management Restrictions 

A

(Person

Would 

services. The cumulative effects on management and operations of personal watercraft use in conjunction with other activities at existing levels also would be negligible. 

newly restricted areas and developing and implementing new educational programs. In the long term, most of these effects would decrease to negligible levels. Increased funding for visitor protection staff would lead to long-term, minor benefits to visitor protection services. Effects on recreation area staff from restrictions on carbureted two-stroke personal watercraft at the end of 2012 would be negligible as most watercraft would already be compliant with EPA emission standards and distribution of education materials would inform users well in advance of the restriction. Without additional funding, staff requirements for additional monitoring could have long-term, negligible to minor, adverse effects on operations of the resource management division. Cumulatively, all recreation area visitors would benefit from the improved education and visitor protection services that would be implemented with alternative B. These could reduce the need to respond to emergencies and improve the ability to focus recreation area services on the protection of resources and the safety of visitors. These would be beneficial, negligible to minor, direct and indirect, long-term effects on recreation area operations. 

these effects would Law enforcement rewould be reduced, adecreased in assocthe long-term effect would be negligible area increases due to visitors finding otpersonal watercraftindividuals who prevarea due to personafunding for visitor prsome of the long-teprotection services. additional cumulativ
66 GLEN CANYON NATIONAL RECREATION AREA

THE ENVIRONMENTALLY PREFERRED ALTERNATIVE 

The environmentally preferred alternative is defined by the Council on Environmental Quality (1978) 

as the alternative that best meets the criteria or objectives set out in section 101 of the National 

Environmental Policy Act. The environmentally preferred alternative best meets the following 

requirements: 

Fulfill the responsibilities of each generation as trustee of the environment for succeeding 

generations. 

Ensure for all Americans safe, healthful, productive, and aesthetically and culturally pleasing 

surroundings. 

Attain the widest range of beneficial uses of the environment without degradation, risk of health 

or safety, or other undesirable and unintended consequences. 

Preserve important historic, cultural, and natural aspects of our national heritage and maintain, 

wherever possible, an environment that supports diversity and variety of individual choice. 

Achieve a balance between population and resource use that will permit high standards of living 

and a wide sharing of life’s amenities. 

Enhance the quality of renewable resources and approach the maximum attainable recycling of 

depletable resources. 

This discussion summarizes the extent to which each alternative meets section 102(1) of the National 

Environmental Policy Act, which asks that agencies administer their own plans, regulations, and laws 

so that they are consistent with the policies outlined above to the fullest extent possible. 

Alternative A would satisfy the majority of the six requirements detailed above. However, 

alternative A would not ensure aesthetically pleasing surroundings because it would allow personal 

watercraft use in areas frequented by recreationists engaged in more reflective outdoor activities. 

Specifically, these include portions of the Colorado, San Juan, Dirty Devil, and Escalante Rivers. 

Alternative A would not attain the widest range of beneficial uses of the environment without 

degradation, risk of health or safety, or other undesirable and unintended consequences because of the 

potential impacts of personal watercraft use to visitor experience, air quality, noise, and other 

recreational opportunities in the recreation area. For this reason, alternative A is not preferred from an 

environmental perspective. 

The modified preferred alternative (alternative B) would have impacts on recreation area resources and 

visitor use and experience at Glen Canyon National Recreation Area that were similar to those 

described for alternative A. The selection of alternative B as the environmentally preferred alternative 

is based on the following. 

Its additional restrictions on the use of personal watercraft within portions of the Colorado, San 

Juan, Dirty Devil, and Escalante Rivers would improve the protection of natural and cultural 

resources in these areas. It also would reduce conflicts with other recreationists in these areas 

and allow for a wide range of recreational uses within the recreation area boundary. 
The Environmentally Preferred Alternative 

FINAL ENVIRONMENTAL IMPACT STATEMENT 67

The establishment of an additional flat-wake zone would improve environmental and safety 

protection. 

It provides for resource protection by phasing out carbureted two-stroke personal watercraft 

engines within the recreation area. The 10-year time frame to phase out the use of carbureted 

two-stroke personal watercraft engines under this alternative allows for the widest range of 

beneficial uses of the environment. 

Enhanced education programs would benefit all recreation area visitors by increasing user’s 

awareness of regulations pertaining to personal watercraft use and safety. These efforts would 

reduce visitor conflicts and improve visitor safety. 

It would allow for access to many of the area’s outstanding geologic and natural amenities by 

personal watercraft users while accommodating more reflective outdoor recreationists who were 

enjoying the quiet soundscapes of the recreation area. 

This alternative would maintain recreational opportunities for visitors while protecting sensitive 

natural and cultural resources. 

It would include future development of a lake management plan, supported by a three-year pilot 

study of potential strategies for minimizing visitor conflicts. This plan would help achieve a 

balance between population and resource uses, would provide high standards of living and wide 

sharing of life’s amenities, and would support diversity and variety of individual choice. 

Alternative C, the no-action alternative, would help ensure safe, healthful, productive, and 

aesthetically and culturally pleasing surroundings for visitors without the noise and safety effects of 

personal watercraft. The no-action alternative would attain a wide range of beneficial uses of the 

environment without degradation, risk of health or safety, or other undesirable and unintended 

consequences of allowing personal watercraft use. However, the no-action alternative would not 

maintain an environment that supports diversity and variety of individual choice, nor would it achieve 

a balance between population and resource use that permits a wide sharing of amenities because it 

would prohibit recreational opportunities for personal watercraft operators. 

Based on this analysis, the modified preferred alternative (alternative B) is the environmentally 

preferred alternative. It best fulfills NPS responsibilities as trustee of the outstanding natural 

resources, including critical habitats for threatened and endangered species; ensuring safe, healthful, 

productive, and aesthetically and culturally pleasing surroundings; and attaining a wider range of 

beneficial uses of the environment without degradation, risk of health or safety, or other undesirable 

and unintended consequences. 
ALTERNATIVES 

68 GLEN CANYON NATIONAL RECREATION AREA
The Environmentally Preferred Alternative 

FINAL ENVIRONMENTAL IMPACT STATEMENT 69

Affected Environment 

Divider 

This page to be removed 

(Needs to be an odd page) 
ALTERNATIVES 

70 GLEN CANYON NATIONAL RECREATION AREA

This page to be removed 

Back of Divider
FINAL ENVIRONMENTAL IMPACT STATEMENT 71

GENERAL PROJECT SETTING 

Glen Canyon National Recreation Area, located in the Colorado Plateau region, extends more than 

200 miles from the Green River in southern Utah downstream to Lees Ferry in Arizona. It is a desert 

region of bare rock and dirt, arid shrublands, grasslands, and low-growing pinyon-juniper woodlands. 

As shown in the Glen Canyon National Recreation Area vicinity map (figure 2), the recreation area is 

bordered by Canyonlands National Park to the northeast; the Redrock Plateau to the east; the Henry 

Mountains to the north; Grand Staircase – Escalante National Monument, Dixie National Forest, and 

Capitol Reef National Park to the northwest and west; and the Navajo Indian Reservation to the south. 

Lake Powell was formed by construction of the Glen Canyon Dam. Congress authorized its 

construction in the Colorado River Storage Project Act of 1956 (PL 84-485). The project’s primary 

purposes were to prevent flooding on the Colorado River, create a reservoir to meet downstream water 

requirements, and generate hydroelectric power. To meet these objectives, the dam was constructed 

between 1960 and 1963. Incidental to dam construction, the city of Page, Arizona was established 

about 2 miles from the dam site to provide housing and other services for workers. Page now serves as 

the largest gateway community to Glen Canyon National Recreation Area. 

The 186-mile-long Lake Powell formed along the courses of the Colorado River and three tributaries – 

the Escalante, San Juan, and Dirty Devil Rivers. Lake Powell is the second largest reservoir in North 

America. The lake includes parts of Arizona and Utah, and is within the jurisdiction of several 

agencies. These include the National Park Service, Bureau of Reclamation, and Bureau of Land 

Management; the Navajo Nation; the states of Utah and Arizona; one Arizona county (Coconino); and 

four Utah counties (Garfield, Kane, San Juan, and Wayne). 

Glen Canyon Dam is managed by the Bureau of Reclamation. It was designed to accommodate lake 

levels ranging from 3,490 feet to 3,700 feet above sea level. As the water level changes, the surface of 

Lake Powell varies in size from 52,000 acres to 163,000 acres and the shoreline fluctuates from 

990 miles to 1,960 miles in length. Usually, the lake surface is about 160,000 acres, which represents 

approximately 13% of the recreation area. Annual fluctuations in lake levels typically are about 

25 vertical feet. 

The lake level rises in the spring as water from snowmelt runoff and spring storms collects behind the 

dam. It then declines throughout the rest of the year, particularly during summer and early fall as water 

is released for electrical power generation and irrigation. 

The 87% of Glen Canyon National Recreation Area that is not inundated by Lake Powell consists of 

upland desert incised by deep canyons, dry washes, and steep cliffs. Other areas consist of talus, and 

clay or slickrock badlands. Much of the lake’s shoreline consists of steep slopes and cliff walls. 

Elevations within the recreation area vary from approximately 3,700 feet to 7,000 feet above sea level. 

Upland areas generally lack vegetation or supports only scattered grasses, saltbush, and annuals. 

In 1972, Congress established Glen Canyon National Recreation Area (PL 92-593) to provide public 

recreation on Lake Powell and adjacent lands. The National Park Service is responsible for managing 

all federal lands and waters within the recreation area boundaries (NPS 1987a). Access to Lake Powell 

within Glen Canyon National Recreation Area is provided at four developed marinas: Wahweap, 

Bullfrog, Halls Crossing, and Hite; and two launch ramps: Antelope Point and Stateline. Locations of 

the marinas are shown on the Glen Canyon National Recreation Area Vicinity map (see figure 2). 
AFFECTED ENVIRONMENT

72 GLEN CANYON NATIONAL RECREATION AREA

The recreation area includes 1,254,306 acres of land and water. The recreation area’s General 

Management Plan (NPS 1979a) divided the recreation area into four management zones (see figure 9). 

Specific land and water use activities are allowed or prohibited within each zone. 

The Natural Zone (668,670 acres) is managed to maintain isolated, natural processes, and 

consumption of renewable resources that are subject to the protection of recreation values of the 

area. The General Management Plan recommended designating all of the lands within this zone 

as wilderness. Although these lands have never received wilderness designation, they are 

managed substantially in conformance with such a designation. About half of the Lake Powell 

shoreline is within the Natural Zone. 

The Recreation and Resource Utilization Zone (557,890 acres) is managed to maintain natural 

processes while allowing mineral leasing, grazing, utility rights-of-way, transportation systems, 

and recreation activities, including motorized recreation such as scenic touring and boating. The 

Recreation and Resource Utilization Zone includes the entire surface (up to 163,000 acres) of 

Lake Powell. The remaining area within this zone (almost 400,000 acres) consists of dry land 

and includes about half of the lake shoreline. The General Management Plan specifically 

identifies speedboating, waterskiing, and houseboat touring as appropriate in the Recreation and 

Resource Utilization Zone. 

The Cultural Zone (25 acres) focuses on the preservation, interpretation, and restoration of 

historic and archeological resources. This small zone is composed of several areas located 

primarily along the Wilson Mesa and the Escalante River. 

The Development Zone (19,270 acres) includes the permanent structures and operations 

necessary to support recreation activities and allows a wide range of recreational use. It includes 

the areas around Lees Ferry; the complex that includes the Glen Canyon Dam, Carl Hayden 

Visitor Center, and Wahweap Marina; and the developments at Halls Crossing, Bullfrog, Hite, 

Dangling Rope, Antelope Point, Llewellyn Gulch, and the Orange Cliffs area. 

Glen Canyon National Recreation Area is a major, regional recreation resource. It receives more than 

2 million visitors each year, the majority of which are associated with the water-based recreation of the 

lake. Boating is very popular, and a variety of boats are common on the lake. Visitors can rent 

houseboats, personal watercraft, canoes, and kayaks, or bring and launch their own boats. Many 

visitors enjoy fishing, waterskiing, and exploring land-based recreation area features. The large area of 

the lake and the inaccessibility of the shoreline from roads make boat travel essential in accessing 

most portions of the lakeshore. 

This environmental impact statement focuses on areas of Lake Powell within Glen Canyon National 

Recreation Area that are used by personal watercraft. The area that was evaluated for most impact 

topics included: 

All of Lake Powell within Glen Canyon National Recreation Area up to the 3,700-foot water 

surface elevation; 

All lands within 500 horizontal feet of the shore when the Lake Powell surface is at an elevation 

of 3,700 feet above sea level; and 

All of the lands that are intermittently inundated as the lake level fluctuates. 
General Project Setting 

FINAL ENVIRONMENTAL IMPACT STATEMENT 73

This page to be removed 

Needs to be odd 

11 x 17 map 

FIGURE 9: GENERAL MANAGEMENT ZONES MAP
AFFECTED ENVIRONMENT

74 GLEN CANYON NATIONAL RECREATION AREA

This page to be removed 

Back of Figure 9 
FINAL ENVIRONMENTAL IMPACT STATEMENT 75

WATER QUALITY 

The drainage basins of the rivers that form Lake Powell in Glen Canyon National Recreation Area 

cover 111,700 square miles. This large watershed is extremely varied in ecosystem type and land use 

management (NPS 1987a). Upstream land uses include mining, irrigated crop production, livestock 

grazing, and urban development. These activities have affected both the chemical and physical 

characteristics of rivers in the watershed. 

The mountains of the watershed in Colorado and Utah receive up to 50 inches of precipitation 

annually, but the Glen Canyon area is arid, receiving only 6 to 7 inches of rainfall each year. Brief, 

intense thunderstorms produce the majority of all moisture received locally. Evaporation and 

transpiration of water by plants greatly exceeds annual precipitation, and Lake Powell loses 

approximately 500,000 acre-feet of water to the atmosphere each year (NPS 1987a). 

Lake Powell contains 27 million acre-feet of water at full pool, or approximately three times the 

average annual flow of the Colorado River. (One acre-foot equals one acre covered with one foot of 

water, or 325,829 gallons.) At full pool, the water surface area is 163,000 acres, or 255 square miles. 

The depth of the reservoir near the dam is 561 feet, and the average depth is 167 feet (NPS 1987a). 

The major tributary rivers to Lake Powell are the Colorado, San Juan, Dirty Devil, and Escalante. The 

Colorado River and its tributary canyons form the body of Lake Powell. The quantity and quality of 

tributary river flows entering Lake Powell are summarized in table 6 and discussed below. 

The rugged terrain, wilderness protection, and variation in the lake level have prevented establishment 

of a comprehensive stream flow data-gathering network (NPS 1987a). As a result, the U.S. Geological 

Survey (USGS) has very few gauging stations on the major tributaries within Glen Canyon National 

Recreation Area. Included in the descriptions of the tributaries, below, are data from the gauging 

stations nearest each river’s confluence with Lake Powell. Data in table 6 are from U.S. Geological 

Survey monthly streamflow statistics (USGS 2002). 

Because all four tributary rivers flow through Utah and enter Lake Powell within the state, Utah 

surface waters criteria were used to assess the quality of the tributary rivers. To protect the water 

resources of the state, Utah has outlined designated beneficial uses for state waters, and defined 

associated water quality criteria for each use. Each of the tributaries serves multiple purposes in the 

state. These uses are identified by a numeric classification system, and all surface waters of the state 

are assigned corresponding uses. The four classifications found in the tributaries addressed in this 

analysis are: 

Domestic water supply (1C); 

Secondary recreation such as boating (2B); 

Nongame fish and aquatic life (also known as warm water fishery) (3B); and 

Agricultural purposes (4). 
AFFECTED ENVIRONMENT

76 GLEN CANYON NATIONAL RECREATION AREA

TABLE 6: CHARACTERISTICS OF THE RIVERS UPSTREAM FROM LAKE POWELL

Parameter Colorado River San Juan River Dirty Devil River Escalante River 

Low mean flow (cubic feet 

per second) and month 

4,844 

January 

1,103 

December 

56.9 

July 

7.1 

July 

High mean flow (cubic feet 

per second) and month 

45,880 

June 

5,671 

June 

138 

June 

23.7 

May 

Watershed size 

(square miles)a

82,700 23,000 5,000 <1,000 

Average annual flow 

entering Lake Powell 

(acre-feet) 

9.7 million 1.6 million 72,000 8,000 

U.S. Geological Survey 

station location and station 

number 

At Hite, Utah 

09335000 

Near Bluff, Utah 

09379500 

Poison Spring Wash, 

Utah 

09333500 

Near Escalante, 

Utah 

09337500 

State of Utah designated 

usesb

1C 

2B 

3B 

4 

1C 

2B 

3B 

4 

2B 

3B 

2B 

3B 

Water quality issuesc Elevated levels of 

nitrogen from 

irrigated agriculture 

return flows, pH and 

thermal changes due 

to upstream dams 

and mining 

Elevated levels of 

copper, lead, zinc, 

and salinity due to 

upstream mining and 

exposure to natural 

Mancos shale 

formations 

Elevated levels of 

sediment and total 

dissolved solids due 

to exposure to 

natural Mancos 

shale 

Elevated levels of 

sediment and total 

phosphorus due to 

geologic formations 

and upstream mining 

of phosphorus 

 

a. The Colorado River watershed size does not include the drainage basins for the San Juan, Dirty Devil, and Escalante Rivers. 

b. State of Utah Administrative Code Rule R317-2. 

c. Environmental Protection Agency no date d.

COLORADO RIVER 

The Colorado River flows into Lake Powell as a large, wide river, prone to large spring floods. The 

widest sections of the lake indicate the previous course of the Colorado River above Glen Canyon 

Dam. Water is released from the reservoir, through Glen Canyon Dam, back into the main stem of the 

Colorado River. The flow then proceeds west through the Grand Canyon. 

The Colorado River contributes approximately 9.7 million acre-feet per year to the reservoir. High 

flows occur in the spring and early summer, with the mean high flow of 45,880 cubic feet per second 

occurring in June. As shown in table 6, the mean high monthly flow in June is almost 10 times the 

low-month flow, which occurs in January. 

The river enters the lake from the northeast, upstream of the Hite marina, as a shallow, sediment-laden 

flow. The sediment load in the Colorado River ranges from 300 parts per million to more than 

18,000 parts per million (USGS 2002). 

The Colorado River above Lake Powell drains an area that includes the mountains of Colorado and the 

eastern portions of Utah. Land uses in this area range from wilderness to mining to urban 

development. The river receives agricultural runoff with a total nitrogen content of up to 9 parts per 

million (drinking water maximum standard is 10 parts per million), and dissolved metals such as 

boron, magnesium, and iron (USGS 2002). Warm summer temperatures also can cause water quality 

concerns, with summer flows that can reach 80°F. 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 77

Above Lake Powell, the state of Utah has designated the Colorado River for four uses: domestic water 

source; secondary recreation such as boating; nongame fish and aquatic life; and agricultural use. 

SAN JUAN RIVER 

The San Juan River is the largest tributary joining the Colorado River within Glen Canyon National 

Recreation Area. It enters Lake Powell from the east, just downstream of the confluence with the 

Grand Gulch drainage. 

The San Juan River is smaller than the Colorado River, averaging about 1.6 million acre-feet in annual 

flow. This river displays a historic flow regimen similar to that of the Colorado, with high spring 

floods and modest flows throughout the remainder of the year (Utah Division of Wildlife Resources 

1996). As shown in table 6, the peak-month flows in June are about five times greater than the flow 

rates in December. 

The San Juan River drains an area in excess of 23,000 square miles that includes the mountains of 

southwestern Colorado and the arid regions of southeastern Utah. Upstream land uses include mining 

and agriculture. In general, the San Juan River watershed has not experienced the amount of urban 

development present in the Colorado River watershed (NPS 1987a). 

The San Juan River can carry very heavy loads of suspended sediment. Water quality samples 

collected since 1990 have exhibited sediment loads ranging from 25 parts per million to 85,000 parts 

per million. Despite these sediment loads, the San Juan River has been designated for four uses in 

Utah: domestic water use, secondary recreation, nongame fish and aquatic life, and agriculture. 

DIRTY DEVIL RIVER 

The Dirty Devil River flows into Lake Powell from the north, upstream from Hite. This small river 

drains an area of approximately 5,000 square miles and contributes about 72,000 acre-feet per year to 

the reservoir. The average flow in this stream is 99 cubic feet per second (USGS 2002). Some 

stretches of this river are frequently dry during summer months. This may be due in part to irrigation 

diversions that occur along the river coupled with evaporation, or it may be the natural, historic pattern 

of flow (NPS 1987a). 

The Dirty Devil River has two designated uses upstream from the recreation area: secondary 

recreation such as boating, and nongame fish and aquatic life. In the past, the quality of water in this 

stream has been affected by high total dissolved solids (salinity) and a heavy sediment load. The state 

of Utah does not have sediment criteria for water quality. Environmental factors that could account for 

the high suspended solids and salinity include flashy flows associated with spring runoff, and the 

bedrock and parent material of the region, which were formed by ancient marine deposits and are high 

in salt. 

ESCALANTE RIVER 

The Escalante River enters Lake Powell from the northwest just upstream from Stevens Canyon, near 

Stevens Arch. The Escalante River watershed is the smallest of those considered in this analysis, with 

an area of less than 1,000 square miles. This stream carries approximately 8,000 acre-feet of water to 
AFFECTED ENVIRONMENT

78 GLEN CANYON NATIONAL RECREATION AREA

Lake Powell each year. Average flow from 1980 to 1999 was 11.5 cubic feet per second (USGS 

2002). Peak flows occur in May, and low flows are in July. 

The Escalante River is not dammed upstream of Lake Powell, but withdrawals are made for irrigation 

during the growing season. Land use practices in the drainage include agriculture and rural 

development (Utah Division of Wildlife Resources 1996; USGS 2002). 

The Escalante River is designated for two beneficial uses above Lake Powell: secondary recreation, 

and nongame fish and aquatic life. This stream reach from Lake Powell upstream to Calf Creek has 

had water quality problems in the past, with elevated levels of total phosphorus and sediment. 

LAKE POWELL 

Hydrology 

Glen Canyon Dam formed Lake Powell by impounding the Colorado River. The reservoir 

environment is dramatically different from the river systems. The waters of the lake are clear, deep, 

and thermally stratified. This is a stark contrast to the rivers, which are shallow, well-mixed, and often 

laden with sediment. Water moves slowly through the reservoir, and the lake typically is cooler than 

the rivers, especially during the summer. 

The dam has eliminated natural spring flooding downstream. High spring flows that formerly ranged 

between 80,000 and 300,000 cubic feet per second are now captured and released throughout the 

remainder of the year. This management strategy has increased average flows during both the summer 

and winter to between 8,000 and 12,000 cubic feet per second, up from pre-dam average flows of 

about 3,000 cubic feet per second. Generally, releases from Glen Canyon Dam are higher in the 

summer than in winter in response to hydropower demands (Utah Division of Wildlife Resources 

1996). 

Hydrologic characteristics of Lake Powell are summarized in table 7. Water releases depend on water 

demands and hydropower production requirements. By law, Glen Canyon Dam must release 

8.23 million acre-feet each year, which represents about a third of its holding capacity. Daily releases 

are highest in the heat of summer (to meet demands for irrigation and electricity production) and on 

cold winter nights (when hydropower helps meet electricity demand peaks). 

Lake Powell is designed to operate between elevation 3,490 and 3,700 feet above mean sea level. The 

varying water surface elevations are illustrated in the photographs below. As the water level changes, 

the surface of Lake Powell varies in size from 52,000 acres to 163,000 acres and the shoreline 

fluctuates from 990 miles to 1,960 miles in length (figure 10). 

During summer months, the surface water temperature typically is more than 70°F, and can reach 

80°F. Below the surface, at a depth varying from 40 to 150 feet, the lake temperature is notably cooler. 

This temperature gradient zone between the warm, near-surface water and the colder water of the 

depths is called the thermocline. The depth to the thermocline changes throughout the year due to lake 

levels and surface temperatures. Below the thermocline the water is cold and low in oxygen and 

productivity (which is measured by the concentration of chlorophyll). These cold, deep waters of the 

lake are called the hypolimnion. 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 79

TABLE 7: HYDROLOGIC CHARACTERISTICS OF LAKE POWELL

Parameter 

Value 

(million acre-feet) 

Volume at full pool 27 

Mean annual inflowa 11.4 

Minimum annual outflowb 8.23 

Annual evaporation 0.5 

 

a. Sum of flows from four major tributaries. 

b. Releases from Glen Canyon Dam. The minimum level is required by law.

FIGURE 10: WATER LEVELS VARIATIONS, AS INDICATED BY SHORELINE FORMATIONS

Lake Powell does not often experience the twice-annual “turnover” seen in northern lakes, where the 

top and bottom layers mix whenever the changing seasons produce equal temperatures throughout the 

water column. Thus, the hypolimnion does not often mix with the upper surface waters, and remains in 

the deep reaches of the lake, low in nutrients and chlorophyll (Utah Division of Wildlife Resources 

1996; NPS, Anderson, pers. com., April 2002e). 

The Glen Canyon Dam penstock elevation draws water from the hypolimnion and discharges it to the 

Colorado River channel downstream from the dam. As a result, the water temperature never exceeds 

48°F (Blakeslee 2002). 

Prior to 1991, the volume of water released from the dam could vary by 20,000 cubic feet per second 

within a single day. However, the large flow changes were destructive, eroding the channel and 

sandbars. They also posed a safety hazard to rafters and could flood out campers on beaches. 

Therefore, in 1991, the Bureau of Reclamation decided to reduce daily fluctuations. Since then, the 

amount of water released downstream could not vary by more than 8,000 cubic feet per second in any 

one day (Blakeslee 2002). 
AFFECTED ENVIRONMENT

80 GLEN CANYON NATIONAL RECREATION AREA

Water Quality 

As the tributary rivers enter the reservoir, the energy needed to carry sediment is lost, causing the 

sediment load to be deposited. As much as 98% of the sediment load is dropped within 25 miles of the 

river mouth. Only very fine clay particles are found near the dam. 

An essential nutrient, phosphorus, adheres to soil particles and is deposited with the sediment on the 

upstream portions of the reservoir bed (Grand Canyon Monitoring and Research Center, Hueftle, pers. 

com., April 2002). The absence of this nutrient limits the growth of phytoplankton (algae) within the 

reservoir body, which produces the clear water that is characteristic of the lake. The areas of the lake 

with the highest biological productivity are located close to tributary inflows. 

Heavy metals such as copper, lead, and zinc also are adsorbed to the soil particles and settle out with 

the sediment. As these toxic metals are covered by subsequent layers of sediment, they become 

biologically unavailable. 

The Grand Canyon Monitoring and Research Center has been conducting water quality testing in Lake 

Powell since 1997. However, none of the water quality parameters measured by the center are related 

to emissions generated by the use of motorized watercraft. The center tests for temperature, pH, 

dissolved oxygen, phosphorus, nitrogen, salinity, and trace metals. No chronic water quality problems 

have been identified (Grand Canyon Monitoring and Research Center, Hueftle, pers. com., April 

202l). The water quality in Lake Powell is generally described as good. The lake is largely suitable for 

swimming and fishing. 

WATER POLLUTION SOURCES WITHIN 

GLEN CANYON NATIONAL RECREATION AREA 

The quality of the water in Lake Powell is affected by many human activities. Pollutants are 

introduced directly to the lake during recreation activities. Sources of contamination include emissions 

from personal watercraft and other motorized watercraft, human waste, and trash. 

The National Park Service is responsible for controlling water-polluting activities within recreation 

area boundaries and meeting state and federal water quality standards. In addition, the National Park 

Service must comply with state anti-degradation requirements. The designated uses for Lake Powell in 

Utah and Arizona, the standards for water criteria to be met in accord with those uses, and antidegradation requirements are discussed later in this section. 

Untreated Sewage 

Human waste is a threat to recreation area resources because it can be a source of pathogenic bacteria 

and nutrients in the water. Control of human and pet waste is being addressed by implementing the 

“Lake Powell Pure” program, which includes education and the enforcement of a sanitary code (NPS 

2001g). 

Lake Powell water quality has been monitored for human waste since 1988. The monitoring 

periodically indicated high concentrations of fecal coliform bacteria, which indicate the presence of 

untreated sewage. In the early 1990s, several beaches were temporarily closed because of high fecal 

coliform bacteria levels. There were 11 beach closures and the closure of Wahweap Marina in 1995. 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 81

In response to these conditions, the National Park Service entered into the Strategic Plan to “Protect 

Water Quality at Lake Powell” with the Arizona Department of Environmental Quality and Utah 

Department of Environmental Quality. The intent of this plan, which was adopted in July 1996, is to 

improve and protect the water quality of Lake Powell. Some of the provisions of the program are as 

follows: 

At vehicle-accessible shorelines, visitors must camp within 200 feet of a vault toilet. 

In other areas of the recreation area, anyone camping within a quarter mile of Lake Powell’s 

shoreline must carry and use a device (not plastic bags) for containing solid human waste. 

Restrooms and dump/pump stations have been constructed at all launch ramps. 

Restrooms and portable toilets are being constructed at selected vehicle-accessible backcountry 

shoreline camping areas. 

Eight floating dump/pump stations and restrooms have been constructed on Lake Powell. 

Additional seasonal rangers have been added to the staff to enforce sewage containment 

regulations. 

The water quality initiatives have been highly successful in reducing contamination of Lake Powell by 

human sewage. The number of beach closures has gradually declined over the years with three 

closures in 1996, two in 1998, and one in 1999 and 2000 (NPS 2003b). 

Personal watercraft use is not believed to contribute substantially to contamination of the lake by 

human waste. Much personal watercraft use occurs close to marinas or launch ramps where restrooms 

are available. When personal watercraft are used in conjunction with houseboats, the sanitary facilities 

of the larger vessels are available to the personal watercraft users. Therefore, none of the personal 

watercraft alternatives include provisions to manage pollution by human waste, and none of the 

alternatives would affect the ongoing efforts to protect the lake and visitors from contamination by 

human wastes. 

Fuel Leaks or Spills at Marinas and Launch Sites 

Fueling stations at the Hite, Halls Crossing, Bullfrog, Dangling Rope, and Wahweap Marinas sell fuel 

to boaters. In addition, fueling frequently occurs at launch sites where boaters fill the tanks of small 

vessels, including personal watercraft, from fuel storage cans. Evidence of pollution can be seen near 

fueling stations and near launch sites, by even casual observation. The “rainbow sheen” seen on the 

water surface in these areas is the result of oil and gasoline floating on the water surface. The odor of 

fuel and combustion can also be detected near these areas. 

The National Park Service complies with recommendations and requirements established by the 

National Park Service Hazardous Waste Management and Pollution Prevention Team to prevent 

environmental damage resulting from oil spills (NPS 1998c). These plans are required by the 

Environmental Protection Agency as stated in 40 CFR, Part 112. The National Park Service and all 

marina operators must comply with these requirements to limit the environmental effects of fueling on 

the lake. In accordance with this federal regulation, ARAMARK, the concessioner at Glen Canyon 

National Recreation Area has developed Spill Prevention Control and Countermeasure Plans for each 
AFFECTED ENVIRONMENT

82 GLEN CANYON NATIONAL RECREATION AREA

fueling station to prevent discharges of oil to Lake Powell and the environment and to define standards 

for spill control and countermeasures (ARAMARK, n.d.). The National Park Service and all marina 

operators must comply with these requirements to limit the environmental effects of fueling on the 

lake. In addition, placards are displayed at marinas and educational materials are made available to 

recreation area visitors to inform boat operators about proper fueling of vessels and containers. 

Away from areas of high boat traffic, observable evidence of hydrocarbon pollution usually 

disappears. In portions of the lake with low motorcraft use, the waters are clear and appear clean to the 

casual observer. No odor from fuel or combustion can generally be detected. 

The persistence of gasoline and oil in lake waters depends on the temperature of the water and the 

amount of mixing. Fuel components volatilize (evaporate) more quickly at warmer temperatures. High 

rates of mixing increase exposure to the air and hasten volatilization (EPA 1994). 

During the summer of 2001, the National Park Service conducted water quality testing at Glen Canyon 

National Recreation Area to determine the levels of 33 hydrocarbons in Lake Powell. Samples were 

taken over a 4-day period from June 29th through July 2nd. This period was selected because it 

represents a high-use period by motorcraft, including personal watercraft. 

The summer 2001 water quality sampling does not provide a complete characterization of hydrocarbon 

contamination of Lake Powell. The results are only a “snapshot” of hydrocarbon levels in the lake’s 

waters on the days of testing. However, in the absence of more complete data, they are useful for 

indicating current conditions. 

Sample areas were chosen to capture different levels of motorboat use. They included: 

A busy marina with fueling station at Bullfrog; 

A high-boat-use area at Moqui Canyon; 

An open-water area in Wahweap Bay; and 

An area closed to all motor vessel access (control area) at Knowles Canyon. 

Three locations were sampled at each test site, and samples were acquired from two depths. A total of 

27 samples were obtained. 

A 0.5-meter-deep (about 20 inches) sample was collected to represent the near-surface 

conditions where lighter-weight contaminants, such as benzene, would presumably concentrate. 

A 3-meter-deep (about 10 feet) sample was collected based on research at Lake Tahoe that 

found complete mixing of polycyclic aromatic hydrocarbon contaminants at this level (NPS, 

Vanmouwerik, pers. com., May 2002p). 

Analyses were performed by the State of Utah, The Woods Hole Group, Inc., and the U.S. Geologic 

Survey research laboratories. Samples were assayed for benzene, toluene, ethylbenzene, and xylenes; 

five gasoline additives, including methyl tertiary butyl ether, ethyl tertiary butyl ether, tertiary amyl 

methyl ether, di-isopropyl ether, and tertiary butyl alcohol; and 24 polycyclic aromatic hydrocarbon 

compounds (NPS, Vanmouwerik, memo, July 2001h). 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 83

Results obtained for the hydrocarbon components that are used in the water quality model in the 

“Environmental Consequences” chapter are presented in table 8. These hydrocarbons were chosen 

because the relative content of these components in gasoline is known (Gustafson et al. 1997). 

Complete results of the values obtained for the 33 pollutants measured in Lake Powell can be found in 

appendix D.1. 

The Environmental Protection Agency drinking water standards are provided in table 8 only for 

comparative purposes, since Lake Powell water is not used as a drinking water source at any of the 

sampled sites. However, there are two drinking water intakes within the lake, one near Hite, Utah and 

one at Glen Canyon Dam that serves the town of Page, Arizona. The intake near Hite is approximately 

one-half mile north (upstream) of the marina, and floats at a depth of approximately 12 feet. The Glen 

Canyon Dam intake is under the jurisdiction of the Bureau of Reclamation. The National Park Service 

has no access to the site, and it not responsible for monitoring at this location. As shown in the table, 

the maximum concentrations detected from the most heavily used site, Bullfrog Marina, were below 

the treated drinking water standard or advisory level for all three compounds for which a standard 

exists. 

The presence of these compounds in water indicates the combustion of fossil fuels, and is not specific 

to two-stroke engines or personal watercraft. All powered watercraft that use gasoline as fuel emit 

these constituents into the water. According to M. Vanmouwerik of the National Park Service National 

Resource Stewardship and Science Office (NPS, Vanmouwerik, memo, July 2001h), “For motorboats, 

each class of boat engine releases different amounts of these contaminants. To complicate matters 

further, emissions within each engine type class can vary significantly, depending on such factors as 

each individual engine’s tuning and the rpm’s it is being operated at.” 

Discharge of Gasoline, Oil, and Other Chemicals by Personal Watercraft Engines 

The vast majority of personal watercraft in use today are powered by conventional two-stroke, 

carbureted engines, which discharge as much as 30% of their fuel directly into the water (NPS 1999c; 

CARB 1999a). As a result, an average 2-hour ride on a personal watercraft with a carbureted twostroke engine will release 3 to 4 gallons of fuel into the water (NPS, Vanmouwerik and Hagemann, 

1999e; Bluewater Network 2001). Such a personal watercraft operated for 7 hours produces more 

smog-forming emissions, including unburned hydrocarbons that are discharged into the water and then 

evaporate, than a passenger car driven for 100,000 miles (CARB 1999a). 

TABLE 8: LAKE POWELL WATER QUALITY, SUMMER 2001 

Contaminant 

EPA Maximum 

Contaminant Level 

for Drinking Water 

Detection 

Limit 

Maximum Value 

and Location 

Minimum Value 

and Location 

Benzo(a)pyrene 0.2 μg/La 0.01 μg/L Below detection limits Below detection limits 

Naphthalene No standard 0.01 μg/L Below detection limits Below detection limits 

1-methyl naphthalene No standard 0.01 μg/L 0.14 μg/L at Bullfrog 

Marina 

Below detection limit at 

Moqui Canyon, Knowles 

Canyon, Bullfrog 

Benzene 5 μg/L 0.5 μg/L 3.43 μg/L at Bullfrog 

Marina 

Below detection limit at 

Knowles Canyon 

Methyl tertiary-butyl ether No standard 0.17 μg/L 1.42 μg/L at Bullfrog 

Marina 

Below detection limit at 

Knowles Canyon 

 

a. μg/L = micrograms per liter, equivalent to parts per billion.
AFFECTED ENVIRONMENT

84 GLEN CANYON NATIONAL RECREATION AREA

The Personal Watercraft Industry Association notes that direct-injection engines have been available 

in personal watercraft for four years; and three personal watercraft manufacturers introduced fourstroke engines for the 2002 model year (PWIA 2002a). The Environmental Protection Agency 

assumes that the existing two-stroke engine models would not be completely replaced by newer 

personal watercraft technology until 2050 (40 CFR 89, 90, 91). 

On October 4, 1996, the Environmental Protection Agency issued a final rule to regulate emissions 

from new spark-ignition gasoline marine engines, including outboard engines, personal watercraft 

engines, and jet boat engines. The rule-making was conducted under section 213 of the Clean Air Act. 

The Environmental Protection Agency had determined that these engines contributed to ozone air 

pollution, and that the technology was available to manufacture cleaner-operating engines. The rule 

stipulates that by the 2006 model year, the entire fleet of marine engines produced by each 

manufacturer, including those for personal watercraft, must have a 75% reduction in hydrocarbon 

emissions compared to the average for the fleet produced by that manufacturer prior to the rule. It also 

established intermediate target dates for emission reductions. 

At its December 1998 meeting, the California Air Resources Board adopted an even more aggressive 

program for reducing emissions from personal watercraft, outboard, and some jet boat engines. It 

stipulated that new marine engines would have to meet the 75% reduction goal in 2001 and would 

have be 90% cleaner in 2008. Four months later, Minnesota-based Polaris Industries, a major 

manufacturer of personal watercraft, received certification from the Environmental Protection Agency 

for a direct-injection two-stroke personal watercraft that met the 75% reduction goal (CARB 1999b). 

Since then, other manufacturers have received certification, and since 2001 only low-emission 

personal watercraft have been sold in California. 

Some manufacturers are using four-stroke engine technology on personal watercraft to reduce 

emissions and meet regulatory standards (EPA 1996a). Others are using the same approach as Polaris 

Industries and installing direct-injection two-stroke engines. The 75% reduction standards have been 

met both by direct-injection two-stroke engines and electronic fuel injection two-stroke engines. 

Rather than producing 2006-certified vessels for the large California market (50,000 personal 

watercraft and outboard units per year) and intermediately clean vessels for use in other states, some 

manufacturers may be choosing to switch their entire product line to low-emission personal watercraft. 

As a result, an estimated 12% of personal watercraft used on Lake Powell in June and July 2001 had 

low-emission engines. Because the low-emission technology has been successfully demonstrated in 

California, its complete implementation in year 2006 models nationwide appears assured. 

In 1996, the Environmental Protection Agency estimated an overall 52% reduction in hydrocarbon 

emissions from marine engines from present levels by 2010, and a 75% reduction by 2030, based on 

converting polluting machines. The 1997 EPA rule delayed implementation by one year (EPA 1996a, 

1997a). 

These milestones could be reached even earlier, based on the effects of the subsequent, more stringent 

California Air Resources Board (1998a) standards. 

The average operating life of a personal watercraft is 5 to 10 years, depending upon the source. The 

formula for determining the operating life of personal watercraft was published in the Federal Register

on October 4, 1996 (EPA 1996a). Based on this formula, the National Park Service expects that by 

2012, most boat owners will already be in compliance with the 2006 EPA marine engine standards. 

The Personal Watercraft Industry Association believes the typical operating life of a personal 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 85

watercraft rental is three years and approximately five to seven years for a privately owned vessel 

(PWIA, pers. com., May 2002a). Water quality conditions associated with the use of personal 

watercraft and other motorcraft will improve, regardless of the management action selected. 

Although overall hydrocarbon emissions will be reduced as a result of implementation of EPA 2006 

marine engine standards, the emission of PAH compounds to the water varies by engine type. A recent 

study by the Tahoe Regional Planning Agency (2003) compared the concentrations of PAH 

compounds released into the water and found that the two-stroke carbureted outboard engine emitted 

lower PAH levels into the water than did the two-stroke direct-injected engine. The four-stroke 

carbureted outboard engine emitted the lowest PAH levels, as well as other gasoline-related 

contaminants into the water (TRPA 2003; CARB 2001). However, the two-stroke carbureted outboard 

engine emitted higher levels of benzene than the two-stroke direct-injected engine model (CARB 

2001). Personal watercraft engines follow the same patterns of emission rates as outboard engines 

(CARB 2001). The TRPA (2003) study confirms other findings regarding emissions into the water and 

does not substantially change NPS conclusions regarding water quality impacts.

CHEMICAL COMPOSITION OF GASOLINE AND COMBUSTION 

PRODUCTS WITH REGARD TO PERSONAL WATERCRAFT MANAGEMENT 

Up to one-third of the fuel delivered to the conventional personal watercraft engine is unburned and 

discharged into the water. Several groups of chemical compounds are released with the unburned 

gasoline and oil mixture, or in the combustion emissions.

Uncombusted gasoline contains about 300 hydrocarbon compounds. About 85% of these 

compounds are highly volatile (low boiling point), short, straight chains consisting of 5 to 

12 carbon atoms. 

Uncombusted gasoline also includes aromatic hydrocarbons, which have a ring structure 

consisting of six carbon atoms. These compounds include benzene, toluene, ethylbenzene, and 

xylenes. These compounds are of concern because they are more soluble in water than other 

gasoline constituents. As reported by Wiedemeier et al. (1999), benzene, toluene, ethylbenzene, 

and xylenes constitute about 15% of fresh gasoline, but represents almost 70% of the organic 

component of gasoline that dissolves in water. In addition, these compounds are more toxic than 

most other components in gasoline, and benzene is a known carcinogen (causes cancer). 

Polycyclic aromatic hydrocarbons are released in engine exhaust, although some polycyclic 

aromatic hydrocarbons are present in unburned fuel. Polycyclic aromatic hydrocarbons that were 

analyzed for impacts on water quality in this document include benzo(a)pyrene, naphthalene, 

and 1-methyl-naphthalene. Polycyclic aromatic hydrocarbon molecules contain two to seven 

benzene rings. Their environmental fate, persistence, and toxicity are related to this molecular 

structure and to the number and configuration of attached carbon/hydrogen groups. The smaller, 

lighter (two- and three-ringed) polycyclic aromatic hydrocarbons compounds are generally more 

water soluble, more biodegradable, and more volatile. Their solubility makes them more 

bioavailable (and therefore more of a risk) to aquatic life, but their low persistence also reduces 

exposure times. 

Methyl tertiary-butyl ether is added to gasoline at the refinery to enhance octane rating, increase 

burning efficiency, and reduce atmospheric emissions. It has been used to improve gasoline 

performance since 1979 (EPA 2001b). About 30% of gasoline sold in the United States currently 
AFFECTED ENVIRONMENT

86 GLEN CANYON NATIONAL RECREATION AREA

contains methyl tertiary-butyl ether or other octane enhancers. Methyl tertiary-butyl ether is 

added to gasoline in both Utah and Arizona (Utah Department of Environmental Quality, 

Taylor, pers. com., 2002c; Arizona Department of Environmental Quality 2002a). 

In the 2001 summer water quality sampling program described earlier, the National Park Service 

targeted five constituents of gasoline and its degradation products for analysis. They included 

benzo(a)pyrene, naphthalene, 1-methyl naphthalene, benzene, and methyl tertiary-butyl ether. 

Benzo(a)pyrene is a polycyclic aromatic hydrocarbon found in exhaust and smoke. It adsorbs to 

sediment particles, and may be removed from the aquatic system as the sediment is deposited. 

Benzo(a)pyrene degrades in light (photodegradation) and also can be degraded by microorganisms. 

Benzo(a)pyrene may accumulate in some aquatic organisms and may bioconcentrate in aquatic 

organisms that cannot metabolize this compound. Oysters and bluegills are susceptible to build-up, but 

mudsuckers and sculpins show no tendency toward accumulation. When it accumulates in aquatic 

organisms, benzo(a)pyrene can cause reproductive abnormalities and changes at the cellular and DNA 

level (EPA 2002c). Chronic exposure to benzo(a)pyrene at levels above the maximum contaminant 

level, 0.002 mg/L, can lead to reproductive difficulties, and a lifetime of exposure above this level has 

the potential to cause cancer in humans (EPA 2002c). 

Naphthalene is released into the air during combustion of oil and coal. It also has been detected in 

cigarette smoke. Its toxicity to insects is evident in that naphthalene is the primary constituent of 

mothballs. 

Naphthalene is mobile and toxic in the aquatic environment, but is not particularly water soluble. It 

evaporates easily and breaks down in sunlight. In surface waters, it volatilizes to the atmosphere; 

which serves as an important pathway for removing this component from the water. 

Acute toxicity in fish is rare. However, bioaccumulation is moderate and risks to aquatic life include 

cancer, liver damage, and kidney damage (NPS 1997). In humans, naphthalene vapors in combination 

with coal tar have been shown to increase cancer risk. Naphthalene alone is not yet classifiable as a 

human carcinogen (EPA 2001a). 

The compound 1-methyl naphthalene is a component of crude oil and is found in effluents from 

refineries and petrochemical plants. It is used as an industrial solvent, and also occurs naturally in 

several food products, including filberts, nectarines, and beans (Spectrum Laboratories n.d.). This 

compound is slightly heavier than water and readily adheres to sediment. Both of these characteristics 

serve to remove it from the water column. In addition, 1-methyl naphthalene is degraded in water, by 

sunlight, and during microbial processes. 

There is little toxicological data available for 1-methyl naphthalene. Acute toxicity in aquatic 

organisms is rare, but damage to embryos and increased tumor development have been reported. It 

does not strongly bioaccumulate, but can be persistent in amphibian tissues (NPS 1997). 

Benzene is a volatile solvent. It evaporates rapidly, and has a half-life of approximately 5 hours. It 

does not persist in the environment because it is degraded by microbes in soil and water. 

Very little benzene is taken up by plants, birds, or fish, and it is not likely to accumulate in aquatic 

organisms. Once the source of contamination is removed, benzene is quickly cleared from most 

organisms (NPS 1997). 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 87

Benzene poses a greater risk to humans than to other life forms. In humans, short-term exposure can 

lead to nervous system disorders, immune system depression, and anemia. It is a known human 

carcinogen (causes cancer). Other effects of long-term exposure may include chromosome aberrations 

and decreased platelets (EPA 2001c). 

As discussed earlier, methyl tertiary-butyl ether is an additive to gasoline. Little is known about the 

risk to aquatic life from exposure to methyl tertiary-butyl ether. Of organisms tested, algae have been 

the most sensitive to methyl tertiary-butyl ether exposure. Fish do accumulate methyl tertiary-butyl 

ether at about 1.5 times the concentration in the water body. Adverse effects on trout have been 

estimated to occur at 4,600 parts per billion, a far greater concentration than acceptable levels for 

human exposure (Vanmouwerik and Hagemann 1999). 

Methyl tertiary-butyl ether may be a human carcinogen at high doses. The 1997 U.S. Environmental 

Protection Agency Drinking Water Advisory found that there is insufficient evidence to establish 

quantitative estimates for health risk, but indicated that methyl tertiary-butyl ether in drinking water 

will likely cause health effects at concentrations of 20 to 40 parts per billion or less (EPA 2001b). The 

Environmental Protection Agency is currently developing a Safe Drinking Water Act standard for this 

pollutant (EPA 2002a). 

Once in the water, a variety of processes determine the fate of these and other components of gasoline 

and its emissions. Volatile components can evaporate to the atmosphere and soluble components can 

dissolve. Normally, some components would be adsorbed to sediment suspended in the water column. 

However, this is uncommon in Lake Powell, where the sediment carried by tributary rivers is 

deposited when water velocity slows upon entering the reservoir. 

STATE WATER QUALITY STANDARDS 

The objective of the Clean Water Act is to “restore and maintain the chemical, physical and biological 

integrity of the nation’s waters.” The overall goal of the Clean Water Act is to produce waters of the 

United States that are “fishable and swimmable.” 

A primary means for evaluating and protecting water quality is the establishment and enforcement of 

water quality standards. Under the Clean Water Act, the federal government delegated responsibility 

for establishing water quality criteria to each state, subject to approval by the Environmental 

Protection Agency. Water quality standards consist of three parts: 

Designated beneficial uses of water (e.g., drinking, recreation, aquatic life); 

Numeric criteria for physical and chemical characteristics for each type of designated use; and 

An “antidegradation” provision to protect uses and water quality. 

In accordance with the Clean Water Act, each state has defined the uses for waters occurring within its 

borders, and each water body must be managed in accordance with its designated uses. Water quality 

standards have been established for each designated use. Standards must be at least as stringent as 

those established by the Environmental Protection Agency. In most cases, states have adopted the 

same standards as the Environmental Protection Agency. 
AFFECTED ENVIRONMENT

88 GLEN CANYON NATIONAL RECREATION AREA

The Environmental Protection Agency has developed recommended water quality criteria for 

approximately 120 priority pollutants to protect aquatic life and human health (EPA 1999a). These 

criteria have been adopted as enforceable standards by most states, including Arizona and Utah. 

Standards have not yet been set for many pollutants, including some of the compounds introduced to 

the water by the use of personal watercraft. If a numeric standard for a pollutant has not been 

determined by the Environmental Protection Agency, each state can establish and enforce its own 

criteria for protection of people and resources. 

In some cases, the Environmental Protection Agency has developed advisory levels. For example, no 

standard for methyl tertiary-butyl ether has been established to protect human health, but an advisory 

level has been named because methyl tertiary-butyl ether can be tasted and smelled at 20 to 40 parts 

per billion. Such advisory levels are not enforceable. 

Other pollutants have been less subject to regulation. For these, the potential for concern is indicated 

by ecotoxicological and human health toxicological benchmarks that can be found in the scientific 

literature. These benchmarks are informational only and are not subject to enforcement. 

Under section 313 of the Clean Water Act, the National Park Service and all other federal agencies and 

departments must comply with all federal, state, interstate, and local requirements regarding the 

control and abatement of water pollution. This includes management of any activity that may result in 

the discharge or runoff of pollutants. 

The National Park Service manages the water of Lake Powell in accordance with the water quality 

standards of the states of Arizona and Utah. In cases where water quality criteria differ between 

governing agencies, the strictest criteria must be met. In addition, the National Park Service must meet 

state antidegradation provisions, which require that the existing quality of state waters may not be 

degraded. This ensures that the lake can serve its intended purposes, as defined by the assigned 

beneficial uses. 

Arizona 

Arizona has established the following designated uses for the waters of Lake Powell within the state 

(Arizona Administrative Code, Title 18, Chapter 11 - Water Quality Standards 1996). 

Aquatic and wildlife coldwater – use of a surface water by animals, plants, or other organisms, 

including salmonids (trout), for habitation, growth, or propagation. 

Full-body contact – use of a surface water for swimming. 

Domestic water supply – use of a surface water source as a potable water supply. This 

designation recognizes that treatment processes such as coagulation, sedimentation, filtration, or 

disinfection may be necessary to yield a finished water suitable for human consumption. 

Fish consumption – use of a surface water by human for harvesting aquatic organisms for 

consumption. 

Agricultural irrigation – use of a surface water for the irrigation of crops. 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 89

Agricultural livestock watering – use of a surface water as a supply of water for consumption by 

livestock. 

The concentrations of contaminants of concern in Lake Powell compared to the Arizona standards for 

the lake’s designated uses are provided in table 9. Because there are no Arizona standards for 1-methyl 

naphthalene or methyl tertiary-butyl ether, ecotoxicological and human health benchmarks for these, 

as well as the other compounds, are provided in table 10. 

Benchmarks for benzo(a)pyrene and benzene (EPA 1999a) that are based on the consumption of 

aquatic organisms, as well as those for consumption of water and aquatic organisms, by humans are 

used to assess impacts (see “Approach to Evaluating Surface Water Quality Impacts from the Use of 

Personal Watercraft” in appendix G). The Environmental Protection Agency promulgated new 

recommended national water quality criteria for these components in November of 2002 (EPA 2002a). 

Incorporation of the new EPA criteria noted in table 10 below, would not result in changes to the 

conclusions of the water quality assessment for personal watercraft use at Lake Powell. The state of 

Utah plans to adopt the new EPA criteria into state water quality standards, effective in the summer of 

2003 (Utah Department of Environmental Quality, Water Quality Division, Pherson, pers. com., April 

2003b).

TABLE 9: ARIZONA AND UTAH WATER QUALITY STANDARDS FOR SELECTED POLLUTANTS

Benzo(a) 

pyrene 

(μg/L)a

Naphthalene 

(μg/L) 

1-methyl 

naphthalene 

(μg/L) 

Benzene 

(μg/L) 

Methyl 

tertiarybutyl ether 

(μg/L) 

Maximum concentration detected in 2001 

sampling at Glen Canyon National 

Recreation Areab

Below 

detection limit 

Below 

detection limit 0.14 3.43 1.42 

Detection limit 0.01 0.01 0.01 0.5 0.17 

Arizona standards for designated uses 

Aquatic and wildlife coldwater, acute NSc 1,100 NS 2,700 NS 

Aquatic and wildlife coldwater, chronic NS 210 NS 180 NS 

Full-body contact 0.2 NS NS 48 NS 

Domestic water supply 0.2 NS NS 5 NS 

Fish consumption 0.002 NS NS 120 NS 

Agricultural irrigation and agricultural 

livestock watering 

NS NS NS NS NS 

Utah standards for designated uses 

Class 1C (domestic purposes) 0.0028 NS NS 1.2d NS 

Class 2A (primary contact recreation) NS NS NS NS NS 

Class 2B (secondary recreation) NS NS NS NS NS 

Class 3B (warm water species) 0.031 NS NS 71 NS 

Class 4 (agricultural uses) NS NS NS NS NS 

Environmental Protection Agency 

recommended criteria for protection of 

human healthe

0.0044 NS NS 1.2e

 NS 

 

a. μg/L = micrograms per liter, or parts per billion. 

b. From table 8. 

c. NS = no standard. 

d. This criterion for benzene is applicable to waters in the immediate vicinity of public drinking water intakes, and not to general surface waters 

of the state (Utah Department of Environmental Quality, Water Quality Division, Moellmer, pers. com., January 2003). 

e. Source: EPA 1999a. 
AFFECTED ENVIRONMENT

90 GLEN CANYON NATIONAL RECREATION AREA

TABLE 10: ECOTOXICOLOGICAL AND HUMAN HEALTH BENCHMARKS

Compound 

Ecotoxicological 

Benchmark 

(μg/L) Source 

Human Health 

Benchmark 

(μg/L) Source 

Benzo(a) pyrene 0.014 Suter and Tsao 1996 0.0044a 

0.049b

EPA 1999a 

Naphthalene 62 Suter and Tsao 1996 

1-methyl naphthalene 34c U.S. Fish and Wildlife 

Service 2000 

 

Benzene 71 warm water fishery State of Arizona 

Administrative Code 1996

1.2a 

71b

EPA 1999a 

Methyl tertiary-butyl ether 

(chronic) 

18,000 freshwater 

chronic 

Mancini et al. 2001 

Methyl tertiary-butyl ether 

(acute) 

 20 to 40, based on 

odor and tasted

EPA 1999a 

 

a. Based on the consumption of water and aquatic organisms. [Note: The EPA recently revised the human health criteria for consumption of 

water and freshwater organisms for benzo(a)pyrene from 0.0044 μg/L to 0.0038 μg/L and for benzene to 2.2 μg/L to 51 μg/L (2002a). 

Conclusions regarding water quality impacts presented below based on the 0.0044 and 1.21 μg/L criteria (EPA 1999a) would not change as 

result of the new criteria.]

b. Based on the consumption of aquatic organisms only. [Note: The EPA recently lowered the human health criteria for water consumption for 

benzo(a)pyrene from 0.049 μg/L to 0.018 μg/L and for benzene from 71μg/L to 51 μg/L (2002a). Conclusions regarding water quality impacts 

presented below based on the 0.049 and 71 μg/L criteria (EPA 1999a) would not change as result of the new criteria.]

c. Based on LC50s of 3,400 μg/L for sheepshead minnow (34 μg/L used for freshwater calculations). 

d. Human health toxicological information for methyl tertiary-butyl ether is currently under review. There is no Environmental Protection Agency 

human health benchmark. 

As shown in the tables, the maximum concentrations found during the summer 2001 sampling for all 

five compounds appear to be below the Arizona standards for all of the designated uses that apply to 

Lake Powell, or below the ecotoxicological and human health benchmarks. However, the detection 

limit for benzo(a)pyrene was 0.01 μg/L, which is greater than the fish consumption limit of 

0.002 μg/L. 

Utah 

The waters of Lake Powell are designated for the following five uses by the state of Utah (Utah 

Department of Environmental Quality, Water Quality Division, Moellmer, pers. com., April 2002b). 

Class 1C – Protected for domestic purposes with prior treatment by processes as required by the 

Utah Division of Drinking Water. 

Class 2A – Protected for primary contact recreation such as swimming. 

Class 2B – Protected for secondary recreation such as boating, wading or similar uses. 

Class 3B – Protected for warm water species of game fish and other warm water aquatic life, 

including the necessary aquatic organisms in their food chain. 

Class 4 – Protected for agricultural uses including irrigation of crops and stock watering. 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 91

The concentrations of contaminants of concern in Lake Powell compared to the Utah standards for the 

lake’s designated uses are provided in table 9. There are no Utah standards for naphthalene, 1-methyl 

naphthalene, or methyl tertiary-butyl ether. 

As shown in the table, the maximum concentration for benzene (3.43 μg/L) found during the summer 

2001 sampling exceeds the standard for Class 1C (domestic purposes). However, according to NPS 

staff, this criterion for benzene is applicable to waters in the immediate vicinity of public drinking 

water intakes, and not to general surface waters of the state (Utah Department of Environmental 

Quality, Water Quality Division, Moellmer, pers. com., January 2003a). 

As described above in the Arizona discussion, the detection limit for benzo(a)pyrene was 0.01 μg/L, 

which is greater than the Utah Class 1C (domestic purposes) standard. 

Environmental Protection Agency Criteria and Recommendations 

The Environmental Protection Agency does not have any recommended water quality criteria, either 

acute or chronic, for polycyclic aromatic hydrocarbons for the protection of aquatic life. However, as 

shown in table 10, two of the compounds evaluated here, benzo(a)pyrene and benzene, have 

Environmental Protection Agency-recommended water quality criteria for protection of human health. 

As described in the discussion of the Utah standards: 

The criterion for benzene is applicable to waters in the immediate vicinity of public drinking 

water intakes, and not to general surface waters of the state. 

Because the detection limit for benzo(a)pyrene is greater than the recommended criterion of 

0.0044 μg/L, conclusions cannot be made regarding the presence of this compound at 

concentrations at or above this Environmental Protection Agency criterion. 

Although there is no federal drinking water standard for methyl tertiary-butyl ether, it is on the 

“Contaminant Candidate List” for consideration in setting health standards (EPA 2001b). In 2001, a 

methyl tertiary-butyl ether water criteria work group was established, consisting of representatives 

from private companies, trade associations, and the Environmental Protection Agency. This 

partnership generated toxicity data for deriving ambient water quality criteria for methyl tertiary-butyl 

ether and calculated preliminary freshwater and marine criteria for acute and chronic exposure effects 

(Mancini et al. 2001). Those criteria are included in table 10. 

ANTIDEGRADATION POLICIES 

A water quality standard defines water quality goals by designating uses for the water, setting 

minimum standards to protect the uses, and establishing the intent to prevent degradation of water 

quality. The intent of a state antidegradation policy is to maintain a water body in a condition suitable 

to serve its intended purpose. For example, an Arizona water used as a source of fish eaten by humans 

must meet the strict “fish consumption” standards for benzo(a)pyrene. Actions that would cause levels 

of this contaminant to exceed the allowable level for the “fish consumption” designation would not be 

allowed. This would be true even if the water remained of adequate quality to serve other uses for 

which it was designated, such as a drinking water source or for swimming. 
AFFECTED ENVIRONMENT

92 GLEN CANYON NATIONAL RECREATION AREA

Part of this antidegradation policy (40 CFR 131.12(a)(2)) is to maintain water quality at existing 

levels, even if it is already better than the minimum standard necessary to protect designated uses. 

Antidegradation should not be interpreted to mean that “no degradation” can or will occur, as 

degradation may be allowed for certain pollutants in even the most pristine waters. However, that 

degradation must be demonstrated to be temporary and short-term in nature (NPS, Rosenlieb, pers. 

com., June 2002l). 

Arizona 

Arizona antidegradation guidelines are included in the Arizona Administrative Code, Department of 

Environmental Quality, R18-11-107, Antidegradation. They closely follow the model provided by 

Region 8 of the Environmental Protection Agency, with modifications to comply with Arizona water 

quality standards. These guidelines define degradation as any discharge that significantly increases the 

pollutant concentration or loading of receiving waters and changes the existing water quality. 

Arizona uses a three-tier approach to protect the state waters from degradation. 

Tier 1 is the minimum protection provided to all waters of the state. This is the protection 

afforded waters that do not meet fishable/swimmable goals. 

Tier 2 is applied to waters where existing water quality is better than applicable water quality 

standards. The existing water quality must be maintained and protected, except that limited 

degradation may be allowed through a public hearing process. 

Tier 3 waters are protected from all degradation. 

Guidance to fully address and implement antidegradation has not been adopted. Because of this, 

characterization of receiving waters does not occur, and permits are written which allow significant 

increases in pollutant levels. While these increases allow the water body to remain in compliance with 

numeric water quality standards, they may result in degradations of existing water quality. 

Lake Powell is an Arizona Tier 2 water body. As a result, some reduction in water quality is allowed, 

with public participation and review required. However, as a drinking water supply, Lake Powell must 

achieve all statutory and regulatory requirements to fulfill this purpose. 

Utah 

The Utah antidegradation policy is included in the Utah Administrative Code, Rule R317-2, Standards 

of Quality for the State. It establishes a plan to maintain and improve the quality of the state’s waters 

for public water supplies; the propagation of wildlife, fish, and aquatic life; and agricultural, industrial, 

recreational, and other legitimate uses. The policy states that no waste will be discharged into any 

waters of the state that would compromise the beneficial uses of the receiving waters. 

Lake Powell has not been designated as a high-quality water, and is not afforded special protection 

under Utah statues. Some reduction in water quality would be allowable to support vital economic 

activities, as long as designated beneficial use is not affected. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 93

AIR QUALITY 

The Environmental Protection Agency defines ambient air as “that portion of the atmosphere, external 

to buildings, to which the general public has access” (40 CFR Part 50). In compliance with the 1970 

Clean Air Act and the 1977 and 1990 Clean Air Act Amendments, the Environmental Protection 

Agency has promulgated national ambient air quality standards and regulations. The standards were 

enacted for the protection of public health and welfare of the environment. To date, the agency has 

issued standards for six criteria pollutants, including: 

Carbon monoxide; 

Sulfur dioxide; 

Particles with a diameter less than or equal to a nominal 10 micrometers or 2.5 micrometers; 

Ozone; 

Nitrogen dioxide; and 

Lead. 

There are two types of air quality standards: primary and secondary. 

Primary standards are designed to protect sensitive segments of the population from adverse 

health effects, with an adequate margin of safety, which may result from exposure to criteria 

pollutants. 

Secondary standards are designed for the protection of public welfare, including visibility and 

damage to animals, vegetation, and buildings. 

Each state and locality has the primary responsibility for air pollution prevention and control. Under 

the Clean Air Act and the Clean Air Act Amendments, state and local air pollution control agencies 

have the authority to adopt and enforce ambient air quality standards that are more stringent than the 

national standards. 

Arizona and Utah are responsible for regulating air quality in the region where Glen Canyon National 

Recreation Area is located. Both states have adopted without change the federal national ambient air 

quality standards, which are shown in table 11. 

The air quality standards set forth within the Clean Air Act (42 U.S.C. 7401-7671q as amended in 

1990) must be maintained. Glen Canyon National Recreation Area partially shares common 

boundaries with three national parks, all of which are designated as class I airsheds. Class I airsheds 

are afforded the highest degree of air quality protection under the Clean Air Act with little allowance 

for deterioration of air quality. Glen Canyon National Recreation Area is designated a class II airshed 

under this law. A class II airshed is defined as an area having moderate to good air quality, with “some 

deterioration in quality resulting from moderate, well controlled growth.” The recreation area’s air 

quality is protected by allowing limited increases (i.e., allowable increments) over baseline 

concentrations of pollution for sulfur dioxide, nitrogen oxides, and particulate matter. 
AFFECTED ENVIRONMENT

94 GLEN CANYON NATIONAL RECREATION AREA

TABLE 11: NATIONAL AMBIENT AIR QUALITY STANDARDS FOR CRITERIA POLLUTANTSa

Pollutant 

Averaging 

Time 

Primary 

Standard 

Secondary 

Standard Purpose 

Carbon monoxide 

(CO) 

1-hour 

8-hour 

35 ppmb (40 mg/m3) 

9 ppm (10 mg/m3

) 

— 

— 

Prevent high levels of carboxyhemoglobin 

Nitrogen dioxide 

(NO2) 

Annual 0.053 ppm (53 ppb) Same as primary Prevent breathing difficulties, 

reduce smog and acid rain 

formation, and improve visibility 

Particulate matter 

(PM10) 

24-hour 

Annual 

150 μg/m3

50 μg/m3

Same as primary Prevent chronic diseases of the 

respiratory tract and improve 

visibility 

Particulate matter 

(PM2.5) 

24-hour 

Annual 

65 μg/m3

15 μg/m3

Same as primary Prevent chronic diseases of the 

respiratory tract and improve 

visibility 

Ozone (O3) 1-hour 

8-hour 

0.12 ppm (125 ppb) 

0.08 ppm (85 ppb) 

Same as primary Prevent breathing difficulties, eye 

irritation, and biological effect on 

sensitive species 

Sulfur dioxide (SO2) 3-hour 

24-hour 

Annual 

0.14 ppm (140 ppb) 

0.03 ppm 

0.50 ppm (500 ppb) 

— 

— 

Prevent increased respiratory 

damage, acid rain, and crop 

damage and to improve visibility 

Lead (Pb) Quarterly 

average 

1.5 μg/m3 Same as primary Prevent impaired production of 

hemoglobin 

 

a. Source: 40 CFR 40, Part 50, July 1991, “Ambient Air Quality Standards.” 

b. ppm = parts per million 

 ppb = parts per billion 

 mg/m3

 = milligrams per cubic meter 

 μg/m3

 = micrograms per cubic meter. 

Glen Canyon National Recreation Area is located within Garfield, Kane, San Juan, and Wayne 

Counties in Utah; and Coconino County in Arizona. The Environmental Protection Agency has 

designated these areas as in attainment for all criteria pollutants (EPA 2002a). 

The recreation area is located in a remote portion of the Colorado Plateau that has relatively few 

developments or major sources of air pollutants. The largest urban centers, including Phoenix, 

Arizona, Salt Lake City, Utah and Las Vegas, Nevada, all are greater than 300 miles away. Thus, air 

pollutants of recent origin generally come from the few local point sources and the area sources 

(including mobile) that are adjacent to the recreation area. 

Localized sources of air pollution within the recreation area primarily include exhaust from 

recreational and motor vehicles (NPS 2002r). Campfires can sometimes be an important source of 

particulates within the recreation area, particularly in popular camping areas. 

There are two point sources of substantial size close to the recreation area. They include the Salt River 

Navajo Generating Station near Page, Arizona (Wahweap area) and the Nuclear Fuel Service Plant 

near the Bullfrog area in Utah. 

The air quality in Glen Canyon National Recreation Area was represented by measurements taken 

during a short-term study over Labor Day weekend in 2001 (NPS 2002r) and data from a regional 

monitoring station at the Navajo Generating Station, near Wahweap. The short-term study collected 

data in the vicinity of Halls Crossing and near the Wahweap area. 
Air Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 95

The 1-week study over Labor Day weekend only provides a snapshot of the air quality since it does 

not meet the minimum three-years monitoring time generally required for comparison to the national 

air quality standards. The data presented here from the week-long study do not define the air quality in 

every location of such a large NPS unit, but rather provide an impression of the air quality in personal 

watercraft use locations at a time when a large number of personal watercraft are active. Wahweap 

represented a high-use area and Halls Crossing reflected air quality conditions at a moderate-use area. 

At both sites, personal watercraft represented about a quarter of all boat use. 

Table 12 presents air quality data for the five criteria pollutants that are produced directly by 

combustion. The values in the table were estimated during the week-long study in the recreation area 

and monitored in 2001 by the Salt River Project, Navajo Generating Station, near Wahweap. Based on 

the data collected in 2001, all ambient air quality levels met the national ambient air quality standards. 

Ozone is created by sunlight acting on nitrogen oxides and volatile organic compounds in the air. 

Ozone measurements recorded at the Salt River Project monitoring station from 1999 through 2001 

indicate a three-year average ozone level of 61 parts per billion, which is 72% of the national ambient 

air quality standard (85 parts per billion). 

High concentrations of ozone and/or long-term exposure can cause injury to plants. A cumulative 

measurement of ozone levels, called the SUM06 (parts per million per hour), looks at extended 

exposures of greater than 60 parts per billion of ozone that occur 12 hours per day over a 

three-consecutive-month sampling period. The SUM06 can provide an indication of ozone levels with 

potential to harm vegetation. Using the Salt River Project monitoring measurements for ozone from 

1998 through 2000, the SUM06 measurement was found to be 11.3. This value is 45% lower than the 

Environmental Protection Agency proposed level (25 parts per million per hour) of ozone associated 

with injury effects on vegetation (NPS 2002r). 

TABLE 12: COMPARISON OF AIR POLLUTANT CONCENTRATIONS FROM 2001 

AT GLEN CANYON NATIONAL RECREATION AREA 

Pollutantsa 

National 

Standard 

Halls 

Crossing 

Study 

(2001) 

% of 

Standard 

Wahweap 

Study 

(2001) 

% of 

Standard 

SRPb

Monitoring 

Data 

(2001) 

% of 

Standard 

Mean 

 NOx Annual 53 ppbc 4.5 ppb 8.5 1.48 ppb 2.8 2.74 ppb 5.2 

 PM2.5 Annual 15 μg/m3 0.41 μg/m3 2.7 7.2 μg/m3 48.0 4.54 μg/m3 30.3 

 SO2 Annual 30 ppb — — — — 1.04 ppb 3.5 

Maximum 

 PM2.5 24-hour 65 μg/m3 1.75 μg/m3 2.7 9.3 μg/m3 14.3 10.2 μg/m3 15.7 

 CO 1-hour 35 ppm 4.92 ppm 14.1 — — — — 

 SO2 24-hour 140 ppb 0.6 ppb 0.44 0.84 ppb 0.6 — — 

 O3 Daily 

1-hour 

125 ppb 84 ppb 67.2 50 ppb 40.0 75 ppb 60.0 

 

a. CO = carbon monoxide. 

 NOx = nitrogen oxides. 

 O3 = ozone. 

 PM2.5 = articulate matter with a diameter less than or equal to 2.5 micrometers. 

 SO2 = sulfur dioxide. 

b. SRP = Salt River Project monitoring station near Wahweap. 

c. ppm = parts per million; ppb = parts per billion; μg/m3

 = micrograms per cubic meter.
96 GLEN CANYON NATIONAL RECREATION AREA

NATURAL SOUNDSCAPES 

Recreation area soundscapes include both natural and human components. The natural soundscape is 

considered a recreation area resource. At Glen Canyon National Recreation Area, the natural 

soundscape includes sounds produced by such sources as wind, thunder, insects and birds, falling 

rocks, streams, and wind-caused waves on the shore. It also includes the “natural quiet” that occurs in 

the absence of natural and human sound sources. 

Engines are a primary source of human-caused sound at Glen Canyon National Recreation Area. 

These include engines on personal watercraft and other vessels, automobiles and trucks, off-road 

vehicles, aircraft, and generators. Other common sources of human-caused sound in the recreation area 

include electronic devices such as radios and automobile horns, human vocalizations, barking of dogs, 

vehicle tires on roads, and wave noise caused by boat wakes. 

NATURAL SOUNDSCAPES AND VISITOR EXPERIENCE 

The opportunity to experience the natural soundscape is an important part of a positive park 

experience for some visitors. According to Director’s Order 47 (NPS 2000b), a system-wide survey of 

park unit visitors revealed that almost as many visitors come to national parks to enjoy the natural 

soundscape (91%) as come to view the scenery (93%). Popular natural sounds include bird songs, 

wind, thunder, and natural quiet. Another soundscape-related aspect of the visitor experience is the 

opportunity to experience solitude and tranquility, primarily in the remote natural parts of the 

recreation area where that opportunity is expected to be available. Some human-caused sound is 

considered acceptable in that it is attendant to purposes and uses for which the recreation area, or park, 

was created. Director’s Order 47 requires park units to determine the level of human-caused sound 

that is necessary for park purposes, and to achieve that level by reducing noise and restoring the 

natural soundscape to the greatest possible extent. 

SOUND VERSUS NOISE 

Sound, in the context of this environmental impact statement, is a physical disturbance in the air 

created by vibration. Its four primary parameters are: 

Amplitude, measured in decibels, which determines loudness; 

Frequency, measured in Hertz, which determines pitch; and 

Duration, measured in elapsed time units such as seconds or hours. 

Audibility, conveying the area or distance through which a human-caused sound, defined using 

the three previous parameters, is propagated. 

Amplitude, frequency, and duration are physical measurements. Loudness and pitch are subjective 

impressions that depend on the amplitude and frequency of the sound, plus the characteristics of the 

listener and the listener’s environment (U.S. Forest Service 1980). Audibility is a modeled 

characteristic that is determined using measured or assumed values for amplitude, frequency and 

duration.
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 97

Noise is generally defined as unwanted or intrusive sound. Sound can be perceived as noise because of 

loudness, pitch, duration, occurrence at unwanted times or from an unwanted source, or because it 

interrupts or interferes with a desired activity. A sound that is considered neutral or desirable by one 

person may be considered unpleasant noise by another person because of a perception of 

inappropriateness or disturbance, and/or unwanted content or meaning. 

Komanoff and Shaw (2000) note that the biggest difference between noise from personal watercraft 

and that from motorboats is that the former continually leave the water, which magnifies noise in two 

ways. Without the muffling effect of water, the engine noise is typically 15 dB(A) louder and the 

smacking of the craft against the water surface results in a loud “whoop” or series of them. With the 

rapid maneuvering and frequent speed changes, the impeller has no constant “throughput” and no 

consistent load on the engine. Consequently, the engine speed rises and falls, resulting in a variable 

pitch. This constantly changing sound is often perceived as more disturbing than the constant sound 

from motorboats. 

NATURAL SOUNDSCAPE AT GLEN CANYON NATIONAL RECREATION AREA 

Director’s Order 47 (NPS 2000b) states that the natural ambient sound level2

 of a park is the basis for 

determining the affected environment in environmental impact statements and other documents 

prepared for compliance with the National Environmental Policy Act. Three acoustic studies 

conducted at Glen Canyon National Recreation Area were used to establish the area’s natural 

soundscape. The L90 referenced in these studies represents the sound level exceeded 90% of the 

measuring time. The L90 is the sound level descriptor specified in Director’s Order 47 to use in 

estimating the natural ambient sound level when only a single descriptor is used. 

Ambient Sound Monitoring Program for Colorado Plateau Parks (Collaboration in Science and 

Technology, Inc. 1990) collected data in 1989 and 1990 in Glen Canyon National Recreation Area at 

Rainbow Bridge and Escalante. 

Hourly L90 levels at Rainbow Bridge ranged from 22 to 34 decibels in April, and from 22 to 

40 decibels throughout the main visitor season in the summer. Average daily L90 levels ranged 

from 22 decibels in October to 34 decibels in August. 

At the Escalante site, the hourly L90 levels ranged from 20 to 40 decibels. 

These measurements were consistent with other quiet park environments in the region that were 

measured during the same study. However, the study notes that many of the L90 measurements were at 

the noise floor of the instruments. That is, the meters could not read anything lower than 20 to 

22 decibels. 

Draft Summary of Measurement Results, Cal Black Memorial Airport (BCS International 1998) 

reported on data collected at seven sites in the Halls Crossing/Bullfrog area of Glen Canyon National 

Recreation Area. Measurements were taken from May 22 to June 4, 1998. The goal of this study, 

conducted for the Federal Aviation Administration, was to measure aircraft and ambient sound levels 

in the vicinity of the Cal Black Memorial Airport. The L90 levels for the seven sites ranged from less 

 

2. The existing sound environment, less all human-caused sound. 
AFFECTED ENVIRONMENT

98 GLEN CANYON NATIONAL RECREATION AREA

than 20 decibels (the noise floor of the instruments) to a high of 55 decibels. The study noted that the 

higher levels were the result of insect activity, and that during early morning hours the levels were 

typically below 20 decibels. 

Draft Technical Report on Noise: Personal Watercraft and Boating Activities at Glen Canyon 

National Recreation Area (Harris Miller Miller & Hanson, Inc. 2002) was prepared to support this 

environmental impact statement. Data were collected during August 2001 at four sites, including one 

in Crosby Canyon, two in Last Chance Canyon, and one at Rainbow Bridge. 

Sound levels in this study were measured at a variety of time periods at different times on several 

days. The lowest and highest sound levels recorded are indicated as Lmin and Lmax. The hourly 

equivalent level (Leq) represents the energy-average A-weighted sound level for each hour. The L90

levels in this study ranged from below 10 decibels to about 40 decibels. 

Data from the low-use site at the end of Last Chance Canyon were used to characterize the natural 

soundscape because at the other sites, the soundscape was heavily influenced by watercraft noise. The 

daytime median L90 measured at the Last Chance Canyon site by the Harris Miller Miller & Hanson, 

Inc. (2002) study was 13.4 decibels. This value is considered representative of the average natural 

soundscape at Glen Canyon National Recreation Area that could be affected by the personal watercraft 

management for the following reasons. 

Personal watercraft and other vessels are active during the daytime. Therefore, it is more 

appropriate to use the daytime median L90 than the nighttime or the 24-hour L90. 

During the studies by Collaboration in Science and Technology, Inc. (1990) and BCS 

International (1998), many of the measurements were at or below the instruments’ noise floor of 

about 20 decibels. Therefore, accurate calculations of L90 levels could not be derived from these 

studies. 

Despite the instrumentation limitations of the earlier studies, all three studies confirmed that natural 

ambient sound levels in the recreation area are typically low to very low. Some of the important 

natural ambient sound sources at Glen Canyon National Recreation Area include weather such as wind 

and thunder; insects (at night during the 2001 summer measurements, the sounds of insects 

substantially raised the natural ambient sound levels compared to daytime levels); wildlife, 

particularly including birds; and water, including streams, seeps, and wind-caused wave action on the 

lakeshore. 

Factors affecting natural ambient sound levels include location with respect to a noise source, 

topography and terrain, wind, and vegetation. In vegetated areas, natural ambient sound levels were 

higher on windy days than on calm days as leaves and branches rustled in the wind. Beaches tended to 

have higher ambient levels than inland areas because of the sound from wave action (some caused 

naturally by wind, and some by boat wakes). The lowest natural ambient levels occurred during calm 

days and nights with little or no wind when other natural sources (especially insects) were quiet 

(Harris Miller Miller & Hanson, Inc. 2002). 
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 99

HUMAN SOUNDSCAPE: NOISE FROM 

PERSONAL WATERCRAFT AND OTHER SOURCES 

Noise within the National Recreation Area’s Management Zones (Noise Context) 

The General Management Plan (NPS 1979a) divided Glen Canyon National Recreation Area into four 

management zones (figure 9, General Management Zones Map). The Recreation and Resource 

Utilization Zone and the noise-sensitive Natural Zone and Cultural Zone are most relevant with regard 

to noise from personal watercraft. Because the Cultural Zone is so small (total of 25 acres), it is not 

addressed separately from the Natural Zone. The land-based Developed Zone does not support 

personal watercraft use, has a low sensitivity to noise impacts, and has many other human-caused 

noises that mask personal watercraft noises that are produced on the lake. 

The lake surface, where virtually all personal watercraft activity takes place and personal watercraft 

noise is generated, is in the Recreation and Resource Utilization Zone. Noises from personal 

watercraft and other vessels are consistent with the purpose and management direction of the 

Recreation and Resource Utilization Zone. The General Management Plan (NPS 1979a) specifically 

identifies noise-producing activities, including speedboating, waterskiing, and houseboat touring, as 

appropriate in the Recreation and Resource Utilization Zone. 

The number of watercraft operating simultaneously affects the sound level. The noise from multiple 

watercraft is greater than that of individual watercraft, and can be detected farther from shore. 

However, based on the study by Harris Miller Miller & Hanson, Inc. (2002), noise from personal 

watercraft, even multiple machines operating in a small area, usually is not discernable above the 

natural soundscape in areas of the recreation area more than 1 or 2 miles away from the shoreline. 

Personal watercraft use in the Recreation and Resource Utilization Zone occurs during all seasons 

except winter. Table 13 provides estimates by month of how much of the Lake Powell surface is in 

general categories of sound. As shown in the table: 

TABLE 13: ESTIMATES OF THE PERCENTAGES OF THE 

LAKE POWELL SURFACE AREA THAT ARE WITHIN GENERAL SOUND CATEGORIES

Month 

High 

Sound Levels 

(percent) 

Medium 

Sound Levels 

(percent) 

Low 

Sound Levels 

(percent) 

January 0 0 100 

February 0 0 100 

March 0 0 100 

April 0 8 92 

May 12 19 69 

June 29 25 46 

July 39 38 24 

August 48 32 21 

September 32 36 32 

October 0 28 72 

November 0 0 100 

December 0 0 100 
AFFECTED ENVIRONMENT

100 GLEN CANYON NATIONAL RECREATION AREA

Low levels of personal watercraft use, and associated noise, prevail annually throughout the lake from 

November through April. Personal watercraft use accounts for less than 6% of the total amount of 

watercraft use during these months; November and December are the lowest use months at less than 

2% of the total. Personal watercraft use increases, as does general boating use, through the remainder 

of the year. For each month of May and October, personal watercraft use represents less than 20% of 

the total monthly watercraft use. In the period of June through September, personal watercraft use 

ranges from 26% to 38 % of the total. A high amount of boating use, including that by personal 

watercraft, and noise associated with it occurs over a substantial part of the lake surface from May 

through September. However, even during these months, visitors can find areas of the lake where 

sound levels are low. Generally, the personal watercraft noise contribution to the total noise generated 

is directly related to the proportion of personal watercraft operating in an area at any given time. 

Tables illustrating the proportion of personal watercraft use are presented in the “Visitor Use and 

Experience” section of the “Affected Environment” chapter. 

Large portions of the lake shore are in the Natural Zone. Personal watercraft noise is obvious in 

Natural Zone areas near the lake during periods of high boating activity, but there are extended periods 

when boating noise is not noticeable. These include winter, nighttime, and most of the time in low use 

areas. 

All of the federal lands in the Natural Zone were proposed as wilderness in the proposed General 

Management Plan (NPS 1979a). Motorized recreation is generally prohibited in the Natural Zone, and 

the management strategy for the Natural Zone includes “maintenance of isolation and natural 

processes.” 

Motorized equipment is only permitted in the Natural Zone when it constitutes the “minimum 

management tool.” Motorized equipment is specifically not included in the list of appropriate 

recreational activities in that zone. 

In the Natural Zone, noise from personal watercraft is loudest at or near the shoreline. Watercraft noise 

diminishes with distance. However, because of the sparse vegetation and exposed rock in many places 

in the Natural Zone, personal watercraft sound can travel long distances. Noise modeling by Harris 

Miller Miller & Hanson, Inc. (2002) indicated that noise from individual vessels could be heard about 

a mile into the Natural Zone. Noise from a single boat with a V-8 engine could be heard about 2 miles. 

These distances assume generally open terrain and summer conditions. Terrain features such as cliffs, 

hills, and buttes close to the lake would tend to shield the area beyond these features from boat noise. 

Features such as canyons may channel sound so that it travels farther on the water surface. As noted 

above, personal watercraft sound may be heard one to two miles from the source over a flat surface. 

But the topography surrounding Lake Powell is not flat. Assuming that a natural barrier to the sound 

would exist where there is an elevation change of 50 feet (approximate height of a five story building), 

approximately 15,400 acres would be affected (between 3,700 feet and 3,750 feet elevations). This 

equals 2.3% of the Natural Zone (668,670 acres). Time of day and season of use would also reduce the 

level of noise in the Natural Zone as the noise would not be continuous, would be encountered only 

during daylight hours, and would be minimal between October and May. 
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 101

Intensity of Noise from Personal Watercraft and Other Sources 

Regulations for boating and water use activities established by the National Park Service prohibit 

vessels from operating at more than 82 decibels measured at 25 meters (82 feet) from the vessel 

(36 CFR 3.7). 

Arizona regulations are less stringent than those of the National Park Service. They prohibit a 

vessel from being operated in a manner that causes it to emit a sound level in excess of 

86 decibels when measured from a distance of 50 feet (15 meters) or more. 

Utah laws and rules are more stringent than those of the National Park Service. They prohibit a 

vessel from being operated in a manner that will cause it to emit more than 75 decibels of noise 

at the shoreline. 

Several of the other boating regulations, laws, and rules for the states of Arizona and Utah that are 

summarized in table 4 also relate to sound. These include flat-wake requirements, other speed 

restrictions, and Utah’s limitation of use to daylight hours. Complete information on the Arizona and 

Utah boating regulations, laws, and rules for personal watercraft are included in appendix B. 

The 2001 noise study (Harris Miller Miller & Hanson, Inc. 2002) included measurement of reference 

pass-bys for a number of vessels, including personal watercraft, and characterization of the noise 

sources. Measurements were taken from August 14 through August 18, 2001 at Crosby Canyon (a 

high-watercraft-use site), the middle of Last Chance Canyon (a moderate-use site), the end of Last 

Chance Canyon (a low-use site), and Rainbow Bridge. 

The results of watercraft pass-bys are shown in table 14. These pass-by measurements are for 

individual machines. Measurements are not 100% additive for multiple machines passing at or about 

the same time because of the logarithmic relationships involved. However, multiple machines add a 

complex of sound characteristics that, in general, is perceived by a listener as being louder and of 

greater duration. Measurements of multiple machines reflect those characteristics. The pass-by 

recordings were made using a microphone mounted above the front of an instrumented boat (Harris 

Miller Miller & Hanson Inc. 2002), not on the shoreline. Therefore, the results cannot be interpreted in 

the context of Utah law regarding noise, which measure sound levels at the shoreline. Analysis of the 

data for individual watercraft indicated the following. 

Maximum sound levels for personal watercraft at 25 meters (82 feet) ranged from approximately 

68 to 76 decibels. 

Maximum sound levels at 25 meters for other motorcraft ranged from about 65 to 77 decibels 

for most motorboats, and up to 86 decibels for boats with V-8 engines. 

Except for the boats with V-8 engines, no significant differences were found in the sound levels 

produced by personal watercraft and the other boats in the study. 

As shown in the table 14, personal watercraft sound levels at steady speeds were measured in the 70- 

to 80-decibel range. However, sound levels varied rapidly as personal watercraft maneuvered and 

jumped wakes. Figure 11 shows fluctuations over a range of about 5 decibels for two or three personal 

watercraft circling during a 2-minute period, with a 180-degree turn producing a fluctuation of 

10 decibels. (People usually perceive a 10-decibel increase in sound level to be “twice as loud” and a 
102 GLEN CANYON NATIONAL RECREATION AREA

TABLE 14: WATERCRAFT 

PASS-BY 

SOUND 

LEVELS 

MEASURED 

IN 

GLEN 

CANYON 

NATIONAL 

RECREATION 

AREA IN 

AUGUST 2001

Category Description 

No. 

Passbysa

Speed 

(mph) 

Throttle 

(rpm) 

SEL at 50 ft.b

(15 m) 

(dBA) 

Lmax a

(1

(d

V-8 “Muscle” V-8 “Muscle” Personal Watercraft Boats At Any One Time Personal Watercraft 

20 foot Inboard V-8 22 foot Inboard V-8 Kawasaki 1100cc (Utah S. P.) Yamaha Twin Outboard (Utah S. P.) Kawasaki 1100cc (Utah S. P.) 

1 1 5 2 2 

32 35 48.6 40.8 37.5 

— — 

6700 

— 

5600 

95.2 93.9 85.0 85.1 84.6 

98877

Personal Watercraft Boats At Any One Time Personal Watercraft Personal Watercraft Boats At Any One Time 

2001 Sea-Doo Bombardier (visitor) 20 foot Outboard 2001 Sea-Doo Bombardier (visitor) Kawasaki 1100cc (Utah S. P.) 16 foot Inboard 

2 1 2 2 1 

60 39 30 

9 

28 

— — — 

3000 

— 

83.9 83.9 83.5 82.8 82.6 

78777

Personal Watercraft Boats At Any One Time Personal Watercraft Boats At Any One Time Boats At Any One Time 

2001 Sea-Doo Bombardier (rental) Yamaha Twin Outboard (Utah S. P.) Kawasaki 1100c (Utah S.P.) 18 foot Outboard 18 foot Outboard 

5 2 2 1 1 

38 27.3 22.5 18 30 

Full throttle 

— — — — 

82.4 81.2 81.2 80.8 80.8 

77777

Boats At Any One Time Personal Watercraft Boats At Any One Time Boats At Any One Time Boats At Any One Time 

20 foot Inboard Other Personal Watercraft 20 foot Outboard 20 foot Outboard 16 foot Outboard 

1 1 1 1 1 

32 26 21.2 23 

9 

— — — — — 

80.4 80.3 79.7 79.7 79.6 

77776

Personal Watercraft Personal Watercraft Boats At Any One Time Boats At Any One Time 

Sea-Doo Bombardier (rental) Other Personal Watercraft 18 foot Inboard 20 foot Inboard 

6 1 1 1 

25 17 23 21 

1/2 throttle 

— — — 

79.2 79.2 78.0 77.3 

7777

Source: Harris Miller Miller & Hanson, Inc. 2002. a. For vehicles with more than one pass-by, similar speeds and throttle settings are grouped, and the table shows average speed and throttle settings, and energy-average

b. SEL represents the total sound energy of the entire pass-by of each vehicle. Lmax represents the maximum pass-by sound level.
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 103

Time History - 1/8 Second Resolution - Simulation Period #3, 

2-3 PWCs circling around starting at 12:50:45

Crosby Canyon, Glen Canyon NRA, August 2001.

30

35

40

45

50

55

60

65

70

12:50:4512:50:5012:50:5512:51:0012:51:0512:51:1012:51:1512:51:2012:51:2512:51:3012:51:3512:51:4012:51:4512:51:5012:51:5512:52:0012:52:0512:52:1012:52:1512:52:2012:52:2512:52:30

Time

SPL(dBA)

One PWC makes a sudden 

180-degree turn

FIGURE 11: A-LEVEL TIME HISTORY

10-decibel decrease to be “half as loud,” assuming that the frequency content of the sound does not 

change.) In contrast, a time history (not included here) of a typical small outboard motorboat showed 

fluctuations of only a couple of decibels. 

Manufacturers’ literature indicates that the newer four-stroke personal watercraft are quieter than those 

with two-stroke engines. In addition, vehicles powered by two-stroke engines may be more noticeable 

than those powered by four-stroke engines because they tend to have a higher-pitched engine sound. 

However, because no four-stroke personal watercraft were observed during the 2001 study at Glen 

Canyon National Recreation Area, no comparative data were collected. 

Many factors other than the engine type influence the sound level emitted from a personal watercraft. 

Some of these include exhaust configuration, muffling, vessel shape, insulation, and engine size. As a 

result, some two-stroke powered vessels may be quieter than some four-stroke powered vessels. 

Operator behavior, such as rapid acceleration and deceleration, jumps, and high speed, can have an 

even larger influence on sound emissions than engine type. 

Many watercraft, including personal watercraft, emit their exhaust beneath the vessel into the water, 

which tends to muffle the sound. However, there are times when the bottom of the personal watercraft 

is exposed, such as during high-speed turns, when the operator jumps over waves or the wakes of 

other boats, or when the craft bounces on the water. Such exposure of the bottom of the craft and 

exhaust can cause noise emissions to fluctuate substantially. Measurements during the 2001 study 

showed that the fluctuations tended to be greater for personal watercraft than for motorboats. 
AFFECTED ENVIRONMENT

104 GLEN CANYON NATIONAL RECREATION AREA

The 2001 study indicated that use of personal watercraft currently does not exceed existing noise 

standards. Regardless of future management actions in Glen Canyon National Recreation Area, it is 

anticipated that noise from personal watercraft may decline from current levels. 

Noise-reducing measures that are being incorporated into the manufacture of vessels, such as the 

use of more rubber, the reduction of vibrations, and use of quieter four-stroke engine and 

exhaust technology could contribute to noise reduction assuming that quieter machines become 

widely used and that usage does not increase. Assertive education programs, by the personal 

watercraft industry, and regulatory action could help reduce noise by encouraging personal 

watercraft users to change noise-producing behaviors, or to limit their extent to certain areas. 

Such behaviors include wake jumping, rapid changes in speed or direction, and excessive 

revving. 

Timing of Noise from Personal Watercraft and Other Sources 

In areas of concentrated watercraft use, summertime noise from personal watercraft and other vessels 

can occur almost constantly from near sunrise to near sunset. During the high-use times, the sound of 

boats can be continuous in popular parts of the Recreation and Resource Utilization Zone and adjacent 

parts of the Natural Zone. In low-use areas, noise from personal watercraft usually is intermittent and 

typically lasts only a few minutes unless an operator chooses to “play” in the area. 

Almost all personal watercraft use on Lake Powell occurs during daylight hours. As shown in table 4, 

Utah laws and rules do not allow the use of personal watercraft between sunset and sunrise. In 

Arizona, which contains only a small part of the lake, personal watercraft can be used after dark only 

if they have lighting that is consistent with U.S. Coast Guard requirements. 

All other vessels, including both motorized and nonmotorized watercraft, are allowed to operate at 

night if they meet the lighting requirements of the U.S. Coast Guard. However, very little boating 

takes place at night. That which occurs primarily is associated with trolling or other fishing activities. 

Because sound carries well over the water and there is little other noise, engine sounds from boats 

operating at night often can be heard over long distances. Other human-generated nighttime noises 

from within the recreation area include generators and electronically amplified music. 

The Harris Miller Miller & Hanson study included a practice called “observer source identification 

logging.”3

 This practice enables the scientist to establish real-time links between recorded sounds and 

sound pressure levels with identified sound sources. Observers note all sounds that are heard during 

the sampling period, logging human caused sounds such as aircraft, watercraft, wheeled vehicles, 

radios, and voices. At the same time, they log natural sounds of birds, vegetation in the wind, waves, 

insects, mammals and other. Logging was accomplished at the sites where all sound data was 

collected, and at the Rainbow Bridge site. Data from this part of the study allows a characterization of 

all human-caused sound sources that are ambient in the park soundscape, as follows. 

In general, considering all sites together, the sound of personal watercraft was dominant about 5% to 

40% of the time, while boats were dominant about 10% to 45% of the time. Personal watercraft and 

boats together were logged separately, accounting for less than 5% of the time. All aircraft types 

 

3. Draft Technical Report on Noise, pages 27-31. 
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 105

together were dominant about 0% to 13% of the time. The percent time audible for all sources is 

displayed, by site, in figure 19 of the draft Harris Miller Miller & Hanson report.

Numerous aircraft operate year-round in the vicinity of Glen Canyon National Recreation Area. These 

include air tours, military aircraft, high-altitude commercial airliners, general aviation, and NPS 

aircraft. During the day in the Recreation and Resource Utilization and Developed Zones, aircraft 

noise mixes with the other human-caused noise. At night and during the winter, the sound of 

occasional aircraft can dominate the soundscape. In remote parts of the Natural Zone, aircraft produce 

the only mechanical noise impacting the natural soundscape. 

Use of personal watercraft generally ceases during periods of inclement weather, even during the 

summer. These include periods of cold temperatures or thunderstorms. 
106 GLEN CANYON NATIONAL RECREATION AREA

WILDLIFE AND WILDLIFE HABITAT 

Glen Canyon National Recreation Area provides habitat for many species of mammals, birds, fish, 

reptiles, amphibians, and invertebrates. Approximately 410 species of wildlife and 20 fish species 

have been inventoried within the recreation area. This resource characterization only addresses the 

species that are strongly or moderately associated with the recreation area’s lake edge, main water 

body, river tributary, or shoreline areas for all or a substantial part of their life cycle. 

As noted previously, Lake Powell is a very popular destination recreation area, receiving a large 

number of visitors. Peak visitor-use months are June through September. Human activity and noise 

from watercraft are common conditions, especially in the marina and campground areas. Wildlife 

populations have been exposed to these conditions since the recreation area opened for visitor use. 

Impounding the Colorado River behind Glen Canyon Dam created a new lacustrine (lake) 

environment in areas that formerly were canyon bottoms, steep canyon sidewalls, and adjacent 

uplands. It also created a near-shore environment where the desert climate, wave erosion, highly 

variable water levels, poor soils, and generally steep shorelines restrict vegetative cover to sparse 

stands of fast-growing vegetation that is occasionally interspersed with small dense stands of saltcedar. 

The wildlife groups that use the lake and near-shore areas are described below. 

WILDLIFE GROUPS OF PRIMARY INTEREST 

The large seasonal and annual variations in water surface elevation resulting from reservoir operations 

and management impose substantial environmental constraints on the types of habitats that can 

develop and persist at near-shore locations. Wildlife species typically associated with the water 

fluctuation zone are highly adapted to using food, cover, and shelter conditions that may develop and 

disappear quickly. In many main lake locations, especially where the inundation frequency is high and 

prolonged, shoreline and near-shore areas consist primarily of unvegetated or sparsely vegetated rock, 

sand, cobbles, and boulders. 

Vegetation and corresponding habitat conditions are different in the tributaries and upper river reaches 

of the recreation area where water fluctuations generally follow normal seasonal patterns. Such 

reaches provide riparian vegetation complexes that support different wildlife species assemblages than 

those encountered along main lake shorelines. 

Mammals 

Shoreline areas that typically are exposed to personal watercraft uses provide limited habitat to the 

large, highly mobile mammals of the recreation area. These areas are typically unvegetated and steep. 

However, shoreline areas may occasionally be briefly occupied by several species of mammals while 

searching for food or water or while moving through the area. These species include desert bighorn 

sheep, mule deer, antelope, feral horse, bobcat, mountain lion, gray fox, badger, kit fox, and coyote. 

However, they spend most of the time in adjacent upland areas. 

Sufficient cover and forage opportunity exists in the near-shore environment for rodents. Rodent 

species that have been documented within the shoreline saltcedar stands include the deer mouse, Ord’s 
Wildlife and Wildlife Habitat 

FINAL ENVIRONMENTAL IMPACT STATEMENT 107

kangaroo rat, little pocket mouse, Arizona pocket mouse, long-tailed pocket mouse, western harvest 

mouse, canyon mouse, brush mouse, pinyon mouse, northern grasshopper mouse, and desert woodrat. 

River otters have been infrequently observed within Last Chance and West Canyon in recent years 

(NPS, Spence, pers. com., May 2002n). Reasons for the presence of the river otter in these locations 

have not been determined, but could be related to foraging for food or their normal movement 

activities. 

Birds 

Shorebirds, waterfowl, and other water-associated bird species frequently use Lake Powell and its 

surrounding shoreline during migration for resting, security, and foraging purposes. Groups commonly 

observed on the lake and near shoreline areas include several species of grebes, cormorants, herons, 

egrets, coots, and ducks. Waterfowl, shorebirds, wading birds, and other water-associated bird species 

tend to concentrate in highest number and greatest diversity at Lake Powell in the late-fall, winter, and 

early spring months during peak migration periods and during the winter months when open water is 

present (NPS, Spence, pers. com., May 2002n; and NPS, Henderson pers. com., May 2002h). 

Wading bird nesting activity and locations are very rare at the recreation area. A few great blue herons 

attempt to breed around the upper edges of Hall’s Creek Bay, but they usually are unsuccessful. Some 

researchers and interested observers have attributed these breeding failures to the constant disturbance 

by boats in the area during the nesting and breeding periods. However, the failures more likely are 

caused by changing water levels (NPS, Spence, pers. com., May 2002n). The birds build their nests in 

the early spring when lake levels are low. As the water level increases in May and June, the nests are 

drowned and abandoned. Other than at upper Hall’s Creek Bay, there are no known breeding 

populations of shore birds (NPS, Spence, pers. com., May 2002n). Typically in large reservoir 

settings, there may be concerns about the presence and location of breeding and nesting colonies of 

colonial water-associated species such as terns, gulls, and pelicans. Breeding and nesting colonies of 

such species do not occur in the recreation area (NPS, Spence, pers. com., May 2002n). 

Several species of raptors (a wildlife group that includes hawks, owls, eagles, and falcons) are known 

to use areas adjacent to and proximal to Lake Powell for nesting and foraging. 

Peregrine falcons have been observed nesting in the recreation area, along the shores of Lake 

Powell and the Colorado River (NPS 1988a). 

A pair of golden eagles uses the Wahweap area for foraging (NPS, Spence, pers. com., 

May 2002n). 

In the past, a pair of ospreys has attempted to breed in the upper Hall’s Creek Bay area, but has 

not successfully raised young in recent years (NPS, Spence, pers. com., May 2002n). 

Active great horned owl nests are found at many locations along tributary and main lake cliffs 

and other rock formations within several hundred feet of the water’s edge. The distance between 

these nest sites and the water’s edge varies seasonally and annually, depending on the water 

elevation. 

During censuses conducted in 1990 on 14 saltcedar stands located around Lake Powell, 19 bird species 

were observed. The greatest densities and diversity of species were found within the Wahweap Bay 
AFFECTED ENVIRONMENT

108 GLEN CANYON NATIONAL RECREATION AREA

area and a site due east of Gregory Butte. Species observed during the censuses at these sites included 

horned lark, several species of swallow, raven, mourning dove, yellow warbler, yellow-headed 

blackbird, and house finch. Songbird density, abundance, and species richness tend to increase at the 

upstream reaches of the lake and major tributary streams where stands of cottonwood, willow, 

saltcedar, and other shrub vegetation have developed. These woody riparian areas provide suitable 

habitats for a wider variety of species. Riparian corridors and stands of trees also are preferred 

foraging and security areas for songbirds during spring and fall migration periods. 

Fish 

The recreation area currently supports an assemblage of fish species that includes those adapted to 

either lake (lacustrine) or flowing-water (riverine) environments. Most of the lake-adapted species 

have been introduced intentionally or unintentionally by man through past fish-stocking or bait release 

programs. These species are more abundant because of the larger abundance of suitable aquatic 

habitat. 

The flowing-water or riverine fish species tend to be native species that are restricted to the flowing 

portions of the main tributary streams and rivers that flow into the lake. These species are relatively 

less abundant and more restricted in distribution than the lake-associated fish species. 

The creation of Lake Powell changed the riverine habitat formerly found on this stretch of the 

Colorado River to such an extent that native fish species have been virtually eliminated from the 

resulting lake environment. As a result of habitat modification and competition by introduced species, 

many native species are now classified as endangered or threatened. However, native species such as 

the Colorado pikeminnow, flannelmouth sucker, bonytail, humpback chub, razorback sucker, bluehead 

sucker, and roundtail chub still occur in extremely limited numbers within the San Juan and Colorado 

Rivers as well as their interfaces with Lake Powell. (USGS n.d.). The status of endangered or 

threatened native fish species is discussed in greater detail in the endangered or threatened species 

section. 

Biological productivity for the reservoir is low because of a nutrient deficiency associated with 

phosphorus settling out close to the river mouths (see the “Water Quality” section). None-the-less, 

Lake Powell supports a number of introduced game and nongame fish species that form the basis for a 

popular and regionally important recreational sport fishery. The Lake Powell sport fishery is generally 

considered to be excellent quality by the states of Utah and Arizona compared to other large reservoir 

fisheries in each state (Gustaveson 2002). Predominant game fish species include the striped bass and 

smallmouth bass, which comprise about 80% and 20% of the annual game fish harvest, respectively 

(Gustaveson 2002). Other game fish species include the largemouth bass, catfish, crappie, and bluegill. 

These species inhabit the reservoir, and spawn either along shoreline areas or within the tributary 

rivers when water conditions are suitable for a successful spawn. Spawning habitats vary by species. 

Abundant nongame fish species include the common carp, red shiner, and threadfin shad. Game 

species primarily depend on the threadfin shad as the key forage species, but they shift to bluegill, 

other sunfish species, and crayfish when threadfin shad become unavailable (Gustaveson 2002). These 

forage species are typically associated with inflow areas and shorelines. 

There are no known fish spawning locations of key or primary importance reported for the reservoir or 

for the major river and tributary streams that enter the reservoir (NPS, Spence, pers. com., May 

2002n). Fish spawning occurs at many locations, with selected locations being determined each year 
Wildlife and Wildlife Habitat 

FINAL ENVIRONMENTAL IMPACT STATEMENT 109

by the best combinations of a species’ spawning habitat requirements, water levels, water flow 

conditions, and water temperature regime. 

There are no documented cases of fish kills or habitat degradation associated with the marinas on Lake 

Powell that were considered serious enough to adversely affect fish populations (Gustaveson 2002). 

Reptiles and Amphibians 

Systematic surveys for reptiles or amphibians in Glen Canyon have not been conducted since the 

construction of the dam (NPS, Spence, pers. com., May 2002n). However, 27 species of reptiles and 

7 species of amphibians are known to occur in the recreation area. During censuses conducted on 

saltcedar stands along the shoreline of Lake Powell, seven species of reptiles were documented, 

including the desert spiny lizard, side-blotched lizard, desert horned lizard, western whiptail, western 

rattlesnake, longnose leopard lizard, and Glen Canyon chuckwalla. 

Densities of reptiles were 30 times lower in saltcedar stands along the shorelines of Lake Powell than 

along the Colorado River in the Grand Canyon. Waring (1992) suggested that low biotic productivity 

within Lake Powell may be a limiting factor for reptile densities in this area. 

Amphibians observed or likely to occur within the area of analysis include the leopard frog, redspotted toad, Woodhouse’s toad, and the canyon treefrog. These species are restricted to protected and 

perennially wet or moist environments, such as springs and perennial streams that occur in the upper 

reaches of tributary canyons. These areas are generally located at elevations higher than the maximum 

reservoir pool elevations and remain unaffected by reservoir operations (NPS, Spence, pers. com., 

May 2002n). 

Aquatic Invertebrates 

A systematic survey of invertebrates within Glen Canyon National Recreation Area has not been 

conducted (NPS, Spence, pers. com., May 2002n). Generally, the abundance, location and type of 

aquatic invertebrates present depend on the water quality and habitat conditions within Lake Powell 

and the tributary rivers and streams that discharge to the reservoir. Due to the fluctuating water levels 

of Lake Powell, the shoreline has little to no aquatic vegetation, so little habitat is available for aquatic 

invertebrate production and support. Thus, the diversity and abundance of aquatic invertebrates along 

the shoreline is expected to be low. In general, higher abundance, species richness, and species 

diversity would be expected in portions of tributary rivers, streams, and other relatively shallow-water 

settings where habitat diversity and flow conditions would favor a larger variety of aquatic 

invertebrate species. 

SEASONAL USE PATTERNS OF WILDLIFE GROUPS OF PRIMARY INTEREST 

Understanding the general seasonal movement patterns of wildlife species and groups of interest is 

useful in evaluating the potential interactions between wildlife and visitors. Such interactions also 

contribute to the qualitative value of the visitor expereince. Sightings of large mammals are often of 

particular visitor interest. 
AFFECTED ENVIRONMENT

110 GLEN CANYON NATIONAL RECREATION AREA

Several hundred mule deer use the recreation area for winter range, especially south of the Escalante 

River. Depending on local terrain conditions, individual deer may be visible from the lake or nearshore area. However, shoreline areas are typically not regular use areas for deer because of the lack of 

or sparse vegetation conditions. Limited winter use occurs along the San Juan River and below the 

Orange Cliffs. Most of the deer migrate outside of the recreation area during the summer months (NPS 

1979a). 

Bighorn sheep are occasionally (every two to three years) observed near the shoreline during the 

winter months near the Dangling Rope residential area and in the lower San Juan River Canyon (NPS, 

Spence, pers. com., May 2002n). There are no known important habitat elements for bighorn sheep in 

this area, and it is thought that the sheep are moving to lower elevations as a retreat from inclement 

winter weather (NPS, Spence, pers. com., May 2002n). 

Seasonal waterfowl and shorebird uses peak during the spring, fall, and winter months as members of 

these migratory groups are attracted to the large water body. Flocks of species tend to congregate in 

open water areas, canyons, and shallow bay areas for security, resting, and feeding. Numbers of birds 

tend to increase during and coincide with the low-use recreation months. Use of the lake and tributary 

streams by these bird groups occur at levels that are lower than would be expected from such a large 

reservoir. Important physical factors contributing to the relatively low use levels include the limited 

number of suitable shallow water areas, general scarcity of wetlands, and absence of lake shore and 

riparian vegetation. Conflicts between these widlife groups and existing recreation and personal 

watercraft use are not considered to be an issue (NPS 1998b; NPS, Spence, pers. com., May 2000n). 

SPECIAL-INTEREST USE AREAS OR HABITAT FEATURES OF CONCERN 

Special-interest use areas or habitat features of concern are elements of the wildlife resource that are of 

high value for maintaining wildlife species presence, productivity, or quality. These elements are of 

particular interest because they are especially susceptible to the disturbance or degradation effects 

from humans or their activities. These areas or features are usually considered important for receiving 

special consideration in planning, resource management, or protection from adverse effects. 

Spawning Areas 

Spawning habitat for native fish species may exist within the inflow areas of the Colorado and San 

Juan Rivers on Lake Powell. Details of these requirements are presented in the “Threatened, 

Endangered, and Special-Concern Species” section. Under current conditions spawning activities in 

these areas are presumed to be subject to predation from non-native fish species. It is likely that 

existing predation is so intense that young have little chance of survival, resulting in no recruitment 

(Henderson 2002). 

Nesting Areas 

Colonial nesting areas, whether they are rookeries in trees or ground-nesting colonies on shorelines, 

are important habitat features because they typically concentrate a large number of breeding 

individuals in a small area for an especially vulnerable portion of their life cycle. There are currently 

no known heron or egret nesting rookeries or shoreline nesting colonies within the area of analysis for 

the main body of the lake. As stated above, a few herons have attempted to next along the shoreline in 
Wildlife and Wildlife Habitat 

FINAL ENVIRONMENTAL IMPACT STATEMENT 111

the upper Hall’s Creek Bay area, but due to fluctuating water levels these attempts have been 

unsuccessful. 

Peregrine falcons nest within the area of analysis, with more than 80 eyries recorded in 2000 (NPS, 

Spence, pers. com., May 2002n). These nests are normally located on cliffs approximately 100 feet 

above the level of the water. The falcons have habituated to the presence of watercraft. 

There are numerous active nests of the great horned owl located in the rock cliffs and other formations 

surrounding the lake’s and tributary stream’s perimeters. Some of these locations may be exposed to 

the activities of water-based visitors. 

Wetlands/Riparian Areas 

Wetlands and riparian areas are typically considered to be important wildlife concentration areas for 

several reasons. These include the availability of good foraging conditions resulting from the high 

degree of vegetation, water interfaces and interspersion (or edge), and structural diversity typically 

associated with vegetation conditions in such areas. General wildlife habitat values and uses typically 

increase as wetland and riparian area size increases. 

Because of the physical shoreline conditions and the operational characteristics of the reservoir, 

wetland sites are limited in number and small in size. Wetlands are typically associated with the 

upstream reaches of tributary or secondary side canyons where water levels fluctuate less. 

Riparian areas are typically found along the shorelines of the four major rivers flowing into the 

reservoir. The riparian corridors of the Colorado River and San Juan River are often extensive, dense, 

and well developed. 

Areas of High Waterfowl and Shorebird Concentration 

During the early, spring waterfowl and shorebirds tend to congregate around the heads of Hall’s 

Creek, Bullfrog, Warm Creek, Wahweap Bays, and Antelope Island (NPS 1998b). These 

concentrations tend to develop during spring migration months with total bird numbers gradually 

decreasing as the birds move towards breeding areas. The timing of increased bird numbers and the 

duration of the congregations are influenced by weather patterns and movements of frontal systems. 

There are no reported high-use or historical concentration areas for these bird groups in the recreation 

area. 

River Refugia 

The perennial tributary rivers flowing into Lake Powell represent examples of the river systems and 

aquatic environments that existed prior to lake impoundment. These areas are of particular scientific 

and resource preservation value because of their general scarcity and because they preserve 

populations and community relationships of previous riverine ecosystem conditions. Relict native fish 

species still survive within the rivers in limited numbers. Major examples include reaches of the 

Colorado, San Juan, Escalante, and Dirty Devil Rivers. 
AFFECTED ENVIRONMENT

112 GLEN CANYON NATIONAL RECREATION AREA

SPECIAL-INTEREST SPECIES 

The recreation area supports one of the last relict desert bighorn sheep herds in Utah. The most critical 

areas for the sheep include the Red, White and Gypsum Canyons branching off of the north-eastern 

portion of Lake Powell. These areas have been identified as possible lambing grounds. The extent of 

the herd’s movement occassionally (every other year) bring them within close proximity of the lake 

near Dangling Rope and possibly in the lower San Juan River Canyon during the winter months (NPS, 

Spence, pers. com., May 2002n). In the Dangling Rope area, the sheep have been observed close to 

existing human-use areas. When close to the lake shoreline, these bighorn sheep are generally not 

exposed to recreators because visitor use is typically at its lowest annual levels. 

The recreation area also supports the Glen Canyon chuckwalla, a Utah state sensitive species. This 

species is closely associated with the lake, and is predominantly found near cliffs, boulders, or rocky 

slopes, where they use rocks as basking sites and rock crevices for shelter (Utah Division of Wildlife 

Resources 2002a). 

EXISTING CONFLICTS BETWEEN WILDLIFE AND PERSONAL WATERCRAFT USERS 

There are currently no interactions between personal watercraft and wildlife that the recreation area 

staff is aware of (Spence 2002a), and there have not been any documented incident reports of known 

conflicts between wildlife and personal watercraft users in Glen Canyon National Recreation Area 

(NPS, Spence, pers. com., May 2002n). 
FINAL ENVIRONMENTAL IMPACT STATEMENT 113

THREATENED, ENDANGERED, AND SPECIAL-CONCERN SPECIES 

SPECIES KNOWN TO OCCUR IN ANALYSIS AREA 

In accordance with threatened or endangered species consultation and coordination activities, the U.S. 

Fish and Wildlife Service identified 13 listed, 1 proposed, and 1 candidate species for portions of 

Coconino County, Arizona and Kane and San Juan Counties, Utah (U.S. Fish and Wildlife Service, 

letter, Maddux, May 2002). Habitat for 12 federally listed endangered, threatened and candidate 

species may occur in the lake or near its shoreline. Database information from the Utah Division of 

Wildlife Resources and the Arizona Game and Fish Department identified additional state specialstatus species that may occur within the project area. Information from federal and state agencies were 

used to prepare the list of federal- and state-listed threatened, endangered, and special-concern species 

shown in table 15. 

The area addressed for this resource characterization includes Lake Powell up to the 3,700-foot water 

surface elevation, the shoreline zone, and uplands within 500 feet of Lake Powell’s 3,700-foot water 

surface elevation or within 500 feet of river shorelines. Species or potentially suitable habitat likely to 

be present within this area are identified and discussed below. Species listed by the U.S. Fish and 

Wildlife Service for which suitable habitat is not present within the recreation area are not discussed 

further. 

PRESENCE OF DESIGNATED CRITICAL HABITATS 

Provisions of the Endangered Species Act require consideration of both species populations and 

designated critical habitats for species listed or proposed for listing. Critical habitat is defined as a 

specific geographic area that is essential for conservation of endangered or threatened species. 

Glen Canyon National Recreation Area supports designated critical habitat for four endangered fish 

species (Utah Department of Environmental Quality, Water Quality Division, Moellmer, pers. com., 

January 2003a). These include the razorback sucker (Xyrauchen texanus), Colorado pikeminnow 

(Ptychocheilus lucius), humpback chub (Gila cypha), and the bonytail (Gila elegans). These fish occur 

in the Colorado River, portions of the lower inlet of the Dirty Devil River, and the San Juan River, 

including their 100-year floodplains up to the full pool elevation of Lake Powell (50 CFR Part 17, 

1994). During the lowest projected lake level, the critical habitat may extend up into Neskahi Canyon 

along the San Juan River. Designated critical habitats for these federally listed species in the recreation 

area are shown in table 16. 

Critical habitats for the Mexican spotted owl (Strix occidentalis lucidia), the southwestern willow 

flycatcher (Empidonax traillii extimus), the California condor (Gymnogyps californianus), and the 

Navajo sedge (Carex specuicola) have been designated by the U.S. Fish and Wildlife Service. None of 

these designated critical habitats are located within the personal watercraft use area (Utah Department 

of Environmental Quality, Water Quality Division, Moellmer, pers. com., January 2003a). 

Suitable habitats for the listed fish species occurs in limited areas of the recreation area. It fluctuates in 

location and areal extent in response to lake water levels, river flow conditions, and season of the year. 

Fluctuation of the reservoir’s water surface levels influences the availability of backwater habitat and 

the length of river channel potentially available for fish use within the recreation area. These 

fluctuations also affect the presence and availability of spawning habitat within backwaters and side 

channels of tributary inlets. 
AFFECTED ENVIRONMENT

114 GLEN CANYON NATIONAL RECREATION AREA

TABLE 15: FEDERAL AND STATE-LISTED CANDIDATE, THREATENED, 

AND ENDANGERED SPECIES BELIEVED TO OCCUR IN THE PERSONAL WATERCRAFT ANALYSIS AREA 

Common Name Scientific Name 

Federal 

Status 

State 

Status 

Habitat Present 

within Analysis 

Area 

Birds 

American peregrine falcon Falco peregrinus anatum N/La E Yes 

Bald eagle Haliaeetus leucocephalus T E Yes 

Brown pelican Pelecanus occidentalis californicus E N/L No 

California condor Gymnogyps californianus E (exp) SC Yes 

Mexican spotted owl Strix occidentalus lucidia T T No 

Southwestern willow flycatcher Empidonax traillii extimus E E Yes 

Western yellow-billed cuckoo Coccyzus americanus CS T Yes 

Fish 

Bonytail Gila elegans E E Yes 

Colorado pikeminnow Ptychocheilus lucius E E Yes 

Humpback chub Gila cypha E E Yes 

Little Colorado spinedace Lepidomeda vittata T N/L No 

Razorback sucker Xyrauchen texanus E E Yes 

Amphibians 

Chiricahua leopard frog Rana chiricahuensis PS N/L No 

Mammals 

Black-footed ferret Mustela nigripes E E No 

Mollusks 

Kanab ambersnail Oxyloma haydeni kanabensis E E No 

Plants 

Brady pincushion cactus Pediocactus bradyi E E No 

Fickeisen pincushion cactus Pediocactus peeblesianus fickeiseniae CS SC No 

Jones cycladenia Cycladenia humilis var. jonessi T T No 

Navajo sedge Carex specuicola T T No 

San Francisco Peaks groundsel Senecio franciscanus T T No 

Sentry milk-vetch Astragalus cremnophylax var. cremnophyla E E No 

Siler pincushion cactus Pediocactus sileri T T No 

Ute ladies'-tresses Spiranthes diluvialis T T No 

Welshs milkweed Asclepias welshii T T No 

 

a. Abbreviations: C = species of concern N/L = not listed

 CS = candidate species PS = proposed species 

 E = endangered SC = state species of concern 

 E (exp) = endangered, experimental population T = threatened 
Threatened, Endangered, and Special-Concern Species 

FINAL ENVIRONMENTAL IMPACT STATEMENT 115

TABLE 16: LOCATION OF ENDANGERED FISH SPECIES CRITICAL HABITAT 

Species Critical Habitat Location 

Razorback sucker Glen Canyon National Recreation Area razorback sucker habitat includes the 100-year floodplain 

of the Colorado River extending to Lake Powell’s full pool elevation, Lake Powell’s arm of the 

Dirty Devil River extending upstream of North Wash, and the San Juan Rivers 100-year 

floodplain extending to Lake Powell’s full pool elevation near Neskahi Canyon. Specific locations 

are as follows: 

Grand, San Juan, Wayne, and Garfield Counties, the Colorado River and its 100-year floodplain 

from Westwater Canyon in T.20S., R.25E., sec. 12 (Salt Lake Meridian) to full pool elevation, 

upstream of North Wash and including the Dirty Devil arm of Lake Powell in T. 33S., R.14E., 

sec. 29 (Salt Lake Meridian). San Juan County, the San Juan River and its 100-year floodplain 

from the Hogback Diversion in T.29N., R.16W., sec. 9 (New Mexico Meridian) to the full pool 

elevation at the mouth of Neskahi Canyon on the San Juan arm of Lake Powell in T.41S., R.11E., 

sec. 26 (Salt Lake Meridian). 

Colorado pikeminnow Glen Canyon National Recreation Area Colorado pikeminnow habitat includes the 100-year 

floodplain of the Colorado River extending to Lake Powell’s full pool elevation, Lake Powell’s arm 

of the Dirty Devil River extending upstream of North Wash, and the San Juan River’s 100-year 

floodplain extending to Lake Powell’s full pool elevation near Neskahi Canyon. Specific locations 

are as follows: 

Grand, San Juan, Wayne, and Garfield Counties, the Colorado River and its 100-year floodplain 

from the Colorado River Bridge at exit 90 north off Interstate 70 in T.6S., R.93W., sec. 16 (6th

Principal Meridian) to North Wash including the Dirty Devil arm of Lake Powell up to the full pool 

elevation in T. 33S., R.14E., sec. 29 (Salt Lake Meridian). San Juan County, the San Juan River 

and its 100-year floodplain from the State Route 371 Bridge in T.29N., R. 13W., sec. 17 (New 

Mexico Meridian) to Neskahi Canyon in the San Juan arm of Lake Powell in T.41S., R.11E., 

sec. 26 (Salt Lake Meridian) up to the full pool elevation. 

Humpback chub Glen Canyon National Recreation Area humpback chub habitat includes the 100-year floodplain 

of the Colorado River along the rapids in Cataract Canyon upstream of Gypsum Canyon. Specific 

locations are as follows: 

Garfield and San Juan Counties, the Colorado River from Brown Betty Rapid in T.30S., R.18E., 

sec. 34 (Salt Lake Meridian) to Imperial Canyon in T.31S., R.17E., sec. 28 (Salt Lake Meridian). 

Bonytail Glen Canyon National Recreation Area bonytail habitat includes the 100-year floodplain of the 

Colorado River along the rapids in Cataract Canyon upstream of Gypsum Canyon. Specific 

locations are as follows: 

Garfield and San Juan Counties, the Colorado River from Brown Betty Rapid in T.30S., R.18E., 

sec. 34 (Salt Lake Meridian) to Imperial Canyon in T.31S., R.17E., sec. 28 (Salt Lake Meridian). 

 

Sources: FR 50 CFR Part 17 Monday March 21, 1994. 

All four fish species are strongly associated with flowing river or stream conditions. Areas that 

provide deep, swift-running currents along river reaches provide the most desirable conditions. Use of 

floodplain backwater areas occur during the spawning period. Occasionally, individual fish may drift 

into the main body of the reservoir near the lake’s headwater areas. No adult native endangered 

species have been captured in Lake Powell since the late 1980s (Utah Division of Wildlife Resources, 

Gustaveson, pers. com., April 2002b). 

Areas where rivers flow into the lake can provide important habitat during certain stages in these 

species life history if the physical characteristics of the flooded areas are suitable for spawning and 

rearing of young fish. River inflow areas provide some sand or silt bar habitat. Periodic scouring of 

substrate caused by flood events create side channel and backwater conditions which are used as 

spawning, nursery, and rearing areas for young fish. Calmer backwaters adjacent to these swift 

currents provide shelter and feeding for early to young life stages. 

Adult life stages of these species tend to use main channel areas including runs and eddies over a 

variety of substrates, preferred water depths vary seasonally. Deeper water areas are preferred during 
AFFECTED ENVIRONMENT

116 GLEN CANYON NATIONAL RECREATION AREA

the winter months and shallower water (sometimes as shallow as 1.5 feet deep) are preferred during 

spawning periods. 

Monitoring and enhancement programs for endangered or threatened fish species have been 

established in the riparian and aquatic habitats of Lake Powell. Recovery efforts for these species 

focus on establishing self-sustaining populations in the free-flowing river reaches of the Colorado and 

San Juan Rivers. In 1988, the U.S. Fish and Wildlife Service developed an Interagency Recovery 

Implementation Program for the Recovery of Endangered Fishes in the Upper Colorado River. These 

native fisheries enhancement programs emphasize recovery in locations above Lake Powell. The 

National Park Service and Utah Division of Wildlife Resources use the recovery implementation 

program guidelines for recovery efforts in critical habitat river reaches located within the recreation 

area (Utah Division of Wildlife Resources 1996). 

Habitats required for conservation of these species include river channels and flooded, ponded, or 

inundated riparian areas, especially those where competition from non-native fishes is absent or 

reduced (U.S. Fish and Wildlife Service 1994). Available habitats are regulated by the water storage 

requirements and fluctuating water elevation of Lake Powell, which the Bureau of Reclamation 

manages. 

Declining aquatic habitats combined with competition and predation from introduced non-native 

fishes have contributed to population declines of the endangered fish species and in endemic fish 

species in general in the Colorado River. Threats to endangered fish habitats include stream flow 

regulation, habitat modification, and predation by nonnative fisheries, parasitism, hybridization and 

pesticides or pollutants. Species-specific information relevant to assessment of potential effect on 

these species is as follows. 

Razorback Sucker (Xyrauchen texanus) is native to the Colorado River and once occupied the entire 

range of the river basin. San Juan, Dirty Devil, and Colorado River inflow areas continue to produce 

some razorback suckers. Eleven adult razorbacks were caught at the San Juan inflow (USGS n.d.). 

Adult razorback suckers are considered to be the products of native fish recovery programs conducted 

further upstream of Glen Canyon National Recreation Area (Utah Department of Environmental 

Quality, Water Quality Division, Moellmer, pers. com., January 2003a). Fish tracking studies 

conducted in Lake Powell from 1995 to 1997 indicated this species primarily used vegetated habitats 

less than 1.5 feet deep in side canyons and backwaters covering sandy or cobble bottoms and open 

waters in upper portions of the river inlets. These areas represent less than 1% of the aquatic areas of 

Lake Powell (Mueller and Karp 2002). 

Colorado Pikeminnow (Ptychocheilus lucius) is a native migratory fish species of the Colorado River 

that once was present basin wide. It is no longer present in the lower basin and is considered rare in 

the upper basin. It is only found upstream of Glen Canyon Dam. Juvenile pikeminnow have been 

found in off-channel and backwater habitats adjacent to lower reaches of the river inflows into Lake 

Powell (Utah Division of Wildlife Resources, Gustaveson, pers. com., April 2002b). Some have been 

found in the San Juan River near Mexican Hat (NPS 1986). A 3.5-pound, 25-inch, Colorado 

Pikeminnow was captured in the lake in 1999 (Utah Division of Wildlife Resources, Bradswisch, pers. 

com., April 2003). Limiting factors include loss of habitat. 

Humpback Chub (Gila cypha) is a native migratory fish species that was once more abundant 

throughout the Colorado River. It currently exists only in the upper basin near Arizona and near the 

confluence of the Colorado and Little Colorado Rivers. The humpback chub has not been captured in 

Lake Powell since the early 1970s. It is assumed to no longer be present in the lake. Habitat 
Threatened, Endangered, and Special-Concern Species 

FINAL ENVIRONMENTAL IMPACT STATEMENT 117

preferences include river channels with deep, fast-moving water and large boulders that are often 

conditions created in river channels bounded by steep cliffs. Adults typically live in eddy currents of 

whitewater canyons. Threats to this species include habitat modification and fluctuating water 

discharges that eliminate preferred current conditions. 

Bonytail (Gila elegans) is a native fish species that has a historic range that includes the Colorado 

River and its main tributaries. Currently this species is found from Lake Powell upstream of the 

Colorado River to its confluence with the Green River. The bonytail is no longer present in the upper 

basin and is believed to be the most endangered of the four fish species. Prior to 1996, fewer than 10 

bonytails were captured in Lake Powell. No individual fish have been observed during annual gill-net 

surveys conducted in the last 20 years. Some populations may be present in Utah but their relative 

abundance is unknown. The species prefers pools and eddies of warm, often heavily silted, swiftmoving rivers. 

Mexican Spotted Owl (Strix occidentalis lucidia) uses a variety of habitats including old growth 

forests, mixed conifer, Ponderosa pine, deciduous riparian, and steep canyons with rocky cliffs. 

Timber harvesting is the main threat to the Mexican spotted owl. Small populations roost in 

abandoned nests, tree cavities, or caves along canyon walls. Steep canyon habitats and drainages 

adjacent to Lake Powell and adjoining rivers may occasionally be used by this species. A juvenile was 

observed in Cataract Canyon several years ago but none have been sighted in the analysis area since. 

There are no potential areas of concern located within the analysis area. Known occupied territories 

are located more than 4 miles from the Lake Powell shoreline (NPS, Spence, pers. com., April 

2002m). 

Southwestern Willow Flycatcher (Empidonax traillii extimus) is associated with low-elevation dense 

willow, cottonwood and saltcedar communities along streams and rivers. This species has been sighted 

about 30 miles from Lake Powell up the Escalante River and the San Juan River near Clay Hills 

Crossing but there is no confirmed nesting or breeding habitat present in the recreation area. (Utah 

Department of Environmental Quality, Water Quality Division, Moellmer, pers. com., January 2003a). 

In Arizona more than 110 pairs occupy 160 territories including breeding territory along the Colorado 

River. Smaller populations are known to exist in Utah. Outside the recreation area, breeding habitat 

typically is present along the larger rivers and lake shorelines at low elevations in areas of dense 

willow, cottonwood and saltcedar or other woodlands along streams and rivers. Loss of native riparian 

habitat combined with predation and brown-headed cowbird parasitism have reduced the species’ 

populations. 

California Condor (Gymnogyps californianus) was reintroduced into the wild by the U.S. Fish and 

Wildlife Service in Arizona in 1996. There is some evidence that the condor historically was present 

in Utah. These birds were released on the Vermilion Cliffs in Coconino County near Page, Arizona 

approximately 20 miles from the Utah border. Roosting habitat includes cliffs, tall evergreens and 

snags. Their population decline is thought to be related to ingestion of lead or cyanide-contaminated 

dead carcasses. Possible shootings, removal from wild of eggs, young, and adults for captive breeding, 

may also have contributed to population declines. Individual birds are known to forage than 100 miles 

for food. No breeding or nesting habitat is present in the recreation area, but individual birds may 

infrequently move across the area. A few individuals have been observed at Lake Powell within the 

last five years (NPS, Spence, pers. com., May 2002n). 

Bald Eagle (Haliaeetus leucocephalus) habitat is present along the larger rivers in southern Utah. In 

the recreation area, this includes the San Juan River and the main lake channel upstream from 

Bullfrog. No nest sites have been observed or recorded along Lake Powell’s shorelines. 
AFFECTED ENVIRONMENT

118 GLEN CANYON NATIONAL RECREATION AREA

Bald eagles winter in small numbers throughout the Lake Powell area, with observations most likely 

along the San Juan River and around Bullfrog (NPS 1986). Annual surveys conducted by the National 

Park Service report that 18 to 20 bald eagles typically overwinter in the recreation area, but as many as 

45 overwintering birds have been observed. 

Potentially favorable bald eagle roosting sites along the rivers and shorelines of reservoirs like Lake 

Powell are monitored (Spence 2002b). There are no known consistently used winter roosting locations 

in the recreation area. Bald eagles have been observed feeding at Antelope Island and other portions of 

Lake Powell during the winter months (NPS 2002b). 

Western Yellow-Billed Cuckoo (Coccyzus americanus) populations have declined throughout this 

species’ range in the western states because of habitat loss. As a result, it is a candidate species 

currently under study for listing by the U.S. Fish and Wildlife Service. Habitat for this neo-tropical 

species consists of cottonwood-willow riparian forests. 

The presence of the western yellow-billed cuckoo and its breeding habitat are well-documented in 

Arizona. The bird has been sighted in Utah, but its presence is not well documented. Western yellowbilled cuckoos have been observed on the Colorado River near Lees Ferry below the Glen Canyon 

Dam and at Clay Hills Crossing on the San Juan River. This bird species has not been observed along 

the shoreline analysis area of Lake Powell, but has been seen in riparian shrub and woodland areas 

along some of the river reaches (Spence 2002b). 

American Peregrine Falcon (Falco peregrinus anatum) was removed from the federal list of 

endangered and threatened species on August 25, 1999 (64 FR 46542). However, it is still listed as an 

Arizona special-status species. Threats to this species include loss of habitat and environmental 

contaminants. 

The peregrine falcon often is observed resting on cliff faces in the recreation area and foraging close to 

the lake shoreline. There are more than 80 known peregrine falcon nesting sites in the recreation area. 

These nest sites are located along cliffs at higher elevations on the canyon walls above the water 

surface of the lake (Utah Department of Environmental Quality, Water Quality Division, Moellmer, 

pers. com., January 2003a). Preferred nest sites are located close to riparian and wetland areas. 

Navajo Sedge (Carex specuicola) is a small grass-like plat that grows in small pockets of sandy to 

silty moist soil in cool and shady seeps or spring alcoves in the San Juan River Canyon at elevations 

ranging from 4,301 to 6,004 feet. No designated critical habitat for the Navajo sedge is located in Glen 

Canyon National Recreation Area (Utah Department of Environmental Quality, Water Quality 

Division, Moellmer, pers. com., January 2003a). Its elevation distribution places it outside the impact 

analysis area.

Ute Ladies-Tresses (Spiranthes diluvialis) is a small, native orchid associated with wet meadows that 

occur along streams or at spring or seep discharges at elevations ranging from about 4,300 to 

7,000 feet above sea level. It typically flowers between late July through August, which is the best 

time to determine its presence. This species is threatened by loss of habitat, agriculture, uncertain 

water availability, and urban stream channelization. 

Ute ladies-tresses are known to occur in Garfield County and other counties in Utah (U.S. Fish and 

Wildlife Service, letter, Maddux, May 2002) but it has not been observed or identified on the shoreline 

or riparian areas along either Lake Powell or any of the river corridors in the recreation area (NPS, 

Spence, pers. com., May 2002n). Its preferred elevation places it outside of the impact analysis area. 
Threatened, Endangered, and Special-Concern Species 

FINAL ENVIRONMENTAL IMPACT STATEMENT 119

KNOWN CONFLICTS WITH PERSONAL WATERCRAFT USERS 

Under current conditions there are no documented or incident reports of known conflicts of federally 

endangered fish or other species with watercraft or personal watercraft users (NPS, Spence, pers. com., 

April 2002m). Current watercraft use of any type has not been reported and is not considered to affect 

any endangered fish species in Lake Powell (Utah Division of Wildlife Resources, Gustaveson, pers. 

com., April 2002b). 
120 GLEN CANYON NATIONAL RECREATION AREA

SHORELINE VEGETATION 

More than 730 native species of plants have been identified in the recreation area. Shoreline vegetation 

is considered to include several types of vegetation communities, including submerged aquatic beds, 

wetlands, riparian areas or zones, beach dunes, and upland vegetation that grows near the shoreline. 

The shoreline zone as used in this document pertains to areas within 50 horizontal feet from the lake’s 

waterline. The area physically included in this zone changes as reservoir water levels change. The 

waterline fluctuates 50 feet vertically and 1,000 feet horizontally during a typical water year. Typical 

shoreline vegetation conditions are shown in figure 12. 

SUBMERGED AQUATIC VEGETATION 

Areas of submerged aquatic vegetation are generally scarce and poorly developed at the recreation 

area. Reasons for this condition include unstable water levels associated with reservoir operations for 

water supply, power generation, and flood storage; poor plant rooting conditions along the lake’s 

shorelines; very steep shoreline slopes; limited availability of low-gradient shorelines; and lack of 

suitable bottom conditions. 

Existing stands (or beds) of submerged aquatic vegetation are restricted to isolated small areas of the 

reservoir and tributary reaches where water clarity, shoreline slope, water depth, and permanence 

create conditions suitable for the development and maintenance of species such as leafy pondweed 

(Potamogeton foliosus), horned pondweed (Zannichellia palustris), and the exotic, spiny naiad (Najas 

marina). These aquatic species are present along shallow-water gradients on sandy substrate near 

Wahweap marina. In this area, spiny naiad has become more noticeable in recent years and seems to 

be slowly increasing its distribution (NPS, Spence, pers. com., May 2002n). There are no reported 

major or extensive distributions of this or other aquatic species in the recreation area. 

FIGURE 12: TYPICAL VEGETATION ALONG LAKE POWELL SHORELINES 
Shoreline Vegetation

FINAL ENVIRONMENTAL IMPACT STATEMENT 121

UPLAND SHORELINE COMMUNITIES 

Shoreline vegetation includes plant species that are associated with upland, beach dune, wetland, 

hanging-garden, and riparian locations near the land-water interface. Shoreline vegetation occurs along 

the main reservoir shoreline and along the tributary streams and rivers that flow into the reservoir. 

Water fluctuation and difficult rooting conditions combined with the desert climate, severely restrict 

development of shoreline and riparian vegetation. Consequently, most shorelines are either bare rock 

or unvegetated sand, gravel, or cobbles. The types of shoreline communities present in limited 

abundance are described below. 

Saltcedar (also commonly referred to as tamarisk), Russian thistle (Salsola kali), seepwillow 

(Baccharis glutinosa), and numerous weed species grow along the lake shoreline. The cottonwoodwillow-saltcedar floodplain association, which is the predominant shoreline vegetation complex that 

comprises almost 1,850 acres along waterways and sandy washes throughout the recreation area is 

described in the General Management Plan (NPS 1979a). These locations are generally small in size 

and scattered throughout various side canyons, coves and drainage outlets adjacent to the rivers and 

marinas. In these locations shoreline vegetation is primarily saltcedar. When the pool elevation of the 

lake drops and stays lowered for more than a year, some adjacent upland plant species such as Russian 

thistle and seepwillow invade the previously flooded area along the shoreline. 

When the lake level reaches maximum pool elevation, adjacent upland plant communities become part 

of the shoreline zone. The near-shore plant communities include both upland desert shrub-scrub and 

small, specialized or relict wetland plant communities called hanging gardens. The dominant species 

of the desert shrub-scrub community typically include the shrubs shadscale (Atriplex confertifolia), 

blackbrush (Coleogyne ramosissima) and sand sage (Artemisia filifolia). Some areas include a higher 

proportion of grass species and a different assemblage of shrub species. Species include Mormon tea 

(Ephedra torreyana), yucca (Yucca angustissima), snakeweed (Xanthocephalum microcephala), 

prickly pear (Opuntia ericacea), galleta (Hilaria jamesii), and Indian ricegrass (Oryzopsis 

hymenoides). 

The hanging garden community type is associated with seep seams and alcoves along canyon walls of 

the river drainages where groundwater seeps and drips from rock walls through cracks, providing a 

dependable water supply. This unique relict plant community is adapted to cool, wet conditions. 

Common plant species include maidenhair fern (Adiantum sp.), monkey flower (Mimulus spp.), white 

columbine (Aquilegia spp.), and California sawgrass (Cladium californica). One hanging garden 

community located on canyon walls near the confluence of the San Juan and the Colorado Rivers has 

been under consideration as a research natural area. These locations may occasionally become 

accessible to visitors in watercraft during high water periods. 

Lake beaches comprise about 3% of more than 1,900 miles of shoreline. Stabilized dunes support a 

relatively dense vegetation of sunflower (Vanclevea stylosa), mint (Poliomentha incana), Mormon tea 

(Ephedra viridis), and Indian ricegrass. Camelthorn (Alhagi camelorum), an invasive species, has 

spread onto the sandy beaches near Clay Hills and Great Bend. Some upland plant communities near 

the shoreline support desert shrub-scrub vegetation, which include shadscale, blackbrush, and sand 

sage. 

During periods of prolonged low-water, where soil texture and soil depth conditions allow, fastgrowing annual and perennial species quickly invade exposed shoreline areas, temporarily increase in 

number, and extent of ground cover, and later disappear when reservoir water level rises during the 

next filling or water storage period. These aggressive and fast-growing species are tolerant of such 
AFFECTED ENVIRONMENT

122 GLEN CANYON NATIONAL RECREATION AREA

environmental disturbance and can typically recover within one or two growing seasons. Saltcedar 

(Tamarix ramosissima) is one of the most common of these aggressive shrub species that forms bands 

along the shoreline. These bands range in density from thickets to isolated individual plants that 

develop in the water fluctuation zone on the banks of the reservoir in sandy or talus substrates. 

Vegetated areas within accessible shoreline areas experience periodic disturbance from visitor use. 

Vegetated areas located below the 3,700-foot elevation contour are susceptible to the disruptive effects 

of inundation. Livestock grazing has influenced the distribution of the mixed-desert shrub 

communities along some shorelines of the San Juan River inlet. 

RIPARIAN VEGETATION 

Riparian vegetation is considered a type of shoreline plant community. It is relatively rare along the 

main lake shorelines. Its abundance and distribution increase along river shorelines and in the upper 

ends of tributary side canyons, particularly where springs and streams are present. Riparian vegetation 

distribution along the banks of the tributary rivers is intermittent. It occupies portions of the 

southeastern side of the lake along the banks of the San Juan River near Clay Hills, Copper Canyon, 

Neskahi, and Paiute Canyon. On the southwestern side of the lake along the banks of the tributary 

inlets small linear riparian communities occur at Last Chance Canyon, Warm Creek, and Crosby 

Canyon. Extended flooding, frequent inundation and fluctuating water levels prevent formation of 

extensive riparian vegetation along the lake shoreline (NPS, Spence, pers. com., April 2002m). 

The riparian community is dominated by saltcedar (Tamarix ramosissima) with an understory of 

Russian thistle, horseweed (Conyza canadensis) jimsonweed (Datura metaloides), with some rubber 

rabbitbrush (Chrysothamnus nauseosus). Alluvial deposits near lower elevations of the river inlets are 

characterized by shadscale, Mormon tea and Indian ricegrass. Plant cover in alluvial areas ranges from 

10% to 15% in shallow wash channels (NPS 1988a). Native riparian species (e.g., cottonwood and 

willow) are not common along the lake although some may be present in the understory in stands of 

saltcedar (Waring 1992). More saltcedar is present along the lake shoreline and side canyons where 

harsher conditions are found (Waring 1992). Although saltcedar is often present along the shoreline 

below mean water levels, much of the shoreline is comprised of bedrock, which does not support 

riparian or other shoreline vegetation. 

Riverbank vegetation in the canyons consist of native cottonwood (Populus fremontii), coyote willow 

(Salix exigua), seepwillow (Baccharis salicina), Arctic rush (Juncus arcticus), and horsetail 

(Equisetum hyemale) (NPS 1995a). Vegetation densities are higher where there are permanent riparian 

communities. Other factors that affect the status of this community type include about 1% or 

1,000 acres of floodplain area has historically supported permitted livestock grazing (NPS 1979a). Of 

the scientifically important riparian communities nearly 200 acres are grazed (NPS 1999a). The 

Bureau of Land Management and National Park Service have jointly developed a grazing management 

plan to maintain and protect riparian vegetation (NPS 1999a). 

WETLANDS 

Wetlands communities are uncommon to rarely present along the lake shoreline throughout much of 

the recreation area. Wetlands associated with nine perennial tributaries and springs along Lake Powell 

contain more diversity and native species than riparian habitats along the lake shoreline (Waring 1992, 

Spence 1995a). These wetlands are comprised of dense stands of black willow (Salix gooddingii), 
Shoreline Vegetation

FINAL ENVIRONMENTAL IMPACT STATEMENT 123

coyote willow, cottonwood, boxelder (Acer negundo), cattails (Typha spp.), with various sedges 

(Carex spp.), and rushes (Juncus spp.). Emergent wetlands expand in size or develop in new areas 

when the lake level is dropped for several years in locations that expose soils with adequate soil 

moisture allowing colonization by these species. 

Small native wetland communities composed of annuals more characteristic of drier soils (such as 

Russian thistle and horseweed) are located along springs that drain into many of the more protected 

coves and side canyons such as Ticaboo Creek, Reflection Canyon, Slickrock Canyon, springs in Rock 

Creek, Oak Bay, Good Hope Bay and areas east of the confluence of Escalante River and south of 

Llewellyn Canyon (Waring 1992). Some wetlands may also be found along Copper Canyon Neskahi, 

Paiute Canyon of the San Juan, Crosby Canyon, and Dirty Devil (NPS 1988a). 

The development and long-term maintenance of wetland communities are dependent on the suitable 

combination and distribution of proper bottom or soil materials, bank slope, water depth, and timing of 

flooding. Lake level fluctuations may either flood or drain areas making them unsuitable for wetlands, 

even for the most flood or drought tolerant species. Some areas contain high saline soils that limit the 

development of many wetland species (NPS 1988a). 
124 GLEN CANYON NATIONAL RECREATION AREA

VISITOR USE AND EXPERIENCE 

Glen Canyon National Recreation Area is one of the premier water-based recreation areas in the 

country. It includes Lake Powell’s 160,000 surface acres and 1,960 miles of shoreline. The lake, its 

96 major side canyons, and related natural, cultural, and geologic resources are the primary recreation 

features of Glen Canyon National Recreation Area. 

A variety of recreational opportunities exist on and around the lake. Powerboating, using houseboats 

and personal watercraft, waterskiing, fishing, riding a tour boat, sailing, and kayaking are among the 

many water sports visitors enjoy. Opportunities also exist for hiking in the surrounding canyon areas, 

many of which are accessible for most visitors only by water. Visitors can enjoy camping 

opportunities ranging from remote and undeveloped campsites to fully developed campgrounds. 

Visitors can also see archeologically and culturally important sites throughout the recreation area. 

The lake occupies only about 13% of the recreation area. The remaining 87% offers backcountry 

experiences in a desert setting that is extraordinarily rugged and beautiful. However, because these 

experiences would not be affected by personal watercraft management except at locations within a 

mile or two of the lake, they were not considered in this analysis. 

WATERCRAFT USE AND DISTRIBUTION 

Boat days and watercraft operating hours were used as a basic unit of measurement of the intensity and 

impact of watercraft use. A boat day equals one watercraft on the lake during a 24-hour period. 

Watercraft operating hours are the average number of hours a vessel is underway during a 24-hour 

period.

A full description of the method used for calculating boat days is included in appendix E. Briefly, total 

annual boat days on Lake Powell were calculated by multiplying the total number of boats estimated 

to enter the recreation area by the average length of time boats spend on the lake during a visit 

(Henderson 2002). Data sources included the following. 

The total number of boats was estimated using boat rental, boat slip, and boat buoy data 

obtained from ARAMARK (the recreation area concession operator), and from NPS monthly 

entry and trailer counts gathered at the Wahweap, Lone Rock, Antelope Point, Bullfrog, Halls 

Crossing, and Hite launch areas. 

The average amount of time each watercraft spent on the lake was estimated by a University of 

Minnesota 2000 visitor survey report, in which watercraft users were asked how many nights 

they spent on the lake during their stay. 

Data was collected from Lake Mead, including vessel ratios and daily operating hours for each type of 

vessel, to estimate use by engine type on Lake Powell. Data from Lake Mead were obtained during an 

extensive boat use study in 1999 (Hagler Bailly 1999). The Lake Mead data are appropriate to apply to 

Lake Powell because the two lakes have very similar volumes, natural and socioeconomic 

environments, visitor uses, and types of activities (table 17). 
Visitor Use and Experience 

FINAL ENVIRONMENTAL IMPACT STATEMENT 125

TABLE 17: DISTRIBUTION OF ENGINE TYPES AND AVERAGE DAILY OPERATING HOURS PRESENT ON LAKE POWELL

Engine Type a/ 

Percent of Boat 

Days 

Number of Boat 

Days 

Operating Hours 

per Boat Day 

Total Operating 

Hours 

Outboard Engines 

 Carbureted two-stroke 6.1 50,696 2.9 147,018 

 Direct injection two-stroke 2.3 19,115 2.9 55,434 

 Electric fuel injection two-stroke 2.3 19,115 2.9 55,434 

 Carbureted or electric fuel 

injection four-stroke 4.7 39,061 2.9 113,277 

Inboard/Sterndrive 

 Carbureted or electric fuel 

injection four-stroke 52.3 434,654 4.7 2,042,874 

 Two-stroke carbureted jet drive 3.0 24,932 4.0 99,728 

 Diesel auxiliary sail 1.6 13,297 3.6 47,869 

Personal Watercraft 

 Carbureted two-stroke 24.0 199,459 2.4 478,702 

 Direct Injection two-stroke 1.8 14,959 2.7 40,389 

 Four-stroke 1.8 14,959 2.7 40,389 

Totals 99.90 830,247 — 3,121,114 

 

a. Average rated horsepower, percent of trips, hours per trip based upon Lake Mead values developed from the Hagler Bailly Report 

Total annual Glen Canyon National Recreation Area watercraft use in 2001 was 831,079 boat days 

(total boat days reported in table 17 vary from this because the figures in table 17 were derived from 

rounded boat day percentages). Watercraft were operated on the lake for a total 3,121,114 hours. There 

are several important characteristics of this use. 

Personal watercraft accounted for 26% of all boat days and 18% of all operating hours estimated 

in 2001. 

The visitor survey identified that typically, many watercraft are used by a large group of friends 

or family, and groups often include more than one boat type. Generally one boat type in the 

group is the primary watercraft. The most common primary watercraft are powerboats. The 

second most common primary watercraft are houseboats. 

It is common for houseboat and powerboat groups on Lake Powell to bring personal watercraft 

on their trips. Of all groups traveling on Lake Powell with houseboats, 39% also included at 

least one personal watercraft and 25% of all powerboat groups included at least one personal 

watercraft. 

Half of all respondents to the summer survey stated that they operated a personal watercraft 

during their visit. 

The distribution of types of watercraft is presented in table 18 (James et al. 2001a).The key points are 

that visitors have and use multiple types of watercraft, including personal watercraft, during a 

recreation trip, and personal watercraft use is not restricted to a specific user group. 
AFFECTED ENVIRONMENT

126 GLEN CANYON NATIONAL RECREATION AREA

TABLE 18: TYPES OF WATERCRAFT USED IN GLEN CANYON NATIONAL RECREATION AREA

Vessel Type 

All Watercraft on the Lakea 

(percentage) 

Groups with Type of Watercraftb

(percentage) 

Powerboat 56 84 

Personal watercraft 21 32 

Houseboat 20 29 

Kayak 1 1 

Other 1 1 

Inflatable toy 1 1 

Sailboat 1 1 

Raft (motor) 1 1 

Raft (no motor) Less than 1 Less than 1 

 

a. Values in the column total more than 100% because of rounding. 

b. Values in the column total more than 100% because many groups had more than one watercraft.

Watercraft use peaks in the months of May through October. In 2001, this six-month period accounted 

for 92% of all boat days. 

As shown in table 19, personal watercraft use in 2001 accounted for 26% of all boat days. Over the 

course of the year, personal watercraft use varied relative to other watercraft, from less than 5% of 

boat days from November through March to a peak of 38% of boat days in September. 

Overall boating use in visitor use zones is shown in figure 13. These zones were established for the 

lake carrying capacity studies completed in the early 1980s (NPS 1987b). The zones are defined 

generally by areas of physiographic change such as narrowing of the main channel, transition from a 

large bay segment to a segment of narrower main channel canyon, or major tributary canyons. The 

zones were developed only to analyze distribution of use on the lake and are not used for other 

management or enforcement purposes. Use of the lake by zone based on data collected in 2001 is 

provided in table 20. As shown in table 20: 

The distribution of personal watercraft use, as indicated by the percent use in each zone, is 

very similar to the distribution of use by other watercraft. 

The four zones near the marinas accounted for almost 60% of all watercraft use. These 

include: 

Wahweap (Zone 1, 26% of total boat days); 

Bullfrog and Halls Crossing (Zone 11, 12%); 

Hite (Zone 13, 11%); and 

Dangling Rope (Zone 6, 10%), which also includes access to Rainbow Bridge 

National Monument. 
Visitor Use and Experience 

FINAL ENVIRONMENTAL IMPACT STATEMENT 127

TABLE 19: ESTIMATES OF PERSONAL WATERCRAFT AND 

OTHER WATERCRAFT USE IN GLEN CANYON NATIONAL RECREATION AREA BY MONTH IN 2001a

 Other Watercraft Personal Watercraft All Watercraft 

Month 

Boat 

Days 

Monthly Use 

(percentage) 

Boat 

Days 

Monthly Use 

(percentage) 

Boat 

Days 

Annual Use 

(percentage) 

January 747 96 30 4 777 <1 

February 1,059 97 33 3 1,092 <1 

March 8,995 97 261 3 9,256 1 

April 18,686 94 1,122 6 19,808 2 

May 68,444 81 15,771 19 84,215 10 

June 137675 74 47,985 26 185,660 22 

July 113,984 70 48,600 30 162,584 20 

August 126,628 72 49,491 28 176,119 21 

September 80,045 62 49,883 38 129,928 16 

October 37,658 86 6,336 14 43,994 5 

November 11,946 96 445 4 12,391 2 

December 5,189 99 67 1 5,256 1 

Total 611,056 74 220,023 26 831,079 100 

 

a. Slight variations in some totals occur between table 19, table 20, and the text because of the calculations used to estimate use. However, 

these variations do not affect any of the percentages or conclusions. 

FIGURE 13: BOATING USE IN VISITOR USE ZONES
AFFECTED ENVIRONMENT

128 GLEN CANYON NATIONAL RECREATION AREA

TABLE 20: ESTIMATES OF PERSONAL WATERCRAFT AND OTHER WATERCRAFT USE BY ZONE IN 2001a

 Other Watercraft Personal Watercraft Total 

Lake Zone Boat Days Percent Boat Days Percent Boat Days Percent 

1 (includes Wahweap Marina) 159,647 26 52,729 24 212,436 26 

2 39,622 6 13,922 6 53,549 6 

3 48,950 8 16,470 8 65,435 8 

4 24,701 4 8,427 4 33,134 4 

5 21,098 3 7,636 3 28,734 3 

6 (includes Dangling Rope Marina) 63,872 10 23,038 10 86,910 10 

7 10,098 2 4,507 2 14,594 2 

8 644 1 70 1 716 1 

9 28,430 5 12,180 5 40,586 5 

10 25,279 4 9,628 4 34,901 4 

11 (includes Bullfrog and Halls 

Crossing Marinas) 

73,067 12 29,993 14 103,016 12 

12 47,597 8 19,607 9 67,174 8 

13 (includes Hite Marina) 68,054 11 21,812 10 89,900 11 

Total 611,056 100 220,023 100 831,079 100 

 

a. Slight variations in some totals occur between table 19, table 20, and the text because of the calculations used to estimate use. However, 

these variations do not affect any of the percentages or conclusions. 

The lowest use occurred in Zone 8, which includes the San Juan arm of Lake Powell upstream from 

Great Bend. This zone experiences fewer than 1,000 boat days of use per year, and accounts for only 

70 personal watercraft boat days annually. 

Watercraft use of the lake originates primarily from the four marinas at Wahweap, Bullfrog, Halls 

Crossing, and Hite, and the two launch ramps at Antelope Point and Stateline. From the marinas, 

watercraft users distribute themselves throughout the lake to popular destinations. As shown in the 

table 20 data, many visitors remain in the vicinity of the marinas. However, because of the availability 

of marinas with fueling stations along the length of the lake (including the floating marina at Dangling 

Rope), houseboats and powerboats have access to and can travel to any point on the lake. Because 

personal watercraft often are towed or carried by these vessels, personal watercraft also have access to 

remote areas of the lake. 

Use of Tributary Canyons 

The National Park Service does not collect data on the distribution of watercraft within each lake zone. 

Therefore, it was necessary to estimate watercraft use in the upper reaches of the Escalante, San Juan, 

Dirty Devil, and Colorado Rivers within the recreation area. The distribution of personal watercraft 

and other watercraft in the upper arms of the rivers was estimated using University of Minnesota 

summer 2000 survey data, and through conversations with staff from the recreation area, Bureau of 

Land Management, the Utah Division of Parks and Recreation, and Canyonlands National Park. 
Visitor Use and Experience 

FINAL ENVIRONMENTAL IMPACT STATEMENT 129

Estimates of personal watercraft and other watercraft were made for each river portion of the lake 

from the point where downstream current is no longer measurable to the points noted in table 21. 

Additionally, on the Colorado and San Juan Rivers, estimates were made of the number of boats per 

day entering the recreation area by water from outside of the recreation area boundary. 

The estimates in table 21 represent instantaneous counts, rather than a total daily number of vessels 

visiting each area. For example, during the high-use season, an observer on the Dirty Devil usually 

would be able to see between 4 and 20 watercraft at a time. Typically, half of these would be personal 

watercraft. Over the course of a day, perhaps 50 entrances and exits by motorcraft of the observed area 

may occur, with a very large percentage of those vessels being the same visitors motoring in and out 

(Schulman 2002b). 

Tributary Canyon Use Originating from Outside of the Recreation Area 

Boating use originates from outside of Glen Canyon National Recreation Area on the San Juan and 

Colorado Rivers. Numbers of boats entering Glen Canyon National Recreation Area annually on the 

Colorado and San Juan Rivers in 2000 and 2001 are shown in table 22. On both rivers, boating use 

occurs in private and commercial watercraft. Vessels include motorized craft and several types of 

human powered craft, including whitewater rafts and kayaks. 

The Bureau of Land Management issues permits for river trips on the San Juan River. Usually, such 

trips originate from the Bureau of Land Management’s Sand Island Recreation Site (river mile 0) or 

Mexican Hat (river mile 27). They usually end at Clay Hills Crossing (river mile 84) within Glen 

Canyon National Recreation Area (Bureau of Land Management, Berkenfield, letter, May 2002). 

TABLE 21: ESTIMATED NUMBERS OF WATERCRAFT TYPICALLY OBSERVABLE 

ON THE TRIBUTARY RIVERS TO LAKE POWELL

High-Use Seasona Low-Use Seasona

River Arm of 

Lake Powell Location 

Personal 

Watercraft 

All Other 

Watercraft 

Personal 

Watercraft 

All Other 

Watercraft 

Upper Colorado River In Cataract Canyon, upriver from 

Sheep Canyon 

<1 <1 <1 <1 

Dirty Devil River Upriver from the Highway 95 Bridge 2–10 2–10 <1 <1 

San Juan River Upriver from Clay Hills Crossing <1 <1 <1 <1 

Escalante River Upriver from Cow Canyon 2–10 2–10 <1 <1 

 

a. High season: months of May through October. Low season: months of November through April. 

TABLE 22: BOATS PER YEAR ENTERING GLEN CANYON NATIONAL RECREATION AREA

ON THE COLORADO AND SAN JUAN RIVERS, 2000 AND 2001 

Location 2000 2001 

Colorado River – from within Canyonlands National Park to Hite Marina 2,250 2,335 

San Juan River – from all points upstream to Clay Hills Crossing 494 564 
AFFECTED ENVIRONMENT

130 GLEN CANYON NATIONAL RECREATION AREA

Canyonlands National Park issues permits for trips on the Colorado River that originate within 

Canyonlands National Park. Typically, such trips end within Glen Canyon at Hite (Utah Department 

of Environmental Quality, Water Quality Division, Moellmer, pers. com., January 2003a). Permits are 

not issued to personal watercraft users, as this use is not permitted on the rivers in Canyonlands 

National Park. 

Personal watercraft are prohibited on the Colorado River within Canyonlands National Park. Personal 

watercraft are allowed on the San Juan River. However, because they must carry a toilet and a spare 

means of propulsion and can only travel at flat-wake speed, the use of personal watercraft on this river 

is highly unusual. 

WATERCRAFT USER MOTIVATIONS, SATISFACTION, AND CONFLICTS 

Desired Experiences 

Personal watercraft users and other watercraft users come to Glen Canyon National Recreation Area 

with motives for and expectations about their visit. These reflect visitor’s desired experiences and 

indicate the basis for a satisfactory visit. 

Respondents to the University of Minnesota summer 2000 watercraft survey (James et al. 2001a) 

described their motives for visiting the recreation area. Respondents were also asked to rate the 

importance of experiences they may have had while visiting the area on a scale of 1 through 5. Using 

this scale, 1 was very unimportant, 2 was unimportant, 3 was neither important or unimportant 4 was 

important, and 5 was very important. The responses to several of the survey questions are presented in 

appendix D.2. 

According to the survey, little difference exists between the desired experiences of personal watercraft 

users and other watercraft users. Among the most important were to “enjoy the scenery of Lake 

Powell,” “do something with my family,” “get away from the usual demands of life,” “be with 

members of my group,” “be with people who enjoy the same things I do,” and “experience nature.” 

(table D.2.1 in appendix D). 

Trip Satisfaction 

Most visitors, including those using personal watercraft and other watercraft, reported that they 

successfully attained their desired experiences. As a result, visitors overwhelmingly were satisfied 

with their visit to Glen Canyon National Recreation Area. 

Experiences receiving a moderate level of attainment were to “experience solitude,” “be away from 

other people,” and “be on my own” (table D.2.2). These results indicate that lake use levels may be too 

high for some visitors. There were no significant differences in experience attainment found between 

personal watercraft operators and operators of other types of watercraft (James et al. 2001a). 

Perception of Conflict 

Visitors who responded to the survey did not experience many problems during their visits 

(table D.2.3). The four situations that were most frequently identified as problems included “finding a 

beach campsite,” “finding an unoccupied site,” “litter on beaches and shoreline,” and “people being 
Visitor Use and Experience 

FINAL ENVIRONMENTAL IMPACT STATEMENT 131

inconsiderate.” The study noted that although these were the most often identified, the mean rating on 

a scale of 1 (no problem) to 5 (very serious problem) was 2.1 or lower, indicating a slight problem. 

Several questions targeted feelings about the use of personal watercraft and feelings about the use of 

other types of watercraft. These questions, with the mean responses from all visitors and the separate 

means for personal watercraft users and users of other watercraft, are shown in table 23. As shown in 

table 23, the two groups of users responded very similarly to questions relating to all motorcraft. 

However, when the same questions were asked just about personal watercraft, the users of other types 

of vessels perceived problems at a statistically significant higher level than did users of personal 

watercraft. 

The personal watercraft users rated both of the areas of potential conflict relating to personal 

watercraft as being no problem or a slight problem. 

Other motorcraft users perceived personal watercraft as representing a slight to moderate

problem for both questions. 

The same trend occurred in response to possible management actions. Complete information on 

responses to questions about possible management actions are provided in table D.2.4 and are 

summarized in table 24. As shown in the table 24: 

Among potential actions that would apply to all users, the differences in responses between 

operators of personal watercraft and other watercraft never differed by more than 0.3 points. 

Both groups almost equally favored providing information about appropriate behavior; 

enforcing safety rules and regulations; and protecting the environment and sensitive resources, 

even if it involved controls and “off-limit” zones. Both groups almost equally opposed actions 

that would limit or prohibit the use of motorized watercraft. 

In all three questions involving management of personal watercraft, the answers given by users 

of other watercraft were 0.8 to 1.0 points higher than those from personal watercraft users. Even 

so, operators of other watercraft did not want to prohibit the use of personal watercraft on Lake 

Powell. 

TABLE 23: PERCEPTION OF CONFLICT BY USERS OF 

PERSONAL WATERCRAFT AND OTHER WATERCRAFT

Experience 

Overall 

Meana

Personal Watercraft 

Operators Mean 

Other Watercraft 

Operators Mean 

Relating to all motorcraft 

Unsafe operation of motorized boats 1.7 1.6 1.8 

Too many motorized boats on the lake 1.6 1.6 1.7 

Relating to personal watercraft 

Unsafe operation of personal watercraft 2.0 1.7 2.4 

Too many personal watercraft on the lake 1.9 1.5 2.3 

 

a. 1 = No problem 

 2 = Slight problem 

 3 = Moderate problem 

 4 = Serious problem 

 5 = Very serious problem. 
AFFECTED ENVIRONMENT

132 GLEN CANYON NATIONAL RECREATION AREA

TABLE 24: SUPPORT FOR POSSIBLE MANAGEMENT ACTIONS 

BY PERSONAL WATERCRAFT AND OTHER WATERCRAFT USERS

Experience 

Overall 

Meana

Personal 

Watercraft 

Operators Mean 

Other 

Watercraft 

Operators Mean 

Relating to all motorcraft 

Provide more information to visitors about appropriate behavior 4.0 3.9 4.1 

Aggressively enforce safety regulations, laws, and rules on lake 3.7 3.7 3.8 

Use management controls to prevent damage to the environment 

by visitors 

3.7 3.7 3.8 

Use management controls to prevent conflicts between lake 

users 

3.3 3.2 3.5 

Establish “off-limit” zones to protect sensitive resources 3.2b 3.3 3.3 

Require visitors to learn about appropriate behavior on the lake 

(e.g., watch a short video presentation) 

3.0 2.9 3.2 

Limit number of boats allowed on lake 2.4 2.3 2.4 

Limit number of motorized watercraft allowed on lake at any one 

time 

2.4 2.1 2.4 

Prohibit motorized watercraft on the lake 1.4 1.4 1.5 

Relating to personal watercraft 

Restrict personal watercraft use to designated areas only 2.7 2.2 3.3 

Limit number of personal watercraft allowed on lake at any one 

time 

2.6 2.1 2.9 

Prohibit personal watercraft on the lake 1.9 1.5 2.3 

 

a. 1 = Strongly oppose 

 2 = Oppose 

 3 = Neither support nor oppose 

 4 = Support 

 5 = Strongly support. 

b. Value was copied accurately from the source (James et al. 2001a), which may have had an averaging error. 

Based on the survey, the perception of conflict was slightly higher among users of other motorcraft 

than among personal watercraft users, and the users of other motorcraft were more likely to favor 

additional controls on personal watercraft. These differences were statistically significant. However, 

both groups consider personal watercraft as an appropriate use of the lake and expressed a high level 

of satisfaction with their visit. 

PERSONAL WATERCRAFT AND OTHER WATERCRAFT USE TRENDS 

Personal watercraft use trends were developed to define characteristics of personal watercraft activities 

and to evaluate the effects of management strategies on recreation area resources. Characteristics of 

other watercraft use patterns were identified to help understand the cumulative effects of both classes 

of watercraft. Understanding such relationships is important because personal watercraft are often used 

in conjunction with powerboats and houseboats. Use trends of personal watercraft and other vessels 

were determined using: 

Data available from the recreation area; 

Discussions with staff; 

Research from the University of Minnesota (James et al. 2001a); and National and state trends. 
Visitor Use and Experience 

FINAL ENVIRONMENTAL IMPACT STATEMENT 133

Pattern of Visitation at Glen Canyon National Recreation Area 

Each year, the National Park Service estimates visitation at Glen Canyon National Recreation Area. 

Data sources include vehicle traffic counts at entry stations and trailer counts at marinas and 

campgrounds. More than 2 million people visit the recreation area each year. 

Personal watercraft and all other watercraft use varies by season. The high-use season includes the 

months of May through October and the low-use season includes the months of November through 

April. As shown in table 19, more than 90% of boat days in 2001 occurred during the high-use season. 

This is a typical use pattern for Lake Powell. 

Since 1995, total recreation area visitation for all types of uses has shown an average annual decrease 

of 1.05%. The average decrease since 1995 for the peak visitor use months of May through October 

has been slightly higher, at 1.5% annually. 

Data are not collected annually that show changes in personal watercraft versus the use of other 

watercraft. However, because so many visitors use both types of vessels, annual changes probably are 

similar for these two vessel types (Arizona Game and Fish Department, Harris, pers. com., April 

2002). 

Many factors could affect future visitation at Glen Canyon National Recreation Area. Some of these 

could include the economy, the price of gasoline, and climatic conditions that control the volume of 

water in the lake. Most projections indicate that no changes to recreation area visitation will occur over 

the next 10 years. 

Comparative National Park Visitation Trends 

An analysis of use trends within units of the national park system indicates that over the past decade 

use within NPS units increased on average by 0.3% per year. Parks with characteristics similar to Glen 

Canyon (e.g., water-based, seashores and lakeshores, recreation areas, western parks, or large popular 

parks) experience average annual use increases 0.25% over the past decade. Similarly, use at the 

personal watercraft regulatory units increased by an average 0.26% annually. Use change in these 

parks ranged from 9.2% average growth at Cape Lookout National Seashore to 4.8% annual decline at 

Big Horn Canyon National Recreation Area. It is expected, for the purposes of analyses within this 

document, that there would be a change in total boat days and watercraft operating hours of between 

–2% and +2% annually over the next 10 years (see appendix F). 

National and State Boating Trends 

National personal watercraft sales increased every year between 1991 (68,000 units) and 1995 

(200,000 units). They then declined so that only 92,000 units were sold in 2000 (National Marine 

Manufacturers Association 2001a) Sales for all boats displayed a similar trend. 

Regionally, boat registrations grew from 1995 to 1999 for Arizona, Colorado, and Utah, the primary 

states of origin for Glen Canyon boaters. Annual growth rates ranged from 0.5% in Utah to 3.4% in 

Colorado (table 25). 
AFFECTED ENVIRONMENT

134 GLEN CANYON NATIONAL RECREATION AREA

TABLE 25: BOAT REGISTRATIONS BY STATE, 1995 THROUGH 1999 

State 1995 1996 1997 1998 1999 

Average 

Annual Change 

(percent) 

Arizona 145,156 150,107 155,010 158,726 153,517 1.45 

Colorado 88,565 95,140 95,924 98,190 101,137 3.40 

Utah 75,748 71,688 74,288 76,346 77,171 0.53 

 

Source: National Marine Manufacturers Association 2000. 

According to the National Marine Manufacturers Association (National Association of State Boating 

Law Administrators 2001a), boating participation on a national level declined slightly from 1997 to 

2000. This same source says that that on average, the availability of free time for Americans was in 

smaller time blocks and, therefore, it was likely that boaters would rely increasingly on water bodies 

and recreation opportunities that were closer to home and required less travel time. 

According to James et al. (2001a), the average length of stay on Lake Powell is 4 nights. Therefore, 

visits to Glen Canyon National Recreation Area require a substantial commitment of time, both for 

travel and for time spent at the recreation area. National trends suggest that in the future, some 

individuals may be less able to commit this amount of time for a trip to Glen Canyon National 

Recreation Area. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 135

VISITOR CONFLICTS AND VISITOR SAFETY 

SAFETY REQUIREMENTS 

Within Glen Canyon National Recreation Area, personal watercraft users are required to comply with 

all applicable federal and state boating laws, rules, and regulations. A summary of the personal 

watercraft regulations, laws, and rules for Arizona and Utah is provided in table 4. Complete personal 

watercraft regulations for the two states are provided in appendix B. 

Personal watercraft users must comply with regulations of the state in which they are operating. 

Because about 95% of Lake Powell is in Utah, most personal watercraft users are subject to Utah laws 

and rules. 

NPS rangers enforce watercraft regulations lake-wide. They use the applicable state regulations, 

provisions of Title 36 CFR Part 7.70, and the United States Coast Guard regulations contained in Title 

33 CFR. State enforcement personnel also patrol the waters and enforce their respective state 

regulations, laws, and rules. 

The superintendent's compendium for Glen Canyon National Recreation Area is established under the 

authority of Title 16 U.S.C., section 3, and Title 36, CFR, Chapter 1, Parts 1 through 7. The 

compendium establishes a broad range of regulations and restrictions on use activities within the 

recreation area. Section 3.6 (Prohibited Operations) applies specific regulations related to watercraft 

safety, and includes the following items within Lake Powell. 

Prohibits operating a vessel in excess of 5 miles per hour or creating a wake in the following 

areas: 

Within harbors, mooring areas, and designated flat-wake areas. 

Within any other “flat-wake” buoyed area. 

Prohibits personal watercraft use: 

From further upstream travel along portions of the Escalante, San Juan, Colorado, and 

Dirty Devil Rivers. 

Launching and retrieval of personal watercraft is permitted at the following locations: 

All public launch ramps. 

The area of beach within Lone Rock off-road use area. 

Vessels up to 25 feet at Lone Rock Beach. 

The beach areas legally accessible by motor vehicles at the primitive camping area of 

Stanton Creek, Upper Bullfrog North, and Upper Bullfrog South. 

San Juan River take-out at Clay Hills Crossing. 

Red Canyon. 
AFFECTED ENVIRONMENT

136 GLEN CANYON NATIONAL RECREATION AREA

Paiute Farms area. 

Hite, from 300 feet upstream of the public launch ramp to 300 feet upstream of the 

marina houseboat loading dock. 

White Canyon area. 

ACCIDENTS 

Watercraft Accidents at Glen Canyon National Recreation Area 

Table 26 summarizes watercraft accident records for Glen Canyon National Recreation Area for the 

three-year period from 1999 through 2001. The percentages can be compared to personal watercraft 

use, which in 2001 represented 18% of all boat operating hours on Lake Powell. Key features include 

the following. 

There were 811 reported boating accidents in Glen Canyon National Recreation Area over the 

three-year period, for an average of 270 per year. This is an average of 1.5 boating accidents 

each day over the six-month high-use period from May through October that accounts for 92% 

of all boat-use days on Lake Powell. 

Personal watercraft represented about 14% of all accidents, or slightly under the proportion of 

all watercraft operating hours (18% of all watercraft operating hours). 

Personal watercraft were involved in only 5% of the property damage accidents. 

Personal watercraft users experienced personal injuries at a higher rate (20% of all accidents) 

than their proportion of accidents (14% of all accidents). However, the injury rate for personal 

watercraft operators was generally equivalent to the proportion of all watercraft operating hours 

that are attributed to personal watercraft (18%). 

TABLE 26: SUMMARY OF WATERCRAFT ACCIDENT RECORDS FOR 

GLEN CANYON NATIONAL RECREATION AREA, 1999 THROUGH 2001 

 1999 2000 2001 Total 

 Number Percent Number Percent Number Percent Number Percent 

All accidents 272 — 284 — 255 — 811 — 

Personal watercraft 32 12 51 18 32 13 115 14 

Other vessels 240 88 233 82 223 87 696 86 

Property damage 

accidents 

124 — 136 — 104 — 364 — 

Personal watercraft 6 5 7 5 4 4 17 5 

Other vessels 118 95 129 95 100 96 347 95 

Personal injury accidents 147 — 147 — 150 — 444 — 

Personal watercraft 26 18 35 24 28 19 89 20 

Other vessels 121 82 112 76 122 81 355 80 

Fatal accidents 1 — 1 — 1 — 3 — 

Personal watercraft 0 0 1 100 0 0 1 33 

Other vessels 1 100 0 0 1 100 2 67 

 

Source: NPS 2001c; U.S. Coast Guard Boating Statistics 2001. 
Visitor Conflicts and Visitor Safety 

FINAL ENVIRONMENTAL IMPACT STATEMENT 137

More than 77% of all personal watercraft accidents resulted in injuries. In contrast, 51% of 

accidents involving other watercraft resulted in personal injuries. 

There was one death of a personal watercraft operator over the three-year period, and two deaths 

involving other types of vessels. The low total of three fatal accidents for all watercraft over this 

period precludes meaningful analysis. 

Glen Canyon National Recreation Area data collection efforts did not attempt to define reasons for 

each personal watercraft accident. However, personal watercraft violations relating to accidents 

included underage operation; unsafe speeds; unsafe proximity to other vessels, objects, and other 

visitors; and lack of personal flotation devices. 

In each of the three years, approximately half of the injury accidents involving personal watercraft 

required emergency medical service. Comparative data for other watercraft were not available. 

National and State Watercraft Accidents 

Nationally in 2000, there were 4,355 reported boating accidents that resulted in personal injury (NPS 

2002d). Approximately 80% of all reported injuries were associated with the use of open motorboats 

(44%) and personal watercraft (36%). Broken bones accounted for the highest number of injuries 

resulting from personal watercraft use. 

The same source reported that in 2000, there were 701 reported fatalities associated with boating 

nationwide. Personal watercraft accounted for 10% of these deaths. 

This report may have underreported personal injury accidents. The ratio of personal injury to fatal 

accidents calculated from this source was 6.2 to 1, compared to a ratio of almost 150 to 1 at Lake 

Powell. However, the information in this study on the causes and outcomes of accidents are useful for 

indicating conditions that typically occur with motorcraft use. 

Increased personal watercraft use in recent years has resulted in more concern about the health and 

safety of operators, swimmers, snorkelers, divers, and other boaters. A 1998 National Transportation 

Safety Board study revealed that while recreational boating fatalities have been declining in recent 

years, personal watercraft-related fatalities have increased (NTSB 1998). Nationwide personal 

watercraft accident statistics provided by the U.S. Coast Guard support the increase in personal 

watercraft-related fatalities (see table 2); however, since a peak of 84 personal watercraft-related 

fatalities in 1997, accidents, injuries, and fatalities involving personal watercraft have decreased (M. 

Schmidt, U.S. Coast Guard [USCG], pers. comm., Sept. 4, 2001). The U.S. Coast Guard’s Office of 

Boating Safety studied exposure data to assess boating risks. This method allows for a comparison 

between boat types based on comparable time in the water. Personal watercraft use ranked second in 

boat type for fatalities per million hours of exposure in 1998, with a 0.24 death rate per million 

exposure hours. 

Industry representatives report that personal watercraft accidents decreased in some states in the late 

1990s.

Two national studies of personal watercraft accidents and injuries report that personal watercraft pose 

a health and safety risk, primarily to operators (Branche et al. 1997; National Transportation Safety 

Board 1998). The National Transportation Safety Board (1998) reported that: 
AFFECTED ENVIRONMENT

138 GLEN CANYON NATIONAL RECREATION AREA

In 1996, personal watercraft represented 7.5% of state-registered recreational boats but 

accounted for 36% of recreational boating accidents. 

In the same year, personal watercraft operators accounted for more than 41% of people injured 

in boating accidents. 

In 1997, personal watercraft operators accounted for approximately 85% of the people injured 

in accidents studied. 

These rates of accidents and injuries are much higher than those recorded in Glen Canyon National 

Recreation Area in the 1999 through 2001 period. 

Since personal watercraft operators can be as young as 12 in several states, accidents can involve 

children. The American Academy of Pediatrics (2000) recommends that no one younger than the age 

of 16 operate personal watercraft. Some manufacturing changes on throttle and steering may reduce 

potential accidents. For example, on more recent models, Sea-Doo developed an off-power assisted 

steering system that helps steer during off-power as well as off-throttle situations. This system, 

according to company literature, is designed to provide additional maneuverability and improve the 

rate of deceleration (Sea-Doo 2001a). 

Personal watercraft accident rates in Utah have declined since 1995 largely due to enactment of laws 

and rules governing the age of personal watercraft users and implementation of an aggressive 

education and certification program. Accident data from Utah in the early 1990s indicated that 

personal watercraft accidents were increasing. In 1994 and 1995, personal watercraft accidents 

constituted 53% of the total accidents, exceeding the number of traditional boating accidents (Utah 

Division of Parks and Recreation 2002). In 1995, Utah implemented a new law requiring personal 

watercraft users between the ages of 12 and 17 possess a personal watercraft education certificate and 

those between 12 and 15 operate under adult supervision (Utah 73-18-15.2). Since the inception of 

Utah’s personal watercraft specific laws, the number of personal watercraft accidents has declined 

significantly. Two years following the inception of the new law, personal watercraft accidents declined 

by 59%. In 2001, personal watercraft made up approximately 6% of the total watercraft registered 

(79,264) in Utah (Millard 2003). Personal watercraft accidents at this time were 50% lower than those 

reported in 1995 and constituted 34% of the total boating accidents (Utah Division of Parks and 

Recreation 2002). 

Fatalities Involving Carbon Monoxide 

There has been only one reported fatality caused by carbon monoxide poisoning involving a personal 

watercraft on Lake Powell. An individual on a broken-down personal watercraft died from carbon 

monoxide poisoning while being towed to shore behind a motorboat (Henderson 2002). Nationally, of 

the 701 boating fatalities reported in 2000, five deaths were attributed to carbon monoxide. None of 

these involved personal watercraft use (NPS 2001e). 

VISITOR USE SURVEY INFORMATION AND PERCEPTIONS OF USE AND SAFETY 

The summer 2000 visitor survey (James et al. 2001a) included visitors’ perceptions of safety and 

identification of safety problems. The results are provided in table D.2.3 in appendix D. 
Visitor Conflicts and Visitor Safety 

FINAL ENVIRONMENTAL IMPACT STATEMENT 139

The scores for safety-related questions from the survey are summarized in table 27. As shown in the 

table, respondents did not experience many problem situations during their visit. The highest-ranked 

safety concerns were “people being inconsiderate” and “unsafe operation of personal watercraft,” both 

of which scored as “slight” problems. For these and the concern “boats closer to my boat than I like,” 

the difference in responses between personal watercraft users and users of other watercraft was 

statistically significant. For all three questions, personal watercraft users perceived a lower level of 

concern than other watercraft users. 

Visitors also were asked whether they observed unsafe boating practices, and whether they felt safe 

during their visit (James et al. 2001b). 

In answer to the question “Did you observe any unsafe boating practices on your most recent 

visit to Glen Canyon National Recreation Area?” Thirty-five percent of respondents stated 

seeing unsafe boating practices. Fewer personal watercraft operators reported seeing unsafe 

boating practices than did other watercraft operators. Unsafe boating practices reported by 

respondents included excessive speed, traveling too close to other boats or swimmers, jumping 

wakes, and lack of personal floatation devices. 

In answer to the question “Did you feel safe on your most recent visit to Glen Canyon National 

Recreation Area?” Ninety-two percent of respondents stated that they felt safe during their visit. 

There was a statistically significant difference between personal watercraft operators and other 

watercraft operators, with 3% of personal watercraft operators reporting that they felt unsafe 

compared to 13% of other visitors. 

EDUCATION 

Personal watercraft users visiting Glen Canyon National Recreation Area are informed of the 

watercraft regulations that apply to Lake Powell and are provided with general safety information. 

Literature containing information about general watercraft safety is provided to visitors at the entrance 

gates, visitor centers, and recreation area headquarters, and on the recreation area website. No 

information is provided that specifically addresses safety issues for personal watercraft. 

TABLE 27: PERCEPTION OF SAFETY CONCERNS 

BY USERS OF GLEN CANYON NATIONAL RECREATION AREA 

Safety Concern Meana

Serious or Very Serious Problem 

(percent) 

People being inconsiderateb 2.0 12 

Unsafe operation of personal watercraft 2.0 14 

Boats closer to my boat than I like 1.9 12 

Unsafe operation of motorized boats 1.7 5 

Conflicts with personal watercraft operators on lake 1.7 10 

Sufficient navigational aids on Lake Powell 1.5 5 

Confusion about rules and regulations 1.5 5 

 

a. Means are based on a 5-point scale: 

 1 = no problem 

 2 = slight problem 

 3 = moderate problem 

 4 = serious problem 

 5 = very serious problem. 

b. Bold font = statistically significant difference in responses between personal watercraft users and users of other watercraft.
140 GLEN CANYON NATIONAL RECREATION AREA

CULTURAL RESOURCES 

Cultural resources have been divided into: 

Prehistoric and historic archeological resources, including resources that were submerged when 

Lake Powell was filled; 

Historic resources, including trails; 

Cultural landscapes; and 

Ethnographic resources, including traditional cultural properties and Native American concerns. 

Museum collections also are a cultural resource. However, because there are no museum collections 

within the project area or its general vicinity, this topic is not addressed. 

“Historic properties” include cultural resources that are listed in, or eligible for listing in, the National 

Register of Historic Places. 

The following sections briefly describe the cultural resources in the area that potentially could be 

affected by personal watercraft management alternatives.

ARCHEOLOGICAL RESOURCES 

The recreation area contains evidence of human occupation during the Paleoindian Period, dating back 

to about 11,500 years before present. Later Archaic peoples moved across the landscape in a seasonal 

pattern as they hunted, gathered foodstuffs, and collected specialized subsistence items. During 

Pueblo II times, the lowland canyon systems were heavily settled, and regional sites include small 

storage areas and kivas. Parts of the canyonlands region have evidence of frequent use for quarrying, 

hunting, and other subsistence activities. 

The general abandonment of the region coincides with that of the northern Ancestral Pueblo areas in 

the late A.D. 1200s. Decreases in population in the canyonlands began slightly earlier than in areas 

further north. These population shifts may have been caused by environmental changes or protohistoric use of the area by Navajo and other Indian groups. 

Euro-Americans have lived in this area for more than 200 years. Their archeological remains are 

discussed in the “Historic Resources” section. 

A total of 429 cultural resource sites have been documented within a half mile of the full pool 

elevation of 3,700 feet above sea level. In addition, three known sites are located below the full-pool 

line, but are submerged and re-exposed every year as the lake level rises with spring runoff and 

declines as water is released through the dam. 

Of the 429 documented sites, 74 have documented human impacts. Eleven sites have been severely 

affected, 43 have experienced moderate effects, 9 have minimal (low) effects, and the degree of effects 

is unknown for 11 sites. However, it is likely that many additional sites have been impacted by 

visitation for the following reasons. 
Cultural Resources 

FINAL ENVIRONMENTAL IMPACT STATEMENT 141

Many of the sites within the area of potential effect were documented prior to collecting impact 

data, and most have not been revisited by qualified cultural resource specialists since they were 

originally documented. 

Submerged sites are likely to have had severe impacts from erosion, boat wakes and wave 

action, repeated wet/dry cycles, boat beaching, and artifact collecting. 

Although the exact number is undetermined, historic and prehistoric archeological sites are present on 

the Navajo Reservation in areas adjacent to the lake. These sites also have been affected by vandalism, 

unauthorized collecting, and natural causes such as erosion (Navajo Nation, Maltonado, pers. com., 

April 2002). 

HISTORIC RESOURCES 

The recreation area’s historic resources include historic structures, trails, cultural landscapes 

(described below), and archeological sites (discussed above). Spanish records document the 1776 

journey of Dominguez and Escalante through this general area. A century later, Charles Hall, a skilled 

carpenter and one of the founders of Escalante, Utah, was one of the first pioneers to settle in southern 

Utah. In the early 1870s he built a ferry to cross the Colorado River at the Hole-in-the-Rock area, and 

operated it with his two sons until 1880 when he moved his business 35 miles upstream to the present 

site of Halls Crossing. The original site continued to be used as a gateway for gold-seekers and 

explorers into Glen Canyon for many years. 

Hole-in-the-Rock is a culturally enhanced natural crevice in the west rim of Glen Canyon. During the 

late 1870s, few Mormon families had settled in the region east of the Colorado River, so the Mormon 

Church organized the San Juan Mission to select a site for settlement in this region. The pioneers 

chose the shortest route, leading first to a rendezvous point at Forty-Mile Spring, south of the town of 

Escalante, then down the Hole-in-the-Rock and across the Colorado River 2.5 miles below the mouth 

of the Escalante River. 

The short-cut was deceptive, and a six-week journey became a six-month ordeal. Using hand tools and 

limited quantities of blasting powder, the pioneers worked though the winter of 1879 to enlarge the 

narrow crack in the canyon wall. Slowly and laboriously they lowered their wagons down the 

precipitous 25- to 45-degree slopes to cross the Colorado River, only to discover a rough, perilous, 

uncharted wilderness ahead. Most of the rugged trail is still visible today, both at the Hole-in-the-Rock 

site and in Cottonwood Canyon. 

On the first of his two trips down the Colorado River in 1869, John Wesley Powell and his 

companions saw and described many of the local features. However the area was largely unknown to 

most until the construction of the Glen Canyon Dam from 1956 to 1962. 

CULTURAL LANDSCAPES 

Cultural landscapes represent a complex of cultural resources within a discrete geographic area. Their 

natural and cultural elements reflect human adaptation and resource use associated with a historic 

activity, event, or person. Cultural landscapes may be expressed in a variety of ways, such as patterns 

of settlement or land use, systems of circulation and transportation, buildings and structures, or parks 
AFFECTED ENVIRONMENT

142 GLEN CANYON NATIONAL RECREATION AREA

and open spaces. The National Park Service recognizes four categories: historic designated landscapes, 

historic vernacular landscapes, ethnographic landscapes, and historic sites. 

Ethnographic landscapes are associated with contemporary groups and typically are used or valued in 

traditional ways. No ethnographic landscapes have been formally identified within the recreation area. 

However, as discussed under “Ethnographic Resources,” the recreation area’s geographic features and 

natural landscapes are important to Native Americans. 

The Hole-in-the-Rock area is not formally defined as a cultural landscape. However, it is an important 

historic site whose broad viewsheds, scarred slopes, and trail remnants connote the hardships and 

determination of the pioneer Mormon families who traversed this rugged area. 

ETHNOGRAPHIC RESOURCES 

Ethnographic resources include traditional cultural properties, a class of cultural resource that 

specifically was addressed in the 1992 amendments to the National Historic Preservation Act. 

Traditional cultural properties or places are locations of special heritage value to contemporary 

communities (often, but not necessarily, Native American groups) because of their association with 

the cultural practices or beliefs rooted in the histories of those communities. Thus, they are important 

in maintaining the communities' cultural identities. 

No traditional cultural properties have been formally defined within a half-mile of Lake Powell’s full 

pool elevation of 3,700 feet above sea level. However, many of the recreation area resources are 

considered sacred by Native Americans. These particularly include the Colorado and San Juan Rivers, 

their side canyons, and landscapes in which they occur. 

Five contemporary Native American tribes are associated with the recreation area. They include the 

Hopi, Kaibab Paiute, Navajo, San Juan Southern Paiute, and Ute Mountain Ute. Glen Canyon National 

Recreation Area also deals with several other tribes or bands because of past environmental documents 

and ethnographic research. These include the Kanosh and Koosharem Bands of the Paiute Indian Tribe 

of Utah. The Havasupai and Hualapai claim affiliation to the Colorado River below the dam. Each 

tribe has its own account of its history and relationships with other tribes and groups that can be only 

partially supplemented by archeological research. 

Programmatic agreements have been formalized for several areas within the recreation area. 

Consultations with tribes are on-going. 

NATIONAL REGISTER OF HISTORIC PLACES 

AND NATIONAL HISTORIC LANDMARK PROPERTIES 

There are no National Historic Landmark properties within the area of potential effect. Four features 

within a half-mile of Lake Powell’s full pool elevation of 3,700 feet are listed on the National Register 

of Historic Places. They include: 

The Davis Gulch pictographs; 

Defiance House Ruin; 
Cultural Resources 

FINAL ENVIRONMENTAL IMPACT STATEMENT 143

Hole-in-the-Rock; and 

The Hole-in-the-Rock Trail. 

PAST CULTURAL RESOURCE INVESTIGATIONS 

Only about 2% of Glen Canyon National Recreation Area has been surveyed for cultural resources. 

Most of the surveys have been in canyon areas. 

A partial listing of past archeological investigations within Glen Canyon National Recreation Area at 

20 shoreline areas that are accessible by automobile is included in the Environmental Assessment and 

Management/Development Concept Plans for Lake Powell’s Accessible Shorelines (NPS 1988a). 

Ethnographic studies (NPS, Sucec, 1996a and 1996b) provide information that has been used to 

support recreation area planning, research, resource management, and interpretive programs. 
144 GLEN CANYON NATIONAL RECREATION AREA

SOCIOECONOMIC ENVIRONMENT 

Glen Canyon National Recreation Area includes more than 1.25 million acres in southern Utah and 

northern Arizona surrounding Lake Powell. The city of Page, Arizona, which is about 2 miles from 

Glen Canyon Dam, is the closest community to the recreation area (see the Glen Canyon National 

Recreation Area Vicinity map) and is the primary gateway community. 

There are essentially no other opportunities for personal watercraft use in areas near Glen Canyon 

National Recreation Area. The closest alternative is Lake Mead National Recreation Area, which is 

approximately 300 miles away. Other areas used by personal watercraft include several small water 

bodies north and east of Glen Canyon National Recreation Area which is nearly 400 miles from Page, 

Arizona (Utah Division of Parks and Recreation 2003). 

The National Park Service contracted for preparation of the report, Economic Analyses of Personal 

Watercraft Regulations in Glen Canyon National Recreation Area (Law Engineering and 

Environmental Sciences, Inc. 2003). Relevant sections of that report are summarized here. 

Visitation to Glen Canyon National Recreation Area ranged between 2.3 and 2.7 million visitors 

annually from 1995 to 2001. Most recreation area visitors (83%) are from Utah, Colorado, and 

Arizona (James et al. 2001b). 

Glen Canyon National Recreation Area is a very popular destination for personal watercraft use. 

According to two surveys, up to 50% of visitors operate personal watercraft during their visit (James 

et al. 2001a; Douglas et al. n.d.). Based on year 2001 visitation of approximately 2.3 million people, 

about 936,000 people used personal watercraft in Glen Canyon National Recreation Area. 

James et al. (2001b) found that only 22% of personal watercraft users identified personal watercraft as 

their primary watercraft used while in Glen Canyon National Recreation Area. The most common 

primary watercraft are powerboats. The second most common primary watercraft are houseboats. It is 

common for houseboat and powerboat groups on Lake Powell to bring personal watercraft on their 

trips. Of all groups traveling on Lake Powell with houseboats, 39% also included at least one personal 

watercraft and 25% of all powerboat groups included at least one personal watercraft. 

PERSONAL WATERCRAFT OWNERSHIP AND RENTAL 

Ownership and rental estimates for personal watercraft used at Glen Canyon National Recreation Area 

are shown in table 28. The ownership and rental values in the table were calculated by applying survey 

results from James et al. (2001b), which showed that about 90% of personal watercraft users in the 

recreation area own their vessel and 10% use rentals, to counts of recreation area visitation and 

personal watercraft boat days. (A boat day equals one watercraft on the lake during a 24-hour period.) 

The calculations of boat days assumed that the number of personal watercraft boat days is distributed 

evenly between rented and personally owned machines. Boat days are defined as the number of 

vessels multiplied by the number of days spent in the recreation area. 

Many visitors trailer personal watercraft to Glen Canyon National Recreation Area from substantial 

distances. One survey estimated that the average distance traveled by visitors to Glen Canyon National 

Recreation Area was 255 miles (Douglas et al. n.d.). 
Socioeconomic Environment 

FINAL ENVIRONMENTAL IMPACT STATEMENT 145

TABLE 28: OWNERSHIP AND RENTAL ESTIMATES FOR PERSONAL WATERCRAFT

Ownership of 

Personal Watercraft 

Visitors Using 

Personal Watercraft 

Personal Watercraft 

Boat Days 

Owned by User 842,411 198,113 

Rented 93,601 22,013 

Total 936,012 220,126 

Annual Rental of Personal Watercraft in Gateway Communities 

Counts of personal watercraft entrance by area of Glen Canyon National Recreation Area indicated 

that about 65% of personal watercraft rentals originated in Page (Law Engineering and Environmental 

Sciences, Inc. 2003). This indicates that there were about 14,300 days of personal watercraft rentals in 

Page in 2001. 

Annual Purchases of Personal Watercraft in Gateway Communities 

Douglas and Harpman (n.d.) estimated the number of unique households that visit Glen Canyon 

National Recreation Area in a year. They used the annual recreation area-wide visitor count and 

applied values obtained from their survey, including: 

The average number of trips to Glen Canyon National Recreation Area per household per year 

(4.1385) and 

The average number of people per household (4.2358). 

For 2001, their calculation suggested that about 133,500 unique households visited Glen Canyon 

National Recreation Area. 

If 40% of the households used personal watercraft and 90% of those used their own vessels, visitors to 

Glen Canyon National Recreation Area own about 48,000 personal watercraft. Assuming that personal 

watercraft are replaced every three years, about 16,000 personal watercraft that are used at Glen 

Canyon National Recreation Area are purchased annually. Based on interviews with local dealerships, 

it appears that 2% of these personal watercraft, or 320 machines, are purchased in Page. 

Businesses Supported by Personal Watercraft Use 

The NPS study identified 11 businesses in Page, Arizona that rent, sell, or service personal watercraft. 

Eight of these businesses rent personal watercraft, three of them sell personal watercraft, and seven 

provide personal watercraft service. Two rental shops were also identified in Big Water, Utah. Most of 

these businesses also provide services for activities other than the use of personal watercraft, such as 

boat rentals, campgrounds, boat and personal watercraft storage, and fuel. 

As indicated by the presence of seven businesses that provide maintenance, personal watercraft 

servicing can be an important economic activity. Because the average visitor travels more than 

250 miles to Glen Canyon National Recreation Area, an inoperative personal watercraft either must be 

serviced locally or cannot be used for the remainder of the visit. 
AFFECTED ENVIRONMENT

146 GLEN CANYON NATIONAL RECREATION AREA

Interviews with local businesses suggest that approximately 95% of all rented personal watercraft used 

on Lake Powell are rented in the local area, including businesses in Page, Big Water, or marinas on 

Lake Powell. The remaining 5% come from businesses that are located relatively far away from Glen 

Canyon National Recreation Area. 

A personal watercraft rental shop with business linked to Glen Canyon National Recreation Area was 

identified in Salt Lake City, Utah (about 390 miles from Glen Canyon Dam). The owner reported that 

approximately 40% of personal watercraft rentals from his shop are to customers who trailer them to 

Glen Canyon National Recreation Area. This business indicated that approximately six businesses in 

the Salt Lake City area rent to customers who take them to Glen Canyon National Recreation Area. 

Another rental shop was identified in Phoenix, Arizona, which is about 275 miles from Glen Canyon 

Dam. Similar to the store in Salt Lake City, the Phoenix shop owner attributed approximately 35% to 

40% of his personal watercraft rentals to Glen Canyon National Recreation Area visitors. 

The National Park Service contacted a business that rents personal watercraft in St. George, Utah, 

which is about 150 miles from Glen Canyon Dam. This business indicated that up to 80% of its 

personal watercraft rental business is related to Glen Canyon National Recreation Area. 

All of the businesses in Page and Big Water reported that visitors to Glen Canyon National Recreation 

Area were the sole source of their business. This was expected, because there are no nearby alternative 

areas for personal watercraft use. 

OTHER EXPENDITURES IN THE PAGE AREA 

According to James et al. (2001b), most visitors stay on the lake or at lodging or campgrounds within 

Glen Canyon National Recreation Area. About 10% of recreation area visitors stay in hotels outside of 

the recreation area during their visit. Eight hotels in Page account for the majority of hotel stays in the 

area. 

Restaurants in the Page area primarily depend on visitors to recreation area. Their patrons include not 

only visitors who are staying in Page hotels, but also those who are using camping or lodging facilities 

inside the recreation area and travel out for a meal. A substantial number of restaurant patrons are in 

transit between the recreation area and their homes. 

Only limited supplies are available at the marinas within Glen Canyon National Recreation Area. 

Many visitors buy their groceries, gasoline, and other supplies at stores in Page. 

DEMOGRAPHY AND ECONOMY 

Glen Canyon National Recreation Area includes part of four counties in Utah and one county in 

Arizona. Selected demographic and economic information for the five counties and two states is 

provided in table 29. 
FINAL 

ENVIRONMENTAL MPACT ISTATEMENT 147

TABLE 29: DEMOGRAPHIC AND ECONOMIC SUMMARY FOR STATES AND COUNTIES ADJOINING GLEN CANYON NATIONAL RECREAT

 Utah 

Garfield Co. 

Utah 

Kane Co. 

Utah 

San Juan Co. 

Utah 

Wayne Co. 

Utah Arizon

Population 2000 2,233,169 4,735 6,046 14,413 2,509 5,130,632 Population 1990 1,722,850 3,980 5,169 12,621 2,177 3,665,339 Percent change 1990 to 2000 29.6 19.0 17.0 14.2 15.3 40.0 Ethnic composition 

White 89.2 95.0 96.0 40.8 97.3 75.5 Native American 1.3 1.8 1.6 55.7 0.4 5.0 Other backgrounds 9.5 3.2 2.4 3.5 2.3 19.5 Also Latino or Hispanic heritage 

9.0 2.9 2.3 3.7 2.0 25.3 

Per capita income, 1997 $20,185 $16,392 $18,258 $11,090 $15,014 $21,998 Civilian labor force 1999 1,083,912 

(49% of population) 

2,698 (57% of population) 

2,695 (45% of population) 

4,920 (34% of population) 

1,419 (56% of population) 

2,363,705 (46% of population) 

Employed by government 17.2% 19.2% 22.5% 32.9% 20.9% 14.2% Unemployment 3.7% 8.3% 4.0% 7.9% 5.9% 4.4% 

Retail sales per capita, 1997 $9,666 $4,021 $5,760 $2,491 $4,124 $9,657 Land area, square miles 82,144 5,174 3,992 7,820 2,460 113,635 Persons per square mile 27.2 0.9 1.5 1.8 1.0 45.2 a. Source: U.S. Census Bureau’s FedStats site (http://www.fedstats.gov). 
AFFECTED ENVIRONMENT

148 GLEN CANYON NATIONAL RECREATION AREA

The Arizona portion of Glen Canyon National Recreation Area is in Coconino County. Coconino 

County encompasses 18,617 square miles, and is the largest county in Arizona and the second largest 

county in the United States. The county seat is in Flagstaff, about 135 miles south of the Glen Canyon 

Dam area. 

The year 2000 population of Coconino County was 116,320 people. This was a 20% increase 

from the year 1990 number. The population of the county grew at about half the rate of the state 

of Arizona, which saw a population increase of 40% over the decade. 

About 63% of the county’s citizens identified themselves as white. American Indians constituted 

28.5% of the population. The remaining 9.5% of the population identified other ethnic 

backgrounds. About 11% of residents identified themselves as also having Latino or Hispanic 

heritage. 

Per capita income in 1997 was $18,180. This was 17% below the state average of $22,000. 

However, retail sales per capita were similar to the statewide value. 

The civilian labor force in 1999 was about 59,100 people, and represented 51% of the county’s 

population. Almost 25% of these people worked for local, state, or federal government agencies. 

Unemployment in 1999 was about 6.8%, which was higher than the state rate of 4.4%. 

Population density was quite low, at 6.2 people per square mile. The Arizona average is more 

than 45 people per square mile. 

The city of Page was founded to provide housing for workers during construction of the dam, and has 

evolved into the gateway community for Glen Canyon National Recreation Area facilities near the 

dam. 

In 1990, the population of Page was 6,598 people. The year 2000 census showed that Page grew 3.2% 

over the decade, to a population of 6,809. Tourism and power generation are the largest sources of 

revenue in Page. The largest employers are Lake Powell Resorts and Marinas, the Navajo Generating 

Station, and the Page Unified School District. 

The four Utah counties include Garfield, Kane, San Juan, and Wayne. All four counties are very 

sparsely populated (all have fewer than 2 people per square mile) and are largely agricultural, with 

some tourism that is generated primarily from their proximity to Glen Canyon National Recreation 

Area and other NPS units. 

The combined populations of the four counties in 2000 was just under 24,000 people. All four 

counties grew between 14% and 19% in the preceding decade, well below the Utah average of 

29.6%. 

Within San Juan County, which includes part of the Navajo Indian Reservation, more than 55% 

of the residents identified themselves as Native American and about 40% identified themselves 

as white. In the other three counties, 95% or more of the residents identified themselves as 

white. The percentage of residents identifying themselves as also having Latino or Hispanic 

heritage ranged from 2.0% to 3.7%. 

Per capita income in 1997 ranged from $18,258 in Kane County to $11,090 in San Juan County. 

In all four counties, per capita income was lower than the Utah average of $20,185. Retail sales 
Socioeconomic Environment 

FINAL ENVIRONMENTAL IMPACT STATEMENT 149

per capita also were low compared to the statewide average of $9,666, ranging from $2,491 in 

San Juan County to $5,760 in Kane County. 

The percentage of the population in the labor force ranged from 34% for San Juan County to 

57% in Garfield County. Throughout the state, the labor force represents about 49% of the 

population. The portion of the labor force that worked for local, state, or federal government 

agencies was about 33% in San Juan County and around 20% in the other counties. Statewide, 

the value was 17.2%. Unemployment in the four counties ranged from 4.0% in Kane County to 

8.3% in Garfield County. 

There are no large population centers in any of these counties. Some of the closer communities to Glen 

Canyon National Recreation Area with populations between 100 and 1,000 include Big Water, 

Blanding, Boulder, Escalante, Hanksviille, Kanab, Mexican Hat, Monticello, and Ticaboo. 
150 GLEN CANYON NATIONAL RECREATION AREA

RECREATION AREA MANAGEMENT AND OPERATIONS 

Management of personal watercraft in the recreation area requires the participation of seven recreation 

area divisions. They include the superintendent’s office, administration, visitor protection, 

interpretation, maintenance, concessions, and resource management. The superintendent’s office and 

the administration division do not expend resources directly to manage personal watercraft. Instead, 

they provide support for the other divisions in their management of personal watercraft use and other 

activities in the recreation area. 

Other agencies also provide management services within the recreation area that may be affected by 

changes in personal watercraft management. These agencies at both the federal and state level 

coordinate closely with the National Park Service. 

The following is a description of the federal and state operations that are involved in the management 

of personal watercraft at Glen Canyon National Recreation Area. 

VISITOR PROTECTION 

Personal watercraft users in the recreation area must comply with Coast Guard boating requirements, 

and with the regulations, laws, and rules set forth by Arizona and Utah while operating on the waters 

within these states. These regulations, laws, and rules are enforced by several agencies, including the 

National Park Service, U.S. Coast Guard, Arizona State Parks and Recreation, Arizona Game and Fish 

Department, Utah State Parks and Recreation, and Utah Department of Natural Resources. 

Federal officers, including NPS rangers and U.S. Coast Guard employees, enforce both federal and 

state regulations, laws, and rules. For areas such as personal watercraft use where there are no federal 

requirements, the federal officers enforce the applicable state regulations (NPS 2002s). State 

requirements for personal watercraft are presented in appendix B and summarized in table 4. Utah’s 

standards generally are more strict than those of Arizona and include age, education, and insurance 

requirements as well as prohibitions on personal watercraft use between sunset and sunrise. 

The states also provide officers, such as state park rangers or conservation officers, to enforce state 

boating laws. Currently, four full-time boat patrol officers from Utah State Parks and Recreation and 

two full-time boat patrol officers from Arizona Game and Fish Department are assigned to enforce 

state boating laws in the recreation area. 

Glen Canyon National Recreation Area normally employs between 25 and 30 permanent rangers who 

patrol and enforce boating laws, including personal watercraft regulations. During high-visitor-use 

periods, the recreation area typically hires about 10 seasonal employees to support existing 

enforcement staff. 

Patrol staff are divided into two districts, uplake and downlake. The districts are divided into seven 

subdistricts on the lake, five of which are actively involved with enforcing personal watercraft 

regulations. 

The distribution of enforcement staff is based on levels of visitor use and the frequency of problems. 

Table 30 shows the distribution of law enforcement rangers in the summer (NPS, Mayer, pers. com., 

April 2002k) compared to watercraft use (from table 20). As shown in table 30, almost half of the law 

enforcement staff is assigned to the Wahweap subdistrict, which accounts for about a quarter of the 

use both by personal watercraft and other watercraft. The Hite area has the lowest number of rangers 

relative to use levels. 
Socioeconomic Environment 

FINAL ENVIRONMENTAL IMPACT STATEMENT 151

TABLE 30: SUMMER DISTRIBUTION OF NATIONAL PARK SERVICE 

LAW ENFORCEMENT RANGERS COMPARED TO LAKE USE LEVELS

Subdistrict 

Number 

of Rangers 

Watercraft Use 

(percent) 

Wahweap 17 26 

Bullfrog 9 12 (combined with Halls Crossing) 

Halls Crossing 4 12 (combined with Bullfrog) 

Dangling Rope 3 10 

Hite 2 11 

NPS rangers are responsible for ensuring the safety of visitors and for protecting recreation area 

resources on both land and water. This presents a challenge because most visitor activity is waterbased while about 85% of the recreation area is dry land. Land-based areas of concentrated visitor 

activity, such as the boat launches and campgrounds, require disproportionate commitments of NPS 

enforcement staff. During high-visitor-use periods, the major land-based developed areas at both the 

uplake and downlake districts require approximately 80% of the patrol staff’s time (NPS, Hibbs, pers. 

com., April 2002i; NPS, Mayer, pers. com., April 2002k). 

During the high-use period, only 20% of recreation area visitor protection staff time can focus on 

water-based activities. As a result, visitor protection on the lake tends to be reactive, with rangers 

responding to accidents or incidents when they occur. As shown in table 26, 14% of accidents on the 

lake involve personal watercraft and 86% involve other vessels. 

INTERPRETATION 

Development and dissemination of materials related to recreation area resources, visitor activities, and 

visitor safety and conflict is provided by the interpretive division. During the high-use season, the 

recreation area employs about 25 interpretive staffers, including 7 full-time and 18 season workers, to 

interact with the public. This interaction occurs at the visitor centers at Wahweap and Bullfrog, at 

presentations such as those regularly scheduled at the Wahweap Amphitheatre, and during personal 

contacts with interpretive rangers throughout the recreation area. Information pertaining to recreation 

area resources and visitor activities also is available through non-personal media such as the recreation 

area newspaper and brochure. These are available to visitors at all entry points and at other developed 

sites throughout the recreation area. 

It is the responsibility of the visitor to know all applicable boating rules and regulations. The 

recreation area provides information regarding boating regulations and general boating safety at 

numerous locations and in various forms. Some of these include: 

Printed information detailing safe use of watercraft, which is included in the recreation area 

brochure and newspaper. These are distributed at entry gates and are available at visitor centers, 

marinas, and recreation area headquarters. 

Displays at locations throughout the recreation area that illustrate proper and improper behavior 

while using a motorized vessel. 

Federal and state boating regulations, laws, and rules, which are available at ranger stations and 

on the recreation area’s website. 
AFFECTED ENVIRONMENT

152 GLEN CANYON NATIONAL RECREATION AREA

MAINTENANCE 

There are about 50 permanent and 20 seasonal maintenance employees in the recreation area. In 

conjunction with their other duties, they perform a variety of services related to personal watercraft 

use. These include, but are not limited to, facilities upkeep, sign construction and repair, dock repair, 

maintenance and placement of navigational devices such as buoys according to changes in lake level, 

and sanitation services. 

CONCESSIONS 

The concessions division manages the concessions program, including concessions contracts, in the 

recreation area. Its staff includes one seasonal and 11 permanent positions. The primary concessioner 

in the recreation area is ARAMARK Leisure Services, Inc., which operates under three contracts. 

These include separate contracts for uplake and downlake services and a contract for raft trips 

downstream from the dam. This concessioner provides many services for personal watercraft users, 

including as fueling stations and personal watercraft rental and repair. 

In 2001, personal watercraft constituted approximately 8% of the concessioner’s total rental fleet (NPS 

2001d). These vessels were available for rent at the Bullfrog, Hall Crossing, and Wahweap marinas. 

Incidental business permits are issued to authorize and document commercial activities occurring 

within Glen Canyon National Recreation Area. Currently, the recreation area has issued 160 incidental 

business permits to companies that provide a wide variety of services (NPS, Schreier, pers. com., June 

2002o). Some of these that relate to personal watercraft include launch and retrieval services for 

private vessels and repair services. 

RESOURCE MANAGEMENT 

The resource management division protects and monitors natural and cultural resources. Its staff of 10 

full-time and up to 10 seasonal employees includes terrestrial and aquatic biologists, archeologists, 

and geographic information system specialists. 

Among other responsibilities, this staff provides monitoring to ensure that the recreation area meets 

state and federal water quality standards. This includes monitoring lake water for Escherichia coli

(E. coli) under the direction of the Technical Advisory Committee. The current level of effort involves 

two resource management division staff members collecting samples twice a year. 

ENFORCEMENT CASES 

Table 31 shows law enforcement cases involving watercraft at Glen Canyon National Recreation Area 

for the three-year period, 1999 through 2001. Definitions for terms used in this table included the 

following. 

Cases included incidents plus accidents. All cases required that action to be taken by federal or 

state visitor protection personnel. 
Socioeconomic Environment 

FINAL ENVIRONMENTAL IMPACT STATEMENT 153

TABLE 31: SUMMARY OF WATERCRAFT ENFORCEMENT CASES FOR 

GLEN CANYON NATIONAL RECREATION AREA, 1999 THROUGH 2001 

 1999 2000 2001 Total 

 Number Percent Number Percent Number Percent Number Percent 

All cases 1,316 100 1,814 100 1,057 100 4,187 100 

Personal watercraft 212 16 304 17 118 11 634 15 

Other vessels 1,104 84 1,510 83 939 89 3,553 85 

Incidents 1,044 79 1,530 84 802 76 3,376 81 

Personal watercraft 180 14 253 14 86 8 519 12 

Other vessels 864 66 1,277 70 716 68 2,857 68 

Accidents 272 21 284 16 255 24 811 19 

Personal watercraft 32 2 51 3 32 3 115 3 

Other vessels 240 18 233 13 223 21 696 17 

All incidents 1,044 100 1,530 100 802 100 3,376 100 

Personal watercraft 

without death, injury 

or property damage 

180 17 253 17 86 11 519 15 

Other vessels without 

death, injury or 

property damage 

784 75 1198 78 613 76 2,595 77 

Personal watercraft 

property damage 

0 0 0 0 0 0 0 0 

Other vessels 

property damage 

4 <1 4 <1 4 <1 12 <1 

Personal injury 

incident (vessel type 

not specified) 

69 7 70 5 93 12 232 7 

Personal watercraft 

fatal 

0 0 0 0 0 0 0 0 

Other vessels fatal 7 1 5 <1 6 1 18 1 

All accidents 272 100 284 100 255 100 811 100 

Personal watercraft 

property damage 

6 2 7 2 4 2 17 2 

Other vessels 

property damage 

118 43 129 45 100 39 347 43 

Personal watercraft 

injury 

26 10 35 12 28 11 89 11 

Other vessels injury 121 44 112 40 122 48 355 44 

Personal watercraft 

fatal 

0 0 1 <1 0 0 1 <1 

Other vessels fatal 1 <1 0 1 <1 2 <1 

 

Source: NPS 2001c. U.S. Coast Guard Boating Statistics 2001. 
AFFECTED ENVIRONMENT

154 GLEN CANYON NATIONAL RECREATION AREA

Incidents were events on the water that were not related to a vessel in motion. Within this 

category, there were fatal incidents that resulted in death but were not caused by a vessel in 

motion (for example, a drowning of a person swimming from an anchored boat), property 

damage only incidents, and personal injury incidents. 

Accidents were events on the water that were a result of a vessel in motion. Fatal accidents 

resulted in a death that involved a vessel in motion in some way. There also were property 

damage only accidents, and personal injury accidents. 

The percentages in table 31 can be compared to personal watercraft use, which in 2001 represented 

26% of all boat days and 18% of all operating hours on Lake Powell. Key features of the accident data 

were provided previously in table 26. The following focuses primarily on the case and incident data. 

There were 4,187 reported boating cases in Glen Canyon National Recreation Area over the 

three-year period, for an average of 1,396 per year. This is an average of 7.75 boating cases each 

day over the six-month high-use period from May through October that accounts for 9% of all 

boat-use days on Lake Powell. 

Personal watercraft averaged 15% of all cases, 15% of all incidents, and 14% of all accidents. 

All of these values are slightly under the proportion of watercraft operating hours attributed to 

personal watercraft (18% of all watercraft operating hours). 

Among all enforcement cases, 81% were incidents and 19% were accidents. These values 

closely matched the personal watercraft data, where 82% of cases were incidents and 18% were 

accidents. 

Personal watercraft did not account for any property damage or any fatal incidents over the three-year 

period. 
Socioeconomic Environment 

FINAL ENVIRONMENTAL IMPACT STATEMENT 155

Environmental Consequences 

Divider 

This page to be removed 

Needs to be an odd page 
AFFECTED ENVIRONMENT

156 GLEN CANYON NATIONAL RECREATION AREA
FINAL ENVIRONMENTAL IMPACT STATEMENT 157

Table 5 provides a summary of the environmental effects of each of the personal watercraft 

management alternatives on each impact topic. Detailed descriptions of the effects evaluation are 

provided in this section. 

SUMMARY OF LAWS AND POLICIES 

Three overarching environmental protection laws and policies guide the National Park Service - the 

National Environmental Policy Act of 1969, and its implementing regulations; the National Parks 

Omnibus Management Act of 1998; and the National Park Service Organic Act. 

The National Environmental Policy Act is implemented through regulations of the Council on 

Environmental Quality (40 CFR 1500–1508). The National Park Service has in turn adopted 

procedures to comply with National Environmental Policy Act and the CEQ regulations, as found in 

Director’s Order 12 and Handbook: Conservation Planning, Environmental Impact Analysis, and 

Decision Making (2001b), and its accompanying handbook. 

The National Parks Omnibus Management Act of 1998 (Title 16 U.S.C. 5901 et seq.) underscores the 

National Environmental Policy Act in that both are fundamental to NPS management decisions. Both 

acts provide direction for articulating and connecting the ultimate resource management decision to 

the analysis of impacts, using appropriate technical and scientific information. Both also recognize 

that such data may not be readily available, and they provide options for resource impact analysis 

should this be the case. 

The Omnibus Act directs the National Park Service to obtain scientific and technical information for 

analysis. The NPS handbook for Director’s Order 12 (NPS 2001b) states that if “such information 

cannot be obtained due to excessive cost or technical impossibility, the proposed alternative for 

decision will be modified to eliminate the action causing the unknown or uncertain impact or other 

alternatives will be selected” (section 4.4). Section 4.5 of the Director’s Order 12 handbook adds to 

this guidance by stating “when it is not possible to modify alternatives to eliminate an activity with 

unknown or uncertain potential impacts, and such information is essential to making a well-reasoned 

decision, the National Park Service will follow the provisions of the regulations of Council on 

Environmental Quality (40 CFR 1502.22).” In summary, the National Park Service must state in an 

environmental assessment or impact statement: 

Whether such information is incomplete or unavailable; 

The relevance of the incomplete or unavailable information to evaluating reasonably foreseeable 

significant adverse impacts on the human environment; 

A summary of existing credible scientific adverse impacts which is relevant to evaluating the 

reasonably foreseeable significant adverse impacts; and 

An evaluation of such impacts based upon theoretical approaches or research methods generally 

accepted in the scientific community. 

The 1916 National Park Service Organic Act (Title 16 U.S.C. 1) commits the National Park Service to 

making informed decisions that perpetuate the conservation and protection of park resources 

unimpaired for the benefit and enjoyment of future generations. 
158 GLEN CANYON NATIONAL RECREATIONAL AREA

GENERAL METHODOLOGY FOR ESTABLISHING 

IMPACT THRESHOLDS AND MEASURING EFFECTS 

GENERAL ANALYSIS METHOD 

While much has been observed and documented about the overall effects of personal watercraft on the 

environment, as well as public safety concerns, the site-specific impacts, or impacts on any particular 

resource, under all conditions and scenarios are more difficult to measure and affirm with absolute 

confidence. Even with monitoring, data collected and interpreted since personal watercraft were 

introduced in parks, and their effects on recreation area resources relative to other uses and influences, 

are difficult to define and quantitatively measure. 

Recognizing this dilemma, the interdisciplinary planning team created a process for impact 

assessment, based upon the directives of the Director’s Order 12 handbook (section 4.5(g)). 

For each impact topic, applicable regulations were identified and the techniques used to perform the 

analysis were defined. Each impact topic analysis then involved the following steps. 

Define issues of concern, based on public scoping. 

Identify the geographic area that could be affected. 

Define the resource within the area that could be affected. This information was included in the 

“Affected Environment” chapter. 

Compare the resources to the area of potential effect. 

Identify the effects caused by the alternative, in comparison to the baseline represented by the 

continuation of management practices outlined in the Superintendent’s Compendium (NPS 2002c), to 

determine the relative change in resource conditions. Characterize the effects based on the following 

factors: 

Whether the effect would be beneficial or adverse. 

The area affected by the alternative’s effects, such as local or regional. 

Duration of the effect, either short term or long term. Unless an impact-topic-specific definition 

of these terms is provided, the following were used. 

A short-term impact would last only a few days or weeks. 

A long-term impact would last several years or more, or would recur periodically over 

several years. 

Whether the effect would be a direct result of the action or would occur indirectly because of a change 

to another impact topic. An example of an indirect impact would be increased mortality of an aquatic 

species that would occur because an alternative would increase soil erosion, which would reduce water 

quality. 
General Methodology for Establishing Impact Thresholds and Measuring Effects 

FINAL ENVIRONMENTAL IMPACT STATEMENT 159

The intensity of the effect, either negligible, minor, moderate, or major. Impact-topic-specific 

thresholds for each of these classifications are provided in each impact topic methodology section. 

Threshold values were developed based on federal and state standards, consultation with regulators 

from applicable agencies, and discussions with subject matter experts. 

Determine whether impairment would occur to resources and values that are considered necessary and 

appropriate to fulfill the purposes of Glen Canyon National Recreation Area. 

Determine cumulative effects by evaluating the effect in conjunction with the past, current, or 

foreseeable future actions for Glen Canyon National Recreation Area and the region. 

If appropriate, identify mitigation measures that may be employed to offset potential adverse impacts. 

ASSUMPTIONS 

Several assumptions were used in evaluating the effects of personal watercraft management on Glen 

Canyon National Recreation Area. These assumptions were applied to all of the impact topics unless 

otherwise noted. 

Analysis Period 

The analysis period is 10 years (2002 to 2012). This management action would not produce any new 

changes after that length of time. Changes after that period would be the result of market and 

regulatory factors beyond the influence of this management action. 

Analysis Area 

Unless otherwise specified, the impact analysis area includes the entire recreation area upstream of 

Glen Canyon Dam, with detailed attention being focused on the area within 500 horizontal feet of the 

maximum pool elevation of 3,700 feet above sea level. The area downstream of the Glen Canyon Dam 

was not included in the analysis area because it is already closed to personal watercraft use. 

Level of Use and Distribution by Watercraft Type 

For all alternatives, it was assumed that there would be a change in total boat days and watercraft 

operating hours of between –2% and +2% annually over the next 10 years. A boat day equals one 

watercraft on the lake during a 24-hour period and watercraft operating hours are the average number 

of hours a vessel is underway during a 24-hour period. The proportion of use by watercraft on the lake 

was not expected to change over the analysis period. Therefore, for these alternatives, 26% of boat 

days and 18% of the operating hours would be personal watercraft, 72% of boat days and 82% of the 

operating hours would be other motorized watercraft, and 2% of the total boat days would be nonmotorized craft. 

It was also assumed that the removal of personal watercraft in alternative C would result in an initial 

decrease in annual boat days in the short-term. However, by the end of the 10-year analysis period, the 

total number of watercraft operating hours and the total number of motorized watercraft using Lake 
ENVIRONMENTAL CONSEQUENCES

160 GLEN CANYON NATIONAL RECREATIONAL AREA

Powell under alternative C would be within the range predicted for alternatives A and B. This would 

be due to either natural growth in visitation, to visitors finding other watercraft to fulfill functions 

previously served by personal watercraft, or to increases in visitation by individuals who previously 

avoided the recreation area due to personal watercraft and now choose to visit in their absence. This 

was the same assumption that was used for the other impact topics.

Engine Emissions 

An EPA 1996 regulation requiring cleaner marine (boat) engines (EPA 1996a) is currently reducing 

the water and air emissions from both newly purchased vessels and the aggregate fleet of watercraft. 

By the 2006 model year, the fleet of marine engines, including those for personal watercraft, produced 

by each manufacturer must be 75% cleaner than the average for the fleet produced by that 

manufacturer in 1996. The improved engines will produce lower levels of hydrocarbon emissions, 

visible smoke, fumes that can be detected by smell, and noise. 

The analyses of water and air emissions used the predictions for emission reductions from the 

Environmental Protection Agency. Table 32 provides a chronology of the estimated hydrocarbon 

reductions. 

Key dates in this chronology begin with 1999, when the Environmental Protection Agency began to 

require production line testing for 75% HC reduction in new outboard motors, and 2000, when testing 

for 75% HC reduction in personal watercraft was started. By 2006 all new personal watercraft and 

outboards manufactured in the United States must have a 75% reduction in HC emissions. In 2005 and 

2012 overall reductions in HC emissions are estimated to be 25% and 50%, respectively, in personal 

watercraft and outboard motors. These estimates are based on interpolations of the emissions reduction 

percentages and associated years reported by the Environmental Protection Agency (1996a), but with a 

one-year delay in the implementation of production line testing (EPA 1997a). 

The average operating life of a personal watercraft is 5 to 10 years, depending upon the source. The 

formula for determining the operating life of personal watercraft was published in the Federal Register

on October 4, 1996 (EPA 1996a). Based on this formula, the National Park Service expects that by 

2012, most boat owners will already be in compliance with the 2006 EPA marine engine standards. 

The Personal Watercraft Industry Association believes the typical operating life of a personal 

watercraft rental is three years and approximately five to seven years for a privately owned vessel 

(PWIA correspondence to NPS, May 28, 2002a: comment on Lake Mead National Recreation Area 

Lake Management Plan and Draft Environmental Impact Statement).

TABLE 32: ESTIMATED EPA REDUCTIONS IN WATERCRAFT EMISSIONS

Date Action 

1999 EPA requires production line testing for 75% HC reduction in new outboards and begins to see reductions as 

newer models are introduced (EPA 1997a). 

2000 EPA requires production line testing for 75% HC reduction in new personal watercraft and begins to see 

reductions as newer models are introduced (EPA 1997a). 

2005 Estimated 25% reduction in HC emissions overall as a result of newer models being gradually used (EPA 

1996a; date modified in EPA 1997a). 

2006 EPA fully implements 75% HC reduction in new outboards and personal watercraft (EPA 1996a). 

2012 Estimated 50% reduction in HC emissions overall (EPA 1996a; date modified in EPA 1997a). 
FINAL ENVIRONMENTAL IMPACT STATEMENT 161

IMPAIRMENT ANALYSIS METHOD 

Management Policies 2001 (NPS 2000d) require analysis of potential effect to determine whether or 

not actions would impair recreation area resources or values. 

The fundamental purpose of the national park system, established by the Organic Act and reaffirmed 

by the General Authorities Act, as amended, begins with a mandate to conserve park resources and 

values. NPS managers must always seek ways to avoid, or to minimize to the greatest degree 

practicable, actions that would adversely affect park resources and values. 

These laws give the National Park Service the management discretion to allow impacts on park 

resources and values when necessary and appropriate to fulfill the purposes of a park, so long as the 

impact does not constitute impairment of the affected resources and values. Although Congress has 

given the National Park Service the management discretion to allow certain impacts within parks, that 

discretion is limited by the statutory requirement (enforceable by the federal courts) that the National 

Park Service must leave park resources and values unimpaired, unless a particular law directly and 

specifically provides otherwise. 

The impairment that is prohibited by the Organic Act and the General Authorities Act is an impact 

that, in the professional judgment of the responsible NPS manager, would harm the integrity of park 

resources or values, including the opportunities that otherwise would be present for the enjoyment of 

those resources or values. Impairment may result from NPS activities in managing Glen Canyon 

National Recreation Area, from visitor activities, or from activities undertaken by concessioners, 

contractors, and others operating in Glen Canyon National Recreation Area. 

An impact on any park resource or value may constitute impairment. However, an impact would be 

most likely to constitute impairment if it affects a resource or value whose conservation is: 

Necessary to fulfill specific purposes identified in the establishing legislation or proclamation of 

Glen Canyon National Recreation Area; 

Key to the natural or cultural integrity of Glen Canyon National Recreation Area or to 

opportunities for enjoyment of Glen Canyon National Recreation Area; or 

Identified as a goal in Glen Canyon National Recreation Area’s general management plan or 

other relevant NPS planning documents. 

A determination on impairment is included in the impact analysis section for all impact topics relating 

to Glen Canyon National Recreation Area resources and values. It is based on the impact-topicspecific definition of impairment that is provided in the methodology section for each impact topic 

that addresses recreation area resources or values. 
162 GLEN CANYON NATIONAL RECREATIONAL AREA

CUMULATIVE EFFECTS ANALYSIS METHOD 

The Council on Environmental Quality (1978) regulations for implementing the National 

Environmental Policy Act require assessment of cumulative effects in the decision-making process for 

federal actions. Cumulative effects are defined as “the impact on the environment which results from 

the incremental impact of the action when added to other past, present, and reasonably foreseeable 

future actions regardless of what agency (federal or non-federal) or person undertakes such other 

actions” (40 CFR 1508.7). Cumulative effects are considered for both the no-action alternative and the 

two action alternatives. 

Cumulative effects were determined by combining the effects of the alternative with other past, 

present, and reasonably foreseeable future actions. Therefore, it was necessary to identify other past, 

ongoing, or reasonably foreseeable future actions within Glen Canyon National Recreation Area and 

in the surrounding region. Future actions that have the potential to have a cumulative effect in 

conjunction with this personal watercraft management action include: 

The future expansion of the Wahweap Campground to increase overnight visitor capacity and 

hookup by 48 units. This expansion could contribute to incremental increases in visitor numbers 

renting and using personal watercraft. 

The concessioner housing master plan (residential accommodations), which would decrease 

accommodations by approximately 41 people. This could cause a small incremental decrease in 

personal watercraft use on Lake Powell. 

The Antelope Point Marina Resort and Development project, which would be located on Lake 

Powell about 3.5 miles southeast of the Wahweap Marina. It would include a floating marina 

village and boat docks, dry storage for boats, campground and recreational vehicle park, resort 

hotel and cultural center, optional employee housing, and supporting infrastructure. 

One future NPS project within the recreation area would not affect personal watercraft launches or 

facilities. The Hite Marina upgrade would be located near the confluence of the Colorado and Dirty 

Devil Rivers in the northeast section of the recreation area. This project would upgrade existing 

facilities and provide additional parking, but would not expand present launch facilities. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 163

WATER QUALITY 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Issues 

Water quality issues related to personal watercraft that were identified during scoping included the 

following. 

The emission of hydrocarbons into lake waters from both burned and unburned fuel. 

The possible toxicity of hydrocarbon emissions to aquatic life. 

Potential contamination of drinking water supplies by hydrocarbon from personal watercraft. 

Management Objectives 

Maintaining and improving water quality has long been recognized as an important management 

objective in all NPS units. Management Policies 2001 (NPS 2000d) emphasizes the need to work 

cooperatively with other agencies and governing bodies to obtain the highest possible standards 

available under the Clean Water Act for the protection of park waters, and to maintain or restore the 

quality of waters within parks. The importance of water quality is also reflected in the goal in the Glen 

Canyon National Recreation Area general management plan to encourage the maintenance of high 

water quality in all bodies and sources of water. 

As identified in table 3, three water quality objectives were identified for personal watercraft 

management. They include: 

Manage personal watercraft emissions that enter the water in accordance with water quality 

protection policies and goals. 

Protect aquatic organisms from personal watercraft effects, including those related to emissions 

and sediment. 

Manage human wastes associated with personal watercraft use in accordance with water quality 

protection policies and goals. 

GUIDING REGULATIONS AND POLICIES 

The Environmental Protection Agency has developed national recommended ambient water quality 

criteria for approximately 120 priority pollutants for the protection of both aquatic life and human 

health (through ingestion of fish, shellfish, or water) (EPA 2001d). These criteria have been adopted as 

enforceable standards by most states. 

There are no EPA water quality criteria for the protection of aquatic life for the five contaminants of 

concern from personal watercraft that were identified in the “Affected Environment” chapter. For 

human health, the Environmental Protection Agency has established the criteria for benzene and some 
ENVIRONMENTAL CONSEQUENCES

164 GLEN CANYON NATIONAL RECREATIONAL AREA

polycyclic aromatic hydrocarbon compounds that are shown in table 9 in the “Affected Environment” 

chapter. 

State water quality standards for Arizona and Utah also were provided in table 9 in the “Affected 

Environment” chapter. The National Park Service must meet the most stringent water quality 

standards from either state throughout Lake Powell. 

As described in the preceding section on management objectives, Management Policies 2001 (NPS 

2000d) contains general goals for water quality. In accordance with these goals, the National Park 

Service works cooperatively with the states of Utah and Arizona, plus watershed management 

agencies throughout the Colorado River watershed upstream from the recreation area to protect and 

enhance the quality of water in the tributary rivers. 

Water quality antidegradation policies for Utah and Arizona were described in the “Affected 

Environment” chapter. As described in that section, both states have policies to maintain water bodies 

in a condition suitable to serve their intended purposes, and to maintain water quality at existing 

levels, even if it is already better than the minimum standard necessary to protect designated uses. 

The designated uses for the waters of Glen Canyon National Recreation Area are described in the 

“Affected Environment” chapter. The reservoir is designated for multiple purposes, including 

recreation, fishery support, irrigation, and a drinking water source. The Safe Drinking Water Act

(42 U.S.C. 300 (f)-(j)) requires that (park) waters used for municipal drinking water comply with all 

federal, state, and local primary drinking water regulations. Standards for either the protection of 

aquatic life or drinking water have been set by the Environmental Protection Agency for acidity and 

for many substances. 

METHODOLOGY AND ASSUMPTIONS 

Emissions of gasoline and exhaust associated with each of the personal watercraft management 

alternatives were compared to existing water quality conditions and to state water quality standards to 

determine their effects. Where standards were not available for the target compounds, ecotoxicological 

and human health toxicity benchmarks were acquired from the scientific literature. 

Summary of Water Quality Evaluation Procedure for Personal Watercraft 

The steps that were used to determine the effects of personal watercraft emissions on water quality 

included the following. 

Emissions of the pollutants of concern to the water during personal watercraft operational hour 

were estimated, based on literature values. The values that were used, and the sources of this 

information are included in appendix G. 

The total loading of the pollutants to the water was calculated, based on the estimated hours of 

personal watercraft use. 

Using the technique described in appendix G, the volume of water required to dilute the 

calculated emission loading to the level of the water quality standard or benchmark, referred to 

as the “threshold volume of water,” was calculated. 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 165

The threshold volume of water was compared to the volume of water available in the most 

limited mixing zone (top 40 feet) that occurs in Lake Powell. 

Mechanisms that would result in the loss of a pollutant from the water were qualitatively 

considered. 

The effect of personal watercraft use in conjunction with the use of other motorized watercraft 

on the lake was calculated (cumulative effect). 

The result of this analysis was a conclusion as to whether the standards or benchmarks would be 

exceeded, even on a short-term basis, by personal watercraft use alone, or by personal watercraft use 

in combination with other boating use of Lake Powell. 

Estimation of Personal Watercraft Use and Other Boating Use 

Glen Canyon National Recreation Area does not have boating use records that include distribution of 

two-stroke and four-stroke engines or engine size. However, during 2001 data were gathered on the 

number of boats using Lake Powell, expressed as boat days. Separate counts were made for personal 

watercraft and other vessels. (A boat day equals one watercraft on the lake during a 24-hour period.) 

These values were combined with data collected from Lake Mead, including vessel ratios and daily 

running times for each type of vessel, to estimate use by engine type on Lake Powell. Data from Lake 

Mead were obtained during an extensive boat use study in 1999 (Hagler Bailly 1999). The Lake Mead 

data are appropriate to apply to Lake Powell because the two lakes have very similar volumes, natural 

and socioeconomic environments, visitor uses, and types of activities. 

Table 33 shows the distribution of engine types and daily running hours that were used in this analysis. 

It is assumed that this distribution will remain constant throughout the analysis period for alternatives 

A and B. Based on Lake Mead data, it was estimated that 75% of the motorized vessels on Lake 

Powell have four-stroke or direct-injection two-stroke engines. Because these engines have emission 

rates that are 75% to 90% lower than those of carbureted two-stroke engines, vessels with carbureted 

two-stroke engines were accounted for separately in the analysis of pollutant loadings. 

The evaluation analyzed boat use in June and July. These two months were selected to correspond to 

the water quality data obtained at Lake Powell on June 29 through July 2, 2001. Data for these 

months, which represent a high-use period, indicate worst-case levels of hydrocarbon pollution. 

For this analysis, it was assumed for all alternatives that there would be a change in total boat days and 

watercraft operating hours of between –2% and +2% annually over the next 10 years. It was also 

assumed that the removal of personal watercraft in alternative C would result in an initial decrease in 

annual boat days in the short-term. However, by the end of the 10-year analysis period, the total 

number of watercraft operating hours and the total number of motorized watercraft using Lake Powell 

under alternative C would be within the range predicted for alternatives A and B. This would be due to 

either natural growth in visitation, to visitors finding other watercraft to fulfill functions previously 

served by personal watercraft, or to increases in visitation by individuals who previously avoided the 

recreation area due to personal watercraft and now choose to visit in their absence. This was the same 

assumption that was used for the other impact topics. 
ENVIRONMENTAL CONSEQUENCES

166 GLEN CANYON NATIONAL RECREATIONAL AREA

TABLE 33: ESTIMATED DISTRIBUTION OF USE BY ENGINE TYPE 

ON LAKE POWELL IN JUNE AND JULY 2001 

Engine Type 

Boat Days 

(total for twomonth period) Running Hours 

per Boat Day 

Total Engine Hours 

(total for two-month 

period) 

Total Hours 

on Lake 

(percent) 

Outboard engine 

Carbureted two-stroke 21,192 2.90 61,457 5 

Direct injection two-stroke 8,077 2.93 23,666 2 

Electronic fuel injection 

two-stroke 

8,077 2.93 23,666 2 

Four-stroke 16,154 2.93 47,331 4 

Inboard/stern drive 

Four-stroke 181,693 4.74 861,225 65 

Two-stroke carbureted, jet 

drive 

10,422 3.99 41,584 3 

Diesel, auxiliary sail 5,916 3.61 21,357 2 

Personal watercraft 

Carbureted two-stroke 84,431 2.44 206,012 15 

Direct injection two-stroke 6,308 2.67 16,842 1 

Four-stroke 6,308 2.67 16,842 1 

Total 348,578 — 1,319,982 100 

Calculation of Lake Loading by Carbureted Two-Stroke Personal Watercraft 

The impacts on water quality were determined by estimating whether the use of personal watercraft 

over a particular time (such as a typical busy weekend day) would result in exceedences of water 

quality standards or toxicity benchmarks. The analysis used the concentrations of components in 

gasoline, the rate of discharge of a two-stroke engine, and the running time of two-stroke engines on 

Lake Powell to calculate potential pollutant loading to the lake. A brief description of the approach is 

provided below, with more detailed information in appendix G. 

The objective of the lake-loading analysis was to determine if Lake Powell would receive 

concentrations of selected compounds from gasoline or its combustion products that would result in an 

unacceptable risk to human health or the environment. Daily pollutant loadings from two-stroke 

personal watercraft were determined, and the quantity of water needed to dilute the loading was 

calculated. This threshold volume was then compared to the amount of water available in the mixing 

zone of Lake Powell to determine if water quality standards or other benchmarks would be exceeded. 

The analysis used data on the composition of gasoline (Gustafson et al. 1997) and estimates for fuel 

discharges from personal watercraft (CARB 1998a). These values were then applied to Lake Powell 

boat-use data and the volume of the lake’s mixing zone. 

This method has been reviewed and accepted by water quality experts at the Water Resources Division 

of the National Park Service. It has been used previously to assess effects of personal watercraft at Big 

Thicket National Preserve in Texas and Assateague Island National Seashore in Virginia and 

Maryland. 

An advantage of this approach is that it provides a mechanism to determine pollution levels, even in 

the absence of baseline water quality data. A limitation is that the calculations yield a total daily load 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 167

that would be instantaneously delivered to the lake, and is assumed to disappear by the start of the next 

boating day. In reality, the pollutant load is added in conjunction with boating activities throughout the 

day, and a small residual concentration of some compounds may carry over from one day to the next. 

The calculation identified the loading of each contaminant in Lake Powell on a daily basis if all of the 

material that was introduced to the water was retained for the entire day. However, as described in the 

“Affected Environment” chapter, these compounds evaporate from the water to the atmosphere, and 

also are subject to chemical breakdown by light, bacterial action, or other processes. Therefore, this 

analysis qualitatively considered mechanisms that result in loss of the pollutant from the water. 

Factors that were evaluated because of their effect on these mechanisms included water temperature, 

mixing, and each compound’s solubility, vapor pressure, and weight compared to water. When the 

half-life of a compound in water was available, it was included in determining lake loadings from 

personal watercraft. Example calculations are included in appendix G. 

In 1994, the Environmental Protection Agency released a public memorandum entitled “The Effects of 

Marine Engine Exhaust on Water Quality: Summary of Findings of Various Research Studies.” This 

document summarized 11 research papers and present volatilization rates and dilution ratios for 

observable effects such as taste, odor and generation of oil film. 

At temperatures commonly found in Lake Powell during the summer boating season (77°F to 86°F), 

78% to 84% of typical two-stroke gasoline/oil mixture (50:1) would be evaporated from the water in 

1.2 hours (EPA 1994). This EPA review also cites a 1974 study by the Boating Industrial Association 

describing the two-stroke gas/oil mixture as having an 11 day half-life in a quiescent water (laboratory 

tank) and a half-life of less than one day in open aerated water (such as a lake).

As described in the “Affected Environment” chapter, some hydrocarbons have the potential to adsorb 

on suspended soil particles. As the particles settle out, the hydrocarbons are removed from the water 

column and accumulate in the sediment. However, most sedimentation in Lake Powell occurs within 

25 miles of each river’s mouth, and there is very little suspended sediment in the body of the lake. 

Therefore, pollutant adsorption to sediment was not considered as an attenuating mechanism in this 

analysis. 

Estimation of Personal Watercraft Emissions Changes in Response to Regulatory Requirements 

The “Discharge of Gasoline, Oil, and Other Chemicals by Personal Watercraft Engines” section in the 

“Affected Environment” chapter describes federal and state requirements that currently are reducing 

the amounts of emissions produced by personal watercraft and other watercraft engines. As a result of 

these regulations, low-emissions personal watercraft represented 12% of the personal watercraft use on 

Lake Powell in 2001, up from an estimated 4% previously. 

This analysis used the following projections to estimate future emissions by personal watercraft at 

Glen Canyon National Recreation Area. 

In 2005, the emissions from the fleet of watercraft using Lake Powell would be reduced by 25% 

compared to emissions in 1996; and 

In 2012, the emissions from the fleet of watercraft using Lake Powell would be reduced by 50% 

compared to emissions in 1996. 
ENVIRONMENTAL CONSEQUENCES

168 GLEN CANYON NATIONAL RECREATIONAL AREA

These projections are slightly more conservative (would indicate greater lake loadings) than those 

included in the EPA rule (1996a) and presented in the “Affected Environment” chapter. They are 

intended to represent the worst conditions of engine emissions that occur from personal watercraft and 

other watercraft at Lake Powell. 

Calculation of Lake Loading by Low-Emissions Personal Watercraft 

A typical conventional (i.e., carbureted) two-stroke personal watercraft engine discharges as much as 

30% of its fuel unburned directly into the water (NPS 1999c; CARB 1999a). At common fuel 

consumption rates, an average two-hour ride on a personal watercraft may discharge 3 gallons of fuel 

into the water (NPS 1999c). According to data from the California Air Resources Board, two-stroke 

personal watercraft engines may consume 5 to 10 gallons of fuel per hour, of which up to 3.3 gallons 

per hour may be discharged unburned (CARB 1998b). (As described in appendix G, an estimated 

discharge rate of 3 gallons per hour is used in the water quality impact calculations.)

As discussed in the “Affected Environment” chapter, the California Air Resources Board is requiring 

personal watercraft and other vessels from model year 2008 and later that are sold in that state to be 

90% cleaner than they were in 1998. Based on this requirement, this analysis assumed that new vessels 

after 2008 at Lake Powell that use two-stroke engines also will emit pollutants at a rate that is onetenth of that produced by carbureted, two-stroke engines. 

The calculation of lake loading by low-emissions personal watercraft included the following. 

The lake-loading values per unit time of use by carbureted, two-stroke personal watercraft were 

multiplied by 10% to determine lake-loading values per unit time of use by low-emissions 

personal watercraft. 

The resulting value was multiplied by the estimated running time of low-emissions personal watercraft 

in that year, based on their proportion of the total number of personal watercraft using the lake. This 

produced an estimate of the volumes of pollutants discharged to the lake that year by low-emissions 

personal watercraft. 

The volumes of pollutants discharged to the lake by low-emissions personal watercraft were added to 

the volumes of pollutants discharged to the lake by carbureted, two-stroke personal watercraft to get 

total lake loading levels by all personal watercraft. 

Although overall hydrocarbon emissions will be reduced as a result of implementation of EPA 2006 

marine engine standards, the emission of PAH compounds to the water varies by engine type. A recent 

study by the Tahoe Regional Planning Agency (2003) compared the concentrations of PAH 

compounds released into the water and found that the two-stroke carbureted outboard engine emitted 

lower PAH levels into the water than did the two-stroke direct-injected engine. The four-stroke 

carbureted outboard engine emitted the lowest PAH levels, as well as other gasoline-related 

contaminants into the water (TRPA 2003; CARB 2001). However, the two-stroke carbureted outboard 

engine emitted higher levels of benzene than the two-stroke direct-injected engine model (CARB 

2001). Personal watercraft engines follow the same patterns of emission rates as outboard engines 

(CARB 2001). The TRPA (2003) study confirms other findings regarding emissions into the water and 

does not substantially change NPS conclusions regarding water quality impacts.
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 169

Comparison to State Standards or Toxicity Benchmarks 

For compounds of concern in gasoline and its emissions that have Arizona or Utah water quality 

standards, the values in table 9 in the “Affected Environment” chapter were used in the analysis. These 

compounds included benzo(a)pyrene, naphthalene, and benzene. For 1-methyl naphthalene and methyl 

tertiary-butyl ether, which do not have state standards, ecotoxicological and/or human health toxicity 

benchmarks were acquired from the scientific literature and are provided in table 10. 

The threshold volume of water is the volume of water required to dilute the calculated emission 

loading to the concentration required to meet the water quality standard or benchmark. For example, 

the results might show that for a target compound, 50 acre-feet of water would be needed to dilute the 

expected emissions to the most stringent state standard. (One acre-foot equals 1 acre of water 1 foot 

deep.) If the receiving body of water is a 100-acre reservoir with an average depth of 20 feet (total 

volume of 2,000 acre-feet) and is well-mixed, there would be little chance that the water quality 

standard would be exceeded. The potential for exceeding the standard would be further reduced when 

mechanisms that reduce the amount of the compound in the water are considered. 

Analysis of Cumulative Effects – Calculation of Lake Loading by All Watercraft 

The analysis of cumulative effects used the same procedures described above for personal watercraft. 

However, contaminant loadings to the lake were calculated based on total boat hours from all 

watercraft, not just personal watercraft. Each boat/engine type has specified hours of use per day, as 

shown in table 33. The different running times were incorporated into the model described in 

appendix G to determine their pollutant loadings. This analysis did not consider the differing 

horsepower ratings or fuel consumption rates of the various vessels. 

For alternative A, it was assumed that in the year 2012, most of the personal watercraft and about 60% 

of the other vessels would have low-emission engines. The average operating life of a personal 

watercraft is 5 to 10 years, depending upon the source (see “Affected Environment” chapter). As a 

result, as noted previously, the 2012 emissions from the fleet of watercraft using Lake Powell would 

be reduced by 50% compared to emissions in 1996. 

Under alternative B, all personal watercraft allowed on Lake Powell would be compliant with the EPA 

requirements beginning in 2012. Benefits of implementation of the EPA requirements would be 

realized in 2013 and beyond. Therefore, carbureted two-stroke personal watercraft would be restricted 

from using the lake at that time. The analysis assumed the same vessel and daily hour use distribution 

as presented for alternative A, with clean technology personal watercraft replacing the carbureted twostroke engines. In addition, the potential for increased or decreased use of the lake for recreational 

boating is captured as a range, through the project period, ending in 2012. An annual increase and 

decrease of 2% was used to estimate the possible future use rates of the lake. 

It was assumed for alternative A and alternative B that the percentages of total hours shown in table 33 

for vessels with outboard engines, vessels with inboard/stern drive engines, and personal watercraft 

would continue throughout the 10-year analysis period. 

The alternative C analysis assumed these same percentages for vessels with outboard engines and 

vessels with inboard/stern drive engines. In addition, the alternative C analysis assumed that personal 

watercraft use does not resume on Lake Powell. Changes in overall recreational boat use are based on 

an assumed change in visitor use of + or – 2% annually over the next 10 years. 
ENVIRONMENTAL CONSEQUENCES

170 GLEN CANYON NATIONAL RECREATIONAL AREA

Impact Threshold Definitions 

The following impact thresholds were established to describe the relative changes in water quality 

under the three personal watercraft management alternatives. 

Negligible — Chemical or physical changes to water quality would not be detectable, would be 

well below water quality standards or criteria, and would be within historical or desired water 

quality conditions. 

Minor — Chemical or physical changes to water quality would be detectable but would be well 

below water quality standards or criteria and within historical or desired water quality 

conditions. 

Moderate — Chemical or physical changes to water quality would be detectable but would be at 

or below water quality standards or criteria. Water quality would be altered on a short-term basis 

compared to historical baseline or desired water quality conditions. 

Major — Chemical or physical changes to water quality would be detectable and would be 

frequently altered from the historical baseline or desired water quality conditions; and/or 

chemical, physical, or biological water quality standards or criteria would be locally slightly and 

singularly exceeded on a short-term and temporary basis. 

Impairment — Chemical or physical changes to water quality would be detectable and would be 

substantially and frequently altered from the historical baseline or desired water quality 

conditions and/or water quality standards. The impacts would involve deterioration of the 

recreation area’s water quality and aquatic resources over the long term, to the point that the 

recreation area’s purpose could not be fulfilled, or resources could not be experienced and 

enjoyed by future generations. 

Geographic Area Evaluated for Impacts 

The geographic area evaluated for water quality impacts included all waters of Glen Canyon National 

Recreation Area upstream from Glen Canyon Dam that provide sufficient depth and flow to support 

personal watercraft use, even on an occasional basis. This includes Lake Powell and the San Juan, 

Dirty Devil, Escalante, and Colorado Rivers. 

The municipal water intake serving Page, Arizona, located at Glen Canyon Dam, is not under the 

jurisdiction of the National Park Service. Potential effects to source drinking water quality are 

discussed in this assessment, but the National Park Service would not have the authority to test water 

quality at this intake. 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Under alternative A, current management conditions would remain in place. The use of personal 

watercraft and other vessels on Lake Powell would not change during the next 10 years. However, 

because manufacturers of personal watercraft and other vessels must meet EPA emissions standards, 

emissions from the fleet of personal watercraft using Lake Powell will decline by at least 25% by the 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 171

year 2005 and 50% by 2012. Table 34 shows estimated daily hydrocarbon pollutant loadings to Lake 

Powell by carbureted, two-stroke engines in 2001 and loadings that will occur in 2005 and 2012 with 

continued implementation of the EPA goals. 

The year 2001 values are used in this analysis because they represent the worst-case condition that 

would occur during the analysis period. Loadings in all subsequent years will be lower, and as shown 

in the table, the emissions from the collective fleet of watercraft using Lake Powell would be reduced 

by 50% in 2012. 

The calculations in table 34 used data from boat counts on Lake Powell in 2001. These showed that 

88% of personal watercraft during the count period used carbureted, two-stroke engines and 12% used 

low-emissions four-stroke or direct-injection two-stroke engines. 

Table 35 shows that the overall two-stroke loadings to Lake Powell decrease with implementation of 

the EPA emission reduction program. Because the distribution of vessel types is assumed to remain 

constant, personal watercraft would contribute twice the pollutant load of other two-stroke vessels, as 

is the case for the 2001 analysis. 

TABLE 34: ESTIMATED DAILY LOADINGS TO LAKE POWELL BY CARBURETED, 

TWO-STROKE ENGINES DURING A HIGH-USE PERIOD IN 2001, UNDER ALTERNATIVE A 

 2001 Loadings to Lake Powella 

Parameter 

From Personal 

Watercraft 

Other two-stroke 

Watercraft Total 

2005 Loading 

(25% reduction) 

2012 Loading 

(50% reduction) 

Benzo(a)pyrene (kilograms)b 0.081 0.040 0.12 0.091 0.061 

Naphthalene (metric tons) 0.14 0.07 0.21 0.16 0.11 

1-methyl naphthalene 

(metric tons) 

0.22 0.11 0.33 0.25 0.17 

Benzene (metric tons) 0.71 0.35 1.06 0.80 0.53 

Methyl tertiary-butyl ether 

(metric tons) 

4.22 2.11 6.33 4.75 3.16 

 

a. All loadings are based on 40-hour watercraft use units. 

b. 1 kilogram = 2.205 pounds; 1 metric ton = 1,000 kilograms or 2,205 pounds.

TABLE 35: ESTIMATED DAILY LOADINGS TO LAKE POWELL BY CARBURETED, 

TWO-STROKE ENGINES DURING A HIGH-USE PERIOD IN 2005 AND 2012, UNDER ALTERNATIVE A 

 2005 Loadings to Lake Powella 

(includes 25% EPA emission reduction) 

2012 Loadings to Lake Powell 

(includes 50% EPA emission reduction) 

Parameter 

From Personal 

Watercraft 

Other Two-Stroke 

Watercraft 

From Personal 

Watercraft 

Other Two-Stroke 

Watercraft 

Benzo(a)pyrene 

(kilograms)b 0.06–0.07 0.028–0.032 0.031–0.05 0.015–0.025 

Naphthalene 

(metric tons) 0.1–0.14 0.053–0.057 0.053–0.087 0.026–0.044 

1-methyl naphthalene 

(metric tons) 0.15–0.18 0.08–0.09 0.083–0.14 0.042–0.068 

Benzene 

(metric tons) 0.49–0.58 0.24–0.28 0.27–0.44 0.13–0.22 

Methyl tertiary-butyl ether 

(metric tons) 2.9–3.43 1.5–1.7 1.57–2.62 0.8–1.31 

 

a. All loadings are based on 40-hour watercraft use units. 

b. 1 kilogram = 2.205 pounds; 1 metric ton = 1,000 kilograms or 2,205 pounds
ENVIRONMENTAL CONSEQUENCES

172 GLEN CANYON NATIONAL RECREATIONAL AREA

As described above in the “Methodology and Assumptions” section the calculation assumed that a 

low-emission engine had one-tenth of the emissions produced by a carbureted two-stroke engine. As a 

result, low-emissions personal watercraft were calculated to contribute less than 2% of the lake 

loading by personal watercraft in 2001, even though they represent 12% of this class of vessels. 

The state standards and toxicity benchmarks from tables 9 and 10, were used with the evaluation 

technique described in appendix G to calculate the volumes of water required to meet toxicological 

thresholds. As shown in table 36: 

The compound that would require the greatest volume of water to meet the ecotoxicological 

criteria was 1-methyl naphthalene. About 5,500 acre-feet of water would be needed to dilute the 

pollutant loading from the personal watercraft that used Lake Powell during the 2001 heavy-use 

period. 

Benzene was the compound that would require the greatest volume of water to meet the state 

standards or human health criteria. Approximately 500,000 acre-feet of water would be needed 

to dilute the pollutant loading from the personal watercraft that used Lake Powell during the 

2001 heavy-use period (table 36). 

As described at the beginning of the “Affected Environment” chapter, the surface of Lake Powell 

varies in size from 52,000 acres to 163,000 acres and usually is about 160,000 acres. At minimum 

pool, the mixing zone of Lake Powell would have to be about 10 feet deep to provide the threshold 

quantity of water needed to prevent human health effects. At the usual pool, a mixing zone of 3.2 feet 

would satisfy this criterion. For ecotoxicological effects, a mixing zone less than 2 inches deep when 

the lake is at minimum pool would provide the threshold quantity of water. 

As noted in the description of the Lake Powell hydrology in the “Affected Environment” chapter, the 

thermocline occurs at a depth varying from 40 to 150 feet below the lake surface. The thermocline 

represents the bottom of the mixing zone. Above this layer, the entire column of lake water has a 

similar temperature and can mix freely in response to inflow of river water, wind action at the surface, 

and boat traffic. 

TABLE 36: ACRE-FEET OF WATER NEEDED 

TO MEET STATE STANDARDS OR TOXICOLOGICAL CRITERIA 

Threshold quantity of water below which 

ecotoxicological effects might occur 

(in acre-feet) 

Threshold quantity of water below which 

human health effects might occur 

(in acre-feet) 

Parameter 

Personal 

Watercraft Only 

Other Two-Stroke 

Engines 

Personal 

Watercraft Only 

Other Two-Stroke 

Engines 

Benzo(a)pyrene 

(fuel and exhaust) 

4,651 2,322 14,883 7,432 

Naphthalene 1,860 929 No standard No standard 

1-methyl naphthalene 5,243 2,617 No standard No standard 

Benzene 8,117 4,054 479,470 239,417 

Methyl tertiary-butyl 

ether (chronic) 

186 93 No standard No standard 

Methyl tertiary-butyl 

ether (acute) 

64 32 262,144 130,898 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 173

It is recognized that this evaluation technique provides a very simplified model of a complex lake 

system. However, it demonstrates that under the most extreme adverse conditions, the size of the 

mixing zone is four times bigger than the threshold quantity of water below which toxicological 

effects might occur. These extreme adverse conditions include: 

The lowest possible pool size for Lake Powell of just 52,000 acres; 

The most shallow thermocline depth (40 feet) the lake experiences; 

A mix of personal watercraft that includes a greater proportion (88%) of high-polluting 

carbureted two-stroke engines than will occur again on Lake Powell; 

Use levels that are found during the heaviest-use period on a 160,000-acre lake; 

The compound (benzene) that would require the greatest volume of water to meet the most 

stringent criterion (human health); and 

A loading scenario where the entire daily pollutant load is introduced simultaneously, without 

any action by attenuating factors such as evaporation or photodegradation. 

Based on the impact threshold definitions, personal watercraft use under alternative A would cause 

negligible to minor, direct, adverse effect on the water quality of Lake Powell. Effects would be long 

term because they would recur during each summer heavy-use season. Under the worst-case 

conditions described above, the chemical changes to water quality sometimes would be detectable but 

would be well below water quality standards or criteria and within historical or desired water quality 

conditions. Most of the time, as demonstrated by the summer 2001 sampling, the chemical changes to 

water quality would not be detectable with current analytical techniques. 

Cumulative Effects. Based on the data in table 33, personal watercraft in 2001 represented only 17% 

of the boating hours on Lake Powell during the two-month count period (18% of total annual 

operating hours). Therefore, pollutant loading from all watercraft must be considered to determine the 

cumulative effects of alternative A. 

As shown in table 33, 15% of the boating hours on Lake Powell during the count period were personal 

watercraft with carbureted, two-stroke engines and 8% were other watercraft with carbureted, twostroke engines. The remaining 77% of boating hours on the lake involved four-stroke engines or 

direct-injection two-stroke engines, both of which emit pollutants at about one tenth the rate of 

carbureted, two-stroke engines. 

The cumulative effects analysis used the same method that was used to evaluate personal watercraft 

effects. It determined pollutant loadings for all of the vessels operating on Lake Powell during a 

heavy-use day. The results are shown in table 37. 

TABLE 37: POLLUTION CONTRIBUTION RELATIVE TO ENGINE TYPE UNDER ALTERNATIVE A 

Engine Type 

2001 Contribution 

(percent total) 

2005 Contribution 

(25% emission reduction) 

2012 Contribution 

(50% emission reduction) 

Carbureted two-stroke 77 58 39 

Personal watercraft 50 38 25 

Other 27 20 14 

All others 23 23 23 

Total (relative to year 2001) 100 81 62 
ENVIRONMENTAL CONSEQUENCES

174 GLEN CANYON NATIONAL RECREATIONAL AREA

The analysis showed that in the year 2001, 50% of the pollutant loading to the lake was from personal 

watercraft. Another 27% was from carbureted, two-stroke engines on other types of watercraft. Other 

engines, including four-stroke and direct-injection engines, collectively contributed less than a quarter 

of the lake’s pollutant load, even though these engines outnumbered carbureted, two-stroke engines by 

a ratio of more than three to one. 

In the year 2005, two-stroke engines on personal watercraft would account for only 58% of the lake 

loading by hydrocarbon pollutants. The other 42% would be from four-stroke and direct-injection 

engines. However, the total daily hydrocarbon loading to the lake would be reduced to 81% of the year 

2001 loadings, and 75% of the lake loadings in 1996, prior to the EPA rule that requires cleaner 

engines. As shown in table 37, the reductions would continue in the year 2012. The total pollution 

contribution by engine type does not amount to 100% because the emissions from two-stroke engines 

are reduced based on EPA mandated standards, and the contribution of pollutants from other engine 

types was assumed to remain constant. 

The worst-case condition, represented by the year 2001 pollutant loadings for all vessels using Lake 

Powell, was generated using the extreme adverse lake loading conditions that were listed previously in 

the personal watercraft analysis. Under these conditions, the size of the mixing zone would be twice as 

large as the threshold quantity of water needed to prevent toxicological effects. 

Although a small portion of the gas/oil mixture may accumulate in the water column, water quality 

testing at Lake Powell did not reveal detectable levels of most PAH components. The low level of 

occurrence (less than 10 parts per trillion) results from all hydrocarbon inputs, including all boat usage 

and runoff from nearby parking lots. Because levels of most PAH contaminants were below detection 

levels at most locations, the effect of accumulation of these pollutants on water quality was assumed to 

be negligible. 

Based on the impact threshold definitions, the cumulative effect from the use of all vessels under 

alternative A would cause negligible to minor, direct, adverse effect on the water quality of Lake 

Powell. Under the worst-case conditions described above, the chemical changes to water quality 

would be detectable but would be well below water quality standards or criteria and within historical 

or desired water quality conditions. However, most of the time, as demonstrated by the summer 2001 

sampling, the chemical changes to water quality would not be detectable with current analytical 

techniques. 

Benzene concentrations in two samples collected during a 2001 high boat-use period at Lake Powell 

exceeded the Utah standard for a drinking water intake of 1.2 μg/L (see table 9). Benzene 

concentrations of 1.4 and 3.43 μg/L were measured at Moqui Canyon and the Bullfrog Marina, 

respectively. However, none of the samples exceeded the EPA benzene standard of 5 μg/L for treated 

drinking water. Testing performed in Knowles Canyon, an area closed to all motorcraft use, did not 

indicate the presence of any hydrocarbons at the limits of detection. 

The Moqui Canyon and the Bullfrog Marina areas are heavily used by all classes of vessels that use 

Lake Powell, including personal watercraft. In addition, the Bullfrog Marina contains a fueling station. 

Under alternative A, concentrations of hydrocarbon pollutants probably would continue to approach or 

slightly exceed water quality standards or benchmarks for at least some of the constituents of concern 

in these and other high-use areas on high-use days. Such elevated concentrations would be short-lived. 

It is highly unlikely that detectable benzene levels would occur near the drinking water intake serving 

Hite since the intake is located upstream from high motorcraft use or fueling stations. The Utah 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 175

Department of Environmental Quality, Water Quality Division, was contacted regarding the benzene 

findings relative to the status of Lake Powell as a drinking water source. The state does not anticipate 

that the elevated benzene concentrations found in Moqui Canyon and Bullfrog Marina areas would 

result in degradation of the lake’s water quality that would result in impairment of the lake as a 

drinking water source (Utah Department of Environmental Quality, Water Quality Division, 

Moellmer, pers. com. 2002b). 

The water quality sampling performed at Lake Powell in the summer of 2001 did not indicate that 

Arizona state water quality criteria were exceeded. As shown in table 9 of the “Affected Environment” 

chapter, Arizona criteria are less stringent that those of Utah for all analyzed gasoline components, 

except naphthalene and benzene (warm water fishery designation). The 3.43 μg/L benzene 

concentration found at Bullfrog Marina is below the Arizona drinking water source criteria of 5 μg/L. 

Under alternative A, no degradation or impairment of Lake Powell for its Arizona designated uses 

would be anticipated. 

The National Park Service established the project area for this analysis to coincide with the areas of 

personal watercraft use at Glen Canyon National Recreation Area. Analysis of downstream impacts is 

outside the scope and mandate of this assessment. However, because uses of Lake Powell do affect the 

quality of water downstream, activities that impair or degrade the lake’s water quality could affect 

downstream water uses. 

The water quality analysis reveals that negligible to minor adverse effects occur due to personal 

watercraft use on Glen Canyon National Recreation Area. Measured water quality showed that no 

established water quality criteria were exceeded, with the exception of benzene. As discussed in the 

water quality analysis, only half of the PAH and other gasoline components found in lake waters 

would be emitted from personal watercraft use, which is the sole subject of this assessment. Given the 

volatile nature and brief half-life of benzene (5 hours) and the method of water release through Glen 

Canyon Dam (from the bottom), it is unlikely that fuel components found in lake waters contributed 

by personal watercraft use on the lake would have detectable effects below the dam.

Conclusion. Under alternative A, personal watercraft have negligible to minor, direct, adverse effects 

on the water quality of Lake Powell. Effects would be long term because they would recur during each 

summer heavy-use season. Cumulatively, the lake loadings from all vessels also would have negligible 

to minor, direct, adverse effects on the water quality of Lake Powell. Alternative A would not result in 

the impairment of the water quality of Lake Powell or any other waters. 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

The management actions included under alternative B would include elimination of carbureted twostroke personal watercraft at the end of 2012. Until the implementation of the restriction in 2012, the 

type and distribution of watercraft on the lake is assumed to change in accord with the EPA forecast. 

This would result in a 25% emission reduction for 2005 and a 50% reduction for 2012. For this 

analysis, the range of anticipated boating use of the lake is expressed as a 2% increase and decrease 

annually over the project period (see the “Visitor Use and Experience” section). 

To meet NPS mandates and to ensure that the waters of Lake Powell continue to serve the multiple 

purposes designated by Utah and Arizona, a lake-wide water quality monitoring program would be 
ENVIRONMENTAL CONSEQUENCES

176 GLEN CANYON NATIONAL RECREATIONAL AREA

implemented under alternative B. The program, to be developed by the Lake Powell Technical 

Advisory Committee, would incorporate existing data and new information to help guide the National 

Park Service in making management decisions that may affect water quality at Glen Canyon National 

Recreation Area. 

Prior to implementation of clean technology restrictions on personal watercraft, the effects of 

alternative B would be the same as those described in alternative A. Overall two-stroke loadings to the 

lake would decrease with implementation of the Environmental Protection Agency emission reduction 

program (see Table 35). About 5,500 acre-feet of water would be needed to dilute 1-methyl 

naphthalene pollutant loading from personal watercraft. Benzene would require the greatest volume of 

water (500,000 acre-feet) to meet the state standards or human health criteria (see Table 36). Under the 

worst case conditions described earlier, the chemical changes to water quality would be detectable 

sometimes, but would be well below the water quality standards or criteria and within historical or 

desired water quality conditions. Personal watercraft use prior to 2012 would cause negligible to 

minor, direct, adverse effects on the water quality of Lake Powell. After implementation of personal 

watercraft compliance standards, there would likely be reduced concentrations of gasoline components 

in the water of Lake Powell. However, these pollutants would still occur in measurable quantities. 

Therefore, the effects of alternative B would be adverse, long-term, and negligible to minor. 

Gross pollutant loadings from personal watercraft under alternative B after implementation of the 

2012 restriction on carbureted two-stroke personal watercraft engines are expressed in table 38. The 

current (2001) loadings, as well as the loadings expected in 2005 and 2012 with the 25% and 50% 

emission reductions anticipated by the Environmental Protection Agency, and without implementation 

of non-compliant personal watercraft restriction, can be seen in tables 34 and 35, above. The 

calculations include the range of anticipated future use. 

By comparing the findings in table 38 with those in tables 34 and 35, a decline in two-stroke pollutant 

loadings can be seen after 2012 restrictions are in place. Implementation of the ban on carbureted twostroke personal watercraft would decrease the pollution contribution of personal watercraft to less than 

that of other two-stroke engines remaining on the lake. This could yield a beneficial effect to water 

quality. However, given the low concentrations of gasoline components measured at Lake Powell in 

2001, any decrease in pollutant concentrations may be difficult to quantify. 

The remainder of this discussion focuses on the effects of alternative B on the San Juan, Colorado, 

Dirty Devil, and Escalante Rivers. Compared to current management, alternative B would prohibit

personal watercraft use in 123 miles of these rivers (see table 4). 

TABLE 38: ESTIMATED DAILY LOADINGS TO LAKE POWELL WITH

EPA 2006 COMPLIANT TECHNOLOGY RESTRICTIONS DURING A HIGH USE PERIOD

Clean Technology Personal Watercraft Loadings to Lake Powell in 2012a

Parameter Compliant Personal Watercraft 

Benzo(a)pyrene (kilograms)b 0.006–0.011 

Naphthalene (metric tons) 0.011–0.017 

1-methyl naphthalene (metric tons) 0.017–0.027 

Benzene (metric tons) 0.054–0.088 

Methyl tertiary-butyl ether (metric tons) 0.32–0.53 

 

a. All loadings are based on 40-hour watercraft use units. 

b. 1 kilogram = 2.205 pounds; 1 metric ton = 1,000 kilograms or 2,205 pounds
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 177

All four rivers have low rates of personal watercraft use. The Colorado and San Juan Rivers are visited 

by fewer than one vessel of any type per day, including personal watercraft. Each day during high-use 

season, the Escalante and Dirty Devil Rivers receive between 2 and 10 visits from personal watercraft, 

and from 2 to 10 visits from other vessels. 

Alternative B would eliminate personal watercraft use in the inflow of the Dirty Devil River for a 

distance of 19 miles and from the Escalante River inflow for a distance of 41 miles. Both of these 

rivers have relative low flow volumes during summer months (see the “Affected Environment” 

chapter). Elimination of personal watercraft use in these tributary arms would potentially provide 

long-term benefits to water quality. The beneficial effects could be important locally, but because of 

the large size of Lake Powell, the effect would be negligible downstream as the tributary flow entered 

the lake. 

Similar analyses were performed for the Colorado River (average July flow of 9,114 cubic feet per 

second) and San Juan River (average July flow of 2,541 cubic feet per second). On both of these 

rivers, the daily flows would be sufficient to dilute the loadings caused by the extremely low levels of 

personal watercraft use (less than one vessel per day), even without considering the attenuating factors 

listed above. Therefore, the water quality effects from removing personal watercraft use in the 

Colorado and San Juan Rivers would be beneficial but negligible.

Cumulative Effects. Through 2005, the cumulative effects of alternative B would be similar to those 

described for alternative A. However, once clean technology restrictions are implemented, the 

pollutant contribution of personal watercraft would decrease. Using the assumption that clean 

technology would produce 90% less loading to water, lake-wide pollutant loading from personal 

watercraft would fall from the current rate of 50% to 5%. Therefore, the total pollutant load from all 

vessels relative to current loadings would fall to 42%. This represents a decrease from total loads 

under alternative A of 47%. 

This alternative would contribute to water quality benefits resulting from the Lake Powell Pure 

Program and Wahweap wastewater treatment plant improvements. The contribution of this alternative 

to these efforts would be long-term and beneficial, and of negligible intensity.

Conclusion. Localized, long-term benefits to water quality would occur in the four tributaries where 

personal watercraft use would be restricted. However, because these areas have low rates of use, the 

intensity would likely be negligible. 

Prior to the end of 2012, effects to water quality would be the same as those described for 

alternative A. This is anticipated because boat usage and engine type distribution are assumed to be 

the same as in alternative A. After implementation of clean technology personal watercraft restrictions, 

pollutant loadings from personal watercraft would decrease. However, changes in water quality may 

be difficult to quantify. The continued contribution of personal watercraft to pollutant loading in Lake 

Powell would result in long-term, adverse effects to water quality of negligible to minor intensity. 

Cumulative effects from all watercraft would be similar to alternative A until 2005. A decrease in 

pollutant loading with implementation of personal watercraft engine type restrictions at the end of 

2012 and other water quality improvement projects would result in long-term negligible benefits. 

Alternative B would not result in the impairment of the water quality of Lake Powell or any other 

waters. 
ENVIRONMENTAL CONSEQUENCES

178 GLEN CANYON NATIONAL RECREATIONAL AREA

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

Alternative C would permanently prohibit personal watercraft use at Glen Canyon National Recreation 

Area. This would eliminate all personal watercraft hydrocarbon pollution in the lake. As shown in 

table 39, personal watercraft contribute approximately 50% of the total emissions to Lake Powell 

during the initial period of the ban. Therefore, implementation of the no-action alternative would 

reduce by half the daily hydrocarbon loadings of Lake Powell, over the short-term. This beneficial 

effect would be negligible to minor in intensity, because personal watercraft currently have only 

negligible to minor adverse effects on the water quality of the lake. 

As the use of motorized craft returns to the levels predicted for 2012 and beyond, the majority of 

pollutant loading would be generated by 2006 compliant engines. A small component of carbureted 

two-stroke engines would also likely be present. This mix of technology is anticipated to result in 

reduced pollutant loadings compared to alternative A, and increased loadings compared to 

alternative B. 

Alternative C would not reduce benzene concentrations from those measured at Bullfrog Marina 

(3.43 μg/L) to levels below the Utah drinking water intake standard (1.2 μg/L). As with alternative A, 

concentrations of hydrocarbon pollutants probably would continue to approach or slightly exceed 

water quality standards for at least some of the constituents of concern in high-use areas on high-use 

days. 

Within the San Juan, Colorado, Dirty Devil, and Escalante Rivers, alternative C would produce direct, 

long-term, beneficial effects on water quality. Because these areas have little personal watercraft use, 

the lake-wide prohibition of personal watercraft would likely make changes in water quality in these 

reaches difficult. This low level of change in contaminant concentration would result in negligible, 

long-term benefits. 

The effect on lake loadings of eliminating personal watercraft use would be short term, because former 

personal watercraft users would return over the next several years using other watercraft. Water 

quality effects from the return of these visitors with other watercraft are included in the discussion of 

cumulative effects for alternative C, below. 

Cumulative Effects. For this analysis, it was assumed for all alternatives that there would be a change 

in total boat days and watercraft operating hours between –2% and +2% annually over the next 

10 years. It was also assumed that the removal of personal watercraft in alternative C would result in 

an initial decrease in annual boat days in the short-term. However, by the end of the 10-year analysis 

period, the total number of watercraft operating hours and the total number of motorized watercraft 

using Lake Powell under alternative C would be within the range predicted for alternatives A and B. 

TABLE 39: POLLUTION CONTRIBUTION RELATIVE TO ENGINE TYPE UNDER ALTERNATIVE C 

Engine Type 

2001 

Contribution 

(percent total) 

Personal 

Watercraft Ban 

2005 Contribution 

(25% emission 

reduction) 

2012 Contribution 

(50% emission 

reduction) 

Personal watercraft 50 0 0 0 

Other two-stroke 27 27 25 17 

All four-stroke 23 23 30 30 

Total (relative to current 100%) 100 50 55 47 
Water Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 179

This would be due to either natural growth in visitation, to visitors finding other watercraft to fulfill 

functions previously served by personal watercraft, or to increases in visitation by individuals who 

previously avoided the recreation area due to personal watercraft and now choose to visit in their 

absence. This was the same assumption that was used for the other impact topics. 

Current and projected daily pollutant loading to Lake Powell from carbureted, two-stroke engines 

under alternative C are represented in two tables from alternative A. The pollution contributions made 

by the remaining two-stroke engines using Lake Powell correspond to the “Other Two-Stroke 

Watercraft” column in the tables. Pollutant loading occurring in 2001, with a full range of engine use 

on the lake, is shown in table 34. Loadings for 2005 and 2012 can be found in table 35. 

For all three years, hydrocarbon loadings from this class of engine would be only about a third of 

those that would occur under alternative A. This would occur because alternative C would remove a 

large number of high-emission vessels from the lake compared to the numbers that would occur in the 

three analyzed years under alternative A. Although pollutant loadings from carbureted, two-stroke 

outboard engines would be reduced over time, they would continue to be a source of pollutant 

loadings in Lake Powell.

Table 39 shows the estimated short- and long-term reduction in pollutant loading under this 

alternative. This alternative would produce short-term reduction in pollutant loadings of 50%, and 

long-term reductions of 47%.

A direct, beneficial, long-term effect on water quality would occur under alternative C from the 

combined action of immediately removing all high-emissions personal watercraft engines from the 

lake in combination with the gradual replacement of high-emission engines on other types of 

motorcraft. This change in water quality sometimes would be measurable. However, as demonstrated 

by the year 2001 water quality sampling program, many of the compounds of concern currently occur 

at concentrations below the detection levels of analytical equipment. Water quality would continue to 

be within the range of historical norms, and would continue to be well below water quality standards 

or criteria. As a result, the cumulative beneficial effect of alternative C would be only negligible or 

minor. 

Conclusion. Alternative C would eliminate personal watercraft pollutant loadings in Lake Powell 

compared to alternatives A and B, both in the short-term and long-term. This would produce a 

negligible to minor, direct, beneficial, long-term effect on the water quality of the lake. The four 

tributary inlets would also experience localized, long-term benefits, but due to their low personal 

watercraft use rates, these would be negligible. Alternative C would not result in the impairment of the 

water quality of Lake Powell. 
180 GLEN CANYON NATIONAL RECREATIONAL AREA

AIR QUALITY 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Issues 

Personal watercraft emit various compounds that pollute the air. For example, most personal 

watercraft are powered by two-stroke carbureted engines. In these engines: 

The lubricating oil is used once and is expelled as part of the exhaust; and 

The combustion process results in emissions of air pollutants such as volatile organic 

compounds, nitrogen oxides, particulate matter, and carbon monoxide (EPA 1996a). Volatile 

organic compounds are a broad class of pollutants encompassing hundreds of specific toxic 

compounds, including polycyclic aromatic hydrocarbons such as benzo(a)pyrene, naphthalene, 

and 1-methyl naphthalene.

Even though personal watercraft engine exhaust is usually expelled below the waterline, a portion of 

the exhaust gases end up in the air. Many organic pollutants that are initially dissolved in the water 

volatilize to the atmosphere, especially if they have high vapor pressures, are lighter than water, and 

mixing occurs at the air/water interface. However, it is difficult to assess the specific evaporation rates 

of exhaust pollutants from personal watercraft because the rates will differ according to the ratio of gas 

to oil used, by fuel brand, by engine, and operating conditions such as temperature. Fuel components 

volatilize (evaporate) more quickly at warmer temperatures. At temperatures commonly found in Lake 

Powell during the summer boating season (77°F to 86°F), 78% to 84% of typical two-stroke 

gasoline/oil mixture (50:1) would be evaporated from the water to the air in 1.2 hours (EPA 1994). 

Personal watercraft also emit fuel components such as benzene and fuel additives that are known to 

cause adverse health effects. Air pollutants from personal watercraft exhaust may adversely impact 

recreation area visitor and employee health, as well as sensitive recreation area resources. Visibility 

effects may also occur from discharge of exhaust smoke into the air and photochemical 

transformations of the engine emissions that contribute to the formation of smog.

For example: 

Hydrocarbons and nitrogen oxide emissions, in the presence of sunlight, form ozone which can 

cause or contribute to respiratory illness (EPA 1996a). 

Ozone also is toxic to vegetation. It causes visible injury to foliage, decreases plant growth, and 

increases plant susceptibility to insects and diseases. 

Carbon monoxide can affect humans. It interferes with the oxygen-carrying capacity of blood, 

resulting in lack of oxygen to tissues. 

Nitrogen oxide and particulate matter emissions associated with personal watercraft use also can 

degrade visibility. 
Air Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 181

Management Objectives 

As identified in table 3, the recreation area objective is to manage personal watercraft activity so that 

exhaust emissions do not appreciably degrade ambient air quality. 

GUIDING REGULATIONS AND POLICIES 

Clean Air Act. The Clean Air Act establishes national ambient air quality standards to protect the 

public health and welfare from air pollution. The act also establishes a program for the prevention of 

significant deterioration of air quality. 

The prevention of significant deterioration program was designed to protect clean air resources. The 

program was developed out of a May 30, 1972 decision by the U.S. District Court for the District of 

Columbia, in a lawsuit brought by the Sierra Club, interpreting the Clean Air Act as requiring the 

prevention of significant deterioration of air quality in all clean air areas of the country. The Supreme 

Court affirmed that decision on June 11, 1973. Prevention of significant deterioration thresholds are 

established in the Clean Air Act (40 CFR, section 51.166). 

One purpose of this program is to preserve, protect, and enhance air quality in national parks, national 

wilderness areas, national monuments, national seashores, and other areas of special national or 

regional natural, recreational, scenic, or historic value (42 U.S.C. 7401 et seq.). The program also 

includes the following classification approach for controlling air pollution. 

Class I areas, which typically are national parks and wilderness areas, are afforded the greatest 

degree of air quality protection. Very little deterioration of air quality is allowed in these areas, 

and the unit manager has an affirmative responsibility to protect visibility and all other class I 

area air-quality-related values from the adverse effects of air pollution. 

Class II areas include all national park system areas not designated as class I. The Clean Air Act

allows only moderate air quality deterioration in these areas. In no case, however, may pollution 

concentrations violate any of the national ambient air quality standards. Glen Canyon National 

Recreation Area is designated a class II area. 

Conformity Requirements. National park system areas that do not meet the national ambient air 

quality standards or whose resources are already being adversely affected by current ambient levels 

require a greater degree of consideration and scrutiny by NPS managers. Areas that do not meet 

national air quality standards for any pollutant are designated as nonattainment areas. Section 176 of 

the Clean Air Act states: 

No department, agency, or instrumentality of the federal government shall engage in, support in 

any way or provide financial assistance for, license or permit, or approve, any activity which 

does not conform to [a State] implementation plan. . . [T]he assurance of conformity to such a 

plan shall be an affirmative responsibility of the head of such department, agency or 

instrumentality. 

Essentially, federal agencies must ensure that any action taken does not interfere with a state’s plan to 

attain and maintain the national ambient air quality standards in designated nonattainment and 

maintenance areas. Because the Arizona and Utah counties that Glen Canyon National Recreation 

Area occupies are designated as in attainment for all six of the criteria pollutants (shown in table 11) 
ENVIRONMENTAL CONSEQUENCES

182 GLEN CANYON NATIONAL RECREATIONAL AREA

(EPA 2002a), there are no state implementation plans that apply to the project area. Therefore, 

personal watercraft management actions would not be subject to particular federal conformity 

determination or requirement. 

Emission Standards for Gasoline-Powered Marine Engines. The Environmental Protection Agency 

issued a spark-ignition gasoline marine engine final rule in August 1996. The rule, which took effect 

in 1998, affects manufacturers of new outboard engines and the type of inboard engines used in 

personal watercraft. In the rule, the agency required reductions in air emissions from marine engines 

using a phased approach. 

By the year 2006, personal watercraft manufacturers must meet a corporate average emissions 

standard that is equivalent to a 75% reduction from their 1998 hydrocarbon emissions. The corporate 

average standard allows manufacturers to build some engines to emission levels lower than the 

standard and some engines to emission levels higher than the standard, and to employ a mix of 

technology types, as long as the overall corporate average is at or below the standard. In making the 

rule, the Environmental Protection Agency recognized that some increase in nitrogen oxides would be 

“technologically inevitable” if hydrocarbon reductions of 75% or more are to be achieved. In 1996, the 

Environmental Protection Agency estimated that an overall 52% reduction in hydrocarbon plus 

nitrogen oxides emissions from marine engines will be achieved by 2010 and a 75% reduction by 

2030. The actual reduction in emissions is dependent on the sale of lower emitting marine engines. 

The 1997 rule delayed implementation by one year (EPA 1996a, 1997a). 

Low-emission engines, including both four-stroke engines and direct-injection two-stroke engines, 

generate reduced amounts of most air pollutants, including carbon monoxide, particulate matter, 

hydrocarbons, and volatile organic compounds. However, the low-emission engines produce more 

nitrogen oxides than do carbureted two-stroke engines (EPA 1996a) and the two-stroke direct injected 

engine has been shown to generate more airborne-particulate PAH emissions, a class of volatile 

organic compounds, than the two-stroke carbureted engines (Kado et al. 2000). The Environmental 

Protection Agency estimates that conversion to four-stroke engines and two-stroke direct injection will 

both result in an increase in the level of nitrogen oxides produced by personal watercraft engines. In 

order to meet stringent hydrocarbon emission reduction contained in the EPA final rule, the 

Environmental Protection Agency estimates that manufacturers will need to recalibrate their engines to 

run at leaner air-fuel ratios, resulting in higher combustion temperatures, more complete combustion, 

and some increase in nitrogen oxide formation. In addition, conversion to two-stroke direct inject and 

four-stroke technology have little internal exhaust gas recirculation (EGR) which could reduce 

emission rates of nitrogen oxides (EPA 1996a). 

Organic Act and Management Policies 2001. The National Park Service Organic Act (16 U.S.C. 1, 

et seq.) and Management Policies 2001 (NPS 2001d) guide the protection of park and wilderness 

areas. The mandates of the Organic Act state that the National Park Service will 

promote and regulate the use of . . . national parks . . . by such means and measures as conform 

to the fundamental purpose of the said parks, . . . which purpose is to conserve the scenery and 

the natural 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. 

Under its Management Policies 2001 the National Park Service will “seek to perpetuate the best 

possible air quality in parks to (1) preserve natural resources and systems; (2) preserve cultural 

resources; and (3) sustain visitor enjoyment, human health, and scenic vistas.” 
Air Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 183

Management Policies 2001 further state that the National Park Service will assume an aggressive role 

in promoting and pursuing measures to protect air-quality-related values from the adverse impacts of 

air pollution. In cases of doubt as to the impacts of existing or potential air pollution on park resources, 

the National Park Service “will err on the side of protecting air quality and related values for future 

generations.” 

The Organic Act and Management Policies 2001 apply equally to all areas of the national park system, 

regardless of Clean Air Act designation. Therefore, the National Park Service will protect resources at 

both class I and class II units. Furthermore, the Organic Act and Management Policies 2001 provide 

protection beyond that afforded by the Clean Air Act’s national ambient air quality standards, because 

the National Park Service has documented that specific park air-quality-related values can be 

adversely affected at levels below the national standards or by pollutants for which no standards exist. 

METHODOLOGY AND ASSUMPTIONS 

The Environmental Protection Agency has promulgated national ambient air quality standards and 

regulations for the protection of public health and welfare and the environment in compliance with the 

Clean Air Act and its amendments. Those standards, shown in table 11 in the “Affected Environment” 

chapter, were the basis for this air quality analysis. 

The analysis of impacts of the personal watercraft management alternatives on air quality separately 

assessed the effects of personal watercraft and other sources of pollution emissions on human health 

and the environment. The following methods and assumptions were used: 

Air quality designations for the recreation area and surrounding area were determined. This 

information is included in the “Affected Environment” chapter. As described there, Glen Canyon 

National Recreation Area and the nearby areas are in attainment for all criteria pollutants. 

Local ambient air quality data from the Salt River Project monitoring site near Wahweap were 

reviewed. The level and frequency of pollutant concentrations were ascertained. 

Short-term sampling within the recreation area at Halls Crossing and Wahweap was conducted during 

the Labor Day weekend 2001 to assess current air quality conditions. Wahweap represented a high-use 

area and Halls Crossing reflected air quality conditions at a moderate use area. For each pollutant, the 

maximum concentration, shown in table 12, was compared with the national ambient air quality 

standards. 

Boat days and watercraft operating hours were used as basic units of measurement of the intensity and 

impact of watercraft use. A boat day equals one watercraft on the lake during a 24-hour period. 

Watercraft operating hours are the average number of hours a vessel is underway during a 24-hour 

period. 

The annual boat days and operating hours for all motorized watercraft at the recreation area were 

determined from visitation records, launching permits, and seasonal observations by recreation area 

personnel. 

Numbers of watercraft of each type, type of engine per watercraft, and hours per trip were estimated 

from information published by Hagler Bailly (1999). Personal watercraft use in Glen Canyon National 

Recreation Area in 2001 was estimated to be 26% of the total annual boat days of all motorized 
ENVIRONMENTAL CONSEQUENCES

184 GLEN CANYON NATIONAL RECREATIONAL AREA

watercraft and 18% of the total watercraft operating hours. For this analysis, it was assumed for all 

alternatives that there would be a change in total boat days and watercraft operating hours between 

–2% and +2% annually over the next 10 years. It was also assumed that the removal of personal 

watercraft in alternative C would result in an initial decrease in annual boat days in the short-term. 

However, by the end of the 10-year analysis period, the total number of watercraft operating hours and 

the total number of motorized watercraft using Lake Powell under alternative C would be within the 

range predicted for alternatives A and B. This would be due to either natural growth in visitation, to 

visitors finding other watercraft to fulfill functions previously served by personal watercraft, or to 

increases in visitation by individuals who previously avoided the recreation area due to personal 

watercraft and now choose to visit in their absence. This was the same assumption that was used for 

the other impact topics. 

The ratio of the number of each type of watercraft to total number of watercraft was not changed under

alternative A. Changes in the proportion of personal watercraft numbers were based on the 

Environmental Protection Agency mandated reduction of emissions from gasoline marine engines. 

Based on EPA data, it was assumed that 21.6% of the carbureted two-stroke engines in use in 1998 

would have been replaced by 2004, and that 58.4% would have been replaced by 2012. 

For alternative B, assumptions regarding the replacement of carbureted two-stroke personal watercraft 

by 2004 are the same as for alternative A. Under the modified alternative B, carbureted two-stroke 

personal watercraft engines would be phased out over the next 10 years. The carbureted two-stroke 

personal watercraft engines would be replaced proportionally with other cleaner types of personal 

watercraft engines by the end of 2012. By 2013, all personal watercraft in the recreation area would be 

required to be 100% compliant with EPA emission standards. The air quality emissions associated 

with alternative B with implementation of the 2012 restriction would be realized beginning in 2013. 

For alternative C, the ratio of other motorized vessels was adjusted to compensate for the removal of 

personal watercraft. 

Data were collected on Lake Powell in 2001 to estimate the emissions of pollutants from personal 

watercraft and other motorized vessels. The average rated horsepower and emission factors for each 

watercraft type were taken or developed from the EPA NONROAD model. This model is used to 

calculate emissions of criteria pollutants from operation of non-road spark-ignition engines, including 

personal watercraft. Model elements included the following. 

The average rated horsepower of each type of watercraft for the State of Utah presented in the 

NONROAD model was assumed to apply to Glen Canyon National Recreation Area. This 

assumption is valid because the average rated horsepower of each type of watercraft for Arizona, 

Colorado, and Utah varies by less than 1%. 

Volatile organic compound emissions comprise approximately 100% of the total hydrocarbon 

for two-stroke engines and 93% of the total hydrocarbon for four-stroke engines (EPA 1997b). 

Volatile organic compound emissions are higher than total hydrocarbon emissions because the 

presence of alcohol and aldehydes, which are not detected by the source test method. 

All particulate emissions were assumed to be less than 10 microns in diameter (PM10). Among 

these, 92% of the PM10 emissions were assumed to be less than 2.5 microns in diameter (EPA 

1999b). 
Air Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 185

The emission factor for two-stroke, direct injection engines was incorrectly set equal to the 

emission factor for two-stroke, carbureted engines in the EPA NONROAD model. This was 

corrected by assuming that the emission factor for two-stroke, direct injection engines on 

personal watercraft would be the same as the emission factor for two-stroke, direct injection 

outboard engines of equal horsepower. 

The NONROAD model does not include emission factors for two-stroke inboard/sterndrive 

engines. Therefore, emission factors for two-stroke inboard/sterndrive engines were estimated 

from emission factors for two-stroke outboard engines of equivalent horsepower. 

The average engine load for all watercraft was assumed to be 21%. 

No engine degradation or nonexhaust total hydrocarbon/volatile organic compound emissions 

were considered in the emission estimates. Non-exhaust hydrocarbon emissions from watercraft 

are less than exhaust emissions but are not negligible. For watercraft, the principal sources of 

non-exhaust emissions are evaporative emissions from fuel tanks when the engine is not in use 

and refueling emissions. The quantities of these emissions are related to the number of pieces of 

equipment, number of trips, and watercraft fuel tank volume. The elements of the three 

alternatives that relate to watercraft type would change engine types, with variations in exhaust 

emissions. Fuel tank volumes would not be anticipated to change substantially. The number of 

trips per year would vary by 2%, at most, under all alternatives. Therefore, non-exhaust 

emissions would not change the impact analysis. In July 2002, the Environmental Protection 

Agency proposed new evaporative emissions standards for gasoline-fueled boats and personal 

watercraft. These proposed standards would require most new boats produced in 2008 or later to 

be equipped with low-emission fuel tanks or other evaporative emission controls.

Any reductions in emissions resulting from implementing control strategies were taken into 

account, as were changes in emissions resulting from increased or decreased usage. 

Established threshold levels of total emission loadings that would characterize the significance criteria 

for mobile sources are not available. Therefore, estimates of total annual emissions from personal 

watercraft under each alternative were compared to prevention of significant deterioration thresholds 

established in the Clean Air Act (40 CFR, section 51.166 (b)(1)(i)(b)) for stationary sources. Under 

prevention of significant deterioration, a major stationary source is: 

Any source in a fixed location that emits at least 250 tons per year of any pollutant regulated 

under the Clean Air Act; or 

Any source of 28 EPA-specified source categories that emit at least 100 tons per year of any 

regulated criteria pollutant. 

These prevention of significant deterioration stationary thresholds were applied to this analysis as 

significance criteria for nonroad mobile sources. 

Ozone injury on sensitive plants found in the recreation area was assessed from regional 

biomonitoring data provided by the U.S. Forest Service, Forest Health Biomonitoring Program (Forest 

Service 1999; 2002). 

A calculation referred to as SUM06 (parts per million per hour) was used for evaluating the 

implications of ozone. The highest three-month, five-year average commonly used for the area was 
ENVIRONMENTAL CONSEQUENCES

186 GLEN CANYON NATIONAL RECREATIONAL AREA

determined by comparing ambient air quality data (available from the National Park Service, Air 

Resources Division) to the Environmental Protection Agency proposed SUM06 level of 25 parts per 

million per hour that is associated with injury effects on vegetation. 

Visibility impacts were determined by assessing particulate matter levels from local monitoring data, 

or from qualitative evidence such as personal observations and photographs. 

Cumulative impacts were analyzed qualitatively, considering only the effects of air emissions from 

personal watercraft and other motorized watercraft. Although the recreation area also has air emissions 

from fueling stations, from land-based vehicles such as cars, trucks, and recreational vehicles, and 

from campfires, emissions from these sources were not assessed. The cumulative impact analysis also 

did not consider emissions from point sources, such as the Navajo Generating Plant near Page and 

Nuclear Fuel Service near the Bullfrog area. A discussion of the emissions from these and other point 

sources in the region is included in the draft air quality report for Glen Canyon National Recreation 

Area (NPS 2002u). 

Impact Threshold Definitions 

Personal watercraft impact thresholds for air quality depend on the type of pollutants produced, the 

background air quality, and the resources in the environment that may be affected by airborne 

pollutants (air quality related values). Air quality related values include “visibility and those scenic, 

cultural, biological, and recreation resources of an area that are affected by air quality” (43 FR 15016). 

Impact thresholds may be qualitative, such as photos of degraded visibility. They also can be 

quantitative, based on impacts on air quality related values or federal air quality standards, or 

emissions based on emission factor models. The type of thresholds used in an analysis depend on what 

type of information is appropriate or available. 

Because the Environmental Protection Agency has established standards that are regulated by states to 

protect human health and the environment, two categories of potential airborne pollution impacts from 

personal watercraft are analyzed. They include: (1) impacts on human health; and (2) impacts on air 

quality-related values in the recreation area. Impact intensity thresholds for each impact category are 

discussed below. 

Human Health Effects from Airborne Pollutants. Based on the national standards and the methods 

described above, the following impact thresholds for human health effects from airborne pollutants 

related to personal watercraft use were defined. To assess a level of impact on human health from 

airborne pollutants, both the emissions of each pollutant related to motorized watercraft activity and 

the background air quality were evaluated and then considered according to the thresholds defined 

below. 

 Activity Analyzed Current Air Quality 

Negligible: Emission levels would be 

less than 50 tons per year for 

each pollutant 

and The first highest three-year maximum for 

each pollutant is below (less than 60%) the 

national ambient air quality standards. 

Minor: Emission levels would be

less than 100 tons per year 

for each pollutant 

and The first highest three-year maximum for 

each pollutant is below (less than 80%) the 

national ambient air quality standards. 
Air Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 187

Moderate: Emission levels would be 

greater than or equal to 

100 tons per year for any 

pollutant 

or The first highest three-year maximum for 

each pollutant is greater than 80% of the 

national ambient air quality standards. 

Major: Emission levels would be

greater than or equal to 

250 tons per year for any 

pollutant 

and The first highest three-year maximum for 

each pollutant is greater than 80% of the 

national ambient air quality standards. 

NOTE: The annual carbon monoxide emission levels presented in the following analysis should not be 

correlated to recent carbon monoxide-related fatalities that occurred in the recreation area. Carbon 

monoxide-related fatalities occurred because of exposure to extremely high levels of carbon monoxide 

in confined, poorly ventilated spaces such as under a boat swimming platform, or near exhaust ports. 

The estimated annual emission levels presented in this analysis represent carbon monoxide levels over 

the entire recreation area, dispersed in a large volume of air, and are based on year-long boating 

activity. 

Air Quality Related Values. Impacts on environmental resources and values include visibility and 

biological resources (specifically ozone effects on plants) that may be affected by airborne pollutants 

emitted from personal watercraft and other sources. These pollutants include ozone, nitrogen oxides, 

total hydrocarbons, and particulate matter. Particulate matter and nitrogen oxide emissions are 

evaluated for visibility impairment. Volatile organic compounds and nitrogen oxides are precursors to 

the formation of ozone and are evaluated in lieu of ozone emissions, which is formed as a secondary 

pollutant. 

To assess the impact of ozone on plants, the five-year ozone index value was calculated and is 

represented as SUM06. The Air Resources Division of the National Park Service, based on local 

monitoring site data, developed SUM06 values used in this analysis. 

To assess a level of impact on air quality related values from airborne pollutants, both the emissions of 

each pollutant related to motorized watercraft activity and the background air quality must be 

evaluated and then considered according to the thresholds defined below. 

Activity Analyzed Current Air Quality 

Negligible: Emission levels would be less 

than 50 tons per year for each 

pollutant 

and There are no perceptible visibility impacts 

(photos or anecdotal evidence); 

and

There is no observed ozone injury to plants; 

and

SUM06 ozone is less than 12 parts per 

million per hour. 

Minor: Emission levels would be less 

than 100 tons per year for each 

pollutant 

and SUM06 ozone is less than 15 parts per 

million per hour. 
ENVIRONMENTAL CONSEQUENCES

188 GLEN CANYON NATIONAL RECREATIONAL AREA

Moderate: Emission levels would be 

greater than 100 tons per year 

for any pollutant 

or

Visibility impacts from 

cumulative personal watercraft 

emissions would be likely 

(based on past visual 

observations). 

or Ozone injury symptoms are identifiable on 

plants; 

and

SUM06 ozone are less than 25 parts per 

million per hour. 

Major: Emission levels would be 

equal to or greater than 250 

tons per year for any pollutant 

or

Visibility impacts from 

cumulative personal watercraft 

emissions would be likely 

(based on modeling or 

monitoring). 

and Ozone injury symptoms are identifiable on 

plants; 

or

SUM06 ozone is greater than 25 parts per 

million per hour. 

Impairment is defined as impacts that: 

Have a major adverse effect on recreation area resources and values; 

Contribute to deterioration of the recreation area’s air quality to the extent the recreation area’s 

purpose could not be fulfilled as established in its enabling legislation; 

Affect resources key to the recreation area’s natural or cultural integrity or opportunities for 

enjoyment; or 

Affect the resource whose conservation is identified as a goal in the recreation area’s general 

management plan or other recreation area planning documents. 

Geographic Area Evaluated for Impacts 

The analysis area includes the immediate locations of personal watercraft use and the surrounding 

near-shore environment where air pollutants may accumulate. For this analysis, the analysis area is 

Lake Powell within Glen Canyon National Recreation Area. 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Personal watercraft use in Glen Canyon National Recreation Area in 2001 was estimated to be 26% of 

the total annual boat days of all motorized watercraft. Under alternative A, a 2% increase or decrease 

annually in visitation to the recreation area is assumed over the next 10 years, however no change in 

the percent of annual number of personal watercraft boat days or operating hours in the recreation area 

would be expected through 2012. However, with full implementation of EPA regulations for reduced 
Air Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 189

emissions from marine engines in 2006, a change in the type of personal watercraft engine used in the 

recreation area would be expected to occur. 

Human Health Impacts from Airborne Pollutants 

The ambient air quality levels in the analysis area meet the national ambient air quality standards (see 

the “Affected Environment” chapter) and would continue to be in attainment under alternative A. No 

change in class II airshed status would result from this alternative, as personal watercraft activity has 

not resulted in a violation of any national air quality standard. Ambient air quality would likely 

improve slightly by 2012 as carbureted two-stroke emissions personal watercraft were gradually 

replaced with personal watercraft that complied with the regulations reduced emissions from marine 

engines. 

Table 40 presents the range of annual estimated personal watercraft emission loads based on visitation 

growth of between –2% and +2% annually and ambient air quality data for 2004 and 2012. Key points 

include the following. 

Volatile organic compounds and hydrocarbons are precursors to the formation of ozone. Based on air 

quality data collected during the 2001 air quality study conducted in the recreation area and available 

from the Salt River Project monitoring site, ozone levels in 2001 did not exceed the national standard. 

In fact, ozone levels in the region are less than 80% of the national ambient air quality standards. 

Using the assumptions noted in the “Methodology and Assumptions” section, emissions levels of 

hydrocarbons and volatile organic compounds would be above 100 tons per year (see table 40). 

No long-term data are available concerning carbon monoxide levels in the recreation area. However, 

carbon monoxide emissions were measured during the busy Labor Day weekend in 2001 and were 

found to be only 14% of the national air quality standards. 

TABLE 40: ALTERNATIVE A PERSONAL WATERCRAFT

EMISSIONS AND AMBIENT AIR QUALITY LEVELS

Annual Emissions 

(tons per year) 

Pollutant 2004a 2012a

Carbon monoxide 2,867–3,168 2,523–3.334 

Nitrogen oxide 19–22 33–43 

Particulate matter 10 microns or less 62–69 50–67 

Particulate matter 2.5 microns or less 57–63 46–61 

Hydrocarbons 1,141–1,261 674–891 

Volatile organic compounds 1,177–1,301 693–915 

Hydrocarbon + nitrogen oxide 1,160–1,283 707–934 

Ambient Air Quality 

National standards Below 80% of the standard Below 80% of the standard 

SUM06 11.3 parts per million/hour 11.3 parts per million/hour 

 

a. Emissions are presented based on a range of visitation growth of –2% or +2%. 
ENVIRONMENTAL CONSEQUENCES

190 GLEN CANYON NATIONAL RECREATIONAL AREA

Implementation of EPA-mandated emission standards would result in a beneficial effect on air quality 

within the recreation area by reducing the emission of volatile organic compounds, hydrocarbons, and 

carbon monoxide over time. However, over the life of the analysis, emission levels of these pollutants 

would exceed 100 tons per year. 

In 2012, an increase in nitrogen oxide emissions would occur under alternative A, because nitrogen 

oxide emissions from clean engine technology are greater than those of carbureted two-stroke engines. 

As described in the “Methodology” section, the sum of hydrocarbons plus nitrogen oxide emissions is 

the standard of the EPA rule. Hydrocarbons and nitrogen oxide are also the principle constituents of 

ozone. Under alternative A, hydrocarbon plus nitrogen oxide emissions would be reduced by 349 tons 

per year by 2012 considering an annual 2% visitor increase over time which would potentially benefit 

regional ozone levels. 

The estimated level of long-term adverse impact on human health from alternative A would be 

moderate. This conclusion was based on the modeling results and the current air quality 

measurements, which are well below the national standard. 

Levels of particulate matter from personal watercraft in 2004 were estimated to be below 100 tons per 

year, indicating a minor adverse impact on human health. Ambient levels of particulate matter with a 

diameter of 2.5 microns or less (PM2.5) measured during the 2001 study and from the Salt River 

Project monitoring site ranged from 3 to 16% of the national ambient air quality standards. By 2012, 

particulate matter emissions from personal watercraft use would be reduced from 2004 levels and 

range between 46 to 61 tons per year because of the increased use of low-emissions engines. The longterm adverse impacts on human health from particulate matter emission would be negligible to minor. 

Air Quality Related Value Impacts from Airborne Pollutants 

Ozone effects were determined by comparing ozone measurements recorded by the Salt River Project 

monitoring station over a three-year period with the Environmental Protection Agency proposed 

SUM06 level of 25 parts per million per hour. This SUM06 level is associated with significant effects 

on vegetation such as crop yield and biomass loss. 

The SUM06 ozone measurement for the recreation area was 11.3 parts per million per hour. As 

described in the human health impact analysis, alternative A would result in a potential reduction of 

regional ozone formation. This would lead to a potential reduction in the SUM06 index. 

The U.S. Forest Service, Forest Health Biomonitoring Program has numerous biomonitoring stations 

in southwestern Utah and within the intermountain region west, including Arizona, New Mexico, 

Nevada, Utah, Colorado, Wyoming, Montana, and Idaho. Based on this monitoring, ozone-induced 

injury to plants has not been detected within this region (Forest Service, Boyer, pers. com., June 

2002). 

As described in the human health impact analysis, the emissions of volatile organic compounds and 

hydrocarbons currently exceed 100 tons per year. By the year 2012, the increased proportion of lowemissions on personal watercraft would substantially reduce the emissions of these pollutants, but they 

would still exceed 100 tons per year. As a result, the estimated level of long-term adverse impact on 

air quality related values from alternative A would be moderate. 
Air Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 191

Particulate matter and nitrogen oxide emissions can degrade visibility. In the presence of sunlight, 

nitrogen oxide is a constituent in the formation of smog. With implementation of alternative A, 

particulate matter emissions would decrease to levels ranging between 46 to 67 tons per year by 2012. 

However, nitrogen oxide emissions would increase from 19–22 tons per year in 2004 to 33–43 tons 

per year in 2012. This would occur because the low-emission engines produce more nitrogen oxide 

emissions than do carbureted two-stroke engines. The emissions of these pollutants from personal 

watercraft activity in high-use areas could cause localized degradation of visibility during peak-use 

periods. The long-term adverse effects of these pollutants produced by personal watercraft on air 

quality and visibility would be negligible to minor. 

Cumulative Effects. Other motorized craft, mostly powerboats and houseboats, represent 72% of the 

total boat days and 82% of the total operating hours on Lake Powell. It was estimated that the inboard 

and sterndrive carbureted or electric direct-injection engines with power ratings of 170 horsepower 

made up 52% of the total boat days and 65% of the total operating hours on the lake. 

Based on the assumption listed above in the “Methodology” section, the cumulative emissions of all 

motorized craft is represented as a range assuming a 2% increase or decrease in visitor use annually to 

the recreation area. It is expected that implementation of Environmental Protection agency emission 

standards for marine engines would maintain ambient air quality levels below 80% of the national 

standards and SUM06 ozone levels would remain below 15 parts per million per hour. The cumulative 

emissions resulting from all motorized boating activities under alternative A are presented in table 41. 

Effects on human health, visibility, and plants due to airborne pollutants were considered. 

As a result of implementation of EPA emission standards, emission levels for carbon monoxide, 

particulate matter, hydrocarbons, and volatile organic compounds would decline, while nitrogen oxide 

emissions would increase by about 5%. However, the emission for all of these compounds would 

exceed 100 tons per year. As a result, the long-term cumulative adverse effects on air quality related 

values and human health from all motorized vessel use would be moderate. 

TABLE 41: ALTERNATIVE A CUMULATIVE EMISSIONS FROM PERSONAL WATERCRAFT

AND OTHER MOTORIZED BOAT USE AND AMBIENT AIR QUALITY LEVELS 

Annual Emissions 

(tons/year) 

Pollutant 2004a 2012a

Carbon monoxide 14,219–15,711 13,679–18,071 

Nitrogen oxide 479–529 486–641 

Particulate matter 10 microns or less 94–104 80–105 

Particulate matter 2.5 microns or less 87–96 73–97 

Hydrocarbons 1,855–2,050 1,318–1,741 

Volatile organic compounds 1,874–2,070 1,316–1,738 

Hydrocarbon + nitrogen oxide 2,334–2,581 1,804–2,382 

Ambient Air Quality 

National standards Below 80% of the standard Below 80% of the standard 

SUM06 11.3 parts per million/hour 11.3 parts per million/hour 

 

a. Emissions are presented based on a range of visitation growth of –2% to +2%.
ENVIRONMENTAL CONSEQUENCES

192 GLEN CANYON NATIONAL RECREATIONAL AREA

With an increase in visitation of 2% annually over the next 10 years and the conversion to lower 

emission engines, the particulate matter emission levels would increase slightly to levels slightly 

above 100 tons per year by 2012. Localized visual impacts from motorized boating exhaust would 

continue to be detectable in the year 2012 during peak use periods in high-use areas. The long-term 

cumulative effects on air quality related values and human health from particulate matter emissions 

would be adverse and minor to moderate. 

Conclusion. Personal watercraft management under alternative A would have the following effects on 

air quality. 

Emission levels of carbon monoxide, hydrocarbons, and volatile organic compounds would 

decrease between 2004 and 2012. Hydrocarbon plus nitrogen oxide emissions, which are the 

principal constituents of ozone, would also decrease by 2012. All of this change would be 

attributable to increased proportions of low-emission engines on the lake. However, these 

pollutants would continue to be emitted by personal watercraft at volumes exceeding 100 tons 

per year. As a result, alternative A would have moderate, long-term, direct, adverse impacts on 

human health and air quality related values. 

Particulate matter emissions from personal watercraft would decrease by 2012 to between 46 to 

67 tons per year. These levels of particulate matter would continue to cause locally degraded 

visibility from personal watercraft exhaust during peak use periods in high-use areas. This 

would be a direct, long-term, negligible to minor, adverse effect on human health and air quality 

related values. 

Air quality in the recreation area would continue to be below national ambient air quality 

standards (negligible effect). 

SUM06 ozone measurements in the recreation area would remain between 8 and 15 parts per 

million per hour (negligible effect). 

No change in class II airshed status would result from this alternative (negligible effect). 

The cumulative effect on air quality related values and human health from all motorized vessel would 

be direct, long-term, adverse, and minor to moderate. This alternative would not result in an 

impairment of the air quality resource or related values. 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

Alternative B would eliminate personal watercraft use in sections of the San Juan, Colorado, Dirty 

Devil, and Escalante Rivers. This action would eliminate personal watercraft exhaust emissions in 

these areas. 

The total quantity of exhaust emissions from personal watercraft engines is related to speed. A new 

flat-wake zone on 7 miles of the Escalante River would result in localized decreases in pollutant 

emissions. 
Air Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 193

Restrictions associated with alternative B would result in localized improvement to air quality in the 

tributary areas. 

Under this alternative, use of personal watercraft with carbureted two-stroke engines would be 

prohibited in the recreation area at the end of 2012 and in subsequent years. Carbureted two-stroke 

personal watercraft would be proportionally replaced with cleaner engines. There would be no 

restrictions on the type of engine permitted for use prior to 2012. As under alternative A, a range of 

emissions is given representing a change in total boat days and watercraft operating hours of between 

–2% or +2% annually over the next 10 years. 

Human Health Impacts from Airborne Pollutants 

Under alternative B, the ambient air quality levels in the analysis area would be expected to meet the 

national ambient air quality standards through 2012, and the area would continue to be in attainment. 

No change in class II airshed status would result from implementation of alternative B, as personal 

watercraft activity has not resulted in a violation of any national air quality standard. Table 42 presents 

the range of annual estimated personal watercraft emission loads and ambient air quality data for 2004 

and 2012. 

Emissions from personal watercraft under alternative B in 2004 would be similar to those shown in 

table 40 for alternative A. Volatile organic compounds, total hydrocarbons, and carbon monoxide 

levels would be higher than 100 tons per year throughout the assessment period. In conjunction with 

ambient air quality measurements that are well below the national standard, the estimated long-term 

level of adverse effect on human health would be moderate. 

TABLE 42: MODIFIED PREFERRED ALTERNATIVE B 

PERSONAL WATERCRAFT EMISSIONS AND AMBIENT AIR QUALITY LEVELS

Annual Emissions 

(tons per year) 

Pollutant 2004a 2012a

Carbon monoxide 2,867–3,168 2,237–2,955 

Nitrogen oxide 19–22 46–61 

Particulate matter 10 microns or less 62–69 40–53 

Particulate matter 2.5 microns or less 57–63 37–49 

Hydrocarbons 1,141–1,261 230–304 

Volatile organic compounds 1,177–1,301 232–306 

Hydrocarbon + nitrogen oxide 1,160–1,283 276–365 

Ambient Air Quality 

National standards Below 80% of the standard Below 80% of the standard 

SUM06 11.3 parts per million/hour 11.3 parts per million/hour 

 

a. Emissions are presented based on a range of visitation growth of –2% or +2%. 
ENVIRONMENTAL CONSEQUENCES

194 GLEN CANYON NATIONAL RECREATIONAL AREA

Under alternative B, hydrocarbon emissions would be reduced by 957 tons per year and volatile 

organic compounds by 995 tons per year by 2012, assuming an increase in visitor use of 2% annually. 

Hydrocarbon plus nitrogen oxide emissions would be reduced by up to 918 tons per year under this 

alternative and a potential beneficial effect on regional ozone levels. The reductions in these 

constituents would occur because carbureted two-stroke engines would be replaced with cleaner 

engines after 2012. However, over the life of the analysis, emission levels of these pollutants would 

exceed 100 tons per year resulting in a long-term adverse impact on human health that would be 

moderate. 

Conversion of carbureted two-stroke engines by 2012 would result in carbon monoxide emissions 

being reduced by 213 tons per year under a positive growth scenario or by 630 tons per year assuming 

a negative growth scenario. The impact to human health from carbon monoxide emissions would be 

moderate. 

Particulate matter emission levels associated with personal watercraft use would be reduced by 14 to 

22 tons per year from 2004 to 2012 with a range of between 37 and 53 tons per year by 2012. This 

would indicate a long-term, negligible to minor, adverse effect on human health.

Air Quality Related Value Impacts from Airborne Pollutants 

The SUM06 ozone measurement for the recreation area was 11.3 parts per million per hour. With no 

change in personal watercraft use expected over the next 10 years, SUM06 levels would not be 

expected to decrease over time with the conversion of two-stroke carbureted personal watercraft to

low-emission engines. 

As described in the human health impact analysis, alternative B would result in a potential reduction 

of regional ozone formation. Hydrocarbon plus nitrogen oxide emission would be reduced by over 

900 tons per year from 1,283 tons per year in 2004 to 365 tons per year in 2012 with the replacement 

of carbureted two-stroke personal watercraft engines in 2012. Total hydrocarbon and volatile organic 

compound emissions however would remain above 100 tons per year over time. The SUM06 ozone 

measurement would be below the national standard. Long-term, adverse impacts on air quality related 

values, including potential ozone injury to plants, would be moderate. 

Emissions of particulate matter and nitrogen oxide from personal watercraft can degrade visibility. In 

the presence of sunlight, nitrogen oxides can contribute directly to the formation of haze. Under 

alternative B, particulate matter of 2.5 microns would be reduced between 14 to 20 tons per year to 

below 50 tons per year by 2012. Particulate matter of 10 microns would be reduced from a potential 

high of 69 tons per year to 53 tons per year. Nitrogen oxide emissions would increase from 21 to 

61 tons per year by 2012. The reduction in particulate emissions would tend to improve visibility, and 

the increase in nitrogen oxide emissions from personal watercraft activity in high-use areas would 

cause localized degradation of visibility that may be detectable by visitors. This would be a long-term, 

negligible to minor, adverse impact on air quality and visibility. 

Cumulative Effects. Cumulative impacts associated with alternative B would be similar to those 

described for alternative A in 2004. With the replacement of two-stroke carbureted personal watercraft 

by the end of 2012, the emissions associated with all motorized vessels including personal watercraft 

would be reduced compared to alternative A. 
Air Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 195

It is expected that even with a 2% annual increase in visitation, implementation of EPA emission 

standards to phase-out all two-stroke carbureted marine engines would maintain ambient air quality 

levels below 80% of the national standards and SUM06 ozone levels would remain below 15 parts per 

million per hour. The cumulative emissions resulting from all motorized boating activities under 

alternative B are presented in table 43. 

Emission levels for hydrocarbons and volatile organic compounds would decline substantially by 2012 

with replacement of two-stroke carbureted personal watercraft engines with cleaner engines. Nitrogen 

oxide emissions would increase by 20 to 130 tons per year depending upon the growth scenario. With 

a negative growth scenario, carbon monoxide emissions would decline over time by nearly 830 tons 

per year. However under a positive growth scenario these emissions would increase by 1,981 tons per 

year. Emissions for all of these compounds would exceed 100 tons per year. As a result, the long-term 

cumulative adverse effects on air quality related values and human health from all motorized vessel 

use would be moderate. 

By the end of 2012 particulate matter of 10 microns would be reduced from 104 tons per year under a 

positive growth scenario to 92 tons per year by 2012. Particulate matter of 2.5 microns would also be 

reduced to between 64 to 85 tons per year by 2012. Localized visual impacts from motorized boating 

exhaust would continue to be detectable in the year 2012 during peak use periods in high use areas. 

The long-term cumulative effects on air quality related values and human health from particulate 

matter emissions would be reduced from minor to moderate adverse levels in 2004 to minor levels by 

2012. 

TABLE 43: ALTERNATIVE B CUMULATIVE EMISSIONS FROM PERSONAL WATERCRAFT

AND OTHER MOTORIZED BOAT USE AND AMBIENT AIR QUALITY LEVELS 

Annual Emissions 

(tons/year) 

Pollutant 2004a 2012a

Carbon monoxide 14,219 – 15,711 13,392 – 17,692 

Nitrogen oxide 479 –529 499 – 659 

Particulate matter 10 microns or less 94 – 104 70 – 92 

Particulate matter 2.5 microns or less 87 – 96 64 – 85 

Hydrocarbons 1,855 – 2,050 874 – 1,154 

Volatile organic compounds 1,874 – 2,070 855 – 1,129 

Hydrocarbon + nitrogen oxide 2,334 – 2,579 1,158 – 1,1813 

Ambient Air Quality 

National standards Below 80% of the standard Below 80% of the standard 

SUM06 11.3 parts per million/hour 11.3 parts per million/hour 

 

a. Emissions are presented based on a range of visitation growth of –2% or +2%. 
ENVIRONMENTAL CONSEQUENCES

196 GLEN CANYON NATIONAL RECREATIONAL AREA

Conclusion. Effects of alternative B would be similar to those of alternative A in 2004. Conversion of 

carbureted two-stroke personal watercraft to cleaner engines under the modified alternative would 

have the following effects on air quality. 

There would be sizeable reductions in volatile organic compounds, hydrocarbon, and 

hydrocarbon plus nitrogen oxide emissions. There would also be reduction in particulates (PM10

and PM2.5) and carbon monoxide emissions. 

Human health effects would be adverse and moderate for volatile organic compounds, carbon 

monoxide, hydrocarbons, and hydrocarbons plus nitrogen oxides. Some beneficial effects would 

occur after 2012 from the elimination of carbureted two-stroke personal watercraft engine 

emissions as hydrocarbon, carbon monoxide, volatile organic hydrocarbons, and particulate 

matter emissions are reduced. 

Adverse impacts to air quality-related values would be reduced from minor levels in 2004 to 

negligible to minor in 2012. Particulate matter reductions would contribute to an improvement 

in visibility, and the reduced ozone production would contribute to a reduced potential for plant 

damage. 

Air quality in the recreation area would continue to be below national ambient air quality 

standards (negligible effect). 

SUM06 ozone measurements in the recreation area would remain between 8 and 15 parts per 

million per hour (negligible effect). 

No change in class II airshed status would result from this alternative (negligible effect). 

The cumulative effect on air quality related values and human health from all motorized vessels would 

be direct, long-term, adverse, and minor to moderate.

This alternative would not result in an impairment of the air quality resource or related values. 

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

Human Health Impacts from Airborne Pollutants 

Alternative C would eliminate all emissions from personal watercraft. The resulting beneficial impacts 

on human health would range from negligible to moderate. 

Air Quality Related Value Impacts from Airborne Pollutants 

Alternative C would eliminate all emissions from personal watercraft. The benefit to air quality, plant 

health, and visibility could range up to moderate. 

Cumulative Impacts. There would be no incremental contribution to cumulative impacts from 

personal watercraft activity because personal watercraft use would no longer be permitted in the 

recreation area. However, emissions from other motorized vessels would continue. 
Air Quality 

FINAL ENVIRONMENTAL IMPACT STATEMENT 197

The ban on personal watercraft would be expected to decrease visitor use of the recreation area in the 

years immediately following the action. As a result, there would be a decrease in all emissions in the 

first few years following the ban that reflected the decline in overall visitor use. The cumulative 

emissions associated with this short-term decline in visitor use are summarized in table 44 for 2004.

By 2012, the total number of boat days and operating hours spent on the lake by all vessels would be 

the same levels as those expected for alternatives A and B. Most of these vessels would have lowemission engines. The cumulative air quality impacts from all motorized vessels under the no-action 

alternative in 2012 are summarized in table 44. As under alternatives A and B, a range of emissions is 

given reflecting a change in total annual boat days and watercraft operating hours of between –2% or 

+2% annually over the next 10 years. 

Under alternative C, the current ambient air quality levels would be expected to remain below 80% of 

the national standard with implementation of EPA emission standards that would apply to all twostroke carbureted marine engines. In addition, SUM06 ozone levels would remain below 15 parts per 

million per hour. 

Alternative C would result in a reduction of cumulative emissions in 2004 (table 44) compared to 

alternative A (table 41). In 2004, particulate matter emissions would be reduced to negligible levels. 

There would be little difference in nitrogen oxide emission levels between these two alternatives. 

Hydrocarbons, volatile organic compounds, and hydrocarbons plus nitrogen oxide emissions would be 

reduced by more than 1,000 tons per year in 2004 when compared to alternative A. In 2004, 

cumulative emissions of carbon monoxide would be reduced by approximately 3,000 tons per year 

under alternative C. However, the emission levels of these compounds would still exceed 100 tons per 

year. As a result, the short-term cumulative adverse effects on human health and air quality related 

values from all motorized vessel use would be moderate. 

TABLE 44: NO ACTION CUMULATIVE EMISSIONS FROM PERSONAL WATERCRAFT

AND OTHER MOTORIZED BOAT USE AND AMBIENT AIR QUALITY LEVELS

Annual Emissions 

(tons/year) 

Pollutant 2004a 2012a

Carbon monoxide 11,352–12,543 15,416–20,366 

Nitrogen oxide 459–508 627–828 

Particulate matter 10 microns or less 32–36 40–53 

Particulate matter 2.5 microns or less 30–33 37–49 

Hydrocarbons 715–789 877–1,158 

Volatile organic compounds 696–769 848–1,121 

Hydrocarbon + nitrogen oxide 1,174–1,297 1,504–1,986 

 Current Air Quality 

National standards Below 80% of the standard Below 80% of the standard 

SUM06 11.3 parts per million/hour 11.3 parts per million/hour 

 

a. Emissions are presented based on a range of visitation growth of –2% or +2%. 
ENVIRONMENTAL CONSEQUENCES

198 GLEN CANYON NATIONAL RECREATIONAL AREA

A comparison of the year 2012 cumulative effects for alternative A (table 41) and alternative C 

(table 44) shows that there would be little difference in the air emissions between these two 

alternatives. Alternative C would have higher emissions of carbon monoxide and nitrogen oxide, but 

lower emissions of particulate matter, hydrocarbons, and volatile organic compounds compared to 

alternative A. These differences would occur because of the differences in engine sizes and different 

emissions rates between the engines used in personal watercraft and the engines used on the other 

motorized vessels that use Lake Powell. Considering that ambient air quality standards would continue 

to be met, the cumulative, long-term, adverse effects on air quality related values and human health 

would be similar to alternative A. 

Particulate matter emissions related to other vessel usage would be reduced to 53 tons per year 

assuming a positive growth scenario. Localized visual impacts from motorized boating exhaust would 

be detectable during peak-use periods, particularly in high-use areas. The cumulative effects on human 

health and visibility from particulate matter emissions would be long-term, adverse, and negligible to 

minor. 

Conclusion. Under the no-action alternative, the air quality condition in the recreation area would 

continue to be below national ambient air quality standards. SUM06 ozone measurements in the 

recreation area would remain below 15 parts per million per hour. No change in class II airshed status 

would be expected because historical motorized boating activity has not resulted in a violation of any 

national air quality standard. 

The no-action alternative would have long-term, negligible to moderate, beneficial impacts on air 

quality related values and human health. These would result from the elimination of personal 

watercraft emissions of hydrocarbons, volatile organic compounds, carbon monoxide, nitrogen oxide, 

and particulate matter in the recreation area. 

In the short-term, total vessel operating hours would be reduced as personal watercraft would be 

prohibited from the park. In 2004, there would be sizeable reductions in the cumulative emissions of 

carbon monoxide, volatile organic compounds, hydrocarbon, and hydrocarbon plus nitrogen oxide 

when compared with alternative A. Particulates (PM10 and PM2.5) would be reduced from minor to 

moderate levels under alternative A to negligible under the alternative C, the no-action alternative. 

In the long-term visitors would replace personal watercraft with a different variety of motorized vessel 

and other vessels usage would continue. This would offset the benefits to air quality from elimination 

of personal watercraft. Considering that ambient air quality standards would continue to be met, 

moderate, long-term, adverse impacts on human health and air quality related values would occur from 

carbon monoxide, nitrogen oxide, hydrocarbon, and volatile organic compound emissions associated 

with all motorized boating activity. The long-term, adverse impacts on human health and visibility 

associated with particulate matter emissions would be negligible to minor. 

Implementation of this alternative would not result in an impairment of the air quality resource. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 199

NATURAL SOUNDSCAPES 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Issues 

Soundscape issues related to personal watercraft that were identified during scoping included the 

following. 

Effects of personal watercraft on natural soundscapes. Noise can directly affect natural 

soundscapes by masking, modifying, or intruding on natural sounds that are an intrinsic part of the 

environment. This can be especially true in quiet places, such as in secluded coves and river corridors, 

and when sounds from the noise source occur in the same sound frequency as sounds in the natural 

soundscape. 

Effects of noise on recreation area visitor experiences. Visitor experience is a resource-based 

opportunity appropriate to a given area within the recreation area. The following issues regarding 

noise effects on the visitor experience in the recreation area were identified. 

The sensitivity of listeners to personal watercraft noise. Typically, a visitor seeking solitude 

would be more affected by personal watercraft noise than would another personal watercraft 

operator. 

The rapid changes in the level and frequency distribution of sound produced by personal 

watercraft. As described in the “Affected Environment” chapter, these changes result from 

personal watercraft operator behaviors such as rapid acceleration and deceleration, frequent 

changes in direction, and jumping into the air. 

Noise effects in areas where personal watercraft operators “play.” Some personal watercraft 

operators use their vessels within a relatively small area for extended periods of time, for such 

activities as turning in circles or repeatedly cruising up and down a stretch of shoreline. This 

behavior contrasts with that of most other vessels, which usually travel from place to place. 

Factors that increase noise or amplify the perception of noise, such as use in confined areas, use 

close to beach areas, and travel of personal watercraft users in groups. 

Noise from personal watercraft during sensitive times of day or season. These can include 

nighttime (in Arizona, a personal watercraft can be operated at night if the vessel has lights) and 

early morning, or any time from October through March when there are few other sources of 

engine noise on the lake. 

Effects on wildlife resources. There was concern that species that make sound in the same frequency 

bands as personal watercraft may especially be adversely affected by interference from personal 

watercraft noise. Effects of noise on wildlife are included in the “Wildlife and Wildlife Habitat” 

section. 
ENVIRONMENTAL CONSEQUENCES

200 GLEN CANYON NATIONAL RECREATIONAL AREA

General Effects of Noise on the Natural Soundscape 

The natural soundscape in a park is defined as its mix of ambient acoustic conditions without the 

intrusion of human-caused sound. The soundscape is a resource to be associated with the natural 

settings and conditions that may be found within a park. A healthy natural soundscape is critical to the 

enjoyment of a park by visitors, and to some natural biological processes that are part of a park’s 

ecosystem, as expressed in some of the issues presented above. 

Noise can adversely affect park resources or values, including but not limited to natural soundscapes, 

cultural resources, wildlife, and visitor experience. It can directly impact them by modifying or 

intruding upon the natural soundscape, masking the natural sounds that are an intrinsic part of the 

environment. This can be especially true in quiet places, such as in secluded coves and when sounds 

from the noise source occur in the same sound frequency bands as sounds in the natural soundscape. It 

is important to distinguish between the intrinsic value of the soundscape as a natural resource, or as 

something to be experienced by people, or as part of wildlife habitat, or as part of a cultural (historic, 

religious) resource. This distinction is not a radical concept, as the Organic Act talks both to 

conserving resources and providing for their enjoyment. Air, water, wildlife, cultural resources, and 

sound all are valued for their existence in parks, as well as for their potential to be enjoyed in that state 

by visitors. 

Noise can adversely impact wildlife resources by interfering with sounds important for animal 

communication, including territory establishment, courtship, nurturing, predation, avoiding predators, 

migration, and foraging functions. Certain types and levels of sound can, especially in non-habituated 

populations, cause animals to use avoidance mechanisms. Avoidance, initiated as it may be by 

annoyance or stress, can cause individual animals to alter normal behavior, move to less preferred 

habitats, and unduly use energy during critical times of the year. In some cases, animals may become 

habituated, or accustomed, to some level of human-caused noise without negative impacts, unless 

habituation itself is a negative impact. However, in cases where animals do not habituate or where 

noise levels are such that normal behavior is altered, a whole suite of negative consequences may 

result. Effects of watercraft use on wildlife, which includes the noise emitted by them, are presented in 

the “Wildlife and Wildlife Habitat” section. 

Noise can adversely impact park visitor experiences. Managing parks for “visitor experience" means 

providing the opportunity for visitors to enjoy a park's resources and values in a manner appropriate to 

the park's purpose and significance. Visitors usually have expectations about the experience being 

offered in units of the National Park System. The impacts of noise on visitor experience can be 

especially evident when visitor expectations include solitude, serenity, tranquility, or contemplation, 

(as in the natural zone of Glen Canyon National Recreation Area). Many visitors have great 

expectations for national park units in this regard, since daily life for many people consists of high and 

constant levels of noise in urban/suburban settings. Effects of watercraft use on visitor experience, 

which includes the noise emitted by them, are presented in the “Visitor Use and Experience” section. 

Management objectives, or desired conditions, for protection of natural soundscapes, cultural 

resources, wildlife, and visitor experience are derived through well-established public planning 

processes. They are based in law, policy, regulations, and management direction applicable to the 

entire national park system and to each specific park unit, as provided in the next two sections.
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 201

Management Objectives 

When the Glen Canyon National Recreation Area general management plan (NPS 1979a) was being 

prepared in the late 1970s, the importance of natural soundscape was not as well recognized as it is 

today. Therefore, the recreation area’s general management plan does not include management 

objectives for soundscapes. 

The emerging recognition of the natural soundscape as an important park resource is demonstrated by 

the recent publication of Director’s Order 47: Soundscape Preservation and Noise Management (NPS 

2000b). This resource also is addressed in Management Policies 2001 (NPS 2000d). 

The soundscape management objective in table 3 is to manage the effects of personal watercraft on 

soundscapes in a manner consistent with recreation area management zones. This objective recognizes 

that the sound-related goals for personal watercraft will vary, depending on the management zone. The 

goals described below conform to the general goals for developed and natural areas that are described 

in Director’s Order 47: Soundscape Preservation and Noise Management (NPS 2000b). 

In the Recreation and Resource Utilization Zone and Development Zone, the management 

objective for sound from personal watercraft is to reduce noise to the level consistent with the 

best technology available. This would mitigate noise impacts without adversely affecting the use 

of personal watercraft. 

The Natural Zone is managed to maintain natural processes and existing conditions, and to 

preserve the land, water, and other natural resources. The Cultural Zone is managed to preserve, 

interpret, and restore (where deemed appropriate by professional analysis) the historic and 

archeological resources of the recreation area. In these zones, the goal is to return the 

soundscape to as near natural conditions as possible over time, while allowing visitors to access 

and enjoy the recreation area in a manner consistent with recreation area management goals. 

GUIDING REGULATIONS AND POLICIES 

The fundamental mission of the national park system, established in law (16 U.S.C. 1 et seq.), is to 

conserve park natural and historic resources, and to provide for the enjoyment of park resources only 

to the extent that the resources will be left unimpaired for the enjoyment of future generations. As 

described in section 1.4.6 of Management Policies 2001 (NPS 2000d), natural soundscapes are 

recognized and valued as a park resource in keeping with the NPS mission. 

The natural soundscape, sometimes called natural quiet, is the aggregate of all of the natural sounds 

that occur in parks, together with the physical capacity for transmitting natural sounds. Management 

goals for soundscapes are included in section 4.9 of Management Policies 2001 (NPS 2000d) and in 

Director’s Order 47: Soundscape Preservation and Noise Management (NPS 2000b). The NPS 

management objectives for managing sound in Glen Canyon National Recreation Area, which are 

presented in the preceding section, reflect the management goals of these two documents. 

Management Policies 2001 (NPS 2000d) requires restoration of degraded soundscapes to the natural 

condition whenever possible, and protection of natural soundscapes from degradation. In section 4.9, 

the National Park Service is directed to “take action to prevent or minimize all noise that, through 

frequency, magnitude, or duration, adversely affects the natural soundscape or other park resources or 
ENVIRONMENTAL CONSEQUENCES

202 GLEN CANYON NATIONAL RECREATIONAL AREA

values, or that exceeds levels that have been identified as being acceptable to, or appropriate for, 

visitor uses at the sites being monitored.” 

Visitor uses of parks will only be allowed if they are appropriate to the purpose for which a park was 

established, and can be sustained without causing unacceptable impacts on park resources or values 

(sections 8.1 and 8.2 of Management Policies 2001). Unless mandated by statute, the National Park 

Service does not allow visitors to conduct activities that, among other things, unreasonably interfere 

with “the atmosphere of peace and tranquility, or the natural soundscape maintained in wilderness and 

natural, historic, or commemorative locations within Glen Canyon National Recreation Area.” 

Director’s Order 47: Soundscape Preservation and Noise Management (NPS 2000b) requires, “to the 

fullest extent practicable, the protection, maintenance, or restoration of the natural soundscape 

resource in a condition unimpaired by inappropriate or excessive noise sources.” It also states that “the 

fundamental principle underlying the establishment of soundscape preservation objectives is the 

obligation to protect or restore the natural soundscape to the level consistent with park purposes, 

taking into account other applicable laws.” Noise is generally considered appropriate if it is generated 

from activities consistent with park purposes and at levels consistent with those purposes. 

Director’s Order 47 provides the following policy direction: “Where natural soundscape conditions 

are currently not impacted by inappropriate noise sources, the objective must be to maintain those 

conditions. Where the soundscape is found to be degraded, the objective is to facilitate and promote 

progress toward the restoration of the natural soundscape.” Where legislation provides for specific 

noise-making activities in parks, the soundscape management goal would be to reduce the noise to the 

level consistent with the best technology available, which would mitigate the noise impact but not 

adversely affect the authorized activity. Where a noise-generating activity is consistent with park 

purposes, “soundscape management goals are to reduce noise to minimum levels consistent with the 

appropriate service or activity.” 

A key concept for noise management in both Management Policies, 2001 and Director’s Order 47 is 

the purpose for which a park was established. The establishing legislation for Glen Canyon National 

Recreation Area (86 Stat 1311) states that the recreation area was established “to provide for public 

outdoor recreation use and enjoyment of Lake Powell and the lands adjacent thereto.” Based on this 

statement, noise generated by watercraft, including personal watercraft, is consistent with the 

recreation area’s purposes, but noise levels must be within the standards established by NPS 

regulations. 

NPS regulations pertaining to noise abatement for boating and other water use activities in parks 

nationwide are included in 36 CFR 3.7. These regulations prohibit operating a vessel on inland waters 

“so as to exceed a noise level of 82 decibels measured at a distance of 82 feet (25 meters) from the 

vessel” and specify testing procedures to determine such noise levels. Watercraft that exceed these 

levels are subject to fine and removal from the recreation area. 

It is important to note that this NPS regulation and the testing procedure were developed for 

enforcement purposes, not impact assessment purposes. Nonetheless, it is reasonable to assume for 

this analysis that 82 decibels at 82 feet is the maximum that would be emitted by any legal watercraft 

at full acceleration (normally the loudest portion of its operation). This regulation sets a limit for the 

maximum allowable noise, but does not imply that there are no noise impacts from vessels operating 

below that noise level. 
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 203

The states of Arizona and Utah also regulate noise from personal watercraft and other watercraft. 

Arizona regulations prohibit a vessel from being operated in a manner that causes it to emit a sound 

level in excess of 86 decibels when measured from a distance of 50 feet or more. Utah laws and rules

prohibit a vessel from being operated in a manner that will cause it to emit more than 75 decibels of 

noise at the shoreline. 

METHODOLOGY AND ASSUMPTIONS 

The technique used to assess noise impacts from personal watercraft in this document is consistent 

with methods being developed for NPS Reference Manual 47, Soundscape Preservation and Noise 

Management (NPS in preparation), in accordance with Management Policies 2001 (NPS 2000d) and 

Director’s Order 47: Soundscape Preservation and Noise Management (NPS 2000b). The evaluation 

method considered noise context, sound characteristics including audibility, and time factors, such as

duration, frequency of occurrence, and sensitive time periods. These all interact to determine the 

degree of impact for an activity. 

Context 

Glen Canyon National Recreation Area resources most likely to be affected by personal watercraft 

noise include the recreation area’s natural soundscape, sites used by Native Americans for traditional 

religious activities, and noise-sensitive wildlife. Sound levels generated by personal watercraft using 

the lake affect recreational users differently, depending on each visitor’s activities and expectations. 

Typically, personal watercraft noise of a specified duration and amplitude would have a greater impact 

on visitor experience in a highly sensitive context. Visitor experiences that are most likely to be 

adversely affected by personal watercraft noise are the opportunities to experience solitude and the 

recreation area’s natural soundscape. Visitors who recreate using motorized means on the lake surface 

are generally less impacted by sound generated in this pursuit, by themselves or others. The Natural 

Zone and Cultural Zone are considered areas of high sensitivity to noise, while the Recreation and 

Resource Utilization Zone and Developed Zone are considered areas of low sensitivity. Impacts on 

visitor experience are presented in the “Visitor Use and Experience” section. Potential impacts of 

personal watercraft use, including noise, on cultural resources and wildlife are presented in those 

sections of this document. Analysis in this section is intended to disclose impacts on the natural 

soundscape specifically, recognizing that sound is an intrinsic part of other resources and values in 

Glen Canyon National Recreation Area.

Sound Characteristics Used in the Analysis 

The L90 is the sound level descriptor specified in Director’s Order 47 to use in estimating the natural 

ambient sound level when only a single descriptor is used. It represents the sound level exceeded 90% 

of the measuring time. The daytime median L90 measured at the low-use Last Chance Canyon site by 

the Harris Miller Miller & Hanson, Inc. (2002) study was 13.4 decibels. This value was used in this 

evaluation as the average daytime natural soundscape that could be affected by the personal watercraft 

alternatives. 

A noise prediction model was employed to evaluate alternatives using a real-time simulation of a 

limited time period at one high-use site. The noise propagation equations in the model were based on 

the Federal Highway Administration’s Traffic Noise Model (Menge et al. 1998) and the U.S. Army 
ENVIRONMENTAL CONSEQUENCES

204 GLEN CANYON NATIONAL RECREATIONAL AREA

Construction Engineering Research Laboratory’s SoundProp Model (White 1994). Model features 

included the following. 

The ground was assumed to be gradually rising away from shore, like many of the beach areas at 

Glen Canyon National Recreation Area. 

A real-time simulation of the various watercraft moving about the lake was created and mated 

with the propagation model to develop a simulated time-history of the sound levels at various 

distances from the shore. This process used a documented 10-minute period of activity at the 

high-use site at Crosby Canyon. The hourly equivalent level (Leq) was computed from these time 

history records. 

For audibility calculations, sound levels in 1/3-octave bands were compared with the 

background sound level and the human threshold of hearing to determine moment-to-moment 

audibility of watercraft. 

The noise prediction model provided qualitative comparisons of the alternatives related to amplitude 

(loudness), time factors, and audibility. This included calculation of the predicted rate at which the 

maximum pass-by sound level of various watercraft would decrease with distance from the shoreline, 

and the predicted distance that the different watercraft could be heard. Predicted distances from the 

sources of sound allows computation of the natural soundscape area affected in each alternative. These 

calculations were done for both single and multiple watercraft. 

Time Factors 

The time of day or time of year influences the impact a given noise will have. This analysis assumed 

that during the summer, the periods of greatest sensitivity to noise include sunset, sunrise, and at night. 

On an annual basis, it was assumed that there is greater sensitivity to noise from personal watercraft 

during the winter when there is very little noise from other human-related sources and, potentially, a 

greater expectation for solitude from recreation area visitors. 

Duration and frequency of occurrence of a noise affect the impact the noise will produce. For example, 

in popular use areas where personal watercraft use is almost constant from dawn to dusk, noises from 

personal watercraft blend with the general noise produced by other watercraft and other sources such 

as generators, automobile engines, and radios. In lightly used areas adjoining the Natural Zone, the 

intermittent sound from a single personal watercraft passing by would have a greater effect than the 

same action in a popular use area. These factors were addressed qualitatively in the impact analysis. 

Other Methods and Assumptions 

The soundscapes analysis assumed for alternative A and alternative B that throughout the analysis 

period, 26% of boat days and 18% of operating hours were personal watercraft, 72% of boat days were 

other motorized watercraft, and 2% were nonmotorized watercraft. (A boat day equals one watercraft 

on the lake during a 24-hour period.) For this analysis, it was assumed for all alternatives that there 

would be a change in total boat days and watercraft operating hours between –2% and +2% annually 

over the next 10 years. It was also assumed that the removal of personal watercraft in alternative C 

would result in an initial decrease in annual boat days in the short-term. However, by the end of the 

10-year analysis period, the total number of watercraft operating hours and the total number of 
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 205

motorized watercraft using Lake Powell under alternative C would be within the range predicted for 

alternatives A and B. This would be due to either natural growth in visitation, to visitors finding other 

watercraft to fulfill functions previously served by personal watercraft, or to increases in visitation by 

individuals who previously avoided the recreation area due to personal watercraft and now choose to 

visit in their absence. This was the same assumption that was used for the other impact topics.

Data collected during the August 2001 sound study were reviewed by noise specialists from the 

National Park Service and from Harris Miller Miller & Hanson, Inc. (2002). Based on their previous 

experience and comparisons with published literature, they determined that the data collected at Glen 

Canyon National Recreation Area were consistent with information from other sites and represented 

the best available data on which to base the impacts analysis. 

Impact Threshold Definitions 

Director’s Order 47 (NPS 2000b) states that the natural ambient sound level of a park is the basis for 

determining the affected environment in environmental impact statements and other documents 

prepared for compliance with the National Environmental Policy Act. Therefore, impact thresholds for 

the soundscape were written as comparisons to the daytime median L90 of 13.4 decibels that was 

measured at the low-use Last Chance Canyon site by Harris Miller Miller & Hanson, Inc. (2002). Each 

threshold integrates sound characteristics, audibility and time factors to indicate the magnitude of 

impact for each of the personal watercraft management alternatives. 

The Recreation and Resource Utilization and Developed Zones in the Glen Canyon Recreation Area 

are established for use by motorized watercraft. These zones are consistent with the purposes for 

which the recreation area was established. During high-use seasons, heavy personal watercraft use 

generates high noise levels within this zone, which the park has determined is consistent with its 

purpose. Therefore, even though the soundscape is heavily impacted in this area, it is not considered to 

be unacceptably impacted as defined by the recreation area’s General Management Plan. 

Consequently, all noise impacts within this area are basically considered to be negligible or minor, 

providing the watercraft are used within the state’s laws, rules, and regulations (speed, behavior, 

operating times, area restrictions) and that these enforceable measures are effectively administered by 

recreation area management and enforcement personnel of Utah and Arizona. 

Noise that is generated within the use and development zone is efficiently carried across the water 

surface and beyond the surrounding shoreline areas. Much of the water surface perimeter and use zone 

immediately abuts the Natural and Cultural Zones. The extent of the impact on these zones depends on 

the sound characteristics of the source; the amount and duration of generated sound; and the distance 

that the sound is propagated into, and audible within, the adjoining zone. The following definitions 

describe the varying levels of impact on the Natural and Cultural Zones. 

Negligible: Natural sounds predominate. Noise impacts are not audible in most of the zone. 

Where noise is audible, it is for short duration with significantly lengthy periods of time that are 

noise-free. Noise is not audible between sunset and sunrise. 

Minor: Natural sounds usually predominate. Noise impacts are not audible in most of the zone. 

Where noise is audible, impacts occur for short durations frequently during the day, and is 

occasionally audible between sunset and sunrise. 
ENVIRONMENTAL CONSEQUENCES

206 GLEN CANYON NATIONAL RECREATIONAL AREA

Moderate: Natural sounds compete with human-caused sounds. Noise impacts are commonly 

audible in some areas for up to half the daylight hours. In locations where noise is commonly 

audible, it occurs occasionally between sunset and sunrise. Noise is audible at times and places 

up to two miles from the shoreline. 

Major: Natural sounds are dominated by human-caused sounds. In some areas, natural sounds 

are commonly impacted by noise during extended periods of time and frequently between sunset 

and sunrise. Noise is audible at times and places more than two miles from the shoreline. 

Impairment: In the Natural and Cultural Zones, the natural soundscape would be impaired at the 

major level of adverse impact. The sound-related management objectives that were provided at 

the beginning of this analysis could not be fulfilled in significantly large areas of the zone.

Geographic Area Evaluated for Impacts 

Personal watercraft use (and its associated noise) occurs on virtually the entire lake surface. 

Concentrated personal watercraft use occurs close to marinas and other developed areas. However, 

locations long distances from marinas or launch ramps routinely are accessed by personal watercraft 

that are used in conjunction with houseboats. Therefore, the entire lake surface, including all coves 

and tributaries that are accessible when the lake surface is at an elevation of 3,700 feet above sea level, 

were included in the geographic area evaluated for noise impacts. 

Most of the time, the tributary rivers to Lake Powell do not have sufficient flow for personal 

watercraft use. However, under certain flow conditions, there is enough water for personal watercraft 

use, and these vessels currently are allowed on the rivers in a downstream direction of travel. 

Therefore, the tributary rivers also were included in the geographic area evaluated for noise impacts. 

Noise modeling by Harris Miller Miller & Hanson, Inc. (2002) indicated that within the Natural Zone, 

noise from individual personal watercraft and from boats other than those powered by V-8 engines 

could be distinguished from the natural soundscape up to a mile from the shoreline. The noise from 

multiple watercraft was greater than that of individual vessels, but modeling showed that it would not 

carry for 2 miles. The land area evaluated for noise impacts extended 2 miles inland from the 

shoreline, and it is therefore assumed from modeled results that there would be no impacts from the 

activity beyond that distance. 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Alternative A would manage personal watercraft consistent with the Superintendent’s Compendium 

(NPS 2002c). All of the effects on the soundscape were determined to be direct. Indirect effects on 

wildlife are included in the “Wildlife and Wildlife Habitat” section. Other indirect effects were 

evaluated in the “Visitor Use and Experience” and “Cultural Resources” sections. 

In the Natural and Cultural Zones, where noise from motorized use is inconsistent with the 

management zoning, only the areas within 2 miles of the lake would be affected by noise from 

personal watercraft. The areas most affected would be where the Natural Zone is adjacent to high use 

“play” areas in the Recreation and Resource Utilization Zone, and where the terrain is relatively open 

without features such as cliffs that act as sound barriers. 
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 207

Modeling was performed to determine sound effects in the Natural Zone for three conditions. 

Tables 45 and 46 summarize the results. The alternative A condition included use of the area, 

primarily for pass-bys, of 53 personal watercraft and 31 boats in 1 hour. This level of use would be 

considered a heavy use condition for an Recreation and Resource Utilization Zone area near the 

Natural Zone. 

In much of the Recreation and Resource Utilization Zone adjacent to the Natural Zone, the typical use, 

even during the summer, would be more like the other modeled conditions of 31 motorized vessels in 

1 hour and 3 motorized vessels in 1 hour. (As demonstrated by the noise study performed by Harris 

Miller Miller & Hanson, Inc. [2002], similar levels of noise were produced by personal watercraft and 

other motorized watercraft [except boats with V-8 engines, which typically were louder]. As a result, 

the number of watercraft is a more important factor in determining the amount of noise than the type 

of watercraft.) 

The modeling results displayed in tables 45 and 46 indicated that Natural Zone areas up to about 

2 miles from the lakeshore would be likely to experience adverse noise impacts from the high use

activity of personal watercraft and other vessels. At or near the shoreline, sound is audible 100% of the 

time at an average sound pressure level of 53 decibels. The sound continues to be audible 100% of the 

time out to a distance of 3,240 feet, but diminishes in loudness arithmetically to 30 decibels over the 

distance. Because the average natural soundscape (L90) assumed in this analysis is at 13.4 decibels, the 

created sound level over this range is substantially louder than natural sounds, and on the average, 

would dominate natural sounds. Occasional peaks of sound at higher decibel levels would intrude, and 

human-caused sound would recede at times. At 3,240 feet (about 0.6 miles), the percent of the time 

personal watercraft are audible begins to diminish, along with its sound pressure level. At 10,240 feet 

from the source (or about 2 miles measured from the shoreline), the sound reaches its limit of 

audibility (is audible 0% of the time) with a sound pressure level of 14 decibels. Up to this modeled 

limit of audibility, the sound of personal watercraft would be distinguishable from the natural sound of 

the environment by virtue of the frequencies and the sound pressure levels at which the sounds were 

generated. Non-natural sounds generated in these frequencies are audible at decibel levels below those 

of the natural soundscape.4 They would also be distinguishable from, and perhaps more audible than, 

other watercraft by virtue of greater fluctuation in noise emissions (see “Affected Environment” 

chapter). 

However, at 0.6 miles from the shoreline, the noise level from 84 watercraft per hour would be only 

30 decibels, which is the noise level typically found in suburbs at night. At 2 miles, the noise level 

produced by the 84 watercraft would differ from the modeled low-use condition by only 1 decibel. 

The effect of this alternative is that the presence and high use of personal watercraft increases the 

audibility of watercraft noise by 24% to a distance of over 3,240 feet from the shoreline, and that it 

elevates the sound level over this distance by 4 to 5 decibels. This would be a noticeable difference for 

most visitors in the affected area. At present use levels and distribution, this impact would occur 

 

4. The sounds of helicopters, snowmobiles, other two-stroke combustion engines, and virtually all human-caused sounds are 

distinguishable from the natural ambient soundscape even at 10 decibels below the natural ambient sound pressure level. 

Audibility is associated not only with loudness, but also the frequency at which the sound is generated. Considering only the 

decibel level does not fully characterize the impact. “Masking” only occurs when the frequencies of natural sounds coincide 

with frequencies of non-natural sounds. At the same frequency and the same decibel level, one sound could be said to mask 

the other - or make them indistinguishable (HMMH 2002; NPS 2003). 
ENVIRONMENTAL CONSEQUENCES

208 GLEN CANYON NATIONAL RECREATIONAL AREA

TABLE 45: COMPUTED WATERCRAFT PLUS

BACKGROUND NOISE AT VARIOUS DISTANCES FROM THE SHORELINE

Leq (decibels) at Distance from Shoreline 

(feet) 

Condition 240 540 990 1290 3240 10,240 

Existing condition (alternative A) 

(53 personal watercraft and 31 boats in 1 hour) 

53 50 45 41 30 14 

No personal watercraft condition (alternative C) 

(31 boats in 1 hour) 

48 45 40 37 26 14 

Low-use condition 

(2 personal watercraft and 1 boat in 1 hour) 

40 36 31 28 18 13 

TABLE 46: WATERCRAFT NOISE PERCENT

TIME AUDIBLE AT VARIOUS DISTANCES FROM THE SHORELINE

Percent Time Audible at Distance from Shoreline 

(feet) 

Condition 240 540 990 1290 3240 10,240 

High-use condition – alternative A or B 

(53 personal watercraft and 31 boats in 1 hour) 

100 100 100 100 100 0 

High-use condition with no personal watercraft – 

alternative C (31 boats in 1 hour) 

76 76 76 76 76 0 

Low-use condition – alternative A or B 

(2 personal watercraft and 1 boat in 1 hour) 

17 17 17 17 17 0 

during four months of the year from June through September. Impacts during most of the remaining 

months would be associated with the low-use scenario shown in the above tables. Personal watercraft 

and boats in the low-use scenario would be audible 17% of the time to a distance of 3,240 feet from 

the shoreline, at sound pressure levels 12 to 14 decibels less than at high use. 

Adverse impacts of personal watercraft on the natural soundscape vary with the amount of use, 

assuming even spatial use distribution in the Recreation and Resource Utilization Zone. During highuse seasons, personal watercraft use impacts areas of the Natural and Cultural Zones for extended 

periods up to 0.6 mile from shoreline. The impact of personal watercraft added to boats is 24% greater 

than the impact of boats alone, and the fluctuating sound quality is such that it is distinguishable from 

boats and marginally more audible than boats. From 0.6 mile to 2 miles, the impact declines to zero. 

This level of effect is defined as moderate, and most of the zone area would not be affected. 

Noise impacts from personal watercraft during lower use times (about seven to eight months of the 

year) would be substantially less frequent, or nonexistent, at lower sound levels and decreasing 

distances to audibility. This corresponds with a negligible to minor level of adverse impact, as defined.

During these times, most of the human-caused noise impacts in the near-shore areas of the Natural and 

Cultural Zones would be from other types of watercraft. 

The above presentation of impacts is based on a general model that assumed a gradual incline in 

elevation from the shoreline. With this assumption, the distance to a limit of audibility is about 2 

miles. This does not account for variation in topography around the shoreline, such as cliff faces that 

would represent effective barriers to propagation of sound over a distance. It also does not account for 

reflection of sound within the canyon confines (in the Recreation and Resource Utilization Zone) that 

would intensify sound and carry it further along the course of the shoreline and up the side channels. 

Relative to impacts on the Natural or Cultural Zones, barriers to sound do exist at the shoreline. 

Recreation Area staff have mapped areas along the shoreline where 50 vertical feet of rock face are 
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 209

assumed to represent an effective barrier to sound propagation. This area is calculated to be about 

16,000 acres, or 2.3% of the 668,670 acre Natural Zone. 

Cumulative Effects. As described in the “Affected Environment” chapter, numerous aircraft operate 

year-round in the vicinity of Glen Canyon National Recreation Area. In many remote parts of the 

Natural Zone, aircraft are assumed to produce the only mechanical noise impacting the natural 

soundscape, given the modeled distance of audibility at 2 miles from shoreline. In the Recreation and 

Resource Utilization and Developed Zones, aircraft noise mixes with the other human-caused noise as 

described below. In much of these zones, watercraft rather than aircraft often are the dominant noise 

source. However, in secluded coves or times of low watercraft use, aircraft can represent an important 

noise source. 

The Harris Miller Miller & Hanson 2002 study included a practice called “observer source 

identification logging.”5

 This practice enables the scientist to establish real-time links between 

recorded sounds and sound pressure levels with identified sound sources. Observers note all sounds 

heard during the sampling period, and log human caused sounds such as aircraft, watercraft, wheeled 

vehicles, radios, and voices. They also log natural sounds of birds, vegetation in the wind, waves, 

insects, mammals and other. Logging was accomplished at the sites where all sound data was 

collected, and at the Rainbow Bridge site, during the heavy use part of the year (August). 

Data from this part of the study allows a characterization of all human-caused sound sources that are 

ambient in the park soundscape. This data is equivalent to sound cumulative effects at the sites in 

question during the sampling period. 

Considering all sites together, the sound of personal watercraft was dominant about 5% to 40% of the 

time, while the sound of boats was dominant about 10 to 45% of the time. The sound of personal 

watercraft and boats together were logged separately from the sounds of boats alone and personal 

watercraft alone. When heard together, they accounted for less than 5% of the time. All aircraft types 

together were dominant about 0 to 13% of the time. The sounds of voices and radios were not evident 

at all sites, nor were personal watercraft or aircraft, but all contribute to the total cumulative impact of 

human-caused sound. The percent time audible for all sources logged by HMMH is displayed, by site, 

in figure 19 of the draft HMMH report. NPS logging at site 3 captured personal watercraft audibility 

nearly 60% of the time, small boats just over 30% of the time, and propeller aircraft, large boats, 

houseboats, people, and other human-related noise less than 5% of the time each. 

In the near shore areas of the Natural or Cultural Zones, within 1 or 2 miles, it is expected that the total 

cumulative impact on the natural soundscape would be dominated by watercraft. The extent to which 

personal watercraft contribute to the total would vary by location around the perimeter of the water 

surface. Beyond two miles, it is assumed (based on the modeled analysis), that aircraft would represent 

the dominant human-caused sound. Aircraft noise would be a mix of commercial aircraft at high and 

lower elevations, military aircraft, and air tour operators. Personal watercraft would not contribute to 

the total cumulative effect in most of the natural zone areas. 

Reasonably foreseeable sources of noise that should be considered, and added qualitatively to this 

analysis, include: the potential for increased numbers and types of overflights, the potential for 

increased numbers of air tours and air tour operators using different types of aircraft, and the potential 

 

5. Draft Technical Report on Noise, pages 27-31. 
ENVIRONMENTAL CONSEQUENCES

210 GLEN CANYON NATIONAL RECREATIONAL AREA

for an increasing use of watercraft of all types when assuming a positive growth scenario of 2% 

annually. These do not necessarily represent new types of impact sources, but they would serve to 

increase the average ambient human-caused noise (Leq) relative to the ambient natural soundscape 

(L90) within the recreation area. In areas where noise is presently audible the frequency, duration, and 

loudness of human-caused sound would increase. 

Collectively, all of these noise sources would have a minor to moderate effect within the Recreation 

and Resource Utilization Zone and Developed Zone. In the Natural Zone and Cultural Zone, most of 

the adverse noise effects from these sources would be minor with occasional moderate effects. Boats 

with V-8 engines and aircraft both could produce moderate effects within the Natural Zone. 

Conclusion. During summer days in the Recreation and Resource Utilization and Developed Zones, 

the existing level and character of noise generated by personal watercraft are acceptable within the 

expressed purpose of the park to provide the motorized watercraft form of recreation. Given this level 

of impact, and the amount of use that occurs during peak seasons, mitigation takes the form of 

education and enforcement of the existing regulations and compendium. Noise-producing behaviors 

are regulated to the greatest possible extent, and use of newer technologies that reduce noise are 

encouraged. During other times of the year, the overall impact of noise within this area decreases. 

Noise generated in this zone, year-round, affects adjacent areas in Natural and Cultural Zones.

In the Natural and Cultural Zones, alternative A would produce negligible to moderate adverse effects 

on the soundscape within a mile of the lakeshore, depending on the level of boating use in nearby 

waters at various times of the year. During high-use periods, areas in which noise is audible would be 

affected at minor to moderate levels. During low-use periods, areas in which noise is audible would be 

affected at negligible to minor levels. These areas consist of about 16,000 acres covering 2.3% of the 

natural and cultural zones. The remainder of the zone area is expected to be unaffected. 

All of these effects would be adverse, both short and long term, and direct. Alternative A would not 

result in impairment of the natural soundscape of Glen Canyon National Recreation Area since a major 

level of impact is not demonstrated. 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

As with alternative A, all of the noise effects of alternative B would be both short- and long-term and 

direct. Several provisions of alternative B would mitigate noise effects from personal watercraft 

compared to current conditions. These include: 

New use restrictions on personal watercraft on the rivers that drain into Lake Powell, including 

the Dirty Devil, Escalante, San Juan, and Colorado Rivers. 

One additional area where flat-wake speeds would be required. 

Improved education, which would provide information on areas of the lake where visitors can 

experience natural quiet and solitude. 
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 211

The mitigation does not reduce the overall impact of personal watercraft sound in terms of loudness, 

distance of audibility, or percent time audible within the Natural and Cultural Zones (see tables 45 and 

46). Therefore, all the impacts shown for alternative A apply to alternative B as well. 

Cumulative Effects. Because the mitigation measures defined for alternative B would not reduce the 

overall noise impacts of personal watercraft within the natural and cultural zones, cumulative effects 

of this alternative would be the same as those described for alternative A. 

Conclusion. Alternative B would have overall noise impacts similar to those described under 

alternative A. During summer days in the Recreation and Resource Utilization and Developed Zones, 

the existing level and character of noise generated by personal watercraft are acceptable within the 

expressed purpose of the park to provide the motorized watercraft form of recreation. During other 

times of the year, the overall impact of noise within this area decreases. Noise generated in this zone, 

year-round, affects adjacent areas in Natural and Cultural Zones. 

In the Natural and Cultural Zones, under alternative B during high-use periods, areas in which noise is 

audible would be affected at minor to moderate levels. During low-use periods, areas in which noise is 

audible would be affected at negligible to minor levels. The area affected would be 2.3% of the natural 

and cultural zones. The remainder of the zone area is expected to be unaffected. 

All of these effects would be adverse, both short and long term, and direct. Alternative B would not 

result in impairment of the natural soundscape of Glen Canyon National Recreation Area since a major 

level of impact is not demonstrated. 

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

Under the no-action alternative, personal watercraft would be permanently eliminated from operating 

within the recreation area. As described in the “Methodology and Assumptions” section, it was 

assumed for all alternatives that there would be a change in total boat days and watercraft operating 

hours of between –2% and +2% annually over the next 10 years. It was also assumed that the removal 

of personal watercraft in alternative C would result in an initial decrease in annual boat days in the 

short-term. However, by the end of the 10-year analysis period, the total number of watercraft 

operating hours and the total number of motorized watercraft using Lake Powell under alternative C 

would be within the range predicted for alternatives A and B. This would be due to either natural 

growth in visitation, to visitors finding other watercraft to fulfill functions previously served by 

personal watercraft, or to increases in visitation by individuals who previously avoided the recreation 

area due to personal watercraft and now choose to visit in their absence. This was the same assumption 

that was used for the other impact topics. 

Recreation and Resource Utilization and Developed Zones. In the Recreation and Resource 

Utilization and Developed Zones, 72% of boat days currently involve use of motorized watercraft 

other than personal watercraft. Although the elimination of personal watercraft would somewhat 

reduce noise (a beneficial effect), the noise levels in the high-use locations at high-use times would 

continue to be minor to moderate. 

In the long term, former personal watercraft users would return to Lake Powell using other types of 

motorized watercraft. As shown in table 14 in the “Affected Environment” chapter, the noise levels 

produced by personal watercraft and motorboats other than those with V-8 engines are similar. 
ENVIRONMENTAL CONSEQUENCES

212 GLEN CANYON NATIONAL RECREATIONAL AREA

Therefore, the noise levels in the Recreation and Resource Utilization and Developed Zones that 

would occur at the end of the planning period (long-term effect) would be similar to those described 

for alternative A. 

Tables 45 and 46 show the modeled effects on noise in the Natural and Cultural Zones. Removing all 

personal watercraft use from a high-use area of the Recreation and Resource Utilization Zone would, 

during the high use season, reduce average noise levels by 4 to 5 decibels at all modeled distances up 

to 3,240 feet from the shoreline. This could be a noticeable change for visitors in that portion of the 

Natural or Cultural Zone. Up to and beyond that distance, during high use periods, watercraft noise 

could be audible 24% less of the time without personal watercraft use. The distinctive audible 

signature of personal watercraft use, that of fluctuating sound levels, and the occasional spikes of 

sound above the average, would be eliminated. 

Modeled results are not presented for alternative C during low use periods. However, it can be stated 

that during periods without personal watercraft use, the impacts would be reduced to the equivalent of 

the passage of one boat per hour. Compared to alternatives A or B, at low use times, this reduction 

would be equivalent to the magnitude of the passage of two personal watercraft per hour. The result is 

that watercraft would be audible substantially less than 17% of the time, and at lower decibel levels 

than would be indicated for two personal watercraft plus one boat per hour (table 45). The distance to 

the limit of audibility would also be reduced and greater noise free intervals of time would be 

expected. 

Cumulative Effects. Please see the general cumulative effects discussion for alternatives A and B, 

which summarizes the data sources used for this type of analysis. The same data is used for assessing 

the cumulative impacts in alternative C. 

For alternatives A and B, considering all sites together, the sound of personal watercraft was dominant 

about 5 to 40% of the time, while the sounds of boats were dominant about 10% to 45% of the time. 

When heard together, the sounds of boats and personal watercraft accounted for less than 5% of the 

time. All aircraft types together were dominant about 0 to 13% of the time. The sounds of voices and 

radios were not evident at all sites, nor were personal watercraft or aircraft, but both contribute to the 

total cumulative impact of human-caused sound. NPS logging captured personal watercraft audibility 

nearly 60% of the time, small boats just over 30% of the time, and propeller aircraft, large boats, 

houseboats, people, and other human-related noise less than 5% of the time each. Alternative C, in 

eliminating personal watercraft would significantly reduce the total cumulative impact on the natural 

soundscape in the environments represented by the sample sites. Considering the times personal 

watercraft or boats and personal watercraft were dominant in the soundscape, the reduction would be 

on the order of about 10% to 45% of the time. Other sources of sound might become more audible at 

times and in some places due to the elimination of personal watercraft as a sound source. 

In the near shore areas of the Natural or Cultural Zones, within 1 or 2 miles, it is expected that the total 

cumulative impact on the natural soundscape would be substantially reduced by elimination of 

personal watercraft. The extent of the reduction would vary by location around the perimeter of the 

water surface. Beyond two miles, it is assumed (based on the modeled analysis), that aircraft would 

remain the dominant human-caused sound. Aircraft noise would be a mix of commercial aircraft at 

high and lower elevations, military aircraft, and air tour operators. Personal watercraft would not 

contribute to the total cumulative effect in most of the natural zone areas. 

Reasonably foreseeable sources of noise that should be considered, and added qualitatively to this 

analysis, include: the potential for increased numbers and types of overflights, the potential for 
Natural Soundscapes 

FINAL ENVIRONMENTAL IMPACT STATEMENT 213

increased numbers of air tours and air tour operators using different types of aircraft and the potential 

for an increasing use of watercraft of all types when assuming a positive growth scenario of 2% 

annually. These do not necessarily represent new types of impact sources, but they would serve to 

increase the average ambient human-caused noise (Leq) relative to the ambient natural soundscape 

(L90) everywhere in the recreation area. Areas and times in which noise is presently audible, would 

experience an increase in the frequency, duration and loudness of human-caused sound. 

Collectively, all of these noise sources would have a minor to moderate effect within the Recreation 

and Resource Utilization Zone and Developed Zone. In the Natural Zone and Cultural Zone, most of 

the noise effects from these sources would be minor with occasional moderate effects. Boats with V-8 

engines and aircraft both could produce moderate effects within the Natural Zone.

Conclusion. Due to the elimination of personal watercraft noise in alternative C, impacts on the 

natural soundscape would be reduced compared to noise levels produced in alternatives A or B. This 

represents a beneficial impact on the natural soundscape – eliminating an adverse impact judged as 

minor to moderate at high use times of the year. Compared to low use times of the year, the level of 

beneficial impact would not be considered as great in magnitude by eliminating a negligible to minor 

adverse impact. Alternative C would not result in impairment of the natural soundscape of Glen 

Canyon National Recreation Area. 
214 GLEN CANYON NATIONAL RECREATIONAL AREA

WILDLIFE AND WILDLIFE HABITAT 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Issues 

Some research suggests that personal watercraft uses may affect fish and wildlife by interrupting 

normal activities, causing alarm or flight, causing animals to avoid habitat near an area of disturbance 

and displacing animals from habitats, causing habitat damage, and affecting reproductive success. 

Such effects may be caused by a combination of personal watercraft speed, noise, human presence and 

ability to access shallow-water and other wildlife habitats where other kinds of watercraft are rarely 

found. Some literature reports and personal testimony suggest that personal watercraft can access 

shoreline areas that are inaccessible to other watercraft and that are important to wildlife species that 

may be typically associated with shoreline areas. 

Literature reports have suggested that personal watercraft and their users may have a relatively greater 

impact on waterfowl and nesting birds associated with beach or shoreline areas because of their noise, 

speed, and ability to access shallow-water areas more readily than other types of watercraft. These 

factors may force nesting birds to either abandon nests and eggs during the incubation stage; may flush 

birds from feeding, refuge, or security areas; or may create additional stresses and associated 

behavioral changes. Literature reports of personal watercraft collisions with birds and other wildlife 

causing animal injury and mortality suggest another mode of potential wildlife impact. 

Management Objectives 

Objectives in taking action include protecting fish and wildlife (including threatened and endangered 

species) and their habitats from: 

Personal watercraft disturbances that result in injury, changes in distribution (both individuals 

and populations), changes in essential habitat features, and/or changes in population 

demographics; and 

Adverse effects that result from the bioaccumulation of contaminants emitted from personal 

watercraft. 

GUIDING REGULATIONS AND POLICIES 

The Organic Act, which directs parks to conserve wildlife unimpaired for future generations, is 

interpreted by the agency to mean that native animal life should be protected and perpetuated as part of 

Glen Canyon National Recreation Area’s natural ecosystem. Natural processes are relied on to control 

populations of native species to the greatest extent possible; otherwise they are protected from harvest, 

harassment, or harm by human activities. 

The National Park Service Management Policies 2001 (NPS 2000d) state that the National Park 

Service will maintain as parts of the natural ecosystems of parks all native plants and animals 

(Section 4.4.1). The National Park Service will achieve this through (Section 4.4.1): 
Wildlife and Wildlife Habitat 

FINAL ENVIRONMENTAL IMPACT STATEMENT 215

Preserving and restoring the natural abundance, diversities, dynamics, distributions, habitats, and 

behaviors of native plant and animal populations and communities and ecosystems in which they 

occur. 

Restoring native plant and animal populations in parks when they have been extirpated by past 

human-caused actions. 

Minimizing human impacts on native plants, animal populations, communities, and ecosystems, 

and the processes that sustain them. 

The mission of Glen Canyon National Recreation Area includes the provision to: 

“...preserve and protect the scenic, scientific, and historic features therein while providing a 

significant understanding to visitors of the scientific and cultural importance of objects, sites, 

populations, beliefs, and habitats of the past and future.” 

One of the recreation area’s significance statements, indicates (NPS 2000g): 

The climate and physical features of Glen Canyon National Recreation Area have created local 

environmental conditions favorable to the preservation of scientifically important objects, sites, 

populations, habitats or communities that are significant in and of themselves or provide 

opportunities to add to our understanding of past or ongoing events. 

Mission goal Ia for preserving recreation area resources states (NPS 2000g): 

Natural and cultural resources and associated values of Glen Canyon National Recreation Area 

and Rainbow Bridge NM are protected, restored, and maintained in good condition and managed 

within their broader ecosystem and cultural context. 

Collectively, these mission statements, significance statements, and mission goals establish long-term 

goals to protect, manage, maintain, and restore wildlife populations and their supporting habitats. 

Additional federal, state, and local regulations and/or policies for wildlife and wildlife habitats at Glen 

Canyon National Recreation Area are shown in table 47. Threatened and endangered species and their 

designated critical habitats are addressed as the next impact topic. 

TABLE 47: LAWS AND NATIONAL PARK SERVICE 

POLICIES RELATING TO WILDLIFE AND WILDLIFE HABITAT

Laws or Policies Management Direction 

General – National Park Service 

National Park Service Organic 

Act 

The National Park Service will “conserve the scenery and the natural 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.” 

Management Policies 2001 

(NPS 2000d) 

“National Park Service Obligation to Conserve and Provide for Enjoyment of Park 

Resources and Values: Congress, recognizing that the enjoyment by future generations 

of the national parks can be assured only if the superb quality of park resources and 

values is left unimpaired, has provided that when there is a conflict between conserving 

resources and values and providing for enjoyment of them, conservation is to be 

predominant.” NPS management policies acknowledge that providing opportunities for 

public enjoyment are a fundamental part of the NPS mission. But they emphasize that 

recreational and other activities, including NPS management activities, may be allowed 
ENVIRONMENTAL CONSEQUENCES

216 GLEN CANYON NATIONAL RECREATIONAL AREA

Laws or Policies Management Direction 

 only when they will not cause impairment or derogation of a park’s resources, values, or 

purposes. The sole exception is when an activity that would cause impairment or 

derogation is specifically mandated by Congress. 

Public Law 92-593 On October 27, 1972 Congress established Glen Canyon National Recreation Area to 

“... provide for public outdoor recreation use and enjoyment of Lake Powell and lands 

adjacent thereto in the States of Arizona and Utah and to preserve the scenic, scientific, 

and historic features contributing to public enjoyment of the area . . .” 

Public Law 95-625; 16 U.S.C. 

1a-7(b)(4) 

NPS management plans must include measures for protecting Glen Canyon National 

Recreation Areas’ resources and “indications of potential modifications to the external 

boundaries of the unit and the reasons therefore.” 

General Wildlife and Natural Resources 

Management Policies 2001 

(NPS 2000d)

Natural Resources Management 

Guideline (Director’s Order 77) 

These guidelines direct the National Park Service to “encourage productive and 

enjoyable harmony between man and his environment; to promote efforts which will 

prevent or eliminate damage to the environment and biosphere and stimulate the health 

and welfare of man and to enrich the understanding of the ecological systems and 

natural resources important to the Nation . . . ” Policies and guidelines for natural 

resources direct that Glen Canyon National Recreation Area must (1) identify and 

complete the inventories of natural resources for baseline information; (2) minimize 

impacts of human activities, developments, and uses on marine and terrestrial 

resources; (3) continue to close areas to protect nests; and (4) manage endangered, 

threatened, and candidate species. 

Fish and Wildlife Coordination 

Act of 1934, as amended 

This act requires consultation with the U.S. Fish and Wildlife Service and the fish and 

wildlife agencies of states where “the waters of any stream or other body of water are 

proposed or authorized, permitted, or licensed to be impounded, diverted ... or 

otherwise controlled or modified” by any agency under a federal permit or license. 

Consultation is to be undertaken for the purpose of “preventing loss of and damage to 

wildlife resources.” 

The Bald and Golden Eagle 

Protection Act of 1940, as 

amended 

This law, originally passed in 1940, provides for the protection of the bald eagle and the 

golden eagle (as amended in 1962) by prohibiting the take, possession, sale, purchase, 

barter, offer to sell, purchase or barter, transport, export or import, of any bald or golden 

eagle, alive or dead, including any part, nest, or egg, unless allowed by permit. “Take” 

includes pursue, shoot, shoot at, poison, wound, kill, capture, trap, collect, molest or 

disturb. 

Migratory Bird Treaty Act of 1918, 

as amended 

The Migratory Bird Treaty Act prohibits the taking, killing, possession, transportation, 

and importation of migratory birds, their eggs, parts, and nests except as authorized 

under a valid permit (50 CFR 21.11). Additionally, the act authorizes and directs the 

Secretary of the Interior to determine if, and by what means, the take of migratory birds 

should be allowed and to adopt suitable regulations permitting and governing take (for 

example, hunting seasons for ducks and geese). “Take” includes pursue, shoot, shoot 

at, poison, wound, kill, capture, trap, collect, molest or disturb. 

Title 36 CFR 1.5, 1.6, 1.10, 2.1, 

2.2, 2.3, 2.4, 2.5 

Title 36 CFR provides authorization for closing areas and limiting public use to protect 

resources; providing public notice of closures or use limits; prohibiting the destruction, 

defacing, or disturbing of resources; and protecting fish and wildlife and permit research. 

Executive Order 11990, 

“Protection of Wetlands” 

This order requires federal agencies to avoid, to the extent possible, the long- and shortterm adverse impacts associated with the destruction of modification of wetlands. 

Executive Order 11988, 

“Floodplain Management” 

This order requires federal agencies to avoid, to the extent possible, the long- and shortterm adverse impacts associated with the occupancy and modifications of floodplains 

and to avoid direct and indirect support of floodplain development wherever there is a 

practicable alternative. 

 

Source: Adapted from Management Policies 2001 (NPS 2000d). 
Wildlife and Wildlife Habitat 

FINAL ENVIRONMENTAL IMPACT STATEMENT 217

METHODOLOGY AND ASSUMPTIONS 

The focus of wildlife and wildlife habitat information gathering and impact analysis was on wildlife 

groups, species, and habitats that were considered most likely to be exposed to potential effects of 

personal and other types watercraft uses in the analysis area. Using technical reports from the 

published literature that described the most susceptible aspects of species life cycle and/or habitat 

needs as a guide, quantitative and qualitative information was gathered regarding the presence and 

status of these features within the recreation area. Knowledgeable scientists and ecologists on the 

recreation area staff, U.S. Fish and Wildlife Service, Arizona Game and Fish Department, and Utah 

Division of Wildlife Resources were contacted for unpublished information and professional 

judgments regarding the status of species, wildlife groups, habitats, special habitat features, and likely 

personal watercraft and other watercraft effects on these wildlife groups and habitat features. 

Wildlife groups considered to be particularly high interest and strong candidates for reflecting 

reactions to personal and other watercraft uses included nesting and feeding shore- and wading birds, 

waterfowl, nesting raptors (which includes hawks, owls, eagles, and falcons), desert bighorn sheep, 

and Glen Canyon chuckwalla. Special-interest habitat features that were evaluated for potential effects 

included wading and shorebird nesting rookeries, active raptor nest sites, gull and/or tern beach or 

shoreline nesting areas, shallow-water fish spawning areas, high-density wildlife concentration areas 

(typically associated with wetlands or submerged aquatic vegetation beds), and colonial roost sites. 

The presence of these features were determined by interviewing knowledgeable scientists and 

ecologists and by reviewing existing geographic information systems resource maps of the recreation 

area. Resource specialists were also interviewed about reports or documentation of past conflicts 

between watercraft users and wildlife and habitat. If such conflicts were documented, information 

regarding the locations, frequency, and causes of the conflicts was acquired and evaluated. 

Threatened and endangered species, which include species that are members of these general groups 

are addressed separately in the “Threatened, Endangered, and Special-Concern Species” section. 

Aquatic species and especially susceptible habitat features are included in this section. 

The area of analysis is the area where personal watercraft are permitted to operate and the adjoining 

shoreline, extending up to 500 feet inland from the maximum pool of 3,700 feet above sea level. 

Beyond this point, personal watercraft noise would be considerably reduced, and effects from personal 

watercraft users would decline substantially. 

Technical wildlife and fisheries literature findings were used to assess potential effects of watercraft 

operations, noise, user behaviors, minimum flushing distances, recommended protective buffer zone 

distances on each target wildlife group and species. The susceptibility of habitat features and 

vegetation communities to adverse effects caused by watercraft and their users was derived from 

literature reports addressing plant community and wildlife species tolerances to human disturbances 

and recovery capabilities. Reported literature findings were supplemented and adjusted to account for 

existing environmental conditions and visitor and watercraft use characteristics currently present in the 

analysis area. 

It was assumed for all alternatives that there would be a change in total boat days and watercraft 

operating hours of between –2% and +2% annually over the next 10 years. It was also assumed that 

the removal of personal watercraft in alternative C would result in an initial decrease in annual boat 

days in the short-term. However, by the end of the 10-year analysis period, the total number of 
ENVIRONMENTAL CONSEQUENCES

218 GLEN CANYON NATIONAL RECREATIONAL AREA

watercraft operating hours and the total number of motorized watercraft using Lake Powell under 

alternative C would be within the range predicted for alternatives A and B. 

Impact Threshold Definitions. The following thresholds were used to determine the intensity or 

magnitude of effects on wildlife and wildlife habitats: 

Negligible — There would be no observable or measurable impacts on native fish and wildlife 

species, their habitats, or the natural processes sustaining them. Impacts would be of short 

duration and well within the range of natural fluctuations.

Minor — Impacts would be detectable, but they would not be expected to be outside the natural 

range of variability and would not be expected to have any long-term effects on native species, 

their habitats, or the natural processes sustaining them. Population numbers, population 

structure, genetic variability, and other demographic factors for species may have small, shortterm changes, but long-term characteristics remain stable and viable. Occasional responses to 

disturbance by some individuals could be expected, but without interference to feeding, 

reproduction, or other factors affecting population levels. Key ecosystem processes may have 

short-term disruptions that would be within natural variation. Sufficient habitat would remain 

functional to maintain viability of all species. Impacts would be outside of critical reproduction 

periods for sensitive species. 

Moderate — Breeding animals of concern are present; animals are present during particularly 

vulnerable life-stages, such as migration or juvenile stages; mortality or interference with 

activities necessary for survival can be expected on an occasional basis, but is not expected to 

threaten the continued existence of the species in the recreation area. Impacts on native fish and 

wildlife species, their habitats, or the natural processes sustaining them would be detectable, and 

they could be outside the natural range of variability for short periods of time. Population 

numbers, population structure, genetic variability, and other demographic factors for species 

may have short-term changes, but would be expected to rebound to pre-impact numbers and to 

remain stable and viable in the long term. Frequent responses to disturbance by some individuals 

could be expected, with some adverse impacts on feeding, reproduction, or other factors 

affecting short-term population levels. Key ecosystem processes might have short-term 

disruptions that would be outside natural variation (but would soon return to natural conditions). 

Sufficient habitat would remain functional to maintain viability of all native fish and wildlife 

species. Some impacts might occur during critical periods of reproduction or in key habitat for 

sensitive native species. 

Major — Impacts on native fish and wildlife species, their habitats, or the natural processes 

sustaining them would be detectable, and they would be expected to be outside the natural range 

of variability for long periods of time or to be permanent. Population numbers, population 

structure, genetic variability, and other demographic factors for species might have large, shortterm declines with long-term population numbers significantly depressed. Frequent responses to 

disturbance by some individuals would be expected, with adverse impacts on feeding, 

reproduction, or other factors resulting in a long-term decrease in population levels. Breeding 

colonies of native species might relocate to other portions of the recreation area. Key ecosystem 

processes might be disrupted in the long term or permanently. Loss of habitat may affect the 

viability of at least some native species. 
Wildlife and Wildlife Habitat 

FINAL ENVIRONMENTAL IMPACT STATEMENT 219

Impairment — Impairment of recreation area’s wildlife resources would occur if an impact 

resulted in the elimination of a native species, significant population declines in a native species, 

or the inability of the recreation area to meet recovery objectives for listed species. 

Geographic Area Evaluated for Impacts. The area being analyzed for possible impacts on wildlife 

and wildlife habitats consists of Lake Powell and its associated tributaries including, but not limited to, 

the San Juan, Colorado, Dirty Devil, and Escalante Rivers within the boundaries of Glen Canyon 

National Recreation Area. The area of analysis includes a terrestrial zone encompassing these water 

bodies from the water-land interface up to either 500 horizontal feet beyond the 3,700-foot water 

surface elevation or the canyon wall apex, depending on the topography of the area being considered. 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Under alternative A, except for natural changes in visitor growth rate that would occur over the next 

10 years, personal watercraft use on Lake Powell would not be substantially different from levels that 

existed when personal watercraft were used in accordance with the Superintendent’s Compendium 

(NPS 2002c). Noise, human disturbance, access into shallow-water, and possible alterations of 

vegetated areas of potential value to wildlife as habitats from personal watercraft use would occur at or 

close to the existing conditions discussed in the “Affected Environment” chapter. 

Several potential impacts on wildlife and wildlife habitats have been associated with personal 

watercraft use. These include habitat disturbance; noise; and the ingestion, absorption and/or 

bioaccumulation of petroleum hydrocarbon additives and derivatives. These potential impacts are 

described briefly below. 

Personal watercraft have the ability to navigate shallow waters using their method of “jet” propulsion. 

This ability gives them access to areas not accessible by other motorized watercraft. These may 

include shallow areas that provide wildlife habitat. As shown in figure 14, the topographic features of 

the recreation area create many conditions that allow other types of motorized watercraft to approach 

very close to the shore. Extensive areas of shallow-water flats that might attract wildlife use and 

exclude all motorized watercraft except shallow-draft personal watercraft are rare conditions in the 

recreation area (see figure 15). 

FIGURE 14: TYPICAL STEEP SHORELINE FIGURE 15: SHORELINE ACCESS BY MOTORIZED VESSELS
ENVIRONMENTAL CONSEQUENCES

220 GLEN CANYON NATIONAL RECREATIONAL AREA

Habitat disturbance from personal watercraft would include impacts due to watercraft wakes, traveling 

through near-shore and shallow-water areas at high speed, and impacts of personal watercraft users 

accessing/trampling shoreline vegetation. Nonmotorized watercraft such as canoes, kayaks, and rafts 

would also be able to access similar shallow-water areas, although the general abundance and radius of 

mobility of these types would not be as extensive as motorized personal watercraft (unless these craft 

are associated with and brought to an area with a houseboat). 

Noise emissions from personal and other motorized watercraft are associated with motorcraft 

operations. Total noise intensities, durations, and frequencies change dramatically throughout the 

recreation area as a function of several variables, including number of engines, engine mixes, distance 

between the wildlife receptor and the noise sources, topographic features that may shield potential 

receptors from noise sources, and the level of noise habituation possessed by the wildlife receptor. 

Current motorized boating and other recreational activities expose wildlife receptors to a wide range of 

noise conditions. Noise levels are generally directly proportional to the levels of visitor use. Noise 

intensity and durations tend to be higher and most persistent near the marina, launch, and fueling 

facilities and most noticeable during the peak use months. 

The vast majority of personal watercraft in use today are powered by conventional two-stroke, 

carbureted engines, which discharge as much as 30% of their fuel directly into the water (NPS 1999c; 

CARB 1999a).This discharge releases contaminants into the water. The possibility exists for some 

aquatic and water-associated wildlife species to inadvertently ingest or absorb some of these 

contaminants, primarily polycyclic aromatic hydrocarbons and the benzene, toluene, ethylbenzene, 

and xylenes complex, during feeding or other activities. 

Mammals. Noise would produce negligible, short-term, adverse impacts on larger mammals 

(i.e., bighorn sheep, mule deer, and coyote) within the area of analysis. The highly mobile large 

mammals found within the Lake Powell area spend relatively limited time near the shoreline where 

expose to noise and human activity would be most intense. These areas are generally avoided because 

of unsuitable habitat conditions. In addition it is likely these animals have already habituated to 

anthropogenic sources of noise, such as noise generated by watercraft engines. Future changes would 

not be expected with this alternative. 

Wagner (1994) and Rodgers and Schwikert (2002) measured noise production from personal 

watercraft compared to other two-stroke outboard motors. They reported that personal watercraft noise 

levels are either lower than or not much different from most other types of watercraft. Noise loudness 

decreased with distance from the watercraft, such that the sound level was within background levels at 

distances of 300 feet or more (Wagner 1994). These findings suggest potential noise impacts from 

personal watercraft would be limited in areal effect, temporary, and similar to the effects of other types 

of two-stroke outboard engine watercraft present in the recreation area (classified as negligible, direct, 

adverse, short-term impacts). 

During their study of the effects of simulated, low-flying aircraft noise (92 to 112 decibels) on mule 

deer and desert bighorn sheep, Krausman et al. (1996) concluded that “the animals in the study 

habituated rapidly [to noise] and probably did not view the stimuli as a threat. The frequency and noise 

level were not detrimental to their well-being, and the noise did not inhibit their reproductive 

mechanisms.” Noise levels produced by personal watercraft are substantially lower than those of the 

aircraft in the study, ranging from 65–78 decibels at 50 feet (decreasing with increasing distance), and 

would be expected to have similar negligible impacts on individuals or herds in the vicinity. Primary 

contact activities, feeding near and/or drinking from Lake Powell and its tributaries would occur from 
Wildlife and Wildlife Habitat 

FINAL ENVIRONMENTAL IMPACT STATEMENT 221

dusk until dawn when very few (1%) personal watercraft users are active and noise levels are at a 

minimum. 

Impacts on rodents due to habitat disturbance would include trampling of burrows, and in very rare 

instances trampling of individuals, by personal watercraft users. These potentially adverse impacts 

would be short-term and negligible, due to the limited amount of suitable habitat found within the area 

of analysis, and the rarity of such occurrences. 

Potential impacts on mammals from possibly ingesting fuel-contaminated surface waters would be a 

negligible, short-term adverse impact because contaminant concentrations would be very low (after 

fuel discharges became diluted by surface waters), the exposure frequency would be very low, and the 

acute and chronic toxicity thresholds for the contaminants are typically very high for mammals 

(generally on the order of thousands or tens of thousands of parts per million) required to produce 

detectable toxic effects. 

The recreation area’s law enforcement and environmental staffs were interviewed as another method 

of determining whether personal watercraft or other types of motorized watercraft uses were 

responsible for adverse impacts on high-interest wildlife resources and wildlife habitats. There were 

no reported or documented cases of problems (NPS, Spence, pers. com., May 2002n). 

Birds. Impacts on water-associated birds, particularly waterfowl, wading, and shore-line nesting 

species, would be a negligible, short-term adverse effect. Several reasons support this conclusion. 

First, concentrations or large numbers of birds that might develop for nesting, breeding, or staging 

purposes do not occur to any significant degree during the months when personal watercraft uses are 

most common. This condition precludes many potential impacts associated with watercraft, including 

flushing birds; creating wakes and disturbances that might disrupt nesting activities; altering habitat so 

that it becomes unsuitable for bird feeding, loafing, or security uses; and injuring birds through 

physical contact. An occasional flushing response may be elicited as watercraft move through areas 

occupied by water or shorebirds. However, these reactions are common with all motorized watercraft, 

not just personal watercraft. Such disturbances are usually temporary events that are restricted to 

limited areas and affect a small number of individuals. 

High-density bird concentration areas, such as nesting or roosting rookeries, feeding areas, and 

shoreline gull or tern nesting colonies are not present at the recreation area (NPS, Spence, pers. com., 

May 2002n). Therefore, there would be no adverse effect on these special-interest bird groups or 

shoreline areas that might provide habitat for such uses. 

Potential boating and personal watercraft disturbance effect on water-associated bird groups were 

recently reported on by Rodgers and Schwikert (2002). The objectives of the investigations were to: 

Determine whether there were differences in minimum flushing distances among different bird 

species when they were exposed to moving personal watercraft and outboard-powered boats 

(14-foot, 30 horsepower boat); and 

Estimate minimum buffer zone distances that would protect the species from either personal 

watercraft or outboard motor disturbances in critical wildlife foraging and loafing areas. 

Twenty-three species of birds were tested, with 16 species producing comparable data for the two 

types of watercraft. For 11 of the 16 species (about 69% of the species tested), there was no significant 

difference in the minimum flushing distances between the two types of watercraft. For four of the five 
ENVIRONMENTAL CONSEQUENCES

222 GLEN CANYON NATIONAL RECREATIONAL AREA

remaining species (80%) where there were significant differences in the minimum flushing distance 

between watercraft types, the outboard-motor powered boat more often elicited a significantly greater 

flush distance than the personal watercraft. A notable finding of the testing revealed highly variable 

results among bird species and among individual birds within the same species in response to vessels 

of both types. 

Recommended buffer distances for exposure to high-speed vessels varied by bird taxonomic group 

and by type of vessel, ranging from about 594 feet for wading birds to about 330 feet for plovers and 

sandpipers. The authors indicated buffer distances could be shortened in flat-wake zones where there 

are low levels of human activity and limited intrusion but provided no specific distances. Burger 

(1998) suggested a buffer zone distance of about 330 feet to protect nesting colonies of common terns 

from disturbance effects of personal watercraft. 

Rodgers and Schwikert (2002) measured the noise levels of the two types of watercraft at fixed 

distances, although the analysis of noise-induced effects were not a focus of the investigation. These 

measurements indicated the outboard-powered boat generated 2 to 5 decibels more noise at each 

33-foot measurement increment than the personal watercraft. Decibel measurements for the outboardpowered boat ranged from 87 decibels at 33 feet to 66 decibels at 165 feet. Decibel measurements for 

the personal watercraft ranged from 83 decibels at 33 feet to 64 decibels at 165 feet. The authors 

concluded flushing distances were primarily determined by the speed and the approach angle of the 

approaching vessel (Rodgers and Schwikert 2002). 

Based on such findings and the existing bird uses of the recreation area shorelines and main lake areas, 

disturbance effects from personal watercraft would be a negligible adverse, short-term impact because 

effect on populations and habitats would be well within the range of natural variability and no 

detectable changes in habitats would result from such activities. 

Water birds, such as herons, gulls, and ducks, feed on aquatic and benthic invertebrates and ingest 

sediments in the process. This may cause concerns about the effects of polycyclic aromatic 

hydrocarbons in sediments and bioaccumulation. However, birds generally tolerate ingestion of 

petroleum hydrocarbons easily. Studies have noted no signs of toxicity, reduction in feeding, loss of 

body weight, or grossly visible pathological abnormalities in mallards fed up to 100,000 parts per 

million of weathered Exxon Valdez crude oil (Neff and Stubblefield, 1995). This concentration would 

not be encountered under normal circumstances within the Lake Powell area, suggesting only shortterm, negligible to minor, adverse impacts would be expected from birds ingesting petroleum 

hydrocarbon additives and derivatives associated with personal watercraft or other types of motorized 

watercraft. Other fuel constituents, such as ethylbenzene, xylene, and toluene are very volatile and 

evaporate or are degraded to non-toxic constituents within hours or days by physical, chemical, and 

microbiological processes. Therefore, at concentrations typically associated with recreational boating, 

these contaminants would be unavailable for bird or other wildlife ingestion. 

Reptiles and Amphibians. There is a general absence of reptile and amphibian populations within the 

reservoir and the river tributary shoreline zones because of environmental constraints. Therefore, 

adverse impacts from personal watercraft or their uses would be negligible and long-term. No changes 

from present conditions would be expected with this alternative. 

The Glen Canyon chuckwalla occurs throughout the terrestrial portion of the area of analysis, most 

commonly in rocky or cliff habitats near the lake shore. As a result, this chuckwalla subspecies would 

be susceptible to capture or disturbances by personal watercraft users. Alternative A would have a 
Wildlife and Wildlife Habitat 

FINAL ENVIRONMENTAL IMPACT STATEMENT 223

negligible, long-term, adverse impact on this species, with effects probably resulting from occasional 

opportunistic collecting by personal watercraft users. 

Fish. Few studies have documented direct impacts of boat activity on individual fish behavior or 

mortality (Asplund 2000). No studies were located that documented such effects from personal 

watercraft operations. Asplund (2000) concluded available studies have demonstrated that boating 

activity can temporarily disturb fish from shallow-water nesting areas, but that overall breeding 

success is likely not adversely affected. Toxic effects on fish have generally not been observed, except 

in extreme situations, such as near boat testing facilities. 

A few laboratory studies conducted on the impacts of noise on the auditory threshold of fish concluded 

that some species (like the fathead minnow and other cyprinid fishes) may experience an elevated 

auditory threshold as a result of exposure to high intensity (142 dB), close range (3 feet), noises 

(Scholik and Yan 2002a). However, the circumstances of this study would rarely, if ever, be 

duplicated in the Lake Powell setting. Under normal conditions effect on fish from noise would 

include occasional flushing when motorized watercraft ran directly over individuals or schools. The 

direct adverse impact on the fish would be short-term and negligible because the effects would 

disappear as soon as the watercraft moved out of the area and effects would be restricted to the 

immediate areas of the watercraft. Such effects could also occur with other motorized watercraft that 

beach or launch in shallow-water areas typically used by minnows and other shallow-water species. 

Impacts on fish from the physical intrusion of personal watercraft would primarily be associated with 

direct or indirect disturbance of their habitat, including spawning habitat. While approaching more 

remote landing areas around the lake, personal watercraft activity may temporarily increase subsurface 

turbidity and scour subgrades. However, personal watercraft operator’s tendency to concentrate near 

central marinas on the lake where there are deeper waters would make the effect on shallow aquatic 

habitats infrequent occurrences. Consequently, direct effects from such activities would be short-term 

and negligible, primarily because of the limited number of instances when such conditions could 

occur. 

Potential direct adverse toxic effects on fish from pollutants in personal watercraft exhaust would be 

short-term and negligible. Average toluene concentrations observed within the limited Lake Powell 

water sample results were less than 3 parts per billion, while levels known to have an effect on fish 

occur at around 6,000 parts per billion (Devlin et al. 1982). Benzene concentrations found within the 

lake also fall well below ecotoxicological levels, as do concentrations of naphthalene, 1-methyl 

naphthalene, and methyl tertiary-butyl ether (see “Water Quality” in the “Environmental 

Consequences” chapter). There have been no reported or documented fish kills or chronic aquatic life 

pollution problems reported for the recreation area that have been linked to personal or other 

watercraft (NPS, Spence, pers. com., May 2002n). 

The U.S. Fish and Wildlife Service conducted a study between 1991 and 1994 in which fish bile was 

tested for concentrations of polycyclic aromatic hydrocarbons (PAH). PAH can be taken up from the 

environment through ingestion and/or absorption and are linked to adverse health effects such as liver 

and skin lesions and tumors. The fish were collected from the main channel, marinas, and San Juan 

arm of the recreation area. PAH were detected in the bile of fish at concentrations consistent with 

values indicating exposure to sediments that are considered to be low to moderately contaminated. 

However, no indication of adverse health effects, lesions or tumors, were found in any of the fish 

collected (U.S. Fish and Wildlife Service 2002b). 
ENVIRONMENTAL CONSEQUENCES

224 GLEN CANYON NATIONAL RECREATIONAL AREA

Aquatic Invertebrates. Most aquatic invertebrates (mussels, clams, insects, zooplankton) are found in 

and on bottom substrates, such that direct impacts from noise and habitat disturbance would not occur. 

This is particularly true on Lake Powell where shallow-water shoreline areas constitute very little of 

the total area. Although some negligible, short-term, adverse direct impacts might occur within a 

localized shallow-water area under certain conditions (e.g., the area supported populations of aquatic 

invertebrates and the area was used frequently and for prolonged periods by personal watercraft), the 

adverse effects would be within the range of natural aquatic system variability. Adverse physical 

conditions would typically involve isolated events, resulting from short-term increases in turbidity and 

scouring of the bottom. 

Reported direct toxic effects of benzene, toluene, ethylbenzene, and xylenes compounds to aquatic 

invertebrates include increases in oxygen consumption, decreased hemoglobin concentration, 

increased appendage movement, reduced ingestion rates, immobilization and mortality. Among the 

polycyclic aromatic hydrocarbons, toxicity is reported to increase with the number of rings, and with 

molecular weight (Foster Wheeler Environmental Corporation 1997). Limited measurements of 

benzene, toluene, ethyl benzene, and xylenes and polycyclic aromatic hydrocarbons concentrations 

within Lake Powell during high-use personal watercraft periods (see “Water Quality” in the 

“Environmental Consequences” chapter) were lower than reported toxic (i.e., immobilization and 

death) concentrations. Indirect impacts from bioaccumulation of benzene, toluene, ethylbenzene, and 

xylenes and polycyclic aromatic hydrocarbons would be short-term, negligible to minor, and adverse. 

Cumulative Effects. The incremental effects resulting from operating personal watercraft as proposed 

by alternative A would be negligible contributors to the cumulative condition of wildlife and fish 

resources in the recreation area. Even when personal watercraft effects were combined with the 

incremental effects resulting from other motorized watercraft operating on the lake, the cumulative 

impacts would be negligible to minor, short-term, and adverse. 

As was described in the preceding sections, the effects would be noticeable but would be temporary 

and localized. Adverse effects on vegetation from personal watercraft users that could provide wildlife 

habitat would be masked by the effects of water level changes associated with reservoir management. 

Fish populations, including their habitats, would be affected substantially more by reservoir operations 

than by the limited effects that personal watercraft equipment and users might have on local 

populations and habitat conditions within the lake. 

The incremental changes in fish and wildlife resources possibly resulting from personal watercraft 

users who would be associated with future projects would also be negligible to minor adverse direct 

impacts because of the low numbers involved. For example, the proposed Wahweap campground 

improvements would accommodate additional campers during peak season by providing 48 additional 

hookup sites. If every additional user were a personal watercraft operator, the total number would 

represent a very small contribution to the current annual visitor population. The Antelope Point marina 

project would facilitate personal watercraft launch and retrieval operations, but would probably not 

result in substantially greater numbers of watercraft on the reservoir. No cumulative impacts on 

wildlife or wildlife habitats due to this small increase in recreation area visitation would be expected. 

Conclusion. Personal and other watercraft uses with alternative A would result in negligible to minor 

short-term adverse impacts. Under some conditions impacts, from noise, high-speed personal 

watercraft operations, shoreline habitat disturbances, and the ingestion or absorption of fuel 

constituents, petroleum hydrocarbon additives and derivatives, could be observable and/or measurable. 

However, changes resulting from such conditions would not be expected to be outside the range of 

natural environmental and biological variability. Population numbers, population structure, genetic 
Wildlife and Wildlife Habitat 

FINAL ENVIRONMENTAL IMPACT STATEMENT 225

variability, and other demographic factors for species may experience small, short-term changes, but 

long-term characteristics of wildlife and wildlife habitat within the area of analysis would remain 

stable and viable. 

Operations of personal watercraft would not adversely impact special-interest wildlife concentration or 

high-quality wildlife habitat areas because such resources are not present in the recreation area. 

Special-interested wildlife features (such as active peregrine falcon nest sites) are present in the 

recreation area and many occur in areas visited by personal watercraft and other types of motorized 

watercraft. 

Alternative A would not contribute to deterioration of the recreation area’s fish or wildlife resources to 

the extent that the recreation area’s purpose could not be fulfilled as established in its enabling 

legislation. It would not affect resources key to the recreation area’s natural integrity or opportunities 

for enjoyment or affect the wildlife or wildlife habitat resource, whose conservation is identified as a 

goal in the recreation area’s general management plan. Implementing this alternative would not result 

in an impairment of wildlife, fish, or supporting habitat resources. 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

Personal watercraft use under alternative B would be the same as alternative A except that additional 

geographic restrictions on personal watercraft use would be implemented and carbureted two-stroke 

personal watercraft would be prohibited at the end of 2012. About 25 miles of the Colorado River 

upstream of Sheep Canyon and upper portions of the San Juan (38 miles), Escalante (41 miles), and 

Dirty Devil (19 miles) Rivers would be closed to all personal watercraft. Flat-wake speed restrictions 

would also be prescribed for upper portions of the Escalante River. 

Current use of these proposed restricted areas is very light, even during the high use season, with an 

average of 2 to 10 personal watercraft and about the same number of other watercraft types observed 

at any time within the restricted areas on the Escalante and Dirty Devil Rivers. Less than one personal 

watercraft and other type of watercraft might be present at any given time on either the Colorado or 

San Juan Rivers. 

Prohibiting the use of carbureted two-stroke personal watercraft under alternative B at the end of 2012 

would provide an indirect beneficial impact to wildlife and wildlife habitat as a result of a decrease in 

emissions to air and water quality. 

Cumulative Impacts. Incremental effect on cumulative impacts from personal watercraft and other 

watercraft associated with either the Wahweap campground improvement project or the Antelope 

Point marina project would be similar to those described for alternative A. 

Conclusion. Impacts on wildlife and wildlife habitats due to alternative B would result in negligible to 

minor short-term adverse impacts. Under some conditions impacts, from noise, high-speed personal 

watercraft operations, shoreline habitat disturbances, and the ingestion or absorption of fuel 

constituents, petroleum hydrocarbon additives and derivatives, could be observable and/or measurable. 

However, changes resulting from such conditions would not be expected to be outside the range of 

natural environmental and biological variability. Prohibiting carbureted two-stroke personal watercraft 

engines at the end of 2012 would indirectly benefit wildlife and wildlife habitat.
ENVIRONMENTAL CONSEQUENCES

226 GLEN CANYON NATIONAL RECREATIONAL AREA

Alternative B would not contribute to deterioration of the recreation area’s wildlife resource to the 

extent that the recreation area’s purpose could not be fulfilled as established in its enabling legislation. 

Implementing this alternative would not result in an impairment of wildlife, fish, or supporting habitat 

resources. 

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

With alternative C, personal watercraft use would be prohibited. Noise and disturbance effect on fish 

and wildlife species and their supporting habitats from existing personal watercraft use on the lake 

would be incrementally reduced by the number of personal watercraft currently present. These effects 

would be short-term, negligible, direct and indirect, beneficial impacts. The beneficial effects of the 

personal watercraft ban would be negligible and temporary because motorized watercraft of several 

types and their users would still use the lake, creating noise emissions and human disturbances. In the 

longer-term when visitor numbers recovered, effects would be similar to those described for 

alternative A. 

Cumulative Effects. Closure of Lake Powell to personal watercraft use would reduce the total number 

of watercraft on the lake by approximately 26%. Other motorized watercraft use would continue. 

Possible short-term and long-term benefits derived from eliminating personal watercraft use would not 

be noticeable or distinguishable from background variations in wildlife population numbers or 

conditions. 

The Wahweap campground improvement project and the Antelope Point marina project would slightly 

increase the use of the lake for water-based recreation. Under alternative C, all of these visitors would 

use watercraft other than personal watercraft. Although this use would be additive with current use of 

the lake, it would differ little from the effects that would occur from personal watercraft under 

alternatives A or B and would have a negligible effect on wildlife and wildlife habitat. 

Conclusion. Alternative C would have a negligible, short-term, beneficial impact on wildlife and 

wildlife habitat from a reduction in boat-days that initially would result from eliminating personal 

watercraft use on the lake. By the end of the analysis period in 2012, the number of boat-days would 

have returned to levels within the range predicted for alternatives A and B. Because the effects on 

wildlife and wildlife habitats from personal watercraft and other types of motorcraft are similar, the 

long-term effect of alternative C on wildlife and wildlife habitats would be negligible. Alternative C 

would not result in impairment of fish and wildlife species or their supporting habitats. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 227

THREATENED AND ENDANGERED SPECIES 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Issues 

The same personal watercraft management issues described for wildlife and wildlife habitats and for 

shoreline vegetation pertain to the species designated as either endangered or threatened. These 

species have the same kinds of environmental needs as species without this designation. Key 

differences are that endangered or threatened species generally are much less abundant, have more 

limited range distributions, and many have less tolerance to habitat alterations. 

Issues for endangered or threatened species relate to noise, human disturbance, toxicity from 

compounds in fuel, and habitat loss or degradation. In addition, endangered or threatened species 

require consideration in accordance with the requirements of the Endangered Species Act. The 

National Park Service must ensure that the effects of personal watercraft management would not 

jeopardize the continued existence of designated species or their designated critical habitats. 

Management Objectives 

Glen Canyon National Recreation Area has several management objectives that provide for the 

management of endangered fish habitat. The Natural Resources Management Plan and Environmental 

Assessment for Glen Canyon National Recreation Area (NPS 1986) established protection of all 

known populations of endangered fish species from impacts of human activities in the recreation area. 

The Fish Management Plan, Glen Canyon National Recreation Area (Utah Division of Wildlife 

Resources 1996) includes provisions for inflow and endangered native species habitat protection. This 

management document acknowledges river inflow areas as a critical habitat and stated that surplus 

endangered fish species provided from the native fish-stocking program occasionally are released in 

the critical habitat reaches at inflows to Lake Powell. 

Three objectives that apply to endangered native species habitat management were included in the 

Fish Management Plan, Glen Canyon National Recreation Area (Utah Division of Wildlife Resources 

1996). They include: 

Maintaining or enhancing forage conditions to allow adequate nutrition of all fish in Lake 

Powell; 

Providing adequate habitats with ample vegetative cover to improve nursery habitat; and 

Understanding and minimizing the impacts of dam operation on native and sport fish 

populations. 

GUIDING REGULATIONS AND POLICIES 

The Endangered Species Act (16 U.S.C. 1531 et seq.) defines the terms and conditions of the Federal 

status of species in the recreation area and requires an examination of impacts on all federally listed, 
ENVIRONMENTAL CONSEQUENCES

228 GLEN CANYON NATIONAL RECREATIONAL AREA

species proposed for listing, and designated critical habitats for threatened or endangered species. 

Management Policies 2001 (NPS 2000d) further states that the National Park Service will consider 

potential effects of agency actions on state or locally listed species. The National Park Service is 

required to perpetuate the natural distribution and abundance of these species and the ecosystems upon 

which they depend. 

Neither Arizona nor Utah has a threatened or endangered fish and wildlife statute, but both have 

statutes that protect endangered and threatened plant species. The Utah State Lands Endangered and 

Threatened Plant Species statute (Title 65A-2-3) defines the terms and conditions of the state status of

endangered or threatened plant species. The State Lands Division may make determinations 

concerning the management, protection, and conservation of plant species officially designated as 

endangered or threatened under the federal Endangered Species Act of 1973, as amended, on state 

lands. Under the schools and state trust lands statute (Title 53C), this is also true for state trust lands. 

Arizona statute Title 3 Chapter 7 (Article 1, section 3-903) authorizes the director to establish and 

maintain a list of state-protected native plants. The statute includes protective coverage of native plants 

that are present on state, public, or privately owned land. Categories of protected native plants include 

species that are: 

In danger of extinction throughout all or a significant portion of their ranges; 

Likely within the foreseeable future to become jeopardized or in danger of extinction throughout 

all or a significant portion of their ranges; or 

Resident to Arizona and listed as endangered, threatened, or category 1 in the federal 

Endangered Species Act of 1973 (PL 93-205; 87 Stat. 884; 16 U.S.C., sections 1531 et seq.), as 

amended, and any regulations adopted under that act. 

Title 3 chapter 7 article 1, section 3-910 defines the terms and conditions for investigations of native 

plants and authorizes the state to determine whether or not protected species exist on the land. 

METHODOLOGY AND ASSUMPTIONS 

Identification of state and federally listed species and designated critical habitats was accomplished 

through discussions with recreation area staff, informal consultation with U.S. Fish and Wildlife 

Service personnel, and reviews of databases maintained by the Arizona Game and Fish Department 

and Utah Division of Wildlife Resources. A letter requesting a current list of federal threatened, 

endangered, and special-concern species was sent to the U.S. Fish and Wildlife Service. The response 

from the U.S. Fish and Wildlife Service to this request is included in appendix H.1. As part of the 

consultation process, the Draft Environmental Impact Statement was submitted to the U.S. Fish and 

Wildlife Service for their review in October 2002. The U.S. Fish and Wildlife Service provided 

response to the Draft Environmental Impact Statement and concurred that the three alternatives 

presented are “not likely to adversely affect” threatened or endangered species or their critical habitat. 

Their response to the Draft Environmental Impact Statement can be found in volume II of this Final 

Environmental Impact Statement. The Arizona Game and Fish Department and Utah Division of 

Wildlife Resources were also contacted to identify state threatened, endangered and special-concern 

species. Responses are included in appendix H.2 and appendix H.3. 
Threatened and Endangered Species 

FINAL ENVIRONMENTAL IMPACT STATEMENT 229

An analysis of the potential impacts on listed species and designated critical habitats occurring in the 

recreation area is included in this section. Species analyzed include the humpback chub, bonytail, 

Colorado pikeminnow, razorback sucker, southwestern willow flycatcher, yellow-billed cuckoo, and 

bald eagle. An impact analysis was not conducted for Federally listed or candidate species that do not 

occur within the analysis area (see table 15). 

Management Policies 2001 (NPS 2000d) states that potential effects of agency actions will also be 

considered on state- or locally listed species. An analysis of the potential impacts on the American 

peregrine falcon, which is classified as an Arizona special-status species and a Utah endangered 

species, is included in this section. The humpback chub, bonytail, Colorado pikeminnow, razorback 

sucker, Mexican spotted owl, and the southwestern willow flycatcher are also listed as endangered or 

threatened by the Utah Division of Wildlife Resources. 

Data used from the recreation area include staff interviews, general management, natural resource 

management, fish management and water resources management plans. 

Steps used in assessing impacts of personal watercraft management alternatives on listed species 

included: 

Establishing current presence, habitat availability, and uses of areas by listed species; 

Identifying species associated with areas most likely to be affected by personal watercraft use 

under each alternative; 

Determining habitat loss or alternation caused by the alternatives; and 

Determining displacement and disturbance potential of the actions and the species’ potential to 

be affected by personal and other watercraft activities. 

The information contained in this analysis was obtained through best professional judgment of 

recreation area staff and experts in the field (as cited in the text), and literature review. Assumptions 

made regarding how personal watercraft and other watercraft operate relative to threatened, 

endangered, and special-concern species included the following. 

The analysis area includes Lake Powell up to the 3,700-foot water surface elevation shoreline, 

and near-shore uplands within 500 horizontal feet of Lake Powell’s 3,700-foot water surface 

elevation. Personal and other watercraft use could involve activities along the shore and on the 

near-shore uplands to approximately 500 feet from the 3,700-foot lake water surface elevation. 

This 500-foot area is assumed to cover the range of personal and other watercraft uses of 

adjacent upland near-shore areas such as travel to and from the shoreline, short-term excursions 

to explore uplands adjacent to the shoreline, and temporary watercraft landing and storage. 

The entire lake is within one management zone, the Recreation and Resource Utilization Zone. 

Near-shore uplands adjacent to the lakeshore include Natural and Development Zones, and the 

coverage of these zones fluctuates in relation to the lake-surface elevation. 

Primary personal watercraft and other watercraft use occurs from Memorial Day to Labor Day. 

The secondary periods of recreation area visitation are May 1 to Memorial Day and Labor Day 

until October 15. 
ENVIRONMENTAL CONSEQUENCES

230 GLEN CANYON NATIONAL RECREATIONAL AREA

Personal watercraft and boat users accessing the shoreline from the recreation area tend to use 

existing boat ramp facilities to launch their watercraft. 

When accessing the shoreline from the lake, most personal watercraft and other boat users stay 

within visual sight of their watercraft. 

Personal watercraft within 60 feet of other watercraft or facilities with other watercraft present 

travel at a speed of 5 miles per hour or less to minimize wake production. 

Impact Threshold Definitions 

The Endangered Species Act effect categories used to define impacts on listed species are as follows: 

No effect/no adverse modification: This conclusion is reached if the proposed action and its 

interrelated and interdependent actions would not directly or indirectly affect listed species or 

adversely modify designated critical habitat. 

May affect/not likely to adversely affect/adversely modify critical habitat: Effects on specialstatus species or designated critical habitat are discountable (i.e., extremely unlikely to occur 

and not able to be meaningfully measured, detected, or evaluated) or completely beneficial. 

May affect/likely to adversely affect species/adversely modify critical habitat: When an adverse 

effect to a listed species or designated critical habitat may occur as a direct or indirect result of 

proposed actions and the effect is either not discountable or completely beneficial. 

Is likely to jeopardize proposed species/adversely modify proposed critical habitat: The 

appropriate conclusion when the National Park Service or the U.S. Fish and Wildlife Service 

identify situations in which personal watercraft use could jeopardize the continued existence of a 

proposed species or adversely modify critical habitat to a species within or outside recreation 

area boundaries. 

The following impact thresholds were used to determine the intensity effects on listed species and 

critical habitat: 

Negligible — No listed species of concern is present; no impacts or impacts with only temporary 

effects are expected. 

Minor — Nonbreeding animals of concern are present but only in low numbers. Habitat is not 

critical for survival; other habitat is available nearby. Occasional flight responses by animals are 

expected, but without interference with feeding, reproduction or other activities necessary for 

survival. 

Moderate — Breeding listed species are present; listed species are present during particularly 

vulnerable life-stages such as migration or juvenile stages; mortality or interference with 

activities necessary for survival expected on an occasional basis, but not expected to threaten the 

continued existence of the listed species in the recreation area. 

Major — Breeding listed species are present in relatively high numbers, and/or listed species are 

present during particularly vulnerable life stages. Habitat targeted by personal watercraft use or 
Threatened and Endangered Species 

FINAL ENVIRONMENTAL IMPACT STATEMENT 231

other actions has a history of use by listed species during critical periods and is somewhat 

limited. Mortality or other effects are expected on a regular basis and could threaten continued 

survival of the species in the recreation area. A taking under section 7 of the Endangered 

Species Act could occur. 

Impairment — Personal watercraft use would contribute substantially to the deterioration of 

natural resources to the extent that the recreation area’s listed species and critical habitat would 

no longer function as a natural system. Listed species and its habitat would be affected over the 

long term to the point that the recreation area’s purpose (Enabling Legislation, General 

Management Plan, Strategic Plan) could not be fulfilled and resource could not be experienced 

and enjoyed by future generations. 

Geographic Area Evaluated for Impacts 

The area being analyzed for possible impacts on threatened and endangered fish species and 

designated critical habitats for this assessment (area of analysis) consists of Lake Powell above the 

Glen Canyon Dam, and its associated tributaries including, but not limited to the San Juan, Colorado, 

Dirty Devil, and Escalante Rivers within the boundaries of Glen Canyon National Recreation Area. 

For all other species the analysis area includes the 500-foot shoreline zone around the 3,700-foot 

elevation within the entire recreation area. 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

With alternative A, personal watercraft and other watercraft would have access to and operate 

throughout Lake Powell and in river inlets where critical habitat for the endangered humpback chub, 

bonytail, Colorado pikeminnow and razorback sucker has been designated. Personal watercraft activity 

may occasionally coincide with peregrine falcon foraging and roosting, and with foraging activities of 

yellow-billed cuckoos or southwestern willow flycatchers along river or tributary riparian habitats. 

Humpback Chub, Bonytail, Colorado Pikeminnow, and Razorback Sucker. Implementation of 

alternative A would have negligible, adverse, direct and indirect, short-term effects on endangered or 

threatened fishes. Under section 7 of the Endangered Species Act, these effects would be unlikely to 

adversely affect federally listed endangered or threatened fish species or their designated critical 

habitats in the recreation area. The magnitude and reasons for the effects are described in the following 

sections. 

Access to the Colorado River and San Juan River inlets would remain open to use where critical 

habitat has been designated. Use of personal watercraft upstream of areas with measurable current

would not be permitted on the Dirty Devil River thereby reducing the likelihood of any potential effect 

on critical habitat of endangered fish present in this river inlet. Effects of personal watercraft use on 

designated critical habitat of endangered fish species are not well known and no studies in the 

recreation area have been conducted on the subject (NPS, Spence, pers. com., May 2002n). The few 

razorback suckers and Colorado pikeminnows observed in the river inlets suggest there may be short 

periods of time that young-of-the-year and adult fish use Lake Powell’s river inlets. There are no 

reported cases in which personal watercraft use in these areas were responsible for adverse impacts on 

these species. 
ENVIRONMENTAL CONSEQUENCES

232 GLEN CANYON NATIONAL RECREATIONAL AREA

Personal watercraft activity may generate audible surface and subsurface noise within or adjacent to 

critical habitat that may influence normal distribution and behavior of endangered fish. This could 

temporarily change normal use of backwaters and eddy currents, reducing the period of time 

fingerlings have to adjust to the river habitat (Radle n.d.). However, this would not likely adversely 

affect the razorback sucker because current personal watercraft use in river inlets during peak season is 

typically less frequent (less than 5%) and use does not occur over extended periods of time, nor is the 

watercraft activity as intense as it is nearer to the marinas (James et al. 2001a). 

A majority of the more intense day-users typically use deeper, open waters of Lake Powell near 

Wahweap, Bullfrog, Halls Crossing, and Hite where no endangered fish or critical habitat are present. 

Because of the limited use of river inlets by endangered fish species, noise from personal watercraft 

would cause direct, short-term, negligible, adverse impacts. These changes may affect but would not 

likely adversely affect endangered fish or their critical habitats. There would be no impacts on these 

species in main reservoir areas because suitable habitat is absent. 

Razorback suckers often use habitats comprised of flooded shorelines of saltcedar in the San Juan 

River inflow and frequent reaches near Neskahi Bay, Nokai Canyon and Paiute Farms to Clayhills 

Crossing (Mueller and Karp 2002). While approaching more remote landing areas around the lake 

personal watercraft may temporarily increase subsurface turbidity and scour subgrades in critical 

habitat. The watercraft launch and takeout area located at Clay Hills Crossing and Paiute Farms on the 

San Juan River provides very limited habitat conducive to razorback sucker use because only a few 

sparse stands of young saltcedar exist along these shorelines (NPS, Peterson, 1979a). However, few 

watercraft use river inlets because fluctuation of the lake water surface limits access to these shallow 

waters. Personal watercraft operators tend to avoid flooded areas containing shrubs, trees and 

emergent vegetation attractive to endangered fish. Minor disturbance to shallow sand or gravel bars 

and cobble substrate in shoreline coves may create or improve microhabitat for endangered fish. Such 

localized disturbance of critical habitat would be a direct, adverse, short-term, negligible impact. 

Under section 7 of the Endangered Species Act, these effects would not be considered likely to 

adversely affect endangered fish. 

When traveling river inlets personal and other watercraft operators may periodically exceed the normal 

watercraft operating speed, intensity and duration. Exhaust from carbureted two-stroke engines during 

such conditions could generate hydrocarbon pollutants that accumulate on water surfaces and in 

sediment. Such exhaust emissions would temporarily change water quality conditions in a small area. 

Under flowing river conditions, concentrations would be diluted rapidly, and the more volatile 

constituents would evaporate and disperse quickly from surface waters. 

Bioaccumulation of fuel pollutants generated by personal watercraft exhaust emissions would not be a 

concern because these constituents would either evaporate or be degraded by microbes within hours or 

days. Fuel discharge concentrations from the low number of personal watercraft that access river areas 

thought to be used by the endangered fish species would be low. Consequently, it is anticipated the 

direct and indirect adverse effects from personal watercraft pollutants would be short-term and 

negligible impacts. Under section 7 of the Endangered Species Act, these effects would be considered 

unlikely to adversely affect endangered fish. 

Effects from personal watercraft use on designated critical habitat areas would be negligible, shortterm, adverse, and direct because temporary channel, bottom, or vegetation changes caused by 

personal watercraft would be indistinguishable from the natural variability of these areas. River 

channel areas have constantly changing bottom configurations because of flow variations and 
Threatened and Endangered Species 

FINAL ENVIRONMENTAL IMPACT STATEMENT 233

changing sediment loads. Physical changes resulting from personal watercraft use would quickly be 

masked by normal bottom and bank changes. 

Bald Eagle. This species winters in the recreation area when limited personal watercraft activity 

occurs. As a result, personal watercraft use under alternative A would have little effect on wintering 

bald eagles or their winter habitat. The occasional disturbance of individual eagles by personal 

watercraft or other motorized watercraft passing nearby during the winter season would be a 

negligible, short-term, direct, adverse effect. Under section 7 of the Endangered Species Act, these 

effects would be considered unlikely to adversely affect the bald eagle. 

American Peregrine Falcon. Direct interaction between personal watercraft and peregrine falcons 

would be unlikely. Indirect adverse effects may result from varying personal and other watercraft 

speed that generate noise levels that reverberate against steep canyon walls frequented by peregrine 

falcon. Depending on the speed, intensity and duration of the engine noise and the distance between 

the motorized personal watercraft, and the physical barriers that may exist between the source and a 

peregrine falcon, temporary exposure to high noise levels may temporarily change or influence 

peregrine falcon behavior. 

The use of personal watercraft may indirectly affect peregrine falcons that forage in the vicinity of 

Lake Powell (NPS, Spence, pers. com., May 2002n). Motorized watercraft, including personal 

watercraft, currently use the upper reaches of the Escalante, Dirty Devil, and Colorado Rivers (James 

et al. 2001a) and the peregrine falcon continues to nest and breed successfully in these areas. The noise 

may cause localized avoidance of these locations by falcons during peak periods of watercraft 

operation, which would be a short-term, adverse, negligible effect on this species. Under section 7 of 

the Endangered Species Act, these effects would be considered unlikely to adversely affect this 

species. 

Southwestern Willow Flycatcher. Alternative A would have negligible adverse effects on the 

southwestern willow flycatcher. This conclusion in based on the: 

Low numbers of birds present throughout its occupied range; 

Infrequent occurrence of this species in the analysis area; 

Limited availability of suitable habitat in the recreation area; and 

Very low likelihood that personal watercraft and their operators would use the shoreline areas 

with suitable habitat that are frequented by this species. 

Designated critical habitat is not present in the recreation area. Therefore, there would be no adverse 

effects on this aspect of the southwestern willow flycatcher’s environment. If interactions between 

personal watercraft operators and this species occurred, the direct adverse effects would be short-term 

and negligible, and probably would be limited to flushing a bird from a perch. Under section 7 of the 

Endangered Species Act, these effects would be considered unlikely to adversely affect the species at 

the population level. 

Western Yellow-Billed Cuckoo. It is unlikely that personal watercraft operators would interact with 

this species. This conclusion in based on the limited availability of suitable cottonwood-willow 

riparian habitat and the limited and infrequent presence of this species along the river corridors. Few 

personal watercraft operators would access riparian shorelines with cottonwood-willow habitat used 
ENVIRONMENTAL CONSEQUENCES

234 GLEN CANYON NATIONAL RECREATIONAL AREA

by this species. On occasions when personal watercraft operators entered an area occupied by this 

species, there may be circumstances when the birds may be flushed from perch sites. This would be a 

short-term, direct, negligible, adverse effect. Under section 7 of the Endangered Species Act, these 

effects would be considered unlikely to adversely affect this species. 

Cumulative Effects. Cumulative effects are not likely to adversely affect federally listed threatened or 

endangered species or their critical habitats. Lake Powell is located in the Recreation and Resource 

Utilization Zone, which permits the use of watercraft, including personal watercraft, and allows the 

development of facilities for these uses. Watercraft activity, support services, and other recreation 

activities allowed in the past would continue throughout the lake, including in river inlets and remote 

side canyons of the lake that contain critical habitat. Other recreational and shoreline access activities 

such as camping, picnicking, hiking, and nonmotorized boating would continue in remote tributaries 

and at more heavily used marinas. Effects of these activities would be negligible to minor for the 

reasons described above. 

Annual and seasonal flooding and draw-down of the reservoir would affect the habitat use, habitat 

availability, and spawning success of endangered fish far more than the negligible potential effects on 

water quality, audible noise, or subsurface turbidity and bottom scouring that would be caused by 

watercraft activities. Shoreline flat-wake speeds applied to all watercraft would reduce engine 

emissions into the surface waters, resulting in minor improvement to water quality and reductions of 

ambient noise. Additional low-pollution engines would incrementally improve water quality over the 

long term. 

Personal and other watercraft use in more remote river inlets such as the San Juan River would be less 

intense than near the marinas. The short-term use of watercraft in these tributaries would be 

considered normal recreational use. Under normal recreational use, engine emissions would have little 

direct effect on water quality (Warrington 1999), and indirectly to the fish species associated with this 

area. 

The proposed Wahweap campground improvements would bring additional campers with motorcraft, 

including personal watercraft. The effects of these vessels would be additive with the effects of vessels 

already using the lake, but probably would not cause any additional adverse impacts on critical 

habitats or endangered fish. Reductions in employee housing in the Wahweap area also would not 

affect these species. The proposed new facilities at Antelope Point also would not change conditions 

for critical habitat or endangered fish. 

Visitor access to remote areas within the river inlets where critical habitat for endangered fish could be 

located would continue at current levels. Visitors would include personal watercraft users, other 

boaters, hikers, and land-based users utilizing accessible shorelines. 

Technological improvements in personal and other watercraft engines would reduce noise emissions. 

This could produce a negligible beneficial effect by reducing disturbances of sensitive individual or 

species. The improved engines also would have lower air and water emissions, which would have 

negligible benefits to critical habitat of endangered fish and bird species within river inlets of Lake 

Powell. 

Beneficial effects on special-concern aquatic species would continue from ongoing implementation of 

the Glen Canyon natural resource management plan (NPS 1986) and the recreation area fish 

management plan (Utah Division of Wildlife Resources 1996). Benefits also would occur from current 

reintroduction of native endangered fish species. However, these species would continue to experience 
Threatened and Endangered Species 

FINAL ENVIRONMENTAL IMPACT STATEMENT 235

adverse cumulative effects from predation, particularly by non-native species, and by the reduction in 

available habitat that was caused by damming the Colorado River and its tributaries. 

Conclusion. Alternative A would not adversely affect any ecological, biological, or physical processes 

associated with endangered fish critical habitats. Continuing the location restriction on upstream 

portions in the Colorado, San Juan, Dirty Devil, and Escalante Rivers would provide some protection 

of critical habitat for endangered fish. Compared to current conditions, alternative A would have 

negligible effects on the bald eagle, American peregrine falcon, southwestern willow flycatcher, or 

yellow-billed cuckoo or their critical habitats within Lake Powell and its tributaries in the recreation 

area. Cumulative impacts are not likely to adversely affect endangered, threatened, or special-concern 

species or their designated critical habitats in the recreation area. 

No impairment to threatened or endangered species or their designated critical habitats would occur 

from the implementation of alternative A. 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

With alternative B, personal watercraft could operate throughout the upper portions of Lake Powell in 

river inlets where critical habitats for the endangered humpback chub, bonytail, Colorado 

pikeminnow, and razorback sucker have been designated in accordance with the restrictions described 

previously. Personal watercraft activity may occasionally coincide with peregrine falcon foraging and 

roosting, and with foraging activities of yellow-billed cuckoos or southwestern willow flycatchers 

along river or tributary riparian habitats. 

Humpback Chub, Bonytail, Colorado Pikeminnow, and Razorback Sucker. Personal watercraft 

use would not be permitted in some portions of the Colorado, Escalante, Dirty Devil, and San Juan 

Rivers. This potentially would improve the protection of critical habitat available for endangered fish 

species. Increased protection of critical habitat located upstream of Sheep’s Canyon in the Colorado 

River and Clay Hills Crossing in the San Juan River where adult razorback suckers occur would 

benefit potential fish uses of the inflow areas of Lake Powell (Mueller et al. 2002; Mueller and Karp 

2002; USGS n.d.). Therefore, there would be a negligible, long-term, direct, localized beneficial 

impact on endangered fish in these areas. Use would be allowed on some portions of the Escalante 

River, but only at flat-wake speeds. The flat-wake restriction potentially would reduce audible 

subsurface noise and the emission of chemical contaminants into surface waters. 

Personal watercraft use within river inlets would not be limited by season. Although peak watercraft 

operations run from late May to early September, a one-month transition season in the spring 

coincides with spawning periods of these species. Personal watercraft could temporarily increase the 

scour of shallow aquatic habitat while approaching or landing on river shorelines. However, personal 

watercraft use in river inlets would be lowest in the spring. Personal watercraft operators would 

typically avoid dense stands of inundated saltcedar where endangered fish larvae would be 

concentrated during the spring season. Thus, potential adverse direct effects on endangered fish 

spawning habitat and production potential would be short-term and negligible because the anticipated 

number and timing of personal watercraft presence would be very low or infrequent at the time fish 

use such areas. Fish use of such areas would be infrequent as well. 
ENVIRONMENTAL CONSEQUENCES

236 GLEN CANYON NATIONAL RECREATIONAL AREA

There would be an indirect beneficial impact on endangered fish under alternative B as a result of 

prohibiting carbureted two-stroke personal watercraft engines at the end of 2012 which would reduce 

the amount of petroleum related pollution being emitted into the water. 

Effect on federally listed endangered fish related to personal watercraft use in other areas under 

alternative B would be similar those discussed for alternative A. Under section 7 of the Endangered 

Species Act, these effects would be considered unlikely to adversely affect any of the four endangered 

fish species or their designated critical habitats. 

Bald Eagle. Bald eagles are transient users that seasonally winter in Glen Canyon National Recreation 

Area. Because of their transient nature and their presence primarily during the winter (in contrast to 

personal watercraft use, which occurs primarily during the summer), there would be negligible, direct, 

beneficial, effects from limiting personal watercraft use along the rivers. Under section 7 of the 

Endangered Species Act, the effects of alternative B may affect, but would be considered unlikely to 

adversely affect the bald eagle. 

American Peregrine Falcon. This alternative would slightly decrease human disturbances and noise 

in some areas of the recreation area used by peregrine falcons. Negligible, long-term benefits could be 

associated with the reduced human access in some areas and reduced personal watercraft speeds in 

other areas. Otherwise, there would be little difference in effects compared to alternative A. Under 

section 7 of the Endangered Species Act, these effects would be considered unlikely to adversely 

affect this species. 

Southwestern Willow Flycatcher. There would be no adverse or beneficial effects of this alternative 

for the same reasons that were described for alternative A. Designated critical habitat is not present in 

the recreation area, therefore, there would be no adverse effects on this aspect of the species’ 

environment. If interactions between personal watercraft operators and this species occurred, the direct 

beneficial effects would be short-term and negligible, probably consisting of only one to two fewer 

cases of not flushing or displacing a bird. Under section 7 of the Endangered Species Act, these effects 

would be considered unlikely to adversely affect this species. 

Western Yellow-Billed Cuckoo. Limited availability of suitable habitat and the infrequent presence 

of this species throughout the analysis area would make it unlikely that personal watercraft and their 

operators would interact with this species. As under alternative A, few personal watercraft operators 

would access riparian shorelines with cottonwood-willow habitat used by this species. On occasions 

when personal watercraft operators entered an area occupied by this species, there may be 

circumstances when the birds would be flushed from perch sites. This would be a short-term, direct, 

negligible, adverse effect. Under section 7 of the Endangered Species Act, these effects would be 

considered unlikely to adversely affect this species. 

Cumulative Effects. Cumulative impacts are not likely to adversely affect federally listed endangered 

or threatened species or their designated critical habitats in the recreation area. Restriction of personal 

watercraft would further reduce the current number of personal watercraft that travel reaches of river 

inlets where critical habitats for the endangered fish species are located. However, because other types 

of motorized watercraft that produce effects similar to those of personal watercraft, the beneficial 

impacts from restricting personal watercraft would be negligible. 

Annual and seasonal flooding and draw-down of the reservoir affect the habitat use, habitat 

availability, and spawning success of endangered fish far more than the negligible potential effects on 

water quality, audible noise, or subsurface turbidity and bottom scouring caused by watercraft 
Threatened and Endangered Species 

FINAL ENVIRONMENTAL IMPACT STATEMENT 237

activities. Shoreline flat-wake speeds applied to all watercraft would reduce engine emissions into the 

surface waters, resulting in minor improvement to water quality and reductions of ambient noise. 

Additional low-pollution engines would incrementally improve water quality over the long term. 

Conclusion. Restrictions on access and designation of flat-wake speeds along sections of river 

shorelines would produce short-term, direct, negligible benefits to habitats of endangered fishes in the 

inflow areas. These would occur because fewer personal watercraft would use these areas, and the 

remaining vessels would operate at lower speeds, producing less site disturbance. These effects would 

not change ecological function or structure of critical habitat and would probably be indistinguishable 

from the range of environmental variation that occurs under natural conditions. The availability, use, 

and location of suitable endangered fish habitat would be more extensively affected by reservoir 

operations and annual river runoff patterns than by operation of personal watercraft. Therefore, the 

impacts on endangered fish species and their designated critical habitat with alternative B would be 

similar to alternative A. Endangered fish would benefit indirectly with the prohibition of carbureted 

two-strike personal watercraft engines at the end of 2012 which would reduce the amount of fuel 

discharge into the water in subsequent years. There would be no distinguishable adverse effects on the 

bald eagle, American peregrine falcon, southwestern willow flycatcher, or yellow-billed cuckoo. As a 

result, this alternative would be unlikely to adversely affect these species in the recreation area. 

Cumulative impacts are not likely to adversely affect endangered, threatened, or special-concern 

species or their designated critical habitats in the recreation area. 

No impairment would be expected to endangered, threatened, or special-concern species or their 

designated critical habitats with this alternative. 

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

With alternative C, personal watercraft would be eliminated. However, former personal watercraft 

users eventually would return to the lake with other types of motorcraft so that by the end of the 

10-year analysis period, lake-wide use levels would be within the range predicted under alternatives A 

and B. This alternative would be unlikely to adversely affect federally listed endangered or threatened 

species or their designated critical habitats. Effects on these species and critical habitats under 

alternative C would be similar to those discussed for alternative A and alternative B. 

Humpback Chub, Bonytail, Colorado Pikeminnow, and Razorback Sucker. Alternative C would 

provide negligible short-term improvements to critical fish habitat by reducing the number of 

motorcraft using the lake, including the river inlets, for two or three years. Reducing the currently 

small number of vessels that pass through shallow-water sand and gravel bars to reach near-shore 

uplands and sand beaches would reduce the potential of inadvertent disruption of some fish habitat. 

The magnitude of this effect on the species would be negligible and would be difficult to distinguish 

from the effects of natural river processes. The overall effect on the endangered fishes and their habitat 

would be direct, short-term, and negligible. Under section 7 of the Endangered Species Act, these 

effects would be considered unlikely to adversely affect any of these four species. 

Bald Eagle. Effects on the bald eagle would be similar to those described for alternative B.

American Peregrine Falcon. The effects on the American peregrine falcon would be similar to those 

described for alternative B. 
ENVIRONMENTAL CONSEQUENCES

238 GLEN CANYON NATIONAL RECREATIONAL AREA

Southwestern Willow Flycatcher. The effects on the southwestern willow flycatcher would be 

similar to those described for Alterative B. 

Western Yellow-Billed Cuckoo. The effect on the western yellow-billed cuckoo would be the similar 

to those described for Alterative B. 

Cumulative Effects. As stated in the “General Methodology” section of this chapter, it was assumed 

that the removal of personal watercraft in alternative C would result in an initial decrease in annual 

boat days in the short-term. However, by the end of the 10-year analysis period, the total number of 

watercraft operating hours and the total number of motorized watercraft using Lake Powell under 

alternative C would be within the range predicted for alternatives A and B. This would be due to either 

natural growth in visitation, to visitors finding other watercraft to fulfill functions previously served by 

personal watercraft, or to increases in visitation by individuals who previously avoided the recreation 

area due to personal watercraft and now choose to visit in their absence. This was the same assumption 

that was used for the other impact topics. Removing personal watercraft from the lake would cause a 

short-term reduction in visitation, which would reduce the potential for the disturbance of some 

endangered or threatened species or their habitats. In the long term, total motorized watercraft 

numbers would return to previous levels. Benefits derived from removing personal watercraft would 

be restricted to the canyon areas where conditions would be similar to alternative B. 

Visitor activity such as river rafting and other watercraft use within river inlets would continue along 

with camping, picnicking, and fishing. Shoreline flat-wake speeds would continue to apply to other 

watercraft. Engine emissions, which directly affect water quality and have an indirect effect on 

endangered or threatened species, would have minor improvements as the percentage of low-emissions 

engines on the lake increased. Combined with these other past, present, and foreseeable future 

activities, alternative C would result in negligible cumulative effects that are not likely to adversely 

affect endangered species or their designated critical habitat. 

Annual and seasonal flooding and draw-down of the reservoir would affect the habitat use, habitat 

availability, and spawning success of endangered fish far more than the negligible potential effects on 

water quality, audible noise, or subsurface turbidity and bottom scouring that would be caused by 

watercraft activities. Shoreline flat-wake speeds applied to all watercraft would reduce engine 

emissions into the surface waters, resulting in minor improvement to water quality and reductions of 

ambient noise. Additional low-pollution engines would incrementally improve water quality over the 

long term. 

Conclusion. Negligible improvements to endangered fish habitat would be expected, resulting in 

short-term, direct beneficial impacts on endangered fish and their designated critical habitats in the 

inflow areas. The bald eagle, American peregrine falcon, southwester willow flycatcher, and yellowbilled cuckoo might experience some negligible short-term beneficial direct impacts from reduced 

disturbance incidents during the two to three years when the total number of boat days are expected to 

decline. Alternative C would be unlikely to adversely affect endangered fish or birds or their critical 

habitat, special-concern species or state-sensitive species known to use critical habitats or frequent 

near-shore uplands and riparian habitats within the recreation area. 

Cumulative impacts are negligible and not likely to adversely affect endangered, threatened, or 

special-concern species or their designated critical habitats in the recreation area. 

No impairment would be expected to endangered, threatened, or special-concern species or their 

designated critical habitats from this alternative. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 239

SHORELINE VEGETATION 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Issues 

Previously identified concerns regarding personal watercraft activities that may disturb, injure or 

eliminate riparian, wetlands and submerged aquatic vegetation are addressed by the following 

analysis. Lake Powell is located within the Recreation and Resource Utilization Management Zone of 

Glen Canyon National Recreation Area. The recreation area’s general management plan (NPS 1979a) 

guidelines encourage the maintenance of natural processes within this zone while allowing the use of 

watercraft and other recreational activities. In general, certain recreational activity such as beaching or 

landing of personal watercraft to access the shoreline could expose shoreline vegetation to trampling 

and compaction in some areas. Once on the shoreline, personal watercraft and other watercraft 

operators may disembark to explore or conduct other recreational activities. Shoreline and near-shore 

upland vegetation could be trampled while accessing trails or other portions of the shoreline. 

Management Objectives 

The management objective for shoreline vegetation for personal watercraft uses is listed in table 3. 

The objective is to manage personal watercraft use to protect native vegetation at or near the shoreline 

from personal watercraft user activity and access. Shoreline vegetation management objectives are not 

addressed by either the general management plan or the strategic plan for the recreation area. 

GUIDING REGULATIONS AND POLICIES 

According to Management Policies 2001 (NPS 2000d), natural shoreline processes such as erosion, 

deposition, dune formation, overwash, inlet formation and shoreline migration should continue 

without interference within a park unit. Where the nature or rate of natural shoreline processes has 

been altered, the National Park Service is directed to identify alternatives for mitigating the effects of 

such activities or structures and for restoring natural conditions. The National Park Service must also 

comply with Executive Order 11990, Protection of Wetlands, which requires federal agencies to avoid 

the short-term and long-term adverse impacts associated with the destruction or modification of 

wetlands whenever possible. 

The state of Arizona limits personal watercraft operations within 60 feet of another vessel unless both 

vessels are flat-wake. The state of Utah prohibits wake-producing speeds within 150 feet of another 

vessel; recreating individuals such as a swimmer, waterskier, or shore fisherman; or facilities such as a 

launching ramp, dock, or swimming area. Maintaining flat-wake speeds helps to reduce surface water 

displacement and compounded waves that may erode shorelines and shoreline substrate where 

vegetation may be present. 
ENVIRONMENTAL CONSEQUENCES

240 GLEN CANYON NATIONAL RECREATIONAL AREA

METHODOLOGIES AND ASSUMPTIONS 

The analysis addressed several types of shoreline vegetation communities, which included riparian 

zones, wetlands, and submerged aquatic communities. All of these community types are associated 

with either the immediate shoreline or shallow standing water areas. Primary steps in assessing 

impacts on shoreline and submerged aquatic vegetation include: 

Determine the presence, distribution, existing characteristics, and quality of submerged aquatic 

vegetation, riparian areas, wetlands, and shoreline vegetation in the recreation area in general 

and in areas routinely used by personal watercraft users in particular. 

Evaluate potential changes in submerged aquatic and shoreline vegetation conditions by 

comparing potential personal watercraft user effects on vegetation location, type, and 

susceptibility to disturbances with each alternative. 

Differentiate intensity of personal watercraft use as compared with other watercraft use and 

effect on the shoreline environment. 

Account for the effects of existing reservoir management and operations in regulating shoreline 

and submerged aquatic vegetation. 

Impact Threshold Definitions 

The following impact thresholds were established to describe the relative changes in shoreline and 

submerged vegetation under the alternatives being considered: 

Negligible — Impacts would have no measurable or perceptible changes in plant community 

size, integrity, or continuity. 

Minor — Impacts would be measurable or perceptible but would be localized within a relatively 

small area. The overall viability of the plant community would not be affected and, if left alone, 

would recover. 

Moderate — Impacts would cause a change in the plant community (e.g., abundance, 

distribution, quantity, or quality); however, the impact would remain localized. 

Major — Impacts on the plant community would be substantial, highly noticeable, and 

permanent. 

Impairment — Personal watercraft use would contribute substantially to the deterioration of the 

shoreline or shallow water environment to the extent that the recreation area’s shoreline or 

submerged vegetation would no longer function as a natural system. These resources would be 

affected over the long term to the point that the recreation area’s purpose could not be fulfilled 

and the resource could not be experienced and enjoyed by future generations. 

Assumptions used for the impact analysis include: 

Shoreline vegetation occurs within 50 feet of the existing water-shoreline interface. This 

location changes with fluctuations in water surface elevations. 
Shoreline Vegetation 

FINAL ENVIRONMENTAL IMPACT STATEMENT 241

Personal watercraft and other watercraft users generally stay within direct or reasonable view of 

their motorcraft. 

Personal watercraft users would travel no more than 500 feet inland from the high-water surface 

elevation (3,700 feet). 

Future impacts related to personal watercraft operator use would be similar to those currently 

occurring. Personal watercraft use over the analysis period, taking into account natural changes 

in visitor growth rate, is not expected to be substantially different from levels that existed when 

personal watercraft were used in accordance with the Superintendent’s Compendium (NPS 

2002c).Natural processes related to fluctuation of the reservoir level influence the presence, 

absence, and distribution of shoreline riparian, wetland, and submerged aquatic vegetation. 

For analysis of alternatives A and B, the number of personal watercraft and other motorized 

watercraft would be proportionately the same as that which is currently occurring. 

Geographic Area Evaluated for Impacts 

The area analyzed for possible impacts on shoreline vegetation consists of Lake Powell and its 

associated tributaries including, but not limited to, the San Juan, Colorado, Dirty Devil, and Escalante 

Rivers within the boundaries of Glen Canyon National Recreation Area. The area of analysis includes 

a terrestrial zone extending from the water-land interface inland to either 500 horizontal feet beyond 

the 3,700-foot water surface elevation or the canyon wall apex. For submerged aquatic vegetation, the 

analysis area extended into the water to the edge of the vegetated zone.

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Riparian Vegetation. Personal watercraft use would occur as managed under the Superintendent’s 

Compendium (NPS 2002c). Most personal watercraft day-use activity would be concentrated in deeper 

water in close proximity to the four marinas Wahweap, Bullfrog, Halls, and Hite (James et al. 2001a; 

Utah Division of Wildlife Resources, Gustaveson, pers. com., April 2002b). Less than 5% of personal 

watercraft users would access river drainages and side canyons located on the San Juan River and 

along upper elevations of the Colorado River (James et al. 2001a). Houseboats or other motorboats 

accessing these more remote sites tend to stay on the lake for three to four days or longer and use the 

personal watercraft they bring along for short periods of time (Utah Division of Wildlife Resources, 

Gustaveson, pers. com., April 2002b). 

Topography prevents watercraft from landing along many portions of the lake where rock and cliffs 

rise vertically from the water surface. These same conditions prevent development of shoreline or 

submerged vegetation. None of the deep-water areas of the lake, many shoreline areas with accessible 

banks, or areas located near boat ramps at the marinas have existing shoreline or submerged vegetation 

that could be affected by personal and other watercraft operations. Therefore, there would either be no 

effect on vegetation or operating and landing personal watercraft in areas occupied by some vegetation 

would produce direct short-term adverse and negligible impacts from the shoreline activities of 

personal watercraft operators. These effects would occur to both native and non-native plant species. 

In many locations, non-native saltcedar would be the primary species affected. 
ENVIRONMENTAL CONSEQUENCES

242 GLEN CANYON NATIONAL RECREATIONAL AREA

To access riparian shorelines personal watercraft operators may occasionally use shallow waters to 

land on sand beaches and rock shores where nonmotorized watercraft, canoes and river rafts also land. 

During landing, some riparian and sand beach vegetation may be temporarily exposed to trampling 

and soil compaction. Based on the low vegetation density and sparse ground cover, these effects 

would be localized and restricted to a limited number of individual plants. 

Under alternative A, personal watercraft would be prohibited from upstream travel into more remote 

coves and canyons of the Escalante, San Juan, Colorado and Dirty Devil Rivers but downstream use 

and access by other watercraft would be allowed. Dense saltcedar stands dominate most riparian areas 

along many of these canyons, which personal watercraft and other watercraft operators avoid to 

prevent damaging their watercraft (Waring 1992). Saltcedar is also resilient to many types of 

disturbance and would not be injured from light trampling. Therefore, there would be a short-term, 

direct, negligible, adverse impact on riparian vegetation dominated by saltcedar stands from trampling 

by personal and other watercraft operators. 

Wetlands. Wetlands are intermittently distributed along protected coves and canyons adjacent to river 

tributaries and inlets. Not only do fewer watercraft access these areas; but natural barriers such as sand 

berms and dense saltcedar stands along the tributaries further limit watercraft access. There are no 

substantial wetland areas located at or near any of the launch areas or any of the popular personal 

watercraft use areas. Therefore, negligible adverse impacts on wetlands would be expected. Its 

location in isolated areas would contribute to infrequent use and the probability for negligible adverse 

impacts. Personal watercraft use would not increase use of wetlands or provide improved access to 

these areas. Therefore, it would not create any direct perceptible loss or changes of wetland 

communities. Effect on wetlands would be short-term, direct, negligible, and adverse. 

Submerged Aquatic Vegetation. The rocky shoreline, cliffs, and canyon walls along the shoreline 

combined with the fluctuating water surface preclude development and restrict growth of submerged 

aquatic vegetation. Scattered populations of pondweed and the exotic, spiny naiad would be more 

affected by lake fluctuation levels than by personal watercraft use. Therefore, personal watercraft use 

would cause short-term, direct, negligible, adverse effects where such use occurred in one of the areas 

occupied by this community. 

Cumulative Effects. Shoreline vegetation has been historically subjected to many sources of 

disturbance since the recreation area was created. The most important has been repeated inundation 

and desiccation as the reservoir level rises and falls. Other sources that have affected, and would 

continue to affect, shoreline vegetation included personal watercraft operators, other watercraft 

operators and passengers, general recreation area visitors, and livestock in some areas. Activity areas 

with the most noticeable effects on shoreline vegetation include boat launches, marinas, and 

campgrounds (both developed and primitive). 

The incremental effect from personal watercraft users on shoreline vegetation conditions would be 

indistinguishable from other visitor-induced effects. Foot traffic from all visitor activities would occur 

on shorelines and lake beaches in accessible shoreline areas. Some of the more remote watercraft 

landing areas at key destination sites located on the Escalante, Dirty Devil, San Juan and Colorado 

Rivers that provide shoreline access also provide multi-use facilities such as camping and trails. 

Limited grazing, which is permitted in some areas of the Recreation and Resource Utilization Zone, 

affects the density of some riparian and other shoreline vegetation. Because personal watercraft use is 

less frequent in these remote areas there would be short-term, direct, negligible effects on shoreline 

vegetation from this activity. 
Shoreline Vegetation 

FINAL ENVIRONMENTAL IMPACT STATEMENT 243

The proposed Wahweap campground improvements would attract additional campers and personal 

watercraft users. It is unlikely that the small proportion of campers with personal watercraft would 

adversely impact shoreline vegetation. 

Conclusion. Personal watercraft use would have negligible, adverse, direct and indirect impacts, for 

both short and long terms. This would occur because there would be no perceptible changes to 

shoreline, riparian, aquatic, or wetland community size, integrity, or continuity. Alternative A would 

not result in any substantial or noticeable physical change of submerged, riparian, or wetland shoreline 

vegetation. 

Past, current, and future use of personal watercraft and other motorized watercraft also would not 

produce any noticeable effect on shoreline vegetation. Therefore, cumulative effects would also be 

short-term, direct, and negligible. Alternative A would not result in impairment of shoreline vegetation 

at Glen Canyon National Recreation Area. 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

Personal watercraft numbers under alternative B would be similar to alternative A except that 

additional geographic restrictions on personal watercraft use would be implemented. 

About 25 miles of the Colorado River upstream of Sheep Canyon and upper portions of the Escalante 

(41 miles), Dirty Devil (19 miles), and San Juan (38 miles) Rivers would be closed to all personal 

watercraft, possibly benefiting riparian vegetation on a localized and very limited basis. Use levels by 

personal watercraft operators within these areas are very low under current conditions. Although this 

alternative would involve the closure of a long reach of the Colorado River, currently less than 1% of 

this area is used by personal watercraft. Also there are no developed shoreline access points that would 

encourage concentrated and prolonged visitor uses, that might adversely affect shoreline vegetation. 

More personal watercraft use occurs in the Escalante River (10% to 14%) (James et al. 2001a) where 

personal watercraft use would only be allowed to operate at flat-wake speeds along a portion of river. 

Shoreline launching occurs in the central and southern portions of the Dirty Devil and the Escalante 

Rivers along with camping and fishing. The sparse, mixed-shrub dune communities and scattered 

pockets of riparian vegetation along these shorelines are comprised primarily of saltcedar. This nonnative, aggressive shrub species is very tolerant of human disturbance activities and would experience 

little, if any permanent adverse effects from personal watercraft landing and shoreline use activities by 

personal watercraft operators. The results would be negligible, short-term, direct adverse degradation 

of existing stands of vegetation. 

Effects on shoreline riparian, wetland, and submerged aquatic vegetation from personal watercraft use 

in areas remaining open under alternative B would be similar to those discussed under alternative A. 

Effects would be essentially the same for the same reasons that were described before. Shorelines are 

rocky and watercraft access would be difficult in these areas, wetland and submerged aquatic 

communities are essentially absent, shoreline vegetation development would be precluded by reservoir 

fluctuations, and where present, shoreline riparian vegetation would be dominated by the resilient nonresident saltcedar. 
ENVIRONMENTAL CONSEQUENCES

244 GLEN CANYON NATIONAL RECREATIONAL AREA

Cumulative Effects. Cumulative impacts related to shoreline riparian, wetland, and submerged 

aquatic vegetation would be similar to those described under alternative A. Closure of river reaches 

would further reduce the current low level of personal watercraft use. Some negligible benefits to 

developing riparian shoreline vegetation might be realized over time by eliminating even the 

occasional trampling that might otherwise occur. Because other watercraft operators and visitors use 

the same river inlets where personal watercraft would be restricted, it is unlikely the potential 

negligible benefits of personal watercraft restrictions would be noticeable or measurable. Compared to 

the substantial influences that existing reservoir fluctuations and shoreline conditions exert on present 

shoreline vegetation conditions, it is very unlikely that personal and other watercraft users would have 

a noticeable cumulative impact on shoreline vegetation (including submerged aquatic, riparian, and 

wetland vegetation). 

Conclusion. Restricting access to upper portions of the Colorado, Escalante, Dirty Devil, and San 

Juan Rivers would provide negligible beneficial protection of riparian shoreline vegetation. Impacts on 

shoreline vegetation in the vicinity of the four main marinas would be similar to those described for 

alternative A and would result primarily from minor short-term foot traffic associated with users of 

personal watercraft and other watercraft when landing on lake shorelines. Limiting personal watercraft 

operations to flat-wake speeds on a portion of the Escalante River would reduce wave production but 

because of the lack of existing shoreline vegetation no benefits to shoreline vegetation would be 

expected. Past, current, and future personal watercraft use would not produce any noticeable effect on 

submerged aquatic, riparian and wetland vegetation. Therefore, cumulative effects would remain 

similar to alternative A and would be short-term, direct, and negligible. 

Alternative B would not result in impairment of shoreline vegetative resources. 

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

Alternative C would make permanent the ban on personal watercraft use on Lake Powell that was 

implemented in November 2002. Permanent elimination of personal watercraft use would reduce a 

portion of the trampling to shoreline vegetation located in the vicinity of existing marinas and more 

remote landing areas along the lakeshore. These changes would not produce measurable changes in 

plant community size or distribution because present visitor and personal watercraft uses have had 

only a negligible adverse effects. 

There would be no discernable beneficial or adverse impacts on riparian or wetland vegetation a result 

of discontinued personal watercraft use because other watercraft would continue to launch and land 

watercraft at existing marinas and landing facilities. There would be no discernable improvements to 

shoreline riparian, wetland, or submerged aquatic vegetation from discontinued personal watercraft 

use. Impacts on shoreline riparian, wetland, and submerged aquatic vegetation would either have no 

noticeable adverse effects or they might be direct, negligible, and locally beneficial over the short 

term. 

Cumulative Effects. Closure of Lake Powell marinas and landing areas to personal watercraft use 

might reduce the number of people using near-shore uplands and sand beaches for landing. If current 

personal watercraft users switch to another type of motorized watercraft and continue to visit the same 

locations, there would be no net change in effect on shoreline vegetation compared to current 

conditions. Other watercraft users and visitors would continue to use marina facilities and other 

recreation services located near the lake shoreline and remote landing areas. Ongoing visitor use and 
Shoreline Vegetation 

FINAL ENVIRONMENTAL IMPACT STATEMENT 245

minor increased use associated with the Wahweap campground improvements along accessible 

shorelines would continue to have negligible adverse impacts on shoreline vegetation. Any benefits 

derived from discontinuing personal watercraft use would not be noticeable. 

Conclusion. Alternative C would not result in any substantial or noticeable adverse physical change of 

riparian, submerged aquatic, or wetland vegetation. The lakeshore does not support extensive areas of 

submerged aquatic vegetation. Short-term and localized negligible improvements to shoreline 

vegetation would be expected as a result of implementing this alternative. Past, current, and future 

motorcraft use would not produce any noticeable effect on submerged aquatic, riparian, and wetland 

vegetation. Therefore, cumulative effects would be similar to alternative A and would be short-term, 

direct, and negligible. 

Alternative C would not result in impairment of shoreline vegetative resources. 
246 GLEN CANYON NATIONAL RECREATIONAL AREA

VISITOR USE AND EXPERIENCE 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Personal watercraft characteristics such as noise, odors, operator behavior, and use in proximity to 

other lake users may affect the experience of some other recreation area visitors. For other recreation 

area visitors, the use of personal watercraft is a primary trip purpose and an important part of the 

recreational experience. 

GUIDING REGULATIONS AND POLICIES 

Management Policies 2001 (NPS 2000d section 8.2) states that the enjoyment of park resources and 

values by the people of the United States is part of the fundamental purpose of all park units and that 

the National Park Service is committed to providing appropriate, high-quality opportunities for visitors 

to enjoy Glen Canyon National Recreation Area units. Because many forms of recreation can take 

place outside of a national park setting, the National Park Service therefore seeks to: 

Provide opportunities for forms of enjoyment that are uniquely suited and appropriate to the 

superlative natural and cultural resources found in a particular park unit. 

Defer to others to meet the broader spectrum of recreational needs and demands that are not 

dependent on a national park setting. Those others can include local, state, and other federal 

agencies; private industry; and non-governmental organizations. 

Unless mandated by statute, the National Park Service will not allow visitors to conduct activities that: 

Would impair park resources or values; 

Create an unsafe or unhealthful environment for other visitors or employees; 

Are contrary to the purposes for which Glen Canyon National Recreation Area was established; 

or 

Unreasonably interfere with the atmosphere of peace and tranquility, or the natural soundscape 

maintained in wilderness and natural, historic, or commemorative locations within Glen Canyon 

National Recreation Area; NPS interpretive, visitor service, administrative, or other activities; 

NPS concessioner or contractor operations or services; or other existing, appropriate park uses. 

Part of the purpose of Glen Canyon National Recreation Area is to provide for public outdoor 

recreation use and enjoyment of Lake Powell and adjacent lands. Part of its significance lies in its 

diversity of both water-based and land-based recreational opportunities. Lake Powell is the second 

largest man-made lake in North America and both provides a unique opportunity for recreation in a 

natural environment and serves as a transportation corridor to remote backcountry areas of the 

recreation area. 

Goals for visitor experience were provided in the recreation area’s five-year Strategic Plan for 2000 

through 2005 (NPS 2000g). They include: 
Visitor Use and Experience 

FINAL ENVIRONMENTAL IMPACT STATEMENT 247

Mission Goal IIa — Visitors safely enjoy and are satisfied with the availability, accessibility, 

diversity, and quality of recreation area facilities, services, and appropriate recreational 

opportunities at Glen Canyon National Recreation Area. 

Long-term Goal IIa1 — 95% of Glen Canyon National Recreation Area visitors are satisfied 

with appropriate recreation area facilities, services, and recreational opportunities. 

METHODOLOGIES AND ASSUMPTIONS 

The purposes of this impact analysis were to determine if the use of personal watercraft under each 

management alternative at Glen Canyon would be compatible with: 

Desired visitor experience goals; and 

The purpose of the recreation area as identified in the enabling legislation and in other laws and 

policies affecting visitor use. 

Staff observations and a 2000 Minnesota visitor survey report (James et al. 2001a) were evaluated to 

determine visitor attitudes and satisfaction in areas where personal watercraft are encountered. The 

potential for changes in visitor experience as a result of each management alternative was evaluated by 

identifying projected increases or decreases in both personal watercraft and other visitor uses, and 

determining whether these projected changes would affect desired visitor experiences and produce 

additional user conflicts. Alternatives were assessed based on their compatibility with the purpose 

established in the recreation area’s enabling legislation. Impacts were evaluated qualitatively, based on 

best professional judgment. 

For this analysis, it was assumed for all alternatives that there would be a change in total boat days and 

watercraft operating hours of between –2% and +2% annually over the next 10 years. It was also 

assumed that the removal of personal watercraft in alternative C would result in an initial decrease in 

annual boat days in the short-term. However, by the end of the 10-year analysis period, the total 

number of watercraft operating hours and the total number of motorized watercraft using Lake Powell 

under alternative C would be within the range predicted for alternatives A and B. This would be due to 

either natural growth in visitation, to visitors finding other watercraft to fulfill functions previously 

served by personal watercraft, or to increases in visitation by individuals who previously avoided the 

recreation area due to personal watercraft and now choose to visit in their absence. This was the same 

assumption that was used for the other impact topics. 

Impact Threshold Definitions 

The following threshold definitions were applied to determine personal watercraft effects on visitor 

use and experience. 

Negligible — Visitors would not likely be aware of the effects associated with changes proposed 

for visitor use and enjoyment of recreation area resources. 

Minor — Visitors would likely be aware of the effects associated with changes proposed for 

visitor use and enjoyment of recreation area resources. However, the changes in visitor use and 

experience would be slight and likely short-term. Other areas in the recreation area would 
ENVIRONMENTAL CONSEQUENCES

248 GLEN CANYON NATIONAL RECREATIONAL AREA

remain available for similar visitor experience and use without effects on recreation area 

resources and values. 

Moderate — Visitors would be aware of the effects associated with changes in visitor use and 

enjoyment of recreation area resources. Changes in visitor use and experience would be readily 

apparent and likely long-term. Other areas in the recreation area would remain available for 

visitor experience and use without effects on resources and values, but visitor satisfaction may 

be measurably affected. Some visitors who want to continue using personal watercraft would 

have to pursue their choice in other available regional areas. 

Major — Visitors would be highly aware of the effects associated with changes proposed for 

visitor use and enjoyment of recreation area resources. Changes in visitor use and experience 

would be readily apparent and long-term. The change in visitor use and experience would 

preclude some visitors’ enjoyment of recreation area resources and values for future generations. 

Visitors who want to continue using personal watercraft would have to pursue their choice in 

other available regional areas. 

Geographic Area Evaluated for Impacts 

The geographic area that was evaluated for visitor use and experience included: 

The entire surface of Lake Powell. 

The tributary rivers in all areas where there is sufficient flow, even occasionally, to support 

personal watercraft use. 

All other locations within the recreation area where effects of personal watercraft use, such as 

noise or the smell of fumes, could be discerned. This area would not extend more than 2 miles 

inland from the shoreline. 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Alternative A would not have any effects on visitor use and experience relating to personal watercraft 

compared to current conditions. With no change in the amount, character, or distribution of use 

expected over the next 10 years, visitors would notice little change from current conditions and 

impacts of the alternative would be negligible. 

As described previously, several areas of the lake currently have restrictions on the use of personal 

watercraft, such as flat-wake speed requirements or closures to upstream travel in tributary arms. The 

visitor experience in all of these areas would to be similar to the condition defined by the 

Superintendent’s Compendium (NPS 2002c). 

A large portion of personal watercraft use would continue to be associated with other watercraft use. 

Groups that used powerboats and houseboats as their primary vessel would continue to tow or 

transport personal watercraft to destinations throughout the lake to be used in conjunction with their 

visit. With multiple watercraft types in one group, visitors would continue to have flexibility to enjoy 
Visitor Use and Experience 

FINAL ENVIRONMENTAL IMPACT STATEMENT 249

the diverse range of opportunities available on the lake. There would be little detectable change over 

time and impacts would be negligible when compared to current conditions. 

Baseline visitor survey data at Glen Canyon National Recreation Area indicate that most visitors are 

satisfied with their current experience (James et al. 2001a). Under alternative A, high levels of 

satisfaction with the lake experience would occur for the overall boating population and for personal 

watercraft users. 

Both personal watercraft and other watercraft users would find opportunities to meet their trip goals 

and achieve expected outcomes from their visit to the recreation area. This would include passive 

outcomes such as enjoying the scenery of Lake Powell, experiencing nature, experiencing natural 

quiet, and experiencing solitude. It would also include more active and social outcomes such as doing 

something with family and members of a group, and participating in recreational activities. 

There would be a small portion of watercraft users, including those in nonmotorized craft, who could 

not achieve one or more objectives of their visit because of the behavior of personal watercraft users, 

such as speed, unsafe or inconsiderate maneuvers, or drunkenness, or because they believed there were 

too many personal watercraft. There would also be a segment of the general recreating public who 

would choose not to visit the recreation area because of the presence of personal watercraft and the 

expected adverse effect that personal watercraft would have on their experience. For these visitors, 

impacts would be negligible in the long term as there would be little detectable difference from current 

conditions. 

Noise from personal watercraft would be perceived as a problem by some watercraft users, although 

the overall boating population would identify little or no problem associated with personal watercraft 

noise. Most watercraft users would feel that their desire to experience natural quiet was somewhat to 

fully attained. A small portion would report that their desires for experiencing natural quiet were not 

met. Some visitors would perceive the noise of personal watercraft to be distinctively different from 

other watercraft and therefore annoying. 

Visitors in the undeveloped Natural Zone up to 2 miles from the lake would be able to detect personal 

watercraft noise, which would detract from the experience of those for whom solitude and natural 

sounds were important. Noise from other types of motorized watercraft would mask or exceed noise 

levels associated with personal watercraft. This would result in negligible adverse effects from the 

implementation of alternative A. In remote and quiet areas of the recreation area where the effect of a 

small number of personal watercraft would be more pronounced, there could be localized adverse 

effects on the visitor experience related to noise, but the change from current conditions would be 

negligible. 

A very small number of personal watercraft users would be able to access the recreation area from 

upstream on the San Juan River. This would be a negligible beneficial effect of alternative A. 

Cumulative Effects. The location and number of other watercraft and the behavior of other watercraft 

users would continue to affect the experience of visitors. Motorized boats would continue to be present 

on the lake in patterns and numbers similar to the present. Undesirable activities and behavior of some 

other watercraft users, such as speed, drunkenness, or operating too close to others, would continue. 

There would be negligible cumulative effects related to personal watercraft and other watercraft on 

visitor experience since there would be little detectable change from current conditions. Most visitors 

would continue to be satisfied with their visit to Glen Canyon National Recreation Area. 
ENVIRONMENTAL CONSEQUENCES

250 GLEN CANYON NATIONAL RECREATIONAL AREA

Conclusions. Alternative A would have negligible effects on visitor use and experience because the 

number of personal watercraft using Lake Powell and their management would not change. The effect 

on the visitor experience for personal watercraft users would continue to be beneficial, while 

experiences for visitors seeking quiet and solitude would continue to be adversely affected. 

Cumulative effects would be either adverse or beneficial, depending on the visitor’s goals. However, 

in either case impacts would be negligible. 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

Under alternative B, personal watercraft use would occur at the same levels and general distributions 

as under alternative A. Their proportions relative to other watercraft (26% of all watercraft boat days) 

would remain the same, and personal watercraft use by groups in association with powerboats and 

houseboats would continue. Therefore, impacts would be similar to those described for alternative A, 

with the following exceptions. 

As described in the “Alternatives” chapter, alternative B would close several areas within the tributary 

arms of the lake to personal watercraft use. Currently, these areas can be used by personal watercraft 

traveling in a downstream (but not upstream) direction. It also would implement and additional flatwake restriction on a portion of the Escalante River. Despite these actions, both personal watercraft 

and other watercraft users would find opportunities within the recreation area to meet most of their trip 

goals and achieve expected outcomes from their visit. Although these management actions would have 

a long-term, direct, adverse effect on the experience of personal watercraft users, the intensity would 

be only negligible to minor. The modified preferred alternative would prohibit personal watercraft use 

along 19 miles of the Dirty Devil River from U.S. Highway 95 Bridge to the recreation area boundary. 

Personal watercraft use would also be prohibited on 41 miles of the Escalante River upstream of the 

confluence with Coyote Creek. These restrictions would reduce conflict with river rafters, fishermen, 

and backcountry hikers; promote visitor enjoyment; and ensure visitor safety. There would be a 

negligible to minor, long-term, direct, beneficial effect on the experience of other recreation area 

visitors who use these areas, particularly nonmotorized users.

Alternative B would prohibit travel by personal watercraft above Sheep Canyon on the Colorado 

River. This would eliminate the opportunity to recreate in these portions of the recreation area with a 

personal watercraft. It also would reduce the flexibility and range of opportunities on the Colorado 

River for powerboat and houseboat users that have personal watercraft in their party. However, as 

shown in table 21, few motorized watercraft parties travel to this section of the lake. Closure of this 

area to personal watercraft would be a negligible to minor, direct, adverse, long-term effect. Some 

individuals who were denied the opportunity to use personal watercraft in this area might perceive the 

adverse effect as minor to moderate. 

Elimination of personal watercraft use on the Colorado River above Sheep Canyon and on the Dirty 

Devil River would reduce intrusions by personal watercraft on the experience of other visitors. These 

would include visitors on river float trips that originate in Canyonlands National Park and end at Hite 

Marina. Currently, visitors on river trips encounter 10 or fewer personal watercraft per day. There 

would be minor, beneficial, direct, long-term effects on the experiences of these visitors. 

The improved visitor education component of alternative B would provide information that might 

change the behavior of some personal watercraft users who would otherwise, under alternative A, act 
Visitor Use and Experience 

FINAL ENVIRONMENTAL IMPACT STATEMENT 251

in a manner that would detract from the experience of others. This would result in negligible to minor, 

indirect, long-term, beneficial effects. 

Noise from personal watercraft would be eliminated or reduced in areas where personal watercraft use 

was prohibited or where flat-wake speeds were implemented. This would be perceived as a direct, 

long-term, beneficial effect by other visitors. However, because these are relatively small areas with 

low levels of personal watercraft use, the effect would be negligible to minor. 

Cumulative Effects. The location and number of other watercraft and the behavior of other watercraft 

users would continue to affect the experience of visitors. The cumulative effect would be similar to 

that described for alternative A. Most visitors would continue to be satisfied with their visit to Glen 

Canyon National Recreation Area. 

Conclusion. Most effects of alternative B would be similar to those described for alternative A. Most 

effects would be long-term and negligible to minor because of the presence of other motorcraft. An 

additional flat-wake zone and closed areas would produce negligible to minor, long-term, direct 

effects. Perceptions of individual visitors would determine if the effects were adverse or beneficial. 

Improvements in visitor education would result in negligible to minor, indirect, long-term, beneficial 

effects. 

Cumulative effects on visitor experience would be long-term, indirect, and moderate because there 

would be detectable change on certain portions of the lake. Perceptions of individual visitors would 

determine if effects were adverse or beneficial. 

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

With alternative C, personal watercraft use would no longer be allowed in the recreation area. Initially, 

this would affect 26% of all visitor boating days and 18% of all boat operating hours, and as many as 

32% of boating days (22% of the boating hours) during the peak summer months. For visitors who use 

personal watercraft as a primary vessel or who consider personal watercraft to be of central importance 

to their visit, this would produce direct, adverse, major, short- and long-term effects on their 

experience in Glen Canyon National Recreation Area. 

Personal watercraft serve multiple recreational functions, as indicated by survey data showing that 

personal watercraft are associated with 44% of all houseboat groups and 25% of all powerboat groups. 

Popular personal watercraft–related activities include camping, fishing, hiking in side canyons, and 

visiting archeological sites. 

Visitors could have other options to pursue many of the activities now associated with personal 

watercraft. For example, many houseboat parties have personal watercraft to allow greater travel and 

recreation flexibility, such as exploring side canyons. Houseboat users would be able to tow a small 

motorized boat and gain equal access to resources and equal flexibility to pursue multiple recreation 

opportunities. For these visitors, eliminating personal watercraft use would cause a direct, short-term, 

minor to moderate, adverse effect. In the long term, the effect on these visitors would be negligible. 

Seven percent of all watercraft users travel to Glen Canyon National Recreation Area solely to use 

personal watercraft. For an undefined number of other visitors, the use of personal watercraft is of 
ENVIRONMENTAL CONSEQUENCES

252 GLEN CANYON NATIONAL RECREATIONAL AREA

central importance to their visit. For these visitors, the elimination of personal watercraft would result 

in major adverse short- and long-term effects. 

In the short term, eliminating personal watercraft would eliminate conflicts between other watercraft 

users and personal watercraft users. This would improve the experience for visitors who report that the 

number of personal watercraft on the lake is a moderate to very serious problem (13% of respondents) 

or that conflicts with personal watercraft operators are a moderate to very serious problem (11%). This 

would be a beneficial, minor to moderate, direct effect. In the long term, some lake visitors with other 

vessels may prefer to operate those vessels in a manner similar to personal watercraft, such as 

performing stunts or focusing activities in a small area. Visitors who previously chose not to visit Lake 

Powell because of the presence of personal watercraft may choose to visit when personal watercraft 

are absent. Therefore, compared to alternative A, the long-term effect of this alternative on visitor 

experience would be minor to moderate beneficial. 

In the short term, shoreline users and visitors in the Natural Zone would have greater periods of 

natural quiet. Elimination of personal watercraft noise on the experience of these visitors would result 

in a minor to moderate, indirect, beneficial effect. In the long term, the effect would be negligible, 

because the volume of watercraft would return to pre-ban levels, and other types of boats make 

approximately the same amount of noise as personal watercraft. 

Cumulative Effects. The experience of visitors would continue to be affected by the presence, 

density, and behavior of all other watercraft. Noises from other watercraft would continue to be heard 

the Natural Zone. In the short term, there would be a negligible to minor beneficial impact compared 

to alternative A, but it would decrease to negligible levels over the long term as former personal 

watercraft users returned to the lake with other watercraft. Most visitors would continue to be satisfied 

with their visit to Glen Canyon National Recreation Area. 

Conclusion. In the short term, visitors who use personal watercraft as a primary vessel or who 

consider personal watercraft to be of central importance to their visit would experience direct, major, 

adverse short- and long-term effects from alternative C. Other users of personal watercraft, such as 

those who use them in conjunction with houseboats, would experience short-term, minor to moderate, 

adverse effects that would decrease to negligible in the long term. 

Visitors who did not use personal watercraft would generally perceive minor to moderate, short-term 

benefits from reduced conflicts and reduced noise. These benefits would decline to negligible in the 

long term. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 253

VISITOR CONFLICTS AND VISITOR SAFETY 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Issues 

Visitor conflicts and visitor safety were two of the areas specified for analysis in the settlement 

agreement between the National Park Service and the Bluewater Network. Issues at Glen Canyon 

National Recreation Area include: 

Potentially unsafe behavior by personal watercraft users, such as underage operation, unsafe 

speeds, unsafe proximity to other vessels, and lack of personal flotation devices. 

The potential for accidents and injuries to occur from the use of personal watercraft at rates that 

are higher than those from other watercraft. 

Conflicts associated with the use of personal watercraft in areas that are popular for 

nonmotorized recreation, including the tributary rivers. 

Management Objectives 

As shown in table 3, the objectives of managing personal watercraft use in Glen Canyon National 

Recreation Area relating to visitor conflicts and visitor safety include the following. 

Manage personal watercraft use to enhance the quality of the visitor experience. 

Reduce potential conflicts associated with personal watercraft use and other uses of Glen 

Canyon National Recreation Area. 

Reduce the potential for personal watercraft user accidents. 

GUIDING REGULATIONS AND POLICIES 

Some of the guiding regulations and policies discussed for “Visitor Use and Experience,” also are 

applicable to visitor conflict and visitor safety. In addition, Director’s Order 9 (NPS 2000a), in 

conjunction with Reference Manual 9 (NPS 2000f), establishes and defines standards and procedures 

for the National Park Service Law Enforcement Program. Commissioned employees perform resource 

stewardship, education, and visitor use management activities, including law enforcement. They 

provide for safe, tranquil, sustainable use and enjoyment of recreation area resources while protecting 

resources from all forms of degradation. 

Section 8.3.1 of Management Policies 2001 (NPS 2000d) states that “The Service will make 

reasonable efforts to provide for the protection, safety, and security of park visitors, employees, 

concessioners, and public and private property, and to protect the natural and cultural resources 

entrusted to its care.” Further, in section 8.2.5.1, the National Park Service “strives to protect human 
ENVIRONMENTAL CONSEQUENCES

254 GLEN CANYON NATIONAL RECREATIONAL AREA

life and provide for injury-free visits. . . . The Service will seek to provide a safe and healthful 

environmental for visitors and employees.” 

Arizona and Utah personal watercraft regulations are enforced within Glen Canyon National 

Recreation Area. These regulations are summarized in table 4, with the full text provided in 

appendix B. Some of the visitor conflict and visitor safety aspects they regulate include the type of 

personal watercraft activities near the shore, the distance that should be maintained between personal 

watercraft and the shoreline and other boats, the timing of personal watercraft use, and the age and 

educational requirements of personal watercraft operators. 

METHODOLOGY AND ASSUMPTIONS 

The method used to evaluate effects of the alternatives to visitor conflicts and visitor safety is similar 

to that used for the visitor experience evaluation. 

Impact Threshold Definitions 

The definitions for impact intensities applied to visitor conflict and visitor safety follow. 

Negligible — The impacts on visitor conflict and safety would not be measurable or perceptible. 

Minor — The impacts on visitor conflict and visitor safety would be measurable or perceptible, 

but it would be limited to a relatively small number of visitors at localized areas. Impacts on 

visitor safety might be realized through a minor increase in the potential for visitor conflicts in 

current accident areas. 

Moderate — The impact on visitor conflict and visitor safety would be sufficient to cause a 

change in accident rates or to change the potential for visitor conflicts throughout large areas of 

the lake. 

Major — The impact on visitor safety would be substantial. Accident rates in areas usually 

limited to low accident potential would substantially increase. 

In situations where adverse impacts on visitor conflicts and visitor safety became moderate or greater, 

it is assumed that current visitor satisfaction and safety levels would begin to decline and some of the 

recreation area’s long-term visitor goals would not be achieved. 

Geographic Area Evaluated for Impacts 

The geographic area that was evaluated for visitor conflicts and visitor safety included: 

The entire surface of Lake Powell. 

The tributary rivers in all areas where there is sufficient flow, even occasionally, to support 

personal watercraft use. 
Visitor Conflicts and Visitor Safety 

FINAL ENVIRONMENTAL IMPACT STATEMENT 255

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Under alternative A, personal watercraft use would occur approximately at year 2001 levels in the 

areas where it is currently permitted. There would be about 40 accidents involving personal watercraft 

each year, of which about 30 would result in personal injury. Operators of other watercraft would view 

personal watercraft as representing a slight safety hazard. These effects of alternative A would 

represent a negligible impact in both the short and long term. 

Downstream use of personal watercraft in tributaries would be allowed under alternative A. This 

would result in conflicts with users of nonmotorized craft such as rafts and kayaks in these areas, 

which often have a narrow navigable channel. There would be a negligible impact with the 

implementation of alternative A. 

Alternative A would enforce Arizona or Utah watercraft regulations, laws, and rules in each state’s 

portion of the lake. As a result, personal watercraft users in Utah, which includes about 95% of the 

lake, would have to meet more strict safety requirements with regard to registration, insurance, 

education, and equipment. While the differences in state regulations, laws, and rules may generate 

some confusion for personal watercraft users, this regulatory approach would have negligible effects. 

Law enforcement levels currently are inadequate to patrol visitor activities on the land and water 

during the peak season. Alternative A would seek additional funding to increase enforcement 

capability and enhance visitor contact. This would have a long-term, direct and indirect, minor, 

beneficial effect on visitor conflicts and safety. The recreation area staff would improve response time, 

and the increased law enforcement presence would reduce illegal personal watercraft activities that can 

lead to personal injury accidents. This action would provide only a minor benefit because only about 

30 injury accidents involving personal watercraft currently occur each year.

The current system for educating visitors and distributing safety information to recreation area users, 

including personal watercraft operators, would continue. This would result in a negligible effect on 

visitor conflict and visitor safety compared to current conditions. 

Cumulative Effects. Accidents would occur among all watercraft at approximately the levels shown 

in table 26. In addition, safety risks would continue to be associated with other recreation area 

activities such as swimming, diving from cliffs, and hiking in side canyons. Risks of all of these 

activities would be greater if participants have been consuming alcohol. These activities would 

continue to account for most watercraft- and recreation-related accidents in the recreation area. In 

response, recreation area managers would continue to take precautions to prevent accidents and 

injuries and provide with visitors with information about safe boating and recreation behavior. The 

effects would be negligible. 

The lake management plan that would be prepared under alternative A would include improved safety 

and reduced visitor conflicts among its primary goals. 

Conclusion. Alternative A would have negligible impacts on visitor conflicts and visitor safety. 

Improvements in visitor protection staffing would result in long-term minor beneficial effects on 

visitor conflicts and safety. Cumulative effects of watercraft use and other visitor activities on visitor 

conflicts and safety combined with NPS management activities to prevent accidents would be 

negligible.
ENVIRONMENTAL CONSEQUENCES

256 GLEN CANYON NATIONAL RECREATIONAL AREA

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

Alternative B would close the tributary rivers to personal watercraft use. Compared to alternative A, 

this action would have a direct, long-term, minor, beneficial effect on visitor conflicts in the following 

areas: 

Colorado River upstream from Sheep Canyon (about 25 river miles). 

Dirty Devil River upstream of Highway 95 Bridge.

Escalante River upstream from the confluence with Coyote Creek (about 41 river miles). 

San Juan River upstream from the Clay Hills pullout (about 38 river miles). 

Alternative B also would reduce visitor conflicts by requiring new flat-wake zones on the Escalante 

River (about 7 river miles). 

Effects of the new closures and flat-wake zones on visitor safety compared to alternative A would be 

long-term, direct, and beneficial. The intensity would be negligible to minor because these areas are 

lightly used by personal watercraft and few accidents involving personal watercraft currently occur in 

these areas. 

With alternative B, the National Park Service would work cooperatively with Arizona and Utah in an 

attempt to develop unified laws for personal watercraft operations throughout the recreation area. This 

would have an indirect, long-term, negligible effect on visitor conflict and visitor safety compared to 

alternative A. If the unified laws matched or exceeded the strict Utah laws, which currently apply to 

95% of the lake, the effect on safety could be slightly beneficial. The effect on safety could be slightly 

adverse if the unified laws were more lenient than those of Utah. There would be a negligible effect on 

visitor safety because of better understanding of which laws apply, since there are no data to indicate 

that the current condition, while sometimes confusing, adversely affects visitor safety. 

Alternative B would seek additional funding to increase enforcement capability and enhance visitor 

contact which would have a long-term, direct and indirect, minor, beneficial effect on visitor conflicts 

and safety. The recreation area staff would improve response time, and the increased law enforcement 

presence would reduce illegal personal watercraft activities that can lead to personal injury accidents. 

This action would provide only a minor benefit because only about 30 injury accidents involving 

personal watercraft currently occur each year. 

Alternative B would include education enhancements to provide more information to visitors 

regarding personal watercraft use and safety. This action would have an indirect, long-term, minor, 

beneficial effect on visitor conflict and visitor safety by reducing the potential for personal watercraft 

users to engage in inconsiderate or unsafe practices. 

Alternative B would provide materials that highlight areas of the lake where visitors can experience 

natural quiet and solitude without conflicts with noisier visitors. This action may produce indirect, 

long-term benefits by reducing visitor conflicts compared to alternative A. The magnitude would be 

negligible because many visitors already know of areas where they can go to experience natural quiet 
Visitor Conflicts and Visitor Safety 

FINAL ENVIRONMENTAL IMPACT STATEMENT 257

and solitude, and because the identified areas may become more busy and conflict-prone as they 

became the destinations for increased numbers of visitors. 

Cumulative Effects. The enhanced visitor education would reduce visitor conflicts and improve 

visitor safety compared to alternative A. Otherwise, the cumulative effects of alternative B and 

alternative A would be similar. 

The lake management plan that would be prepared under alternative B would include improved safety 

and reduced visitor conflicts among its primary goals. 

Under alternative B, enhanced information would be provided to visitors regarding safe boating, safe 

use of personal watercraft, the prevention of accidents and injuries, and appropriate, courteous 

behavior that should be applied by all boaters in Glen Canyon National Recreation Area. Cumulative 

visitor conflict and visitor safety impacts related to improved education of visitors would be indirect, 

long-term, beneficial, and negligible to minor in intensity. 

Conclusion. Compared to alternative A, alternative B would have direct and indirect, long-term, 

minor, beneficial impacts on both visitor conflicts and visitor safety. Cumulatively, the improved 

education components of this alternative would have indirect, long-term, beneficial, negligible to

minor effects on visitor conflicts and visitor safety.

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

With alternative C, personal watercraft use would no longer be allowed in the recreation area. Initially, 

this could reduce the number of accidents occurring annually by about 14% and the number of injury 

accidents by about 20%. This would produce a direct, beneficial, short-term, moderate effect on visitor 

safety. 

For this analysis, it was assumed for all alternatives that there would be a change in total boat days and 

watercraft operating hours of between –2% and +2% annually over the next 10 years. It was also 

assumed that the removal of personal watercraft in alternative C would result in an initial decrease in 

annual boat days in the short-term. However, by the end of the 10-year analysis period, the total 

number of watercraft operating hours and the total number of motorized watercraft using Lake Powell 

under alternative C would be within the range predicted for alternatives A and B. This would be due to 

either natural growth in visitation, to visitors finding other watercraft to fulfill functions previously 

served by personal watercraft, or to increases in visitation by individuals who previously avoided the 

recreation area due to personal watercraft and now choose to visit in their absence. This was the same 

assumption that was used for the other impact topics. 

The data in table 26 indicate that other vessels have a slightly higher accident rate in Glen Canyon 

National Recreation Area than personal watercraft. Therefore, the number of accidents occurring 

annually would be at least as high as the alternative A levels and could increase slightly per year. 

However, because people in other vessels are less prone to injury than personal watercraft users, the 

change in the long-term injury rate may not be measurable compared to alternative A. 

Alternative C would eliminate personal watercraft use of the tributary rivers. This would have a direct, 

long-term, minor, beneficial effect on visitor conflict in the tributary rivers and a direct, long-term, 

negligible to minor, beneficial effect on visitor safety in these areas. 
ENVIRONMENTAL CONSEQUENCES

258 GLEN CANYON NATIONAL RECREATIONAL AREA

The state boating laws in Arizona and Utah for vessels other than personal watercraft are based on 

Coast Guard requirements and are quite similar. Therefore, alternative C may reduce confusion among 

operators about which regulations, laws, and rules apply in various areas of the lake. This would have 

a negligible effect, since there are no data to indicate that the current condition adversely affects visitor 

safety. 

Law enforcement levels currently are inadequate to patrol visitor activities on the land and water 

during the peak season. Similar to alternative A, the National Park Service would seek additional 

funding to increase enforcement capability and enhance visitor contact which would have a long-term, 

direct and indirect, minor, beneficial effect on visitor conflicts and safety.

The current system for educating visitors and distributing safety information to recreation area users 

would continue. However, with the absence of personal watercraft, more attention could be focused on 

conflict and safety issues relating to boats. The long-term effect would be beneficial, but the intensity 

would be negligible. 

Cumulative Effects. Under alternative C, personal watercraft could not use Lake Powell. Therefore, 

cumulative effects would not differ from those described above for alternative A. 

Conclusion. In the short term, alternative C would have a direct, beneficial, moderate effect on visitor 

safety. However, as visitors returned in other watercraft, which have higher accident rates on Lake 

Powell than personal watercraft, the long-term effect on safety would be adverse and negligible to 

minor. Visitor conflicts would be reduced in the long term and improvements in visitor protection 

staffing would produce both direct and indirect, minor, beneficial effects. Cumulative effects of 

watercraft use and other visitor activities on visitor conflicts and safety combined with NPS 

management activities to prevent accidents would be negligible.
FINAL ENVIRONMENTAL IMPACT STATEMENT 259

CULTURAL RESOURCES 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Issues 

With their shallow draft design, personal watercraft can come close to shore and facilitate the use of 

areas generally inaccessible by other types of watercraft or motor vehicles. Cultural sites in isolated 

areas such as canyons that can be reached using personal watercraft can be vulnerable to trampling, 

looting, and vandalism. 

Personal watercraft can facilitate visitor access to isolated areas containing ethnographic sites or areas 

where traditional cultural practices occur. The noise from personal watercraft and the presence of 

visitors in these areas can interrupt religious activities or disturb sites valued by tribes. 

Management Objectives 

Management objectives for cultural resources were included in table 3. On a recreation area-wide 

basis, management objectives include interpreting historical and archeological resources and the 

culture of traditional societies while centering interpretive themes around outdoor recreation. 

Management objectives associated with personal watercraft involve managing personal watercraft use 

and access to enhance protection of cultural resources. 

GUIDING REGULATIONS AND POLICIES 

Numerous legislative acts, regulations, and NPS policies provide direction for the protection, 

preservation, and management of cultural resources on public lands. These laws and policies establish 

what must be considered both in planning, such as in general management plans and implementation 

plans, and in administrative actions, such as rule-makings. They also define how cultural resources 

must be managed in future undertakings resulting from approved plans and rules, regardless of the 

final alternative chosen. 

Applicable NPS policies relevant to cultural resources are included in Management Policies 2001

(NPS 2000d) and Director’s Order 28: Cultural Resource Management (NPS 1996d). Applicable laws 

and regulations include the: 

Antiquities Act of 1906 (PL. 59-209); 

Organic Act of 1916 (PL 64-235); 

National Historic Preservation Act of 1966 (PL 89-665); 

National Environmental Policy Act of 1969 (PL 91-190); 

Archaeological Resources Protection Act of 1979 (PL 96-95); and 
ENVIRONMENTAL CONSEQUENCES

260 GLEN CANYON NATIONAL RECREATIONAL AREA

Native American Graves Protection and Repatriation Act of 1990 (PL 101-601). 

The Antiquities Act authorized the president to establish historic landmarks and structures as 

monuments owned or controlled by the United States government. It also instituted a fine for 

unauthorized collection of artifacts. 

The Organic Act established the National Park Service to manage parks and monuments. Its purposes 

specifically include conserving historic objects within these lands and providing for their enjoyment. 

The National Historic Preservation Act, as amended, required in section 106 that federal agencies with 

direct or indirect jurisdiction over undertakings take into account the effect of those undertakings on 

properties that are listed on, or eligible for listing on, the National Register of Historic Places. The act 

further requires federal land managers to establish programs in consultation with the state historic 

preservation office to identify, evaluate, and nominate properties to the national register. This act 

applies to all federal undertakings or projects requiring federal funds. The act also provides for 

confidentiality provisions where the release of sensitive site location information could endanger the 

resource. 

The National Environmental Policy Act declared a federal policy to preserve important historic, 

cultural, and natural aspects of our national heritage. It required federal agencies to employ a 

systematic, interdisciplinary approach to ensure the integrated use of the natural and social sciences in 

planning and in decision-making activities that may affect the human environment. 

The Archaeological Resources Protection Act further strengthened the federal government’s efforts to 

protect and preserve archeological resources on public lands. It increased criminal penalties and 

instituting civil penalties for the unauthorized collection of artifacts. Additionally, it established a 

permit system for the excavation and removal of artifacts from public lands, including their final 

disposition. 

The Native American Graves Protection and Repatriation Act set forth procedures for determining the 

final disposition of any human remains, funerary objects, or objects of cultural patrimony that are 

discovered on public lands or during the course of a federal undertaking. 

METHODOLOGY AND ASSUMPTIONS 

General Analysis Method 

Cultural resources typically include buildings, archeological sites, structures, districts, and objects as 

defined in the National Historic Preservation Act. This act and its implementing regulations provide 

guidance for deciding whether cultural resources are of sufficient importance to be determined eligible 

for listing on the National Register of Historic Places. 

The effects of personal watercraft management actions were described in terms of whether they were 

beneficial or adverse, the area they would affect (such as site-specific, local, or regional), their 

intensity, their duration, and whether they were direct or indirect. They also were evaluated to 

determine if they would impair the recreation area’s cultural resources. 

Cumulative impacts on cultural resources were determined by combining the impacts of each 

alternative with other past, present, and reasonably foreseeable future actions. 
Cultural Resources 

FINAL ENVIRONMENTAL IMPACT STATEMENT 261

The most important past action that affected cultural resources in the region was the construction 

of Glen Canyon Dam and filling of Lake Powell. Construction of the dam and appurtenant 

facilities, including the City of Page, disturbed or destroyed some surface artifacts. Filling of the 

lake submerged numerous prehistoric and historic sites in the river bottoms and along the 

canyon walls of the Colorado River and its tributaries. Because of the desert setting, these were 

the areas where most human activity in the region previously had occurred. 

Other important actions that occurred in the past and will continue into the future are the 

vandalism of and unauthorized collection from archeological and historical sites. Cultural 

resources are non-renewable, so over time, small incidents of vandalism or unauthorized 

collecting within and outside of the recreation area cumulatively diminish the regional resource 

base. These losses reduce the number and variety of cultural sites available for visitor 

appreciation and scientific study. 

Future development in the area will occur, such as development of the Antelope Point Marina 

and growth of the City of Page. These actions probably would cause some disturbance of 

cultural resources, particularly archeological sites. If the sites are on federal land, they would 

have to be mitigated in accordance with the National Historic Preservation Act. If they are on 

private land, they could be permanently lost. 

Impacts on Cultural Resources, and Section 106 of the National Historic Preservation Act 

This impact analysis is intended to comply with the requirements of section 106 of the National 

Historic Preservation Act (36 CFR Part 800, Protection of Historic Properties) as well as the National 

Environmental Policy Act. In accordance with the Advisory Council on Historic Preservation’s 

regulations implementing section 106, impacts on cultural resources were identified and evaluated by: 

Determining the area of potential effects; 

Identifying cultural resources present in the area of potential effects that were either listed in or 

eligible to be listed in the National Register of Historic Places; 

Applying the criteria of adverse effect to affected cultural resources either listed in or eligible to 

be listed in the National Register; and 

Considering ways to avoid, minimize or mitigate adverse effects. 

Under the Advisory Council’s regulations, a determination of either adverse effect or no adverse effect 

must be made for affected, National Register eligible cultural resources. 

An adverse effect occurs whenever an impact alters, directly or indirectly, any characteristic of a 

cultural resource that qualifies it for inclusion in the National Register. Examples could include 

diminishing the integrity of the resource’s location, design, setting, materials, workmanship, 

feeling, or association. Adverse effects also include reasonably foreseeable effects that would 

occur later in time, be farther removed in distance, or be cumulative (36 CFR Part 800.5, 

Assessment of Adverse Effects). 
ENVIRONMENTAL CONSEQUENCES

262 GLEN CANYON NATIONAL RECREATIONAL AREA

A determination of no adverse effect means there may be an effect, but the effect would not 

diminish in any way the characteristics of the cultural resource that qualify it for inclusion in the 

National Register. 

The Council on Environmental Quality (1978) regulations and Director’s Order 12 and Handbook: 

Conservation Planning, Environmental Impact Analysis, and Decision Making (NPS 2001b) call for a 

discussion of the appropriateness of mitigation, as well as an analysis of how effective the mitigation 

would be in reducing the intensity of a potential impact (e.g., reducing the intensity of an impact from 

major to moderate or minor). Any resultant reduction in intensity of impact due to mitigation, 

however, is an estimate of the effectiveness of mitigation under the National Environmental Policy Act

only. It does not suggest that the level of effect as defined by section 106 is similarly reduced. 

Although adverse effects under section 106 may be mitigated, the effect remains adverse. 

A section 106 summary is included in the impact analysis sections for archeological resources, historic 

structures and buildings, cultural landscapes, and ethnographic resources. The recreation area’s 

collections would not be affected by any of the proposed actions for managing personal watercraft, 

and are not included in the analysis. 

The section 106 summary is intended to meet the requirements of section 106 of the National Historic 

Preservation Act. It also is intended to provide an assessment of the effect of the undertaking 

(implementation of the alternative) on cultural resources, based upon the criteria found in the Advisory 

Council’s regulations. 

Impact Threshold Definitions 

Archeological Resources. Many important questions about human history can only be answered by 

the physical material of archeological resources. An archeological site can be eligible to be listed in 

the National Register of Historic Places if the site has yielded, or may be likely to yield, information 

important in prehistory or history. An archeological site can be nominated to the National Register in 

one of three historic contexts or levels of significance: local, state, or national (see National Register 

Bulletin #15, How to Apply the National Register Criteria for Evaluation, NPS n.d.). Impact intensity 

thresholds are based on the potential of the site to yield important information, and the probable 

historic context of the affected site. Table 48 lists the definitions of intensity levels for cultural 

resources, including archeological resources. 

Historic Structures/Buildings. To be listed in the National Register of Historic Places, a structure or 

building must meet the following criteria. 

Be associated with an important historic context. That is, it must possess significance such that a 

meaning or value is ascribed to the structure or building. 

Have integrity of those features necessary to convey its significance. Typically, these would include 

location, design, setting, workmanship, materials, feeling, and national association. 

Complete information on criteria for listing is included in National Register Bulletin #15, How to 

Apply the National Register Criteria for Evaluation. Impact thresholds for historic structures and 

buildings are defined in table 48. 
Cultural Resources 

FINAL ENVIRONMENTAL IMPACT STATEMENT 263

TABLE 48: DEFINITIONS OF INTENSITY LEVELS FOR CULTURAL RESOURCES

Archeological Resources 

Negligible Impact is at the lowest levels of detection – barely measurable with no perceptible consequences, either 

adverse or beneficial, to archeological resources. For purposes of section 106, the determination of effect 

would be no adverse effect. 

Minor Adverse impact – disturbance of a site is confined to a small area with little, if any, loss of important 

information potential. For purposes of section 106, the determination of effect would be no adverse effect. 

Beneficial impact – preservation of a site in its natural state. For purposes of section 106, the determination 

of effect would be no adverse effect. 

Moderate Adverse impact – disturbance of the site does not result in a substantial loss of important information. For 

purposes of section 106, the determination of effect would be adverse effect. 

Beneficial impact – stabilization of the site occurs. For purposes of section 106, the determination of effect 

would be no adverse effect. 

Major Adverse impact – disturbance of the site is substantial and results in the loss of most or all of the site and 

its potential to yield important information. For purposes of section 106, the determination of effect would be 

adverse effect. 

Beneficial impact – active intervention occurs to preserve the site. For purposes of section 106, the 

determination of effect would be no adverse effect. 

Impairment A major, adverse impact occurs to an archeological resource whose conservation is necessary to fulfill 

specific purposes identified in the establishing legislation of Glen Canyon National Recreation Area; key to 

the natural or cultural integrity of the recreation area; or identified as a goal in the recreation area’s general 

management plan or other relevant NPS planning documents. 

Historic Resources 

Negligible Impact is at the lowest levels of detection – barely measurable with no perceptible consequences, either 

adverse or beneficial, to historic resources. For purposes of section 106, the determination of effect would 

be no adverse effect. 

Minor Adverse impact – impact does not affect the character-defining features of a National Register of Historic 

Places-eligible or -listed structure or building. For purposes of section 106, the determination of effect would 

be no adverse effect. 

Beneficial impact – stabilization/preservation of character-defining features occurs in accordance with the 

Secretary of the Interior’s Standards for the Treatment of Historic Properties (NPS 1995b) to maintain 

existing integrity of a structure or building. For purposes of section 106, the determination of effect would be 

no adverse effect. 

Moderate Adverse impact – impact alters a character-defining feature of the structure or building but does not 

diminish the integrity of the resource to the extent that its National Register eligibility is jeopardized. For 

purposes of section 106, the determination of effect would be no adverse effect.

Beneficial impact – rehabilitation of a structure or building occurs in accordance with the Secretary of the 

Interior’s Standards for the Treatment of Historic Properties (NPS 1995b) to make possible a compatible 

use of the property while preserving its character-defining features. For purposes of section 106, the 

determination of effect would be no adverse effect. 

Major Adverse impact – impact alters a character-defining feature of the structure or building, diminishing the 

integrity of the resource to the extent that it is no longer eligible to be listed in the National Register. For 

purposes of section 106, the determination of effect would be adverse effect. 

Beneficial impact – restoration occurs in accordance with the Secretary of the Interior’s Standards for the 

Treatment of Historic Properties (NPS 1995b) to accurately depict the form, features, and character of a 

structure or building as it appeared during its period of significance. The section 106 determination of effect 

would be no adverse effect. 

Impairment A major, adverse impact occurs to a historic resource whose conservation is necessary to fulfill specific 

purposes identified in the establishing legislation of Glen Canyon National Recreation Area; key to the 

natural or cultural integrity of the recreation area; or identified as a goal in the recreation area’s general 

management plan or other relevant NPS planning documents. 
ENVIRONMENTAL CONSEQUENCES

264 GLEN CANYON NATIONAL RECREATIONAL AREA

Cultural Landscapes 

Negligible Impact is at the lowest levels of detection - barely measurable with no perceptible consequences, either 

adverse or beneficial, to cultural landscapes. For purposes of section 106, the determination of effect would 

be no adverse effect. 

Minor Adverse impact – impact does not affect the character defining features of a National Register of Historic 

Places-eligible or -listed cultural landscape. For purposes of section 106, the determination of effect would 

be no adverse effect. 

Beneficial impact – preservation of character-defining features occurs in accordance with the Secretary of 

the Interior’s standards to maintain existing integrity of the cultural landscape. For purposes of section 106, 

the determination of effect would be no adverse effect. 

Moderate Adverse impact – impact alters a character-defining feature of the cultural landscape but would not diminish 

the integrity of the landscape to the extent that its National Register eligibility is jeopardized. For purposes 

of section 106, the determination of effect would be no adverse effect. 

Beneficial impact – rehabilitation of a landscape or its features occurs in accordance with the Secretary of 

the Interior’s standards, to make possible a compatible use of the landscape while preserving its characterdefining features. For purposes of section 106, the determination of effect would be no adverse effect. 

Major Adverse impact – impact alters a character-defining feature of the cultural landscape, diminishing the 

integrity of the resource to the extent that it is no longer eligible to be listed in the National Register. For 

purposes of section 106, the determination of effect would be adverse effect. 

Beneficial impact – restoration occurs in accordance with the Secretary of the Interior’s standards, to 

accurately depict the features and character of a landscape as it appeared during its period of significance. 

For purposes of section 106, the determination of effect would be no adverse effect. 

Impairment A major, adverse impact occurs to a cultural landscape whose conservation is necessary to fulfill specific 

purposes identified in the establishing legislation of Glen Canyon National Recreation Area; key to the 

natural or cultural integrity of the recreation area; or identified as a goal in the recreation area’s general 

management plan or other relevant NPS planning documents. 

Ethnographic Resources 

Negligible Impact is barely perceptible and would alter neither resource conditions, such as traditional access or site 

preservation, nor the relationship between the resource and the affiliated group’s body of beliefs and 

practices. There would be no change to a group’s body of beliefs and practices. For purposes of 

section 106, the determination of effect on ethnographic resources would be no adverse effect. 

Minor Adverse impact – impact is slight but noticeable. It does not appreciably alter resource conditions, such as 

traditional access or site preservation, or the relationship between the resource and the affiliated group’s 

body of beliefs and practices. For purposes of section 106, the determination of effect on ethnographic 

resources would be no adverse effect. 

Beneficial impact – impact enhances traditional access and/or accommodates a group’s traditional 

practices or beliefs. For purposes of section 106, the determination of effect on ethnographic resources 

would be no adverse effect. 

Moderate Adverse impact – impact is apparent and alters resource conditions. Interference occurs with traditional 

access, site preservation, or the relationship between the resource and the affiliated group’s beliefs and 

practices, even though the group’s beliefs and practices would survive. For purposes of section 106, the 

determination of effect on ethnographic resources would be adverse effect. 

Beneficial impact – a group’s beliefs and practices are facilitated. For purposes of section 106, the 

determination of effect on ethnographic resources would be no adverse effect. 

Major Adverse impact – impact alters resource conditions. Traditional access, site preservation, or the 

relationship between the resource and the affiliated group’s body of beliefs and practices are blocked or 

greatly affected, to the extent that the survival of a group’s beliefs and/or practices would be jeopardized. 

For purposes of section 106, the determination of effect on ethnographic resources would be adverse 

effect. 

Beneficial impact – a group’s beliefs or practices are encouraged. For purposes of section 106, the 

determination of effect on ethnographic resources would be no adverse effect. 

Impairment A major, adverse impact occurs to an ethnographic resource or value whose conservation is necessary to 

fulfill specific purposes identified in the establishing legislation of Glen Canyon National Recreation Area; 

key to the natural or cultural integrity of the recreation area; or identified as a goal in the recreation area’s 

general management plan or other relevant NPS planning documents. 
Cultural Resources 

FINAL ENVIRONMENTAL IMPACT STATEMENT 265

Cultural Landscapes. Cultural landscapes are the result of the interaction between people and the 

land, and reflect the influence of human beliefs and actions over time on the natural landscape. 

Cultural landscapes are shaped through time by historical land-use and management practices, politics, 

property laws, levels of technology, and economic conditions. Cultural landscapes are a living record 

of an area’s past, providing a visual chronicle of its history. 

The dynamic nature of human life contributes to the continual reshaping of cultural landscapes. This 

makes them a good source of information about specific times and places, but renders their long-term 

preservation a challenge. 

For a cultural landscape to be listed in the National Register, it must possess significance (the meaning 

or value ascribed to the landscape) and have integrity of those features necessary to convey its 

significance. The character-defining features of a cultural landscape include spatial organization and 

land patterns; topography; vegetation; circulation patterns; water features; and structures or buildings, 

site furnishings, and objects. These character-defining features are detailed in The Secretary of the 

Interior’s Standards for the Treatment of Historic Properties With Guidelines for the Treatment of 

Cultural Landscapes (NPS 1995b). Impact intensity thresholds for cultural landscapes are defined in 

table 48. 

Ethnographic Resources. Ethnographic resources relate to cultural content and context of cultural 

resources. They involve the identity and heritage of contemporary peoples or groups. As defined by 

the National Park Service, an ethnographic resource is a site, structure, object, landscape, or natural 

resource feature that has been assigned a traditional legendary, religious, subsistence, or other 

significance in the cultural system of a group traditionally associated with it. Some specific places of 

traditional cultural use may be eligible for inclusion in the National Register of Historic Places if they 

meet national register criteria for traditional cultural properties. Impact intensity thresholds for 

ethnographic resource are defined in table 48. 

Durations of Impacts on Cultural Resources. Impacts on virtually all cultural features other than 

vegetation components would be long-term effects because most cultural resources are non-renewable. 

These would include any effects on archeological, historic, or ethnographic resources, and on nonvegetation elements of a cultural landscape.

Short-term impacts would involve such things as treatment effects on the natural elements of a cultural 

landscape that would extend for no more than about five years. Examples would include the 

restoration of historic plantings or the regrowth of vegetation. 

Geographic Area Evaluated for Impacts 

The geographical area that was evaluated for impacts on cultural resources extends 0.5 miles 

(horizontally) from the full-pool line at 3,700 feet above sea level. 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Archeological Resources. Under alternative A, most personal watercraft use would occur in open lake 

areas. Although personal watercraft would not be allowed to travel upstream into the canyons of the 
ENVIRONMENTAL CONSEQUENCES

266 GLEN CANYON NATIONAL RECREATIONAL AREA

San Juan, Escalante, Dirty Devil, and Colorado Rivers, downstream travel in the rivers would be 

allowed. 

The most noticeable effects on archeological sites that are potentially eligible for listing in the 

National Register of Historic Places would result from personal watercraft users who land in areas 

such as narrow, steep-walled canyons that are inaccessible to most other visitors. Damage to these 

sites, including submerged sites, from personal watercraft users could result from inadvertent actions, 

such as the landing of craft or trampling of sites, or from deliberate actions such as illegally collecting 

artifacts or vandalizing resources. Canyon areas where archeological sites reflect the most damage 

include Moqui, Slick Rock, Lake, and Iceberg. 

Access to the canyons varies with water levels. In addition, the distance traveled from shoreline by 

personal watercraft users in some areas can be limited by a lack of suitable footwear and clothing. 

(This constraint is less common with users of other watercraft, who can more readily carry extra 

clothing and shoes.) This constraint helps reduce disturbances by personal watercraft users at sites 

away from the shoreline. 

In areas other than narrow canyons, archeological sites are equally accessible to users of all vessels. 

They often also can be accessed by hikers and people using automobiles. In these areas, the frequency 

of trampling, vandalism, and illegal collecting by personal watercraft users under alternative A would 

occur at the same rate as that from other recreation area users. However, the damage caused by 

personal watercraft users may be less than that of other visitors because of the inconvenience of 

carrying tools such as shovels on a personal watercraft. While the effect from personal watercraft users 

would be additive, it would be indistinguishable from damage to archeological sites caused by visitors 

using other means of access. 

The presence of other visitors can sometimes be a deterrent to vandalism. Therefore, isolated sites in 

the upper canyons that are accessible primarily by personal watercraft could be more vulnerable to 

vandalism and looting than sites in more visible areas. 

Most personal watercraft users, like other recreation area visitors, are conscientious about protecting 

the recreation area’s archeological resources and do not engage in the deliberate disturbance of sites. 

In addition, alternative A’s prohibition of upstream travel by personal watercraft limits the number of 

personal watercraft users who can easily access the archeological resources in the canyon areas. 

Therefore, while direct effects on archeological resources from personal watercraft use under 

alternative A would be adverse and long-term, the intensity would be negligible to minor, depending 

on-site vulnerability and accessibility. 

Wave action over time tends to erode soils around archeological sites and wear away petroglyphs and 

pictographs. Under alternative A, wakes created by watercraft would have a negligible to minor 

adverse effect on vulnerable archeological sites. The impact would be limited to the small number of 

sites directly on the lake shore, and to submerged sites that are exposed as lake levels fall. While 

personal watercraft contribute to this indirect adverse effect, their contribution would be negligible 

because of their relatively small size and water displacement. 

Historic Resources. Most of the recreation area’s historic resources, including the Hole-in-the-Rock 

area and the Hole-in-the-Rock Trail, can be accessed by automobile (sometimes limited to 4-wheeldrive vehicles), by boat, or on foot. Direct and indirect adverse impacts on historic sites from 

unauthorized collecting or vandalism would be likely to continue at negligible to moderate levels, 

based on records of past resource disturbance. In these areas under alternative A, adverse effects from 
Cultural Resources 

FINAL ENVIRONMENTAL IMPACT STATEMENT 267

personal watercraft users would occur at the same rate as those from other recreation area users. While 

the effect from personal watercraft users would be additive, it would be indistinguishable from 

disturbance to historic resources caused by visitors using other means of access. 

Cultural Landscapes. No cultural landscapes have been formally defined within Glen Canyon 

National Recreation Area. However, areas like the Hole-in-the-Rock comprise an important historic 

scene enjoyed by visitors. Impacts on this and other historic landscapes would be similar to those 

described above for historic resources. 

Areas valued by tribes for traditional activities comprise an ethnographic landscape. Impacts on these 

areas would be similar to those described for ethnographic resources, below. 

Ethnographic Resources. The recreation area’s ethnographic sites have not been formally evaluated as 

traditional cultural properties. However, traditional uses are known to occur along river corridors, 

cliffs, beaches, and shorelines (NPS 1988a). To protect their integrity and values, the locations of sites 

that are sacred and highly valued by tribes are not disclosed. 

The shallow draft of personal watercraft allows them to maneuver close to shore, and to reach areas of 

Glen Canyon National Recreation Area that are difficult to access by other types of vessels. The 

presence of personal watercraft users in these areas could be intrusive when tribes are conducting sitespecific traditional activities. Even though these intrusions often would be unknowing and short-term, 

they still could be disruptive. The presence of personal watercraft, their users, and trash also could 

constitute a visual intrusion on traditional activities. 

The variable noise from personal watercraft associated with their rapid direction changes and frequent 

acceleration and deceleration may be especially disruptive to tribal religious activities. The disturbance 

caused by this noise could be sufficient to discourage tribal use of some areas for activities that require 

quiet. This could occur either in the short term until the personal watercraft users leave the area, or on 

a long-term basis, particularly at sites that are close to popular personal watercraft use areas. 

Some ceremonial activities or collecting of special resources require that practitioners have solitude 

and privacy. Activities also may be time sensitive and must be completed during a particular time 

period. These activities could be adversely affected by the presence of any nearby recreational users. 

However, practitioners probably would find visitors on personal watercraft “playing” in a nearby cove 

more disruptive than the same number of people on a houseboat anchored in the cove over the same 

period. 

Alternative A would prohibit upstream use of personal watercraft in the San Juan, Colorado, 

Escalante, and Dirty Devil Rivers. This would help limit the number of visitors who might 

inadvertently intrude on traditional practitioners in these areas. However, direct and indirect adverse 

effects on ethnographic resources from downstream personal watercraft use would occur. 

Impacts of personal watercraft use on ethnographic resources would be adverse and both direct and 

indirect, and would vary from negligible to moderate. Duration would be both short-term and longterm. The intensity would depend on the location, importance of the area to tribes, time of year, type 

of ethnographic activity, number of personal watercraft, and how the personal watercraft was being 

used (for example, travel from point to point versus “playing” in a cove). 

Cumulative Effects. Throughout the recreation area, direct, adverse effects on cultural resources from 

trampling, unauthorized collecting, and vandalism by unscrupulous visitors would be likely to 
ENVIRONMENTAL CONSEQUENCES

268 GLEN CANYON NATIONAL RECREATIONAL AREA

continue. The impact intensity would vary from negligible to moderate, depending on site 

vulnerability and accessibility, with an overall impact intensity of minor. Negligible to minor, adverse, 

indirect effects on cultural sites that are near the shore or are sometimes submerged would continue 

from the wave action caused both by boats and wind. 

Under alternative A, most visitors would value the recreation area’s cultural resources and would 

continue to be conscientious about protecting them. They would not engage in the deliberate 

disturbance of sites and sometimes would serve as ad hoc sentries, reporting suspicious activities to 

authorities and discouraging illegal collecting and vandalism simply by their presence. 

The recreation area would continue measures to protect cultural resources. These would include 

monitoring site conditions and educating visitors about the importance of and the need to protect the 

recreation area’s cultural resources. Eroding or damaged sites would be recorded and stabilized. Some 

sites could be hardened, fenced, or placed off-limits to visitation. Interpretive programs, signing, and 

ranger patrols would help prevent site disturbance. In special cases, data recovery might be initiated 

where sites are in imminent danger. 

The Navajo Nation also has an interest in protecting the area’s cultural resources. The tribe would 

continue its current work with the National Park Service and other federal agencies to identify 

threatened sites on the reservation, and to develop mitigating measures. 

Cultural resources outside of the recreation area would continue to be disturbed or destroyed by 

vandals or those who would profit from artifact sales. Because cultural resources are non-renewable, 

incidents of vandalism or unauthorized collecting within and outside the recreation area would 

cumulatively diminish the region’s cultural resource. These losses would reduce the number and 

variety of cultural sites available for public appreciation and scientific study. 

Cultural resources also would continue to be lost to development of the area. The loss of sites near the 

Colorado River and its tributaries would be especially detrimental to the cultural record because so 

many of these types of sites were lost during the filling of Lake Powell. In areas of new development, 

major resources that are listed in the National Register of Historic Places or potentially would be 

eligible for listing would be mitigated in accordance with the National Historic Preservation Act. Less 

significant sites would be lost. While the loss of individual sites may not appear important, the 

collective loss of many sites would diminish the ability to appreciate and draw accurate conclusions 

about the record of people, both prehistoric and historic, in the region. 

Cumulatively, the recreation area’s cultural resources would continue to derive a substantial measure 

of protection from their location within Glen Canyon National Recreation Area. Outside of the 

recreation area, most effects on cultural resources would continue to be adverse. Impact intensities 

would vary by resource type and accessibility, and would range in intensity at individual sites from 

negligible to major. Regionally, the cumulative effect on cultural resources would be adverse, 

moderate, and long-term. 

Conclusion. Effects on cultural resources from the implementation of alternative A would be adverse 

and mostly long-term. While most personal watercraft users would be conscientious about protecting 

the recreation area’s cultural resources, a few would engage in destructive actions such as illegal 

collecting of artifacts or vandalism. The effects of this behavior would be most noticeable in the 

narrow, steep-walled canyon areas that are inaccessible by most other types of motorcraft, but that can 

be traveled in a downstream direction by personal watercraft under alternative A. In these areas, 

impact intensities mostly would be negligible to minor. Impact intensities from personal watercraft 
Cultural Resources 

FINAL ENVIRONMENTAL IMPACT STATEMENT 269

users would be of similar magnitude in other areas, but would be indistinguishable from the adverse 

effects caused by the relatively few destructive visitors who used other transport methods to access the 

sites. 

Cumulatively, direct, adverse, long-term effects on the cultural resources in the recreation area would 

vary in intensity from negligible to moderate, depending on individual site vulnerability and 

accessibility. Negligible to minor, adverse, indirect effects on near-shore cultural sites would continue 

from the wave action caused both by boats and wind. The contribution of personal watercraft under 

alternative A to wave-caused effects would be negligible. Overall, the direct effect within the 

recreation area would be adverse and minor. Regionally, the effect from activities that occur outside of 

the recreation area would continue to be adverse and moderate. The contribution of alternative A to the 

regional effects would be negligible. 

Alternative A would not result in impairment of the cultural resources of Glen Canyon National 

Recreation Area. 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

As shown in table 4 and figures 6 through 8, alternative B would close the upper canyons of the Dirty 

Devil, Escalante, San Juan, and Colorado Rivers to all use by personal watercraft. This action would 

make archeological sites, ethnographic sites, and ethnographic landscapes along these approximately 

123 miles of river less accessible and less vulnerable to vandalism and illegal collection of artifacts. 

Compared to alternative A, this would produce direct, long-term, negligible to minor, beneficial 

effects on the archeological and ethnographic resources of these areas. The effects of these closures on 

historic resources would be negligible because few resources of these types occur in the steep canyon 

areas. 

Rafters and other users of nonmotorized vessels could still access the canyon areas. However, the 

tendency of these visitors to travel in fairly large groups and to observe each other’s activities would 

limit the potential for individuals to collect artifacts or vandalize sites. The absence of engines on 

these watercraft would reduce noise intrusions on traditional activities in the canyons compared to 

alternative A, which would be a direct, beneficial, negligible to moderate effect. 

Alternative B would include a new flat-wake zone along a total of about 7 miles of the Escalante River 

(see table 2). The resulting reductions in wave action from personal watercraft might slow the erosion 

process and subsequent loss of vulnerable archeological resources along the shoreline and at 

submerged sites. This effect would be negligible compared to alternative A because personal 

watercraft wakes currently are causing only negligible adverse effects on these resources, and because 

these areas would continue to be subject to the sometimes-violent action of wind-caused waves. 

Alternative B would include an improved education program for personal watercraft users. This 

program could include information on such subjects as the need to protect cultural resources, ways to 

avoid damaging cultural resources when beaching a craft, and procedures for contacting recreation 

area staff when a visitor observed a site being vandalized. The beneficial effects of improved 

education could be negligible to moderate for individual sites, but on a recreation area-wide basis 

would be negligible to minor. 
ENVIRONMENTAL CONSEQUENCES

270 GLEN CANYON NATIONAL RECREATIONAL AREA

Other effects of alternative B on cultural resources would be similar to those described under

alternative A. However, physical intrusions and noise reductions associated with this alternative would 

produce modest reductions in disturbances to traditional sites and activities. 

Cumulative Effects. Cumulative effects of alternative B would be similar to those described for 

alternative A. 

Conclusion. Compared to alternative A, alternative B would have direct, long-term, negligible to 

minor, beneficial effects on archeological and ethnographic sites along the river canyons. Effects on 

traditional practices would be beneficial and negligible to moderate in intensity. In other areas, the 

effects of alternative B may be beneficial compared to alternative A, but the intensity would be 

negligible. Cumulative effects would be similar to alternative A. Alternative B would not result in 

impairment of the cultural resources of the recreation area. 

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

Alternative C would make permanent the ban personal watercraft use on Lake Powell. This would 

eliminate the use of personal watercraft in the canyons areas. The effects in these areas would be 

similar to those described for alternative B. 

In the remainder of the lake, visitor use may decline by as much as 25% immediately following the 

ban. Visitor disturbances to cultural resources would be decrease by an equivalent amount. However, 

the intensity of this short-term, beneficial effect on cultural resources would be negligible, because 

visitors usually do little harm to the recreation area’s cultural resources on an annual basis. Except for 

rare cases of major damage by vandals or artifact collectors, adverse effects on most cultural sites 

would accumulate slowly over extended periods of time. 

As stated in the “General Methodology” section of this chapter, it was assumed that the removal of 

personal watercraft in alternative C would result in an initial decrease in annual boat days in the shortterm. However, by the end of the 10-year analysis period, the total number of watercraft operating 

hours and the total number of motorized watercraft using Lake Powell under alternative C would be 

within the range predicted for alternatives A and B. This would be due to either natural growth in 

visitation, to visitors finding other watercraft to fulfill functions previously served by personal 

watercraft, or to increases in visitation by individuals who previously avoided the recreation area due 

to personal watercraft and now choose to visit in their absence. By the year 2012, visitor use in the 

recreation area may return to prior levels or slightly higher and personal watercraft use may be 

replaced on Lake Powell with other types of watercraft. While these vessels would produce 

approximately the same noise as personal watercraft, they are not as noticeable because they tend to 

travel from point to point rather than concentrating their use in a small area, usually operate farther 

away from shore, and would not typically make rapid turns and changes in speeds. As a result, the 

change in type of watercraft would have a long-term, beneficial, negligible to minor effect on 

traditional practices that are conducted within a mile of the lake shore throughout the recreation area. 

Cumulative Effects. The cumulative effects of alternative C would be similar to those of 

alternative A. 

Conclusion. Compared to alternative A, alternative C would have direct, long-term, negligible to 

minor, beneficial effects on archeological and ethnographic resources, and negligible to moderate, 
Cultural Resources 

FINAL ENVIRONMENTAL IMPACT STATEMENT 271

beneficial effects on traditional practices in the river canyons in the recreation area. It also would have 

direct, long-term, negligible to minor, beneficial effects on traditional practices that are conducted 

within a mile of the lake shore. 

In the short term, the reduced visitation that would follow implementation of alternative C would 

result in a negligible, short-term reduction in disturbances to cultural sites. This condition would end 

by 2012 if visitor use of the recreation area increases due to natural growth in visitation, to visitors 

finding other watercraft to replace personal watercraft, or to increases in visitation by individuals who 

previously avoided the recreation area due to personal watercraft use. Other cumulative effects would 

be similar to alternative A. Alternative C would not result in impairment of the cultural resources of 

Glen Canyon National Recreation Area. 

SECTION 106 SUMMARY 

This draft environmental impact statement provides detailed descriptions of three alternatives 

(including a no-action alternative) and analyzes the potential impacts associated with possible 

implementation of each alternative. The analysis of potential impacts of personal watercraft at Glen 

Canyon National Recreation Area also considered access by other types of watercraft. 

Visitors access areas of the recreation area by many transport modes, including motor vehicles and 

airplanes, in boats of all types, by hiking, and by personal watercraft. Because of this diversity of 

modes of access, the impacts on archeological and historic cultural resources directly attributable 

solely to personal watercraft users are difficult to define. Effects can best be defined in the upper 

canyons where access is limited by area topography to shallow-draft watercraft like personal 

watercraft and nonmotorized vessels such as canoes or kayaks. Under alternative B, in these upper 

canyon areas, negligible to minor benefits to archeological resources could result from reductions in 

the number of personal watercraft accessing the area. This would constitute a “no adverse effect” on 

archeological resources. 

Reduced wake zones under alternative B would slow damage to a few vulnerable archeological 

resources that are partially submerged, or that are located along the beaches and canyon walls. 

However, because of their small size and amount of water displacement, wakes from personal 

watercraft would make up an extremely small part of the lake wave action. Thus, beneficial impacts of 

reduced wake zones outlined under alternative B would be negligible, resulting in no adverse effects

from this source under this alternative. 

Continuation of traditional religious activities is crucial to preservation of tribal cultural values and 

identity. Visitors using personal watercraft, as well as other means of transport, can deliberately or 

unknowingly intrude on ceremonial activities or disturb resources and archeological sites valued by 

tribes. Under alternative B, personal watercraft use would be eliminated in the upper canyons. Most of 

this use would transfer to more developed areas containing fewer ethnographic resources. Closure of 

the area above the Clay Hills pullout on the San Juan River to personal watercraft would help reduce 

noise and other intrusions on ethnographic sites and resources valued by tribes, resulting in minor 

benefits (no adverse effects) on ethnographic resources. Other types of watercraft such as rafts and 

canoes could still access these areas and intrude on traditional practices, resulting in negligible to 

minor adverse impacts (no adverse effects). 
ENVIRONMENTAL CONSEQUENCES

272 GLEN CANYON NATIONAL RECREATIONAL AREA

Under alternative B, fewer personal watercraft users would be present in some areas, resulting in 

minor benefits (no adverse effect) on ethnographic landscapes. Impacts on historic resources and 

cultural landscapes would be likely to continue at negligible to moderate levels (no adverse effect). 

To help reduce impacts on cultural resources, resources would continue to be monitored on a regular 

basis. Vulnerable resources listed on or potentially eligible for the National Register would have 

priority for protective measures, and the recreation area staff would continue to actively work with 

tribes to protect ethnographic resources and privacy for traditional activities. During periods of drawdown and potential exposure of vulnerable submerged archeological resources, appropriate 

management actions would be implemented. These could include such actions as monitoring, site 

stabilization, and visitor management actions such as signing, ranger patrols, or interpretive messages. 

In cases where it was determined there was a potential for adverse impacts (as defined in 36 CFR 800) 

to cultural resources listed on or eligible for listing on the National Register of Historic Places, the 

National Park Service would coordinate with the state historic preservation officers of Utah and 

Arizona to determine the level of effect on the property, and to determine what mitigation measures 

would be needed. 

Glen Canyon National Recreation Area staff would continue to educate visitors regarding 

archeological and ethnographic site etiquette to provide long-term protection for surface artifacts, 

architectural features, and traditional activities. If necessary, additional mitigation measures would be 

developed in consultation with the state historic preservation officers and concerned Native American 

tribes. 

Concerned Native American tribes will receive copies of this draft environmental impact statement for 

review and comment. This draft environmental impact statement also will be sent to the Arizona and 

Utah state historic preservation officers, and to the Advisory Council on Historic Preservation for 

review and comment as part of the section 106 compliance process. 

Pursuant to 36 CFR Part 800.5, implementing regulations of the National Historic Preservation Act

(revised regulations effective January 2001), addressing the criteria of effect and adverse effect, the 

National Park Service finds that the implementation of the plan in Glen Canyon National Recreation 

Area, with identified mitigation measures, would be beneficial, and would not result in any new 

adverse effects (no adverse effect) to archeological, historic, ethnographic, or cultural landscape 

resources currently identified as eligible for or listed on the National Register of Historic Places. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 273

SOCIOECONOMIC ENVIRONMENT 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Changes in personal watercraft management at Glen Canyon National Recreation Area could affect the 

local economy in several ways, including changes in recreation area visitation, sales and profits of 

local businesses, local employment, and local and state sales tax revenue. 

GUIDING REGULATIONS AND POLICIES 

The National Environmental Policy Act requires analysis of social and economic impacts resulting 

from proposed major federal actions in an environmental impact statement. From this requirement, the 

National Park Service has identified conditions that it wants to achieve in association with its 

management of national parks. These conditions are described in Management Policies 2001 (NPS 

2000d) and for Glen Canyon National Recreation Area. They include the following: 

Public participation in planning and decision-making ensures that the National Park Service 

fully understands and considers the public’s interests in Glen Canyon National Recreation Area, 

which is part of their national heritage, cultural traditions, and community surroundings. The 

service actively seeks out and consults with existing and potential visitors, neighbors, people 

with traditional cultural ties to recreation area lands, scientists and scholars, concessioners, 

cooperating associations, gateway communities, other partners, and government agencies. 

The service works cooperatively with others to improve the condition of Glen Canyon National 

Recreation Area; to enhance public service; and to integrate the recreation area into sustainable 

ecological, cultural, and socioeconomic systems. 

In the spirit of partnership, the service seeks opportunities for cooperative management 

agreements with state or local agencies that would allow for more effective and efficient 

management of Glen Canyon National Recreation Area. 

Possible conflicts between alternatives and land use plans, policies, or controls for the area 

concerned (including those of local and state governments and Indian tribes) and the extent to 

which the recreation area would reconcile the conflict are identified in environmental 

documents. 

METHODOLOGY AND ASSUMPTIONS 

This section summarizes the socioeconomic impacts associated with the proposed regulatory 

alternatives for personal watercraft use in Glen Canyon National Recreation Area. A detailed 

description of these impacts and a complete list of references are provided in Economic Analysis of 

Personal Watercraft Regulations in Glen Canyon National Recreation Area (Law Engineering and 

Environmental Sciences, Inc. 2003). 
ENVIRONMENTAL CONSEQUENCES

274 GLEN CANYON NATIONAL RECREATIONAL AREA

Impact Threshold Definitions 

Impacts on socioeconomics were evaluated using the process described in the “General Methodology 

for Establishing Impact Thresholds and Measuring Effects” section. Impact threshold definitions for 

socioeconomic conditions were defined as follows. 

Negligible — Economic and socioeconomic conditions would not be affected, or effects would 

not be measurable. 

Minor — The effect on economic and socioeconomic conditions would be small but measurable, 

and would affect a small portion of the population. Few effects could be discerned outside of the 

Page area. 

Moderate — The effect on economic and socioeconomic conditions would be readily apparent 

and widespread in the vicinity of Page, with effects being evident at the five-county level. 

Major — The effect on economic and socioeconomic conditions would be readily apparent and 

would substantially change the economy or social services within the five-county area. 

Short-term impacts would be effects that would end within three to five years after the implementation 

of the management action. Long-term effects would occur beyond the 10-year analysis period of this 

study. 

Geographic Area Evaluated for Impacts 

The socioeconomic impact analysis focused primarily on the city of Page, Arizona, with secondary 

consideration of the five-county area surrounding the lake. There are businesses outside of this area, 

such as Salt Lake City, Utah or Grand Junction, Colorado that rent or sell personal watercraft to Glen 

Canyon visitors. While these businesses could be affected by personal watercraft management 

decisions at the recreation area the value of this business contributes little to the local economy 

compared to other activities. Effects of the alternatives on these businesses and economies are 

considered qualitatively.

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Alternative A would allow personal watercraft use at Glen Canyon National Recreation Area 

consistent with the Superintendent’s Compendium (NPS 2002c). While some manufacturers have 

reported a drop in personal watercraft sales nationally, there is no indication that this trend is 

substantially affecting sales of personal watercraft intended for use at Glen Canyon National 

Recreation Area. Therefore, it is assumed that personal watercraft use would either change in a manner 

similar to overall recreation area use or would continue to occur at recent levels through the next 

10 years. 

Rentals, sales, and visitor expenditures related to personal watercraft use at the recreation area would 

contribute to the regional economy at generally the same levels as recent years. As a result, personal 

watercraft use and its contributions to income and sales, both in Page and regionally, would not 
Socioeconomic Environment 

FINAL ENVIRONMENTAL IMPACT STATEMENT 275

change from recent conditions. The effects of alternative A on socioeconomic conditions would be 

negligible. 

Cumulative Effects. Alternative A would not change overall recreation or visitation at Glen Canyon 

National Recreation Area. Therefore, the cumulative effects of alternative A would be negligible. 

Conclusion. Alternative A would have a negligible socioeconomic effect by itself and cumulatively 

with other actions. 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

As discussed in the “Visitor Use and Experience” section, the management actions included under

alternative B would not change the levels of personal watercraft use. However, the distribution of use 

would change in response to changes in access to river sections. High levels of satisfaction with the 

lake experience would occur, similar to alternative A. As a result, rentals, sales, and visitor 

expenditures related to personal watercraft use at Glen Canyon National Recreation Area would 

contribute to the economy of Page and the regional at generally the same levels as alternative A (Law 

Engineering and Environmental Science, Inc. 2003). The effect on socioeconomic conditions would be 

negligible. 

A ban on carbureted two-cycle personal watercraft at the end of 2012 would have little effect on the 

local and regional economy. It is assumed, based on recent trends and based on the commercial 

availability of newer technology that suppliers of personal watercraft sales and services would have 

converted to newer technology by 2012. Some visitors may still have old technology and would no 

longer visit the recreation area. This would result in a direct reduction in local service and repair 

business and would result in a negligible adverse economic effect. 

Cumulative Effects. Alternative B would not change overall recreation or visitation at Glen Canyon 

National Recreation Area. Therefore, the cumulative effects of alternative B would be negligible. 

Conclusion. Alternative B would have a negligible socioeconomic effect by itself and cumulatively 

with other actions. 

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

For this analysis, it was assumed for all alternatives that there would be a change in total boat days and 

watercraft operating hours of between –2% and +2% annually over the next 10 years. It was also 

assumed that the removal of personal watercraft in alternative C would result in an initial decrease in 

annual boat days in the short-term. However, by the end of the 10-year analysis period, the total 

number of watercraft operating hours and the total number of motorized watercraft using Lake Powell 

under alternative C would be within the range predicted for alternatives A and B. This would be due to 

either natural growth in visitation, to visitors finding other watercraft to fulfill functions previously 

served by personal watercraft, or to increases in visitation by individuals who previously avoided the 

recreation area due to personal watercraft and now choose to visit in their absence. This was the same 

assumption that was used for the other impact topics. 
ENVIRONMENTAL CONSEQUENCES

276 GLEN CANYON NATIONAL RECREATIONAL AREA

This analysis considered the socioeconomic effects of both of these conditions. 

The report Economic Analyses of Personal Watercraft Regulations in Glen Canyon National 

Recreation Area (Law Engineering and Environmental Services, Inc. 2003) identified the following 

short-term effects on the economy of Page with the implementation of alternative C. 

Annual visitation to Glen Canyon National Recreation Area would decline by 238,000 to 

425,000 people. This represents approximately 10% to 20% of the more than 2 million visitors 

to Glen Canyon National Recreation Area each year. 

If personal watercraft users stay in hotels outside of the recreation area at the same rate as all 

recreation area visitors (10%), hotel stays in Page would decrease by 23,800 to 42,500 visitors 

per year. 

Restaurants and retail sales in Page would experience declines in business proportional to the 

decreases in visitor numbers. 

Personal watercraft rentals and sales in Page would probably be eliminated. This would occur 

because there are no other locations within the five-county region that can support use by large 

numbers of personal watercraft. 

Companies that service personal watercraft would see a decline in business. 

The annual loss of revenues to the business sector in Page would be between $25 million and 

$42 million. This could cause some retailers and service providers to go out of business. 

Based on these effects, alternative C would cause a major, adverse, long-term effect on the economy 

of Page (Law Engineering and Environmental Sciences, Inc. 2003). Other communities in the counties 

surrounding the recreation area also would experience adverse effects. However, they would be less 

severe because the economies of these communities are less dependent on visitation at Glen Canyon 

National Recreation Area. 

The adverse effects would be both direct and indirect. Direct effects would be experienced by 

companies that provide for the sales, storage, service, and/or rental of personal watercraft. Indirect 

effects would include, but would not be limited to such things as lower retail sales at stores and 

restaurants, fewer hotel nights, reduced sales tax revenues, and less spending by Page residents who 

experienced income reductions or lost their jobs. 

Over time, visitor numbers would return to the levels that occurred before alternative C was 

implemented. As a result, some sectors of the Page economy would return to their previous levels. 

These sectors would include restaurants, hotels, and retail stores for products other than personal 

watercraft. Businesses providing servicing and storage of watercraft also would experience a recovery. 

Businesses in Page that sold personal watercraft would probably lose most or all of their business on a 

permanent basis (Law Engineering and Environmental Sciences, Inc. 2003). Because boats can be 

very expensive, visitors are less likely to buy boats in Page than personal watercraft. Boat sales might 

rise in cities such as Phoenix and Salt Lake City, but compared to the much larger and more diverse 

economies of these areas, such increases would have a negligible beneficial effect on the economy. 

Reduced sales in watercraft in Page would produce a moderate, long-term, direct, adverse effect in this 

city. 
Socioeconomic Environment 

FINAL ENVIRONMENTAL IMPACT STATEMENT 277

Cumulative Effects. While personal watercraft-related visitation, rentals, and sales are substantial 

contributors to the overall economy of Page, people who only use personal watercraft constitute just 

7% of all visitors. These are the visitors who would be most likely to stop visiting Glen Canyon 

National Recreation Area when personal watercraft use was prohibited. The remaining 90% to 95% of 

current visitors would continue to come to the area and would support the area’s revenues, 

employment, personal income, taxes, sales and other economic measures. While personal watercraft 

use is an important contributor to the local economy, Page and other communities in the area do not 

solely depend on personal watercraft use at Glen Canyon National Recreation Area. While businesses 

that depend on this form of recreational vessel would experience major impacts, the overall effect, in 

consideration with other economic factors influencing the regional economy, would be moderate. 

Conclusion. Alternative C would cause a major, adverse, long-term effect on the economy of Page. 

Other communities in the counties surrounding the recreation area would experience less intense 

adverse effects. The effects would be both direct and indirect as reduced demand for sales and service 

related to personal watercraft-based recreation rippled through the economy. Cumulative effect on the 

regional economy would be moderate. In the long term, the economy would recover to previous levels, 

except for businesses that had focused on personal watercraft sales and rentals. Therefore, the longterm effect on the local economy would be moderate to major. 
278 GLEN CANYON NATIONAL RECREATIONAL AREA

RECREATION AREA MANAGEMENT AND OPERATIONS 

ISSUES AND MANAGEMENT OBJECTIVES 

RELATED TO PERSONAL WATERCRAFT USE 

Issues 

Personal watercraft management issues that have been associated with management and operations of 

Glen Canyon National Recreation Area include the following. 

Management of personal watercraft in the recreation area involves seven NPS divisions plus 

boating enforcement agencies from Arizona and Utah. Any changes in management of personal 

watercraft may affect the operations of these entities. 

Staffing levels in the recreation area may not be adequate to manage personal watercraft issues 

or changes in personal watercraft management. 

Boating regulations for Arizona and Utah are enforced on their respective waters. These states 

have differences in their personal watercraft requirements. While the differences in the state 

regulations do not affect the ability to enforce the regulations, they cause confusion for some 

personal watercraft operators that makes compliance difficult. 

Management Objectives 

As shown in table 3, two objectives for recreation area management and operations were identified for 

personal watercraft management. They included: 

Maintain cooperation with state entities that regulate personal watercraft use and protect quality 

of air and water. 

Provide sufficient staffing levels as funding allows to adequately manage personal watercraft 

use and to resolve personal watercraft user-related conflicts. 

These objectives tier from the recreation area management and operations objectives that were 

included in the general management plan and strategic plan. The more general objectives from these 

plans that are relevant to personal watercraft management include: 

Maximizing the efficiency and effectiveness of the management of the recreation area and 

adjacent lands. 

Cooperating with the Bureau of Reclamation in their management of the reservoir. 

Cooperating with the Navajo Tribe in managing and developing the southern shoreline of Lake 

Powell for recreational use. 
Recreation Area Management and Operations 

FINAL ENVIRONMENTAL IMPACT STATEMENT 279

GUIDING REGULATIONS AND POLICIES 

In Glen Canyon National Recreation Area, boating regulations from the U.S. Coast Guard and from 

the states of Arizona and Utah apply. Based on Management Policies 2001 (NPS 2000d), “the Service 

will seek to acquire concurrent legislative jurisdiction for all units of the national park system, as 

required by the 1976 amendment to the General Authorities Act. Concurrent jurisdiction allows the 

National Park Service to enforce federal criminal statutes and also to assimilate state law under 18 

U.S.C. 13, when no applicable federal law or regulation exists.” Personal watercraft operation falls 

under this statement because there are no federal requirements for this type of vessel. Concurrent 

jurisdiction allows for the more efficient conduct of both state and federal law enforcement functions 

within the parks. 

Management Policies 2001 (NPS 2000d) guide maintenance activities in park units. Section 9.1.4.1 

states that 

the Service will conduct a program of preventive and rehabilitative maintenance and 

preservation to (1) provide a safe, sanitary, environmentally protective, and esthetically pleasing 

environment for park visitors and employees; (2) protect the physical integrity of facilities; and 

(3) preserve or maintain facilities in their optimum sustainable condition to the greatest extent 

possible. Preventive and rehabilitative maintenance programs will incorporate sustainable design 

elements and practices to ensure that water and energy efficiency, pollution prevention, and 

waste prevention and reduction are standard practice. 

The Concession Division manages three concession contracts with ARAMARK Leisure Services, Inc. 

Alternatives to manage personal watercraft in the recreation area may result in the modification of the 

concessions contracts. According to section 10.2.3.2 of Management Policies 2001 (NPS 2000d), 

“Concession contracts may be modified only by written amendment. Amendments developed after the 

issuance of a concession contract must be consistent with current NPS policies and orders.” 

Guidelines for interpretation and educational programs are provided in Chapter 7 of Management 

Policies 2001 (NPS 2000d). These guidelines direct the National Park Service to disseminate to the 

public the history and significance, the resources, and the mission goals of Glen Canyon National 

Recreation Area. In instances when park managers must make difficult resource decisions that may be 

highly controversial, the interpretive and educational programs can build public understanding of, and 

support for, such decisions and initiatives, and for the NPS mission in general. Section 7.5.3 directs 

that “parks should, in balanced and appropriate ways, thoroughly integrate resource issues and 

initiatives of local and Servicewide importance into their interpretive and educational programs. . . . 

Resource issue interpretation should be integrated into both on and off site programs, as well as into 

printed and electronic media whenever appropriate.” 

METHODOLOGY AND ASSUMPTIONS 

Impact Threshold Definitions. The following thresholds were used to determine the magnitude of 

effects on recreation area management and operations. 

Negligible — Recreation area management and operations would not be affected or the effect 

would be at or below the lower levels of detection. 
ENVIRONMENTAL CONSEQUENCES

280 GLEN CANYON NATIONAL RECREATIONAL AREA

Minor — The effect would be detectable, but would be of a magnitude that would not have an 

appreciable effect on recreation area management and operations. If mitigation were needed to 

offset adverse effects, it would be relatively simple and successful. 

Moderate — The effects would be readily apparent and would result in a substantial change in 

recreation area management or operations in a manner noticeable to staff and the public. 

Mitigation measures would probably be necessary to offset adverse effects and would likely be 

successful. 

Major — The effects would be readily apparent and would result in a substantial change in 

recreation area management or operations in a manner noticeable to staff and the public. 

Mitigation measures to offset adverse effects would be needed, could be expensive, and their 

success could not be guaranteed. 

Geographic Area Evaluated for Impacts. Most recreation area management and operations activities 

directly relating to personal watercraft would occur on Lake Powell. However, staffing constraints 

often mean that committing additional resources to one area requires a reduction in services in another 

area. For example, additional water-based law enforcement needs could reduce ranger availability to 

patrol campgrounds. Therefore, the entire recreation area was included in the geographic area 

evaluated for impacts on recreation area management and operations. 

ALTERNATIVE A: CONTINUE PERSONAL WATERCRAFT 

USE AS CURRENTLY MANAGED UNDER A SPECIAL REGULATION 

Because Glen Canyon National Recreation Area is a proprietary jurisdiction, the states of Arizona and 

Utah have primary law enforcement jurisdiction on waters within their boundaries. Therefore, no 

conflicts between recreation area regulations and other personal watercraft regulations exist. NPS 

rangers would continue to enforce both Arizona and Utah personal watercraft regulations, laws, and 

rules, plus the personal watercraft and other boating requirements in the superintendent’s 

compendium. 

Current differences in state regulations, laws, and rules between Arizona and Utah (see table 4 and 

appendix B) do not have an adverse effect on NPS rangers’ ability to enforce regulations. With 

alternative A, there would continue to be a lack of understanding of the applicable state regulations 

among some personal watercraft users. This would lead to a frequency of accidents and incidents 

similar to those presented in table 31. Compared to current conditions, this would produce a 

negligible, long-term effect on enforcement operations. 

Current recreation area staffing levels would be maintained, interpretation, maintenance, resource 

management, and concessions. Recreation area visitor protection personnel would continue to commit 

about 20% of their time to responding to water-based recreational situations. Arizona and Utah law 

enforcement staff would continue their full-time assignments of patrolling the lake and enforcing their 

respective state’s boating regulations laws, and rules. 

Other divisions within the recreation area currently commit few resources directly to the management 

of personal watercraft. The short- and long-term adverse effects of alternative A on these divisions 

would be negligible. 
Recreation Area Management and Operations 

FINAL ENVIRONMENTAL IMPACT STATEMENT 281

Alternative A would increase funding for visitor protection staff. This would allow for proactive boat 

patrols and would give recreation area staff an opportunity to interact with personal watercraft 

operators in situations other than incidents and accidents. Rangers could provide visitors with a clearer 

understanding of applicable state regulations, laws, and rules, potential consequences of unsafe or 

inconsiderate actions, and the need to protect the recreation area’s resources. This would have a 

beneficial, long-term, minor effect on visitor protection services. 

Cumulative Effects. No conflicts with state or other regulations or policies would be anticipated with 

the continuation of current boating practices under alternative A. Each year there would be about 

1,400 watercraft-based incidents and accidents that would result in 5 to 10 deaths. About 85% of these 

would involve vessels other than personal watercraft and about 80% would not involve a vessel in 

motion. 

The improvements visitor protection staff and proactive boat patrols would improve the understanding 

of boating regulations and safe practices on the water among all boaters, not just personal watercraft 

operators. This potentially would decrease the number of incidents and accidents that occur on the 

lake. As a result, rangers could focus on the protection of resources and the safety of visitors, and 

reduce time spent responding to emergencies. This would be a beneficial, long-term, negligible to 

minor effect. 

Recreation area commitments of staff resources to provide visitor services, education, and the upkeep 

and maintenance of facilities that relate to all activities in the recreation area would not change. 

Recreation area operation needs for all other user groups would be similar to existing conditions, 

because the number of visitors and boats would not be altered by this alternative. Cumulative impacts 

on management and operations from all recreational use would continue to place demands on 

recreation area personnel and resources and the effects of alternative A would be considered 

negligible. 

Conclusion. Use of personal watercraft in the recreation area under alternative A would have 

negligible, short- and long-term effects on operations. Increased funding for visitor protection staff 

would offset some of the long-term impacts to visitor protection services. The cumulative effects on 

management and operations of personal watercraft use in conjunction with other activities at existing 

levels also would be negligible. 

ALTERNATIVE B (MODIFIED PREFERRED ALTERNATIVE): 

PROMULGATE A SPECIAL REGULATION TO CONTINUE PERSONAL 

WATERCRAFT USE WITH ADDITIONAL MANAGEMENT RESTRICTIONS 

Under alternative B, new restrictions on personal watercraft use would be implemented by prohibiting 

personal watercraft use in the upper areas of the tributaries and zoning other areas of the tributaries as 

flat-wake. These restrictions would not conflict with state personal watercraft regulations or 

jurisdiction. There would be no impacts related to conflicts with state or local requirements or policies. 

The new closed areas and wake restriction areas would be marked by navigation devices. Increased 

maintenance staff time and funding would be required to construct and install new buoys and signs in 

these areas. Once the markers were installed, periodic repair and replacement would be required. 

Initially, these activities would result in a short-term, minor, adverse effect on management and 

operations. Long-term effects would be adverse and negligible to minor. 
ENVIRONMENTAL CONSEQUENCES

282 GLEN CANYON NATIONAL RECREATIONAL AREA

It is anticipated that the newly closed or flat-wake areas would be self-regulating after the signs and 

markers were installed. Little additional staff time would be needed to enforce the restrictions, and 

staff demands to respond to accidents or incidents in the tributaries might be reduced. The long-term 

effect on enforcement from these restrictions would be negligible. 

Prohibiting the use of carbureted two-strike personal watercraft after 2012 would result in short-term 

negligible adverse effects on recreation area operations including rangers and visitor services staff. 

The average operating life of a personal watercraft is 5 to 10 years, depending upon the source (see 

“General Methodology” section of the “Environmental Consequences” chapter). By 2012, the 

National Park Service expects most personal watercraft owners will already be in compliance with the 

2006 EPA standard. In addition, over the next 10 years educational materials produced by recreation 

area staff would inform visitors of the new restriction. It is expected that by 2012, little staff time 

would be required to enforce the restriction. 

Under alternative B, the recreation area would work with Arizona and Utah jurisdictions to unify 

boating regulations. This would produce a negligible effect on law enforcement because there is no 

evidence or information indicating that the current condition, while sometimes confusing, would 

increase the number of incidents or accidents. 

Alternative B would increase funding for visitor protection staff. This would allow for proactive boat 

patrols and would give recreation area staff an opportunity to interact with personal watercraft 

operators in situations other than incidents and accidents. This would have a beneficial, long-term, 

minor effect on visitor protection services similar to alternative A. 

Alternative B would increase funding for visitor protection staff. This would allow for proactive boat 

patrols and would give recreation area staff an opportunity to interact with personal watercraft 

operators in situations other than incidents and accidents. Rangers could provide visitors with a clearer 

understanding of applicable state regulations, laws, and rules, potential consequences of unsafe or 

inconsiderate actions, and the need to protect the recreation area’s resources. This would have a 

beneficial, long-term, minor effect on visitor protection services compared to alternative A. 

Alternative B also would provide additional funds for enhanced educational materials. This could 

include the use of such media as brochures, newsletters, wayside exhibits, interpretive programs, and 

the recreation area’s website to teach safe boating and highlight activities and behaviors that result in 

violations, citations, and accidents. The improved education program would potentially reduce the 

number of incidents and accidents involving personal watercraft operators that require ranger 

response. Beneficial, long-term, negligible to minor effects on visitor protection operations would 

occur from the improved educational program. 

Additional staff time initially would be needed to develop the educational materials for distribution to 

personal watercraft users. This activity would include participation by the concession division, 

because the occasional renter would be less likely to be familiar with area restrictions and safe 

operating procedures than a personal watercraft owner. The education materials would highlight the 

new area restrictions as prescribed under this alternative. As the public became more familiar with the 

new restrictions, the time devoted to educating the public would decrease to levels similar to those 

under alternative A. Adverse impacts on interpretation and concessions operations would be negligible 

to minor in the short term and would decrease to negligible over the long term. 

Under alternative B, resource management staff would continue to monitor water quality in the 

recreation area for Escherichia coli (E. coli). The resource management staff also would develop and 
Recreation Area Management and Operations 

FINAL ENVIRONMENTAL IMPACT STATEMENT 283

implement new monitoring programs to establish baseline conditions and assess the effects of personal 

watercraft emissions and noise on the water quality, air quality, and soundscapes of the recreation 

area. This increased monitoring would require additional staff and time to collect, compile, interpret, 

and report the data. Monitoring would occur throughout the life of the plan. Without any increase in 

current staffing levels, it would result in a long-term, negligible to minor, adverse effect on operations 

of the resource management division. 

Cumulative Effects. No conflicts with regulations or policies at the state or local levels would be 

anticipated from implementing additional restrictions under alternative B. The restrictions would apply 

to the recreation area only, and would not affect other regulations. 

The improvements in educational materials, visitor protection staff, and proactive boat patrols would 

improve the understanding of boating regulations and safe practices on the water among all boaters, 

not just personal watercraft operators. This potentially would decrease the number of incidents and 

accidents that occur on the lake. As a result, rangers could focus on the protection of resources and the 

safety of visitors, and reduce time spent responding to emergencies. This would be a beneficial, longterm, negligible to minor effect. 

NPS staff would continue to provide visitor services, upkeep and maintenance of facilities, and 

resource management associated with all other recreational uses of the recreation area. Changes in 

these services, aside from those mentioned previously for personal watercraft-related management, 

would be negligible. 

Conclusion. Alternative B primarily would affect the enforcement, interpretation, and facilities 

maintenance components of recreation area operations. Short-term impacts would be minor, as staff 

resources were committed to marking newly restricted areas and developing and implementing new 

educational programs. In the long term, most of these effects would decrease to negligible levels. 

Increased funding for visitor protection staff would lead to long-term, minor benefits to visitor 

protection services. Effects on recreation area staff from restrictions on carbureted two-stroke personal 

watercraft at the end of 2012 would be negligible as most watercraft would already be compliant with 

EPA emission standards and distribution of education materials would inform users well in advance of 

the restriction. Without additional funding, staff requirements for additional monitoring could have 

long-term, negligible to minor, adverse effects on operations of the resource management division. 

Cumulatively, all recreation area visitors would benefit from the improved education and visitor 

protection services that would be implemented with alternative B. These could reduce the need to 

respond to emergencies and improve the ability to focus recreation area services on the protection of 

resources and the safety of visitors. These would be beneficial, negligible to minor, direct and indirect, 

long-term effects on recreation area operations. 

ALTERNATIVE C: NO-ACTION 

(PERSONAL WATERCRAFT USE WOULD BE ELIMINATED) 

Alternative C would permanently eliminate personal watercraft use in the recreation area. Because 

recreation area managers have the right to regulate the types of activities that take place, and because 

there are no provisions in state personal watercraft regulations forbidding additional controls or bans, 

there would be no conflicts. Impacts related to conflicts with other regulations or policies would be 

non-existent or negligible. 
ENVIRONMENTAL CONSEQUENCES

284 GLEN CANYON NATIONAL RECREATIONAL AREA

A primary point of information regarding the ban on personal watercraft could occur at the recreation 

area entrance gates, where visitors trailering personal watercraft could be informed that the vessels 

could not be launched or used on Lake Powell. Visitors seeking explanations could cause delays at the 

entry points. If substantial numbers of visitors requested additional information, noticeable lines could 

form at entry points and additional staff would have to be assigned to these stations. In the short term, 

this would cause direct, minor, adverse effects on recreation area operations. The effect would 

decrease to negligible levels as visitors became familiar with the situation and the number of staff 

assigned to entry stations returned to normal. 

Some visitors enter the recreation area during evening, night, or early morning periods when the gates 

are not staffed by the National Park Service. Therefore, additional information would be needed at key 

locations such as launch ramps. There would be a minor, short-term commitment of staff to create 

educational materials and install signs, but the effect would rapidly decrease to negligible levels. 

Much of the ban would be self-enforcing, as informed visitors at sites such as launch ramps notified 

people intending to launch personal watercraft that the vessels were no longer allowed on the lake. 

However, law enforcement staff occasionally would be needed. Therefore, there would be negligible 

to minor requirements for law enforcement services to monitor compliance. 

As described in the “Affected Environment” chapter, personal watercraft currently account for 15% of 

water-based law enforcement cases, including 15% of all incidents and 14% of all accidents. Banning 

these vessels would eliminate personal watercraft-related incidents and accidents, which in the short 

term would produce a 15% decrease in water-based law enforcement cases. 

As stated in the “General Methodology” section of this chapter, it was assumed that the removal of 

personal watercraft in alternative C would result in an initial decrease in annual boat days in the shortterm. However, by the end of the 10-year analysis period, the total number of watercraft operating 

hours and the total number of motorized watercraft using Lake Powell under alternative C would be 

within the range predicted for alternatives A and B. This would be due to either natural growth in 

visitation, to visitors finding other watercraft to fulfill functions previously served by personal 

watercraft, or to increases in visitation by individuals who previously avoided the recreation area due 

to personal watercraft and now choose to visit in their absence. By the year 2012, visitor use in the 

recreation area may return to prior use levels or slightly higher and personal watercraft use may be 

replaced on Lake Powell with other vessels. The data in table 31 indicate that other vessels have a 

higher law enforcement case rate in Glen Canyon National Recreation Area than personal watercraft. 

Therefore, in the long term, the number of incidents and accidents requiring law enforcement action 

would be similar to or slightly higher than the alternative A levels, resulting in a negligible to minor 

adverse effect. The beneficial effects of improvements to visitor protection staff similar to those 

described under alternative A would offset some of the long-term adverse impacts to visitor protection 

services.

Minor, short-term, adverse effects would occur on other recreation area management and operations 

with implementation of a personal watercraft use ban. In particular, concession contracts and 

incidental business permits would need to be modified to reflect the prohibition of personal watercraft 

use in the recreation area. In the long term, these effects would be negligible. 

Cumulative Effects. There would not be any differences between the effects described above for 

alternative C and the cumulative effects from this alternative on management and operations of the 

recreation area. 
Recreation Area Management and Operations 

FINAL ENVIRONMENTAL IMPACT STATEMENT 285

Conclusion. Alternative C would cause short-term, direct, minor, adverse effects on recreation area 

operations, primarily because of time commitments needed to inform visitors about the ban on 

personal watercraft. In the long term, these effects would decline to negligible levels. Law 

enforcement requirements on the lake initially would be reduced, as the number of visitors decreased 

in association with the ban. However, the long-term effect on law enforcement activities would be 

negligible if visitor use of the recreation area increases due to natural growth in visitation, to visitors 

finding other watercraft to replace personal watercraft, or to increases in visitation by individuals who 

previously avoided the recreation area due to personal watercraft use. Increased funding for visitor 

protection staff would offset some of the long-term impacts on visitor protection services. There 

would not be any additional cumulative effect from alternative C. 
286 GLEN CANYON NATIONAL RECREATIONAL AREA

SUSTAINABILITY AND LONG-TERM MANAGEMENT 

UNAVOIDABLE ADVERSE IMPACTS 

Unavoidable adverse impacts are those environmental consequences of an action that cannot be 

avoided, either by changing the nature of the action or through mitigation if the action is taken. 

Therefore, they would remain throughout the duration of the action. 

There would be unavoidable adverse impacts on the experience of some visitors under alternatives A 

and B, who find personal watercraft annoying or disruptive. Under the no-action alternative 

(alternative C), there would be unavoidable adverse impacts on personal watercraft users who could no 

longer participate in this activity in the recreation area and have to pursue this activity elsewhere. 

Alternatives A and B would continue unavoidable adverse impacts on the natural soundscape. Both 

alternatives A and B would continue personal watercraft emissions of air and water pollutants, 

although total emissions would decrease with gradual conversion of personal watercraft engines to 

less-polluting models. 

With alternative A, ethnographic resource experiences in some upper canyons would continue to be 

adversely affected by inadvertent intrusions associated with the use of personal watercraft. 

RELATIONSHIP BETWEEN LOCAL SHORT-TERM USES OF THE ENVIRONMENT 

AND THE MAINTENANCE AND ENHANCEMENT OF LONG-TERM PRODUCTIVITY 

The intent of this determination is to identify whether the proposed action would trade-off the 

immediate use of the land or resources for any long-term management possibilities, adversely 

affecting the productivity of recreation area resources. This determination also discloses whether the 

proposed action or alternatives would be a sustainable action that could continue over the long term 

without environmental problems (NPS 2001b). 

None of the alternatives suggest substantial loss or impairment of natural resources or ecosystems in 

the recreation area as a consequence of their implementation. There would be some trade-offs from a 

local or short-term perspective as is described below. 

Alternative A would continue personal watercraft use at the recreation area over the long term. 

This alternative does not propose any additional management actions to minimize adverse 

impacts. Trade-offs would include continued emissions into water and air resources and the 

natural soundscape for recreation by those who want to experience the recreational area by 

personal watercraft. Personal watercraft impacts on these resources would range from negligible 

to moderate. 

Alternative B would close about 123 miles of river and reduced personal watercraft speed in 

about 7 miles of river and would prohibit the use of carbureted two-stroke personal watercraft at 

the end of 2012. This alternative would reduce, in these areas, long-term incremental 

contributions of personal watercraft noise, water, and air pollutants which would benefit these 

resources. 
Sustainability and Long-Term Management 

FINAL ENVIRONMENTAL IMPACT STATEMENT 287

Alternative C would trade removal of personal watercraft from the recreation area with 

concurrent, long-term improvements in water, noise, and air quality (due to reduced emissions 

from personal watercraft) and improvements in the desired recreational experiences for some 

visitors. 

IRREVERSIBLE OR IRRETRIEVABLE COMMITMENTS OF RESOURCES 

The intent of this determination is to identify whether the proposed action or alternative would result 

in effects or impacts that could not be changed over the long term or would be permanent. An effect 

on a resource would be irreversible if the resource could not be reclaimed, restored, or otherwise 

returned to conditions that existed before the disturbance. An irretrievable commitment of resources 

involves the effects on resources that, once gone, cannot be replaced or recovered (NPS 2001b). 

All three alternatives would involve the irretrievable commitment of energy resources (gasoline, fuel 

oil, electrical power) for the operations of personal watercraft and other motorcraft that use Lake 

Powell. None of the alternatives would be expected to result in the irreversible or irretrievable 

commitment of recreation area resources. 
ENVIRONMENTAL CONSEQUENCES

288 GLEN CANYON NATIONAL RECREATION AREA
Sustainability and Long-Term Management 

FINAL ENVIRONMENTAL IMPACT STATEMENT 289

Consultation and Coordination 

Divider 

This page to be removed 
ENVIRONMENTAL CONSEQUENCES

290 GLEN CANYON NATIONAL RECREATION AREA

This page to be remove 

Back of Divider 
FINAL ENVIRONMENTAL IMPACT STATEMENT 291

HISTORY OF PUBLIC INVOLVEMENT 

SCOPING PROCESS AND PUBLIC PARTICIPATION 

The scoping process for managing personal watercraft in Glen Canyon National Recreation Area 

began in May 2001 with a meeting of the National Park Service planning team. The team discussed 

the recreation area’s objectives for management of personal watercraft, identified issues related to 

personal watercraft management, and developed a range of preliminary alternatives. 

In August 2001, the recreation area notified the public of the intent to prepare an environmental impact 

statement for managing personal watercraft in an announcement in the Federal Register (NPS 2001i). 

The notice requested the public to comment on the scope of the environmental impact statement, 

issues and alternatives related to personal watercraft management, and other personal watercraft 

resource concerns. The notice also announced the recreation area’s intent to hold public scoping 

workshops to further facilitate public participation in the process. 

Public meetings were held in Salt Lake City, Utah and in Page and Phoenix, Arizona in August 2001 

to solicit early input into the scope and range of issues to be analyzed related to the management of 

personal watercraft within Glen Canyon National Recreation Area. Scoping comments continued to be 

accepted and considered within the planning process. During this comment period, the National Park 

Service facilitated several hundred discussions and briefings to recreation area staff, congressional 

delegations, elected officials, tribal representatives, public service organizations, educational 

institutions, and other interested members of the public. 

More than 3,500 letters and e-mail messages concerning personal watercraft use on Lake Powell were 

received. A mailing list of interested parties was compiled from attendees at the meetings and from 

any written comments received at the recreation area. During this first comment period, Glen Canyon 

National Recreation Area received: 

503 individual written letters of concern; 

270 petition form letters originating from the American Watercraft Association requesting that 

personal watercraft be regulated just as any other type of watercraft and access should not be 

denied; 

325 petition postcards originating from the American Watercraft Association requesting that 

Glen Canyon National Recreation Area adopt reasonable regulations to support continued access 

by all boaters versus implementing discriminatory regulations; and 

523 e-mail letters. 

Glen Canyon National Recreation Area also received more than 1,100 electronic form letters. These 

included: 

152 titled ‘No Jet Skis at Glen Canyon!’ supporting the elimination of personal watercraft; 

926 titled ‘End Jet Ski Pollution at Glen Canyon’ supporting the elimination of personal 

watercraft on Lake Powell; and 
CONSULTATION AND COORDINATION

292 GLEN CANYON NATIONAL RECREATION AREA

109 titled ‘Free Glen Canyon National Recreation Area of Jet Skis’ also supporting personal 

watercraft elimination. 

Lake Powell Magazine obtained 533 signatures from boating shows supporting continued rights for 

personal watercraft use on Lake Powell. 

During the public workshops, 146 written comments regarding issues, concerns, and alternatives for 

management were received. These comments ranged from the support of the continued use of personal 

watercraft throughout the recreation area (over 80%), to a total ban on personal watercraft use, to 

restrictions in selected areas of the recreation area. 

Issues generated during the comment period included: 

Visitor safety concerns related to illegal and reckless operation of personal watercraft; 

Conflicts among different user groups; 

Educational requirements for all boaters; 

Potential resource impacts; and 

The impacts of personal watercraft use related to other motorized vessels. 

The planning team used the public comments and agency input to revise the preliminary alternative 

concepts into the three personal watercraft management alternatives for Glen Canyon National 

Recreation that were evaluated in this environmental impact statement. Public input also was used to 

define the issues that were evaluated within each impact topic. 

The Draft Environmental Impact Statement: Personal Watercraft Rule-Making, Glen Canyon National 

Recreation Area was made available for public review in September 2002. The document was 

available in hard copy, on computer disk, and on the recreation area’s website at 

www.nps.gov/glca/plan.htm. 

The draft environmental impact statement was on public review for 60 days after the Environmental 

Protection Agency had accepted the document and published a notice of availability in the Federal 

Register (67 FR 178). The 60-day review and public comment period ended on November 27, 2002. 

Public meetings were held from October 7 through October 10 following the release of the draft 

environmental impact statement. Public meetings were held in Salt Lake City, Utah; Grand Junction, 

Colorado; and Phoenix and Page, Arizona. The National Park Service provided notification of public 

meetings on the Glen Canyon National Recreation Area website and through press releases to 

newspapers and television and radio stations in the region including each of the cities where meetings 

were held. 

Members of the NPS interdisciplinary planning team were available at the public meetings to answer 

questions concerning the environmental impact statement. Comment sheets were provided for people 

to submit written comments, and a stenographer was available to record verbal comments. The public 

was also encouraged to comment via the Internet. 
History of Public Involvement 

FINAL ENVIRONMENTAL IMPACT STATEMENT 293

During the public comment period, over 30,000 comments were received on the draft environmental 

impact statement. The National Park Service and its contractor analyzed all comments that were 

received during the public comment period in order to identify and respond to substantive issues. The 

introduction to Volume 2, “Comments and Responses to the Draft Environmental Impact Statement,” 

contains a description of the purpose and methodology used in reviewing and responding to public 

comments, provides a brief summary of comments received, and describes the organization of that 

volume. 

ENDANGERED OR THREATENED SPECIES CONSULTATIONS 

In accordance with section 7 of the Endangered Species Act (16 U.S.C. 1531 et seq.), the National 

Park Service conducted informal consultation with the U.S. Fish and Wildlife Service. A letter from 

the U.S. Fish and Wildlife Service dated May 9, 2002 and included in appendix H.3 identified seven 

species for Coconino County, Arizona and eight species for Kane and San Juan Counties, Utah that 

may occur within or adjacent to the personal watercraft analysis area. Of the 15 species identified, 

13 are listed, 1 is proposed, and 1 is a candidate species. Lake Powell also provides critical habitat for 

four endangered fish species. 

The analysis of actions that “may affect” listed or proposed species, or designated critical habitat is 

provided in this environmental impact statement. The evaluation determined that the proposed action 

is not likely to jeopardize the continued existence of any species listed as endangered or threatened 

(listed species). The proposed action also would not result in the loss or adverse modification of 

habitat designated as critical. 

The Draft Environmental Impact Statement was submitted to the U.S. Fish and Wildlife Service in 

October 2002 for their review as part of the consultation process. Their response can be found in 

volume II of this Final Environmental Impact Statement. 

CULTURAL RESOURCES CONSULTATIONS 

On April 26, 2002 Glen Canyon National Recreation Area sent letters to the Utah and Arizona state 

historic preservation officers (appendix H.1) and the Advisory Council on Historic Preservation 

(appendix H.2). The letters invited them to participate in the planning process and informed them that 

the National Park Service plans to use this environmental impact statement to fulfill the requirements 

of section 106 of the National Historic Preservation Act as well as to comply with provisions of the 

National Environmental Policy Act. A reply dated May 7, 2002 was received from the Utah State 

Historic Preservation Officer acknowledging that the recreation area will be using the environmental 

impact statement process to accomplish section 106 compliance. A copy of this correspondence is 

included in appendix H.1. The Draft Environmental Impact Statement was submitted to the Arizona 

and Utah state historic preservation officers in September 2002. 

Glen Canyon National Recreation Area also sent letters to the Navajo Tribal Historic Preservation 

Officer on April 26, 2002. The Navajo Nation Historic Preservation Department, Traditional Cultural 

Program responded on May 14, 2002, noting that the Navajo Nation does not have any concerns with 

the proposed project at this time, but requested that they be notified should Navajo resources be 

identified. A copy of this correspondence is provided in appendix H.6. 
CONSULTATION AND COORDINATION

294 GLEN CANYON NATIONAL RECREATION AREA

Traditionally associated tribes were contacted by letter in May 2000 and August 2002 to begin 

government-to-government consultation regarding this project. Copies of this correspondence are 

provided in appendix H.6. As of August 12, 2002, a reply had been received only from the Navajo 

Nation. A copy of this letter is included in appendix H.6. Recreation area staff will make follow-up 

calls to ensure that the tribes are kept informed about the project. 

List of Native American Tribes 

Hopi Tribe 

Kaibab Paiute Tribe 

Kanosh Band of the Paiute Indian Tribe of Utah 

Koosharem Band of the Paiute Indian Tribe of Utah 

Navajo Nation 

San Juan Southern Paiute Tribe 

Ute Mountain Indian Tribe 
FINAL ENVIRONMENTAL IMPACT STATEMENT 295

LIST OF PREPARERS 

NATIONAL PARK SERVICE 

Glen Canyon National Recreation Area, Planning Team Members 

Kitty Roberts, Superintendent 

Bill Pierce, Deputy Superintendent 

John Ritenour, Chief of Resource Management 

Norm Henderson, Resource Specialist 

Phil Hibbs, District Ranger 

John Spence, Botanist and Wildlife Biologist 

Mike Mayer, Assistant Chief Ranger 

Brian O’Dea, Criminal Investigator 

Pauline Wilson, American Indian Liaison 

Washington Office 

Rick Ernenwein, Noise/Soundscapes Specialist 

John Ray, Air Quality Specialist 

Bob Rossman, Soundscape Specialist 

Mark Vanmouwerik, Water Quality Specialist 

Madoline Wallace, National Environmental Policy Act Compliance Specialist 

Aaron Worstell, Air Quality Specialist 

Intermountain Region Office 

Chris Turk, Regional Environmental Quality Coordinator 

Parsons 

Timberley Belish, Environmental Scientist 

Jacklyn Bryant, Environmental Scientist 

Connie Chitwood, Environmental Scientist 

Pat Ditzel, Word Processor 

John Hoesterey, Environmental Scientist 

Don Kellett, Environmental Scientist 

Greg Matthews, Geographic Information Systems Specialist 

Carolyn Nobel, Environmental Scientist 

Mark Norman, Environmental Scientist 

Diane Rhodes, Environmental Scientist 

Bruce Snyder, Project Manager 

Jan Snyder, Environmental Scientist and Technical Editor 

Nicole White-Scott, Environmental Scientist 
CONSULTATION AND COORDINATION

296 GLEN CANYON NATIONAL RECREATION AREA

RED, Inc. Communications 

Juanita Barboa, Technical Editor 

Susan Hale, Technical Editor 

April Dinneen, Technical Editor 

Cheryl Priest, Text Processor 

Sandy Criddle, Text Processor 
FINAL ENVIRONMENTAL IMPACT STATEMENT 297

LIST OF RECIPIENTS 

The following agencies, tribes, groups, and organizations have been identified as having an interest in 

this issue and NEPA decision-making process. Each listed entity, as well as numerous interested 

individuals, has been sent a copy of this draft environmental impact statement. 

FEDERAL AGENCIES 

Advisory Council on Historic Preservation 

Bureau of Land Management, Utah and Arizona 

Bureau of Reclamation 

House Interior Appropriations Subcommittee 

House Parks Subcommittee 

National Park Service, Office of the Director 

National Park Service, Intermountain Regional 

Office 

Natural Resources Conservation Service 

Senate Interior Appropriations Subcommittee 

Senate Parks Subcommittee 

U.S. Department of the Interior, Office of the 

Solicitor 

U.S. Coast Guard 

U.S. Environmental Protection Agency, 

Region 8, Region 9, and EIS Filing Section, 

Washington 

U.S. Fish and Wildlife Service 

U.S. Forest Service, North Kaibab District 

U.S. Geological Survey, Grand Canyon 

Monitoring Research Center 

NATIVE AMERICAN TRIBES 

Hopi Tribe 

Kaibab Paiute Tribe 

Kanosh Band of the Paiute Indian Tribe of Utah 

Koosharem Band of the Paiute Indian Tribe of 

Utah 

Navajo Nation, Parks and Recreation 

San Juan Southern Paiute Tribe 

Ute Mountain Indian Tribe 

White Mesa Ute Council 

STATE OF ARIZONA 

Arizona Boating Coordinator 

Arizona Department of Environmental Quality 

Arizona Department of Natural Resources 

Arizona Game and Fish Department 

Arizona NPS State Coordinator 

Arizona Office of Tourism 

Arizona State Historic Preservation Office 

City of Page 

City of Page Chamber of Commerce 

Coconino County Board of Supervisors 

Congressman Bob Stump 

Congressman Ed Pastor 

Congressman J.D. Hayworth 

Congressman Jeff Flake 

Congressman Jim Kolbe 

Congressman John Shadegg 

Governor Jane D. Hull 

Governor’s Northern Arizona Office 

Senator John Kyl 

Senator John McCain 

STATE OF NEW MEXICO 

San Juan County Commission 

STATE OF UTAH 

Bigwater Town Council 

Blanding Chamber of Commerce 

City of Kanab 

Congressman Chris Cannon 

Congressman James Hansen 

Congressman Jim Matheson 

Garfield County Commission 

Garfield County Sheriff 

Governor 

Kane County Commission 

Kane County Travel Council 

Moab Area Travel Council 

San Juan County Commission 

San Juan County Sheriff 

Senator Orrin G. Hatch 

Senator Robert F. Bennett 

Utah Boating Coordinator 
CONSULTATION AND COORDINATION

298 GLEN CANYON NATIONAL RECREATION AREA

Utah Department of Environmental Quality, 

Division of Water Quality 

Utah Department of Natural Resources 

Utah Division of Parks and Recreation 

Utah Division of State History 

Utah Division of Wildlife Resources 

Utah NPS State Coordinator 

Utah State Historical Society 

Utah Travel Council 

Wayne County Commission 

STATE OF IDAHO 

Idaho Department of Parks and Recreation 

LIBRARIES 

Burton Barr Central Library, Phoenix, Arizona 

Denver Public Library, Colorado 

Flagstaff City – Coconino County Public 

Library, Arizona 

Mesa County Public Library District, Grand 

Junction, Colorado 

Page Public Library, Arizona 

Salt Lake City Public Library, Utah 

PARKS, MONUMENTS 

AND RECREATION AREAS 

Arches National Park 

Bryce National Park 

Canyonlands National Park 

Capitol Reef National Park 

Grand Canyon National Park 

Grand Canyon Parashant National Monument 

Grand Staircase Escalante National Monument 

Lake Mead National Recreation Area 

Natural Bridges National Monument 

Navajo National Monument 

Vermilion Cliffs National Monument 

Zion National Park 

BUSINESSES AND ORGANIZATIONS 

All American Boat & RV Storage 

Alpine PowerSports 

American Canoe Association 

American Watercraft Association 

Anchors Away Rental & Storage 

ARAMARK Lake Powell Resorts and Marinas 

B. B. Financial Benefits Group, Inc. 

B & T Marine 

Beautiful Lady House Boat, Inc. 

Big Water Boat Storage 

Blanding Chamber of Commerce 

Blue Ribbon Coalition 

Bluewater Network 

Bullfrog Clinic 

Bullhead 4 Wheelers, Inc. 

Charles Gustafson, P. C., Attorney at Law 

Chiropractic Associates, Inc. 

Dee’s Launch and Retrieval 

Deep Creek Recreation 

Desert Phantom, Inc. 

Desert Service Inc. 

DJ Rentals/Offshore Marina 

Donn's Boat Ship, Inc 

Doo Powell Inc. 

Escalante Wilderness Project 

Friends of Lake Powell 

Frontier Biomedical 

Glacier Guides, Inc. 

Glen Canyon Action Network 

Glen Canyon Institute 

Glen Canyon Natural History Association 

Grand Canyon Trust 

H20 Zone PWC Rentals & Repairs 

Hidden Canyon Kayak LLC 

High Desert Adventures 

Jerry's Marine Service 

John Wesley Powell Memorial Museum 

Lake Powell Chronicle 

Lake Powell Communications 

Lake Powell Kayak Adventures 

Lake Powell Magazine 

Lake Powell Marine 

Lake Powell Suites 

Lake Powell Waterworld 

Lake Powell Yacht Club 

Living Rivers 

Maverick Boat Services, Inc. 

MHF Enterprises 

Moab Area Travel Council 

Multiple Access Conservation Coalition 

National Marine Manufacturers Association 

National Park Foundation 

National Parks Conservation Association 
List of Recipients 

FINAL ENVIRONMENTAL IMPACT STATEMENT 299

North American Wild Sheep – Utah Chapter 

Old West Marine Service 

Outdoor Sports 

Page Chamber of Commerce 

Page Honda 

Paradise Valley Community College 

Personal Watercraft Industry Association 

Precision Die & Stamping Inc. 

River Runners for Wilderness 

Saco Management, Inc. 

Salt River Project, Navajo Generating Station 

San Juan Expeditions 

Sierra Club 

Sierra Club – Grand Canyon Chapter 

Sierra Club - Recreation Issues Committee 

Sierra Club – Utah Chapter 

Skylite Boat Rentals 

Steadman’s Recreation, Inc. 

Sundance Marine 

TAB Associates, Inc. 

Tracy Duepner Services 

Utah Shared Access Alliance 

Utah Travel Council 

Wet Desert WaterSports 

Wilderness Society, The
CONSULTATION AND COORDINATION

300 GLEN CANYON NATIONAL RECREATION AREA
List of Recipients 

FINAL ENVIRONMENTAL IMPACT STATEMENT 301

Appendixes 

Divider 

This page to be removed 

(Needs to be an odd page) 
CONSULTATION AND COORDINATION

302 GLEN CANYON NATIONAL RECREATION AREA

This page to be removed 

Back of divider 
FINAL ENVIRONMENTAL IMPACT STATEMENT 303

APPENDIX A 

PARTS OF THE SUPERINTENDENT’S COMPENDIUM, 2002

APPLICABLE TO PERSONAL WATERCRAFT 

Lees Ferry 

Personal Watercraft Use Below Glen Canyon Dam: The use of personal watercraft is prohibited on the waters 

of the Colorado River between Glen Canyon Dam and the downstream river boundary of Glen Canyon National 

Recreation Area where it adjoins Grand Canyon National Park. 

Determination: This closure will provide for the protection of environmental values and the avoidance of 

conflict among traditional visitor use activities. 

River Travel Upstream of Lees Ferry: River travel is prohibited upstream of the three closure buoys, 

approximately 1/4 mile downstream of Glen Canyon dam without a permit. A sign is posted on the shoreline on 

both sides of the river designating this closure. 

Determination: The area above the closure signs is closed due to safety and security reasons: The proximity to 

water releases from Glen Canyon dam, and the possibility of items being dropped from the bridge. Authorized 

concession, administrative and scientific work is permitted in the closure. Additionally this area is closed by 

33 Code of Federal Regulations (CFR) Part 165, National Security Closure. 

36 CFR SECTION 3.3 – BOATING AND WATER USE ACTIVITIES, PERMITS 

Vessels are prohibited from remaining within the lands and/or waters of Glen Canyon National Recreation Area 

for more than 30 consecutive days without a valid Boat Storage Agreement for a slip or buoy with an authorized 

concessioner. There must be a minimum break of 24 hours from the time the vessel leaves the recreation area 

until it re-enters. 

Private vessels over 75 feet in total length and 22 feet total beam are prohibited. For purposes of this section, 

total length and beam include all temporary and permanent appurtenances. Manually operated gangplanks 

designed for passenger boarding that retract flush with the hull when the vessel is underway will be exempted 

from the appurtenance clause. Total length will be determined by a straight line measurement from the foremost 

part of the vessel to the aftmost part of the vessel, measured end-to-end over the deck excluding sheet, and 

measured parallel to the centerline, with all appurtenances, (excluding gangplanks) in a fully extended position. 

Total beam will be determined by a straight-line measurement from the outermost sides of the vessel at its widest 

point with all appurtenances in a fully extended position. 

Determination: The 75 foot total length and 22 foot total beam are dictated by natural and/or design limitations 

of marinas, fairways, docks, slips, buoy fields, boat ramps, fueling and pumpout facilities. Vessels exceeding 

that length and/or beam pose potential safety hazards when operated in and around these areas. Specifically, 

those hazards include but are not limited to collision with a fixed object, collision with a floating object, and 

collision with another vessel or vessels. The hazards increase when these areas and facilities are congested with 

other vessel traffic and/or when weather conditions are less than favorable. Vessels equipped with auxiliary 

equipment such as bow/stern thrusters and camera systems can increase a vessel’s maneuverability, but do not 

necessarily mitigate the hazards. 

The term total length used in this section is not to be confused with the term length overall. Length overall does 

not include appurtenances such as bowsprits, rudders, outboard motor brackets, davits, booms, platforms, slides, 

handles, fittings, attachments, and extensions. Inclusion of moveable appurtenances in their fully extended, 

deployed, or operating configuration as part of the total measurement of the vessel will place a limit on the 

length of vessels that may be operated with such equipment deployed. Deployment of appurtenances may be 
APPENDIX A 

304 GLEN CANYON NATIONAL RECREATION AREA

intentional, particularly if the equipment was designed to be deployed while underway, or may be accidental, 

particularly if the equipment was not secured properly. Recent trends in recreational boat construction have led 

to some innovative additions to basic hull configurations and these additions can result in a vessel that is 

significantly longer than a vessel measurement that does not include appurtenances. The terms total length and 

total beam used in this section are derived from definitions found in Title 36 CFR section 183.3 

36 CFR SECTION 3.6 – PROHIBITED OPERATIONS 

All motorized vessels are prohibited from further upstream travel at the following areas: 

Escalante River at the confluence of Coyote Creek 

Determination: Allowing motorized watercraft to be operated up the Escalante Arm of Lake Powell to Coyote 

Creek will enable motorized visitors reasonable access to view Stevens Arch, a popular geological landmark and 

sightseeing attraction, as well as to hike nearby canyons — including Coyote Gulch. Areas upstream will 

subsequently maintain an atmosphere of quiet and solitude, qualities that backpackers and other backcountry 

hikers desire while visiting the area. Similarly, fragile riparian areas upstream will be protected from exceeding 

physical and social carrying capacities due to easy access by motorized watercraft. Also, river water quality will 

be protected from fuel spills or other discharges and additional human waste accumulations. 

Coyote Gulch is the most popular destination of backcountry hikers in the Escalante Canyons and most visitors 

to the canyon hike all the way to the Escalante River confluence. Allowing motorized watercraft traffic upstream 

to the Coyote confluence presents a reasonable accommodation of both categories of visitors to the vicinity. 

San Juan River at the Clay Hills pullout 

Colorado River at the base of Imperial Rapid 

Dirty Devil River at that point where measurable downstream current is encountered 

Except in instances of emergency circumstances directly affecting the health and safety of visitors, upstream 

motorized travel by all motorized vessels will be prohibited upstream from Clay Hills pullout on the San Juan 

River and Imperial Rapid on the Colorado River. Upstream-motorized vessel travel will be permitted on the 

Dirty Devil River along the entire length of the Dirty Devil Arm of the Lake to that point where measurable 

downstream current is encountered. 

Any motorized vessels on those open portions of the rivers will be subject to all other restrictions applicable to 

other river parties including, but not limited to, camping permit requirements, human waste sanitation, and 

campfires. 

Determination: The state of Utah has established the “last active rapid” on The Colorado River as the location 

where rafting parties are no longer required to wear Personal Flotation Devices at all times (Utah R651-215-12). 

Upstream-motorized running of rapids is an advanced boating skill that most visitors to the recreation area do not 

possess. Restricting motorized boating parties to areas below these rapids prevents visitors from endangering 

themselves to the unrecognized dangers inherent in running up rapids, and in doing so violating State PFD 

regulations should they not be wearing their life jackets. Boaters attempting to run upstream in these rapids pose 

a high risk to themselves and to downstream traffic. 

In the recent past the rapids have been the last active rapids on the Colorado River. Extreme fluctuation of the 

lake levels of Lake Powell could result in other “rapids” being present. For the sake of consistency this rapid will 

be considered the “last active rapid.” 
Parts of the Superintendent’s Compendium, 2002 Applicable to Personal Watercraft 

FINAL ENVIRONMENTAL IMPACT STATEMENT 305

Imperial Rapid has also been used by the commercial rafting companies as a location where they meet river trips 

with motorized vessels launched at Hite to tow the rafts across the flatwater sections to Hite. Restricting 

motorized travel below this point would alter this traditional use. 

Clay Hills is the traditional termination and pullout retrieval point for rafting parties on the San Juan River. 

Designating this point for prohibited upstream traffic will preclude recreational use conflicts. 

Operating a vessel in excess of 5 mph or creating a wake in the following areas is prohibited: 

– Within harbors as defined above, mooring areas, and wakeless areas 

– Within any other “No Wake” buoyed area 

– Rainbow Bridge National Monument 

Launching and retrieval of vessels is permitted at the following locations: 

– All public launch ramps 

– Vessels up to 25 feet at Lone Rock Beach may be launched at the designated area as signed in 

accordance with section 1.7. 

– The beach areas legally accessible by motor vehicles at the primitive camping area of Stanton Creek, 

Upper Bullfrog North, and Upper Bullfrog South 

– The San Juan River take-out at Clay Hills Crossing 

– The Red Canyon area 

– The Paiute Farms area 

– At Hite, from 300 feet upstream of the public launch ramp to 300 feet upstream of the marina 

houseboat loading dock 

– The Farley Canyon area 

– The White Canyon area 

Bullfrog and Halls Crossing Ferry Ramp or areas adjacent to the marina may be used only when authorized by 

the Superintendent or his/her designee. 

Determination: The above areas are public launch ramps specifically developed for vessel launching and 

retrieval or areas accessible by road which are beaches or other areas which are suitable for launching and 

retrieving boats and which do not suffer undue degradation of natural or cultural values as a result. 

Lone Rock Beach, an undeveloped launch area, has an angle of underwater slope that precludes the launching of 

vessels exceeding 25 feet in length. 

The use of ferry launch ramps or areas adjacent to marinas as additional launch and retrieval areas is intended to 

reduce occasional congestion or overcrowding at regular launch ramps. 
306 GLEN CANYON NATIONAL RECREATION AREA

APPENDIX B 

ARIZONA AND UTAH WATERCRAFT REGULATIONS 

APPLICABLE TO PERSONAL WATERCRAFT 

UTAH PERSONAL WATERCRAFT REGULATIONS 

73-18-13.5. Personal watercraft accidents — Investigation and report of operator security — Agency action if 

no security — Surrender of registration materials. 

(1) Upon request of a peace officer investigating an accident involving a personal watercraft, the operator 

of the personal watercraft shall provide evidence of the owner's or operator's security required under 

section 73-18c-301. 

(2) The peace officer shall record on a form approved by the division: 

(a) the information provided by the operator; 

(b) whether the operator provided insufficient or no information; and 

(c) whether the peace officer finds reasonable cause to believe that any information given is not 

correct. 

(3) The peace officer shall deposit all completed forms with the peace officer's agency, which shall forward 

the forms to the division no later than ten days after receipt. 

(4) (a) The division shall revoke the registration of a personal watercraft involved in an accident unless the 

owner or operator can demonstrate to the division compliance with the owner's or operator's security 

requirement of section 73-18c-301 at the time of the accident. 

(b) Any registration revoked may not be renewed for a period of one year following the date of 

revocation. 

(5) A person may appeal a revocation issued under subsection (4) in accordance with procedures 

established by the board by rule that are consistent with Title 63, Chapter 46b, Administrative 

Procedures Act. 

(6) (a) Any person whose registration is revoked under subsection (4) shall return the registration card and 

decals for the personal watercraft to the division. 

(b) If the person fails to return the registration materials as required, they shall be confiscated under 

section 73-18-13.6. 

(7) The board may make rules for the enforcement of this section. 

(8) In this section, “evidence of owner's or operator's security” includes any one of the following: 

(a) the operator's: 

(i) insurance policy; 

(ii) binder notice; 
Arizona and Utah Watercraft Regulations Applicable to Personal Watercraft 

FINAL ENVIRONMENTAL IMPACT STATEMENT 307

(iii) renewal notice; or 

(iv) card issued by an insurance company as evidence of insurance; 

(b) a copy of a surety bond, certified by the surety, which conforms to section 73-18c-102; 

(c) a certificate of the state treasurer issued under section 73-18c-305; or 

(d) a certificate of self-funded coverage issued under section 73-18c-306. 

Enacted by Chapter 348, 1997 General Session 

73-18-15.2. Minimum age of operators — Boating safety course for youth to operate personal watercraft. 

(1) (a) Except as provided in subsection (2), a person under 16 years of age may operate a motorboat on the 

waters of this state, if he is accompanied by a person who is at least 18 years of age. 

(b) A person under 16 years of age may operate a sailboat, if he is under the direct supervision of a 

person who is at least 18 years of age. 

(2) A person under 16 years of age and 12 years of age or older may operate a personal watercraft provided 

he: 

(a) is under the direct supervision of a person who is at least 18 years of age; 

(b) completes a boating safety course approved by the division; and 

(c) has in his possession a boating safety certificate issued by the boating safety course provider. 

(3) A person under 18 years of age and 16 years of age or older may operate a personal watercraft, if he: 

(a) completes a boating safety course approved by the division; and 

(b) has in his possession a boating safety certificate issued by the boating safety course provider. 

(4) A person required to attend a boating safety course under subsection (3)(a) need not be accompanied by 

a parent or legal guardian while completing a boating safety course. 

(5) No person may give permission to another person to operate a vessel in violation of this section. 

(6) As used in this section, “direct supervision” means oversight at a distance within which visual contact is 

maintained. 

(7) (a) The division may collect a fee not to exceed $12 from each person who takes the division's boating 

safety course to help defray the cost of the boating safety course. 

(b) Money collected from the fee collected under subsection (7)(a) shall be deposited in the Boating 

Account. 

Amended by Chapter 205, 1998 General Session 

73-18-15.3. Personal watercraft — Prohibition on operation between sunset and sunrise. 

A person may not operate a personal watercraft on the waters of this state between sunset and sunrise. 
APPENDIX B 

308 GLEN CANYON NATIONAL RECREATION AREA

Enacted by Chapter 205, 1998 General Session 

73-18-11. Regulation of muffling devices — The board shall adopt rules for the regulating of muffling devices 

on all vessels. 

Amended by Chapter 197, 1986 General Session 

ARIZONA PERSONAL WATERCRAFT REGULATIONS 

5-350. Personal watercraft; requirements for operation; definition 

A. A person shall not operate a personal watercraft unless each person aboard is wearing a wearable personal 

flotation device that is approved by the United States coast guard. 

B. A person who operates a personal watercraft that is equipped by the manufacturer with a lanyard type 

engine cutoff switch shall attach the lanyard to his body, clothing or personal flotation device as appropriate 

for the specific watercraft. 

C. A person shall not operate or knowingly allow another person to operate a personal watercraft under his 

ownership or control in a reckless or negligent manner endangering the life or property of another person. 

Prima facie evidence of reckless operation exists if the person commits two or more of the following acts 

simultaneously: 

1. Operates the personal watercraft within a zone of proximity to another watercraft closer than sixty feet 

unless both are leaving a flat wake or are traveling at a speed of five nautical miles per hour or less. 

2. Operates the personal watercraft within the vicinity of a motorboat in a manner that obstructs the 

visibility of either operator. 

3. Heads into the wake of a motorboat that is within a zone of proximity closer than sixty feet and causes 

one-half or more of the length of the personal watercraft to leave the water. 

4. Within a zone of proximity to another watercraft closer than sixty feet, maneuvers quickly, turns 

sharply or swerves, unless the maneuver is necessary to avoid a collision. 

D. If equipped by the manufacturer, a person shall not operate a personal watercraft without a functioning 

spring-loaded throttle mechanism that immediately returns the engine to an idle speed on release of the 

operator's hand from the control or without any other engine cutoff feature that is installed by the 

manufacturer. 

E. A personal watercraft shall not be loaded and operated with passengers or cargo beyond its safe carrying 

capacity or the manufacturer's recommended limits. 

F. A person who owns, leases or hires a personal watercraft or who has charge or control over a personal 

watercraft shall not authorize or knowingly permit the personal watercraft to be operated in violation of this 

section. 

G. This section does not apply to a performer who engages in a professional exhibition or to a person who 

participates in an officially sanctioned regatta, race, marine parade, tournament or exhibition. 

H. For purposes of this section, “personal watercraft” means a watercraft that is less than sixteen feet long, 

propelled by machinery powering a water jet pump and designed to be operated by a person who sits, stands 

or kneels on rather than sitting or standing inside the watercraft. 
Arizona and Utah Watercraft Regulations Applicable to Personal Watercraft 

FINAL ENVIRONMENTAL IMPACT STATEMENT 309

5-336. Muffling devices 

A. Every motor driven watercraft shall at all times be equipped with effective equipment, in good working 

order and in constant operation, to prevent excessive or unusual noise except as provided in subsection C. 
310 GLEN CANYON NATIONAL RECREATION AREA

APPENDIX C 

PROPOSED PILOT STUDY TO RESEARCH SOCIAL CONDITIONS 

IN SUPPORT OF A LAKE MANAGEMENT PLAN 

Glen Canyon National Recreation Area proposed to conduct a three-year pilot study that would evaluate the 

effects of visitor conflicts between boat users in the several areas with the associated management actions 

outlined below. The purpose of the pilot study would be to test whether certain management actions would 

mitigate visitor conflict issues such as complaints about noise, reckless driving (speed and proximity), and erratic 

use around campsite areas at unusual hours. Canyon and bay area sites where the pilot study would be conducted 

would be selected using five criteria: 

Close proximity to a launch ramp and/or marina. Law enforcement cannot expend resources responding 

long distances away from duty stations unless it is for emergency response Therefore, closer locations 

would be selected for better enforceability. The sites also would be chosen to facilitate visitor access. 

Shoreline camping opportunities. Locations would be selected that exhibited both large numbers of 

shoreline access and limited shoreline access for camping. 

High visitation sites. Perceived high visitation sites are likely to have greater potential for visitor conflicts. 

The more visitors that will use these study areas, the more data that may be collected and the greater 

potential for conflict. 

Safety. Although safety is not a major problem at Glen Canyon National Recreation Area, it would not 

hurt to designate areas wakeless that are already geographically challenging to maneuver through due to 

their narrowness and high use. 

Geography and Closure Points. Closure points would need to be placed in areas that geographically 

facilitate the posting of wakeless or non-motorized zones. Locations would be selected where a fairly 

clear distinction could be made from where the zones started and sign posting could be accomplished 

effectively. 

A geographic information systems or UTM coordinates would be provided to show approximate location of 

wakeless and non-motorized areas. These exact locations would be determined on a seasonal basis by the 

recreation area, while taking into account present and fluctuating lake levels. A large education campaign to 

advertise or publish these areas would be proposed. The education and outreach program would include, but 

would not be limited to: 

Flyers at all entry gates and visitor centers 

Webpage flyer 

Bulletin boards at marina launch sites 

Article in annual recreation area newspaper 

Press releases 

Weekly local radio spots 

Interpretative talk at Wahweap/Bullfrog campgrounds explaining pilot study 

Education and interaction with visitors at the launch ramps 
Proposed Pilot Study to Research Social Conditions in Support of a Lake Management Plan 

FINAL ENVIRONMENTAL IMPACT STATEMENT 311

The actions proposed in the pilot study would be included in the personal watercraft rule-making environmental 

impact statement, but not the special rule. If necessary, the special rule would address the pilot study in theory, 

but would not address specific locations on Lake Powell. 

In the absence of a comprehensive lake management plan with several years of baseline data, it is very difficult 

to select specific areas of Lake Powell to apply certain management actions without further analysis. Glen 

Canyon National Recreation Area has collected baseline data for air, water and noise analyses and plans to 

continue to collect data to solidify its understanding of baseline resource conditions in these areas. However, 

very little information exists on visitor use, experience and conflict in regards to specific areas on Lake Powell. 

A visitor use and experience survey was conducted in fiscal year 2000 to collect data on WHAT some of the 

visitor conflicts are in relation to personal watercraft use on the Lake, WHO (type of user) are experiencing the 

conflicts and WHY the conflicts exist. However, little information was collected on WHEN and WHERE they 

are occurring or HOW to resolve the conflicts. A pilot study that tests specific management actions in certain 

locations for specific scientific purposes to carefully analyze hypotheses and reactions of the visitors to these 

actions would provide significant information and insight to better management practices at effective location 

areas. 

The results of the pilot study would provide essential social data and visitor use and experience information to 

include in a lake management plan and to apply adaptive management principles to areas on Lake Powell to 

enhance and maximize a positive experience for all recreational users. During the three-year study period, areas 

or locations, as well as different types of management action may be applied as required to effectively collect 

social condition data and maximize visitor experience. 

At the end of the three-year pilot study, it would be anticipated that recreation area managers would have enough 

information to make informed decisions regarding permanent management actions that may be applied to areas 

on Lake Powell. 

The following provides a sample of the criteria and logic that would be used initially to determine the pilot study 

locations and proposed management actions. It is only a preliminary outline that will be developed over time 

after additional interviews are conducted and further analysis of how current lake elevations have affected the 

shoreline conditions that visitors relay on for beach recreation and camping. The sites referenced are only used to 

outline how the criteria will be applied to later select the study locations. 

The purpose of the following text is to provide a sample of the logic that would be used to select specific areas 

on Lake Powell for the pilot study. These sites may or may not be selected, based on the data and information 

that is on hand at the time of the selection process. Glen Canyon National Recreation Area anticipates 

conducting additional interviews with staff and other agencies with a presence on the lake to gain further insight 

for determining the best study locations. 

Last Chance Bay: The far reaches of this canyon would be designated wakeless to all vessel traffic. All vessels 

would be authorized use, but only while wakeless, in the back quarter of this very large canyon. This canyon is 

located in close proximity to the Wahweap and Antelope Point launch ramps and provides some of the best 

hiking, back canyon sight-seeing and shoreline camping opportunities. The mouth of this canyon area is heavily 

used by all vessels, particularly for water sports such as skiing, however, the back end of the canyon usually does 

not receive quite as much visitation. The concept of allowing a wakeless use area for all vessels would test 

whether all users can recreate without the conflicts associated with some personal watercraft use, i.e. the thrillseeker types of personal watercraft users. Wakeless zones would eliminate the speed, maneuverability and noise 

issues associated with the primary complaints non-users have. The visitor survey indicated that those that do not 

like personal watercraft, generally state it is because of noise, feeling unsafe, their maneuverability 

(unpredictability) and their use after what is considered regular use hours. This action would test the hypothesis 

that if a personal watercraft is wakeless, all the characteristics associated with personal watercraft use would no 

longer exist. 
APPENDIX C 

312 GLEN CANYON NATIONAL RECREATION AREA

Rock Creek Bay: Same theory would be tested in this canyon, only less shoreline access and fewer camping 

sites exist. The far reaches of this canyon are more narrow. This location would provide another option for users 

from the Wahweap/Antelope Point access areas to coexist. A wakeless area would be designated for the back 

third of the canyon. 

North Gulch and Moqui Canyon: North Gulch and Moqui are extremely popular canyons for uplake visitors, 

usually originating from either Bullfrog or Halls Crossing. Again, the same theory would be applied to these 

areas as at Last Chance, wakeless only for all vessels. These areas have ruins and petroglyphs in the back of their 

canyons, which make them very popular hiking and day use targets. These canyons are also popular for camping 

and water sports such as skiing. 

Knowles Canyon: Knowles Canyon has been closed to all motorized traffic for over a year for purposes of 

conducting scientific studies (control canyon). This canyon is also in the Bullfrog/Halls Crossing region. The 

entire Knowles Canyon would be designated non-motorized, restricting access to all motorized vessels. Only 

non-motorized vessels would be allowed in this canyon. This action would test the feasibility and public 

acceptability of canyons with non-motorized vessel access only. It would also continue to serve as a control 

canyon for resource monitoring activities in support of water quality and other similar studies. 

Hite Area: Actions may not be proposed in the Hite area due to previous management actions identified for 

Cataract Canyon and the Dirty Devil River, both in close proximity to the Hite Area. Also, the Hite area has very 

little personal watercraft use relative to the rest of the lake. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 313 

APPENDIX D 

RESULTS OF SAMPLING AND SURVEYS 

D.1: Water Quality 2001 Sample Results 

The National Park Service conducted water quality testing at Glen Canyon National Recreation Area to 

determine the concentrations of hydrocarbons in Lake Powell. Samples were taken over a 4-day period from 

June 29, 2001 through July 2, 2001. This period was selected because it represents a high-use period by 

motorcraft, including personal watercraft. 

Sample areas were chosen to capture different levels of motorboat use. They included: 

An open-water area in Wahweap Bay. 

An area closed to all motor vessel access (control area) at Knowles Canyon. 

A busy marina with fueling station at Bullfrog. 

A high-boat-use area at Moqui (sometimes spelled Moki) Canyon. 

Three locations were sampled at each test site, and samples were acquired from two depths. A total of 

27 samples were obtained. At each site: 

A 0.5-meter-deep (about 20 inches) sample was collected to represent the near-surface conditions where 

lighter-weight contaminants, such as benzene, would presumably concentrate. 

A 3-meter-deep (about 10 feet) sample was collected based on research at Lake Tahoe that found 

complete mixing of polycyclic aromatic hydrocarbon contaminants at this level (NPS, Vanmouwerik, 

pers. com., May 2002). 

Analyses were performed by the State of Utah, The Woods Hole Group, Inc., and the U.S. Geologic Survey 

research laboratories. 

Table D.1.1 presents results from the State of Utah and U.S. Geologic Survey 

Table D.1.2 presents results from the Woods Hole Group, Inc. 

Table D.1.3 presents results from the State of Utah and U.S. Geologic Survey 

Table D.1.4 presents results from The Woods Hole Group, Inc. 

The summer 2001 water quality sampling does not provide a complete characterization of hydrocarbon 

contamination of Lake Powell. The results are only a “snapshot” of hydrocarbon levels in the lake’s waters on 

the days of testing. However, in the absence of more complete data, they are useful for indicating current 

conditions. 
314 GLEN CANYON NATIONAL RECREATION AREA Area sampled date, time Parameter Reporting Limit

equipment 

blank, day 1

W1-.5m

W1-3m

W2-.5m

W2-.5m dup

W2-3m

W3-.5m

W3-3m

equipment 

blank, day 2

K1-.5m

K1-3m

K2-.5m

K2-3m

K3-.5m

K3-.5m dup

water and 

organsms organisms only

 (μg/L) (μg/L)

temperature (deg. F) -- -- -- -- 78.9 75.3 76.9 -- 75.9 78.2 78.0 -- -- 79 81.8 79.5 81.6 -- 

(St. of UT lab results)benzene 0.5 μg/L 1.2 71 U NA 0.8 0.8 f 1.1 0.7 J 0.8 U NA U U U U g toluene 0.5 μg/L 6,800 200,000 U NA 2.6 2.8 f 2.6 2.4 2.9 U NA U U U U g ethylbenzene 0.5 μg/L 3,100 29,000 U NA J 0.3 J 0.3 f J 0.3 J 0.3 J 0.4 U NA U U U U g xylenes 0.5 μg/L na na U NA 2.2 2.2 f 2.5 2.1 2.4 U NA U U U U g naphthalene 1.0 μg/L na na U NA U U f U U U U NA U U U U g MTBE a 1.0 μg/L na na U NA J 0.8 1.3 f 1.5 J 0.5 J 0.6 J 0.3 NA U U U U g 

1,3,5 trimethylbenzene 0.5 μg/L U U U U f U U U U NA U U U U g 1,2,4 trimethylbenzene 0.5 μg/L U U 1.1 1.4 f 0.6 0.5 0.6 U NA U U U U g (USGS-NJ lab results)Benzene 0.035 μg/L 1.2 71 NA 0.954 NA NA NA NA NA NA NA U NA NA NA NA NA 

Toluene 0.05 μg/L 6,800 200,000 NA 3.56 NA NA NA NA NA NA NA 0.102 NA NA NA NA NA Ethylbenzene 0.030 μg/L 3,100 29,000 NA 0.677 NA NA NA NA NA NA NA U NA NA NA NA NA m- and p-Xylene 0.06 μg/L na na NA 2.85 NA NA NA NA NA NA NA U NA NA NA NA NA o-Xylene 0.038 μg/L na na NA 1.06 NA NA NA NA NA NA NA U NA NA NA NA NA MTBE a 0.17 μg/L na na NA 0.620 NA NA NA NA NA NA NA U NA NA NA NA NA 

ETBE b 0.054 μg/L na na NA U NA NA NA NA NA NA NA U NA NA NA NA NA 

TAME c 0.11 μg/L na na NA U NA NA NA NA NA NA NA U NA NA NA NA NA 

DIPE d 0.10 μg/L na na NA U NA NA NA NA NA NA NA U NA NA NA NA NA TBA e 1.0 μg/L na na # # # U # # 

Footnotes:a - Methyl tert-butyl etherb - Ethyl tert-butyl ether c - tert-amyl methyl ether d - Diisopropyl ethere - tert-butyl alcoholg - bottles broken in transit.h - trace levels detected.na - criterium not available (does not exist).

NA - "not applicable" because this sample not collected for this lab to analyze.

 6/29/01, 4 - 6:15 pm 7/2/01, 9am >|

State of Utah numeric criteria for use 

designation 1C

f - duplicate sample never received by lab; either not collected or lost.

 Knowles Canyon 

 6/30/01, 12 - 5:50pm

J - Estimated value, below the reporting limit.

U - this analyte was analyzed for but not detected at the reporting limit concentration.

 Wahweap Bay

TABLE D.1.1: BTEX AND 

ANALYTICAL 

RESULTS FOR 

LAKE 

POWELL 

WATER 

SAMPLES

(ALL 

UNITS IN μG/L, OR 

PARTS PER 

BILLION). RESULTS 

EXCEEDING 

CRITERIA 

ARE IN 

BOLD FONT
FINAL 

ENVIRONMENTAL MPACT ISTATEMENT 315

TABLE D.1.2: PAH ANALYTICAL RESULTS FOR LAKE POWELL WATER SAMPLES

ALL UNITS IN NG/L, OR PARTS PER TRILLION) 

Area sampled

date, time

Parameter

Reporting 

Limit

equipment 

blank, day 1

W1-.5m

W1-3m

W2-.5m

W2-.5m dup

W2-3m a

W3-.5m

W3-3m

equipment 

blank, day 2

K1-.5m

K1-3m

K2-.5m

K2-3m

K3-.5m

K3-.5m dup

water and 

organisms organisms only

(ng/L) (ng/L)

temperature (degrees F) -- -- -- -- 78.9 75.3 76.9 -- 75.9 78.2 78.0 -- -- 79.3 81.8 79.5 81.6 -- (Woods Hole lab results)naphthalene 10 or 11ng/L na na U 170 140 120 130 100 150 180 J 9.0 J 7.4 J 7.2 U J 6.9 J 5.4 J 7.7 2-methylnaphthalene 10 or 11ng/L na na U 120 93 78 92 65 100 120 U U U U U U U 1-methylnaphthalene 10 or 11ng/L na na U 59 50 39 48 35 52 59 U U U U U U U biphenyl 10 or 11ng/L na na U U U U U U U U U U U U U U U 2,6-dimethylnaphthalene 10 or 11ng/L na na U 12 J 9.3 J 9.7 11 J 8.4 12 12 U U U U U U U acenaphthylene 10 or 11ng/L na na U J 7.1 J 8.1 J 6.6 J 6.6 J 5.9 J 7.8 J 7.7 U U U U U U U acenaphthene 10 or 11ng/L 1,200,000 2,700,000 U U U U U U U U U U U U U U U flourene 10 or 11ng/L 1,300,000 14,000,000 U U U U U U U U U U U U U U U 2,3,5-trimethylnaphthalene 10 or 11ng/L na na U U U U U U U U U U U U U U U phenanthrene 10 or 11ng/L na na U J 11 J 8.8 J 8.3 J 7.5 J 8.9 J 8.9 J 8.0 U U U U U U U anthracene 10 or 11ng/L 9,600,000 na U U U U U U U U U U U U U U U 1-methylphenanthrene 10 or 11ng/L na na U U U U U U U U U U U U U U U fluoranthene 10 or 11ng/L 300,000 370,000 U U U U U U U U U U U U U U U pyrene 10 or 11ng/L 960,000 11,000,000 U U U U U U U U U U U U U U U benz[a]anthracene 10 or 11ng/L 2.8 31 U U U U U U U U U U U U U U U chrysene 10 or 11ng/L 2.8 31 U U U U U U U U U U U U U U U benzo[b]fluoranthene 10 or 11ng/L 2.8 31 U U U U U U U U U U U U U U U benzo[k]fluoranthene 10 or 11ng/L 2.8 31 U U U U U U U U U U U U U U U benzo[e]pyrene 10 or 11ng/L na na U U U U U U U U U U U U U U U benzo[a]pyrene 10 or 11ng/L 2.8 31 U U U U U U U U U U U U U U U perylene 10 or 11ng/L na na U U U U U U U U U U U U U U U indeno[1,2,3-cd]pyrene 10 or 11ng/L 2.8 31 U U U U U U U U U U U U U U U dibenz[a,h]anthracene 10 or 11ng/L 2.8 31 U U U U U U U U U U U U U U U benzo[g,h,i]perylene 10 or 11ng/L na na U U U U U U U U U U U U U U U Footnotes:a - the reporting limit for this sample was 12 ng/L.b - bottle broken in transitna - criterium not available (does not exist)J - Estimated value, below the reporting limit.U - this analyte was analyzed for but not de-

 Knowles Canyon 

 tected at the reporting limit concentration.

State of Utah numeric criteria for 

use designation 1C

 6/29/01, 4 - 6:15 pm 7/2/01, 9am 6/30/01, 12 - 5:50pm 

 Wahweap Bay
316 GLEN CANYON NATIONAL RECREATION AREA

TABLE D.1.3. BTEX AND 

ANALYTICAL 

RESULTS FOR 

LAKE 

POWELL, RESULTS 

EXCEEDING 

CRITERIA ARE IN 

BOLD FON

Water Depth

temperature 

(deg. F)

benzene 

(ug/L)

toluene 

(ug/L)

ethylbenzene 

(ug/L)

xylenes 

(ug/L)

naphthalene 

(ug/L)

MTBE a 

(ug/L)

1,3,5 

trimethylbenzene 

(ug/L)

1,2,4 

trimethylbenzene 

(ug/L) Benzene (ug/L)

Toluene 

(ug/L) 

Et

(

1.2 6,800 3,100 na na na 1.2 6,800 3

71 200,000 29,000 na na na 71 200,000 2

0.5 0.5 0.5 0.5 1 1 0.5 0.5 0.035 0.05 0

Wahweap Bay

equipment blank, day 1 -- U U U U U U U U NA NA 

W1-.5m 78.9 NA NA NA NA NA NA U U 1.0 3.6 

W1-3m 75.3 0.8 2.6 J 0.3 2.2 U J 0.8 U 1.1 NA NA 

W2-.5m 76.9 0.8 2.8 J 0.3 2.2 U 1.3 U 1.4 NA NA 

W2-.5m dup -- f f f f f f f f NA NA 

W2-3m 75.9 1.1 2.6 J 0.3 2.5 U 1.5 U 0.6 NA NA 

equipment blank, day 2 -- U U U U U J 0.3 U U NA NA 

W1-.5m -- NA NA NA NA NA NA NA NA U 0.102 

W1-3m 79.3 U U U U U U U U NA NA 

W2-.5m 81.8 U U U U U U U U NA NA 

W2-3m 79.5 U U U U U U U U NA NA 

W2-.5m 81.6 U U U U U U U U NA NA 

W2-.5m dup -- g g g g g g g g NA NA 

W2-3m 78.8 U U U U U U U U NA NA 

equipment blank, day 3 -- NA NA NA NA NA NA NA NA U J 0.08 

BM1-.5m 79.8 NA NA NA NA NA NA NA NA 3.43 10.25 

BM1-3m 79.0 1.6 3.9 J 0.4 2.8 U J 0.5 J 0.3 0.5 NA NA 

BM2-.5m 79.2 1.4 3.2 J 0.3 2.2 U J 0.4 U 0.5 NA NA 

BM2-3m 78.3 0.8 1.4 U 1.0 U J 0.3 U U NA NA 

BM3-.5m 79.3 2.3 6.1 0.7 4.7 U J 0.8 0.5 1.2 NA NA 

BM3-.5m dup -- 2.3 6.1 0.7 4.6 U J 0.8 J 0.4 1.2 NA NA 

BM3-3m -- 1.1 2.4 U 1.6 U J 0.3 U J 0.3 NA NA 

M1-.5m -- NA NA NA NA NA NA NA NA 0.755 1.68 0

M1-3m 77.5 J 0.3 J 0.4 U J 0.3 U J 0.9 U U NA NA 

M2-.5m 74.6 1.9 2.6 J 0.3 3.3 U J 0.9 J 0.4 1.0 NA NA 

M2-3m 77.8 1.6 1.8 U 2.3 U J 0.8 U J 0.3 NA NA 

M3-.5m 79.9 2.0 4.1 J 0.5 3.2 U 1.2 J 0.3 J 0.6 NA NA 

M3-3m 77.4 1.4 1.9 J 0.3 1.6 U 1 U U NA NA 

Footnotes:b - Ethyl tert-butyl ether d - Diisopropyl ethere - tert-butyl alcohol

Bullfrog MarinaMoki Canyon

h - trace levels detected.

State of Utah Lab Results

Reporting Limit

State of Utah numeric criteria for use 

designation 1C - Water and organisms 

(ug/L)

State of Utah numeric criteria for use 

designation 1C - Organisms only (ug/L)

a - Methyl tert-butyl ether

Knowles Canyon

na - criterium not available (does not exist).NA - "not applicable" because this sample not collected for this lab to analyze.c - tert-amyl methyl ether g - bottles broken in transit.

f - duplicate sample never received by lab; either not collected or lost

J - Estimated value, below the reporting limit.U - this analyte was analyzed for but not detected at the reporting limit concentration.
FINAL 

ENVIRONMENTAL MPACT ISTATEMENT 317

TABLE D.1.4. PAH ANALYTICAL RESULTS FOR LAKE POWELL WOODS HOLE LAB RESULTS

Water Depth temperature (degrees F)

naphthalene 

(ug/L)

2-methylnaphthalene 

(ug/L)

1-methylnaphthalene 

(ug/L) biphenyl (ug/L)

2,6-dimethylnaphthalene 

(ug/L)

acenaphthylene 

(ug/L)

na na na na na na na na na na na na 

10000 or 11000 10000 or 11000 10000 or 11000 10000 or 11000 10000 or 11000 10000 or 11000 

equipment blank, day 1 -- U U U U U U 

W1-.5m 78.9 170000 120000 59000 U 12000 J 7000.1 

W1-3m 75.3 140000 93000 50000 U J 9000.3 J 8000.1 

W2-.5m 76.9 120000 78000 39000 U J 9000.7 J 6000.6 

W2-.5m dup -- 130000 92000 48000 U 11000 J 6000.6 

W2-3m a 75.9 100000 65000 35000 U J 8000.4 J 5000.9 

W3-.5m 78.2 150000 100000 52000 U 12000 J 7000.8 

W3-3m 78.0 180000 120000 59000 U 12000 J 7000.7 

equipment blank, day 2 -- J 9000.0 U U U U U 

K1-.5m -- J 7000.4 U U U U U 

K1-3m 79.3 J 7000.2 U U U U U 

K2-.5m 81.8 U U U U U U 

K2-3m 79.5 J 6000.9 U U U U U 

K3-.5m 81.6 J 5000.4 U U U U U 

K3-.5m dup -- J 7000.7 U U U U U 

K3-3m 78.8 J 5000.9 U U U U U 

equipment blank, day 3 -- 13000 U U U U U 

BM1-.5m 79.8 400000 240000 140000 J 9000.5 34000 24000 

BM1-3m 79.0 51000 21000 14000 U U U 

BM2-.5m 79.2 120000 56000 33000 U J 8000.0 J 9000.2 

BM2-3m 78.3 14000 U U U U U 

BM3-.5m 79.3 250000 130000 73000 J 6000.1 19000 22000 

BM3-.5m dup -- 210000 100000 60000 J 5000.1 15000 16000 

BM3-3m -- 27000 J 6000.7 U U U U 

M1-.5m -- J 8000.0 U U U U U 

M1-3m 77.5 J 8000.1 U U U U U 

M2-.5m 74.6 b b b b b b 

M2-3m 77.8 70000 27000 18000 J 5000.4 J 7000.2 U 

M3-.5m 79.9 130000 68000 39000 U 13000 J 6000.5 

M3-3m 77.4 47000 18000 11000 U U U 

Reporting Limit

State of Utah numeric criteria for use designation 1C - Water and organisms 

(ug/L)

State of Utah numeric criteria for use designation 1C - Organisms only (ug/L)

Wahweap BayKnowles CanyonBullfrog MarinaMoki Canyon
318 GLEN CANYON NATIONAL RECREATION AREA D.1.4: (CONTINUED) Water Depth 2,3,5-trimethyl- naphthalene (ug/L) phenanthrene (ug/L) anthracene (ug/L) 1-methyl- phenanthrene (ug/L) fluoranthene (ug/L) pyrene (ug/L) benz[a] anthracene (ug/L) chrysene (ug/L) 

State of Utah numeric criteria for use designation 1C - Organisms only (ug/L) na na 9,600,000 na 300,000 960,000 2.8 2.8 

State of Utah numeric criteria for use designation 1C - Organisms only (ug/L) na na na na 370,000 11,000,000 31 31 

Reporting Limit 10000 or 11000 10000 or 11000 10000 or 11000 10000 or 11000 10000 or 11000 10000 or 11000 10000 or 11000 10000 or 11000 1

Wahweap Bay equipment blank, day 1 U U U U UUU U 

W1-.5m U J 11000 U U U U U U 

W1-3m U J 8000.8 U U U U U U 

W2-.5m U J 8000.3 U U U U U U 

W2-.5m dup U J 7000.5 U U U U U U 

W2-3m a U J 8000.9 U U U U U U 

W3-.5m U J 8000.9 U U U U U U 

W3-3m U J 8000.0 U U U U U U 

Knowles Canyon equipment blank, day 2 U U U U UUU U 

K1-.5m U U U U U U U U 

K1-3m U U U U U U U U 

K2-.5m U U U U U U U U 

K2-3m U U U U U U U U 

K3-.5m U U U U U U U U 

K3-.5m dup U U U U U U U U 

K3-3m U U U U U U U U 

Bullfrog Marina equipment blank, day 3 U U U U UUU U 

BM1-.5m 15 19000 U U J 9000.7 J 9000.2 U U 

BM1-3m U J 5000.9 U U U U U U 

BM2-.5m U J 6000.4 U U U U U U 

BM2-3m U U U U U U U U 

BM3-.5m J 7000.3 12000 U U J 6000.5 J 5000.7 U U 

BM3-.5m dup J 5000.7 J 9000.0 U U J 5000.8 J 5000.1 U U 

BM3-3m U U U U U U U U 

Moki Canyon M1-.5m U U U U J 7000.1 U U U 

M1-3m U U U U J 7000.0 U U U 

M2-.5m b b b b b b b b 

M2-3m J 5000.5 J 6000.8 U U J 6000.6 U U U 

M3-.5m U J 7000.9 U U J 6000.5 U U U 

M3-3m U U U U U U U U 

Footnotes: a - the reporting limit for this sample was 12000 ug/L. b - bottle broken in transit na - criterium not available (does not exist) J - Estimated value, below the reporting limit. U - this analyte was analyzed for but not detected at the reporting limit concentration.
FINAL ENVIRONMENTAL IMPACT STATEMENT 319

D.2: RESPONSES TO VISITOR USE SURVEY 

In 2000, the National Park Service contracted with the University of Minnesota to conduct visitor surveys on 

Lake Powell. Questionnaires were distributed to watercraft users that asked about travel patterns, length of trip, 

group characteristics, types of watercraft used, attitudes towards the quality of their trip, conditions encountered 

on the lake, and potential management actions. The results were published in the Final Report: Visitor Use at 

Glen Canyon National Recreation Area, Comparison of personal watercraft Users and Nonusers, Summer 2000 

Data Collection (James et al. 2001a). 

The information from the questionnaires and report was used in the “Visitor Use and Experience” sections in the 

“Affected Environment” and “Environmental Consequences” chapters. Responses to four of the questions that 

are most relevant to the management of personal watercraft are provided in the tables in this appendix. 
320 GLEN CANYON NATIONAL RECREATION AREA

TABLE D.2.1: RESPONSE TO “INDICATE HOW IMPORTANT EACH EXPERIENCE WAS TO YOU ON YOUR MOST RECENT VISIT TO THE 

Percent of All Respondents 

by Response Categorya

Personal Watercraft 

Operators 

Experienceb N Mean 1 2 3 4 5 N Mean To enjoy the scenery of Lake Powell 184 4.5 4 0 3 23 70 93 4.5 To do something with my familyc 179 4.4 6 2 7 14 71 88 4.7 To get away from the usual demands of life 178 4.4 2 2 6 32 59 91 4.5 To be with members of my group 171 4.2 4 5 13 28 52 87 4.3 To be with people who enjoy same things I do 177 4.2 4 3 13 33 47 90 4.3 To experience nature 176 4.1 3 5 11 40 42 87 4.2 To experience natural quiet 178 4.0 3 5 17 43 33 88 4.0 To participate in recreational activities 175 4.0 4 8 11 37 40 88 4.0 To relax physically 181 4.0 3 4 14 43 36 91 4.1 To be close to nature 173 3.9 3 5 18 45 30 88 4.0 To use my own equipment 177 3.8 8 8 14 37 34 88 4.0 To have thrills and excitement 177 3.8 6 3 27 35 31 90 3.9 To stargaze 178 3.7 5 10 23 42 22 89 3.8 To be away from other people 173 3.7 5 11 22 36 25 87 3.7 To feel healthier 175 3.7 4 3 32 37 24 89 3.9 To experience solitude 172 3.6 5 8 31 36 22 86 3.5 To experience an undeveloped lake 168 3.5 7 14 29 29 22 83 3.5 

To experience new and different things 174 3.5 5 12 25 41 17 89 3.5 To think about my personal values 175 3.5 5 11 36 30 18 87 3.4 To get exercise 179 3.5 6 10 30 38 17 90 3.5 To learn about the cultural history of the area 175 3.4 5 11 31 40 10 87 3.3 To be on my own 177 3.3 9 20 26 30 11 88 3.3 To test my skills and abilities 176 3.2 6 18 36 31 17 89 3.1 To share my skill and knowledge with others 176 3.2 8 12 47 22 9 87 3.2 To challenge myself 174 3.1 8 18 40 23 11 87 3.1 To be creative by doing something such as sketching, painting, taking photographs 

169 2.8 18 21 34 18 8 85 2.7 
FINAL 

ENVIRONMENTAL MPACT ISTATEMENT 321

Percent of All Respondents 

by Response Categorya

Personal Watercraft 

Operators 

Experienceb N Mean 1 2 3 4 5 N Mean 

To meet new people 175 2.6 21 26 35 13 6 88 2.6 To participate in ranger-led activities 174 2.1 35 30 31 3 1 88 2.0 Source: Mail-back survey, Question 2. a. Rank ordered by mean importance scores for total sample respondents. b. Responses based on a 5-point scale:  1 = very unimportant  2 = unimportant  3 = neither unimportant or important  4 = important  5 = very important. c. Bold font = differences between groups are statistically significant at the p<0.05 level.
322 GLEN CANYON NATIONAL RECREATION AREA

TABLE D.2.2: RESPONSE TO “FOR EACH EXPERIENCE FOR WHICH YOU CIRCLED EITHER A 4 OR 5, 

PLEASE INDICATE HOW MUCH YOU WERE ABLE TO ATTAIN EACH OF THOSE EXPERIENCES” 

Percent of All Respondents 

by Response Categorya

Personal 

Watercraft 

Operators 

Experienceb N Mean 1 2 3 4 N Mean 

To be with members of my group 117 3.9 0 0 14 86 63 3.8 To do something with my family 133 3.8 1 3 14 83 71 3.8 To be with people who enjoy same things I do 126 3.8 0 4 17 79 63 3.8 To enjoy the scenery of Lake Powell 150 3.8 0 3 15 83 73 3.8 To use my own equipment 112 3.7 0 7 17 76 56 3.7 To stargaze 95 3.7 1 4 22 73 50 3.7 To participate in recreational activities 123 3.6 0 7 29 64 62 3.6 To be close to nature 112 3.5 0 5 45 50 57 3.5 To get away from the usual demands of life 141 3.5 1 6 31 61 73 3.6 To have thrills and excitement 100 3.5 0 6 38 56 55 3.5 To experience nature 123 3.4 1 12 37 50 59 3.4 To test my skills and abilities 57 3.4 0 7 51 42 24 3.3 To think about my personal values 70 3.4 1 4 47 47 32 3.4 To get exercise 86 3.4 1 9 42 48 44 3.3 To share my skill and knowledge with others 46 3.4 0 4 52 44 20 3.4 To feel healthier 90 3.4 0 13 37 50 45 3.4 To be creative by doing something such as sketching, painting, taking photographs 

38 3.3 0 13 42 45 17 3.2 

To relax physically 122 3.3 2 7 46 45 62 3.4 To experience an undeveloped lake 78 3.2 3 21 33 44 37 3.1 To experience new and different things 83 3.2 2 16 43 39 42 3.1 To challenge myself 52 3.2 0 14 56 31 26 3.2 To experience natural quiet 117 3.1 5 23 33 33 61 3.1 To be on my own 69 2.9 4 23 42 42 32 3.1 To learn about the cultural history of the area 72 2.9 6 25 44 44 28 3.1 To learn about the natural history of the area 83 2.9 4 24 51 51 35 3.0 To participate in ranger-led activities 7 2.9 29 0 29 29 1 4.0 To be away from other people 94 2.9 10 20 39 39 48 3.0 
FINAL 

ENVIRONMENTAL MPACT ISTATEMENT 323

Percent of All Respondents 

by Response Categorya

Personal 

Watercraft 

Operators 

Experienceb N Mean 1 2 3 4 N Mean 

To experience solitude 87 2.9 10 24 30 30 39 3.1 To meet new people 104 2.7 13 26 42 42 50 2.7 Source: Mail-back survey, Question 2. a. Responses based on a 4 point scale:  1 = did not attain  2 = somewhat attained  3 = moderately attained  4 = totally attained. b. Rank ordered by mean attainment scores of total sample.
324 GLEN CANYON NATIONAL RECREATION AREA

TABLE D.2.3: SITUATIONS 

RESPONDENTS 

MAY 

HAVE 

EXPERIENCED WHILE 

VISITING 

GLEN 

CANYON 

NATIONAL 

RECREATION 

Percent of All Respondents 

by Response Categorya

Persona

Watercra

Operator

Experience N Meanb

No 

Problem 

Slight 

Problem 

Moderate 

Problem 

Serious 

Problem 

Very 

Serious 

Problem N M

Finding beach campsite 166 2.1 42 22 23 9 4 89 Finding an unoccupied campsite 165 2.0 50 22 18 6 5 83 Litter on beaches and shoreline 180 2.0 43 27 21 3 6 91 People being inconsiderate 180 2.0 46 26 17 5 7 89 Unsafe operation of personal watercraft 181 2.0 51 19 17 6 8 91 Too many personal watercraft on the lake 180 1.9 57 18 13 3 8 92 Boats closer to my boat than I like 179 1.9 54 20 15 7 5 91 Poor water quality 168 1.7 60 19 16 4 3 85 Unsafe operation of motorized boats 181 1.7 59 24 12 2 3 91 Too much noise on the lake 185 1.7 59 27 6 5 3 91 Conflicts with personal watercraft operators on lake 

179 1.7 67 15 9 5 5 92 

Evidence of pets and their droppings 181 1.7 59 24 6 6 5 91 Adequate floating toilet facilities on lake 157 1.7 66 13 12 5 4 77 Too many motorized boats on the lake 181 1.6 61 23 11 2 3 92 Human waste on shore or in water 171 1.6 71 16 6 1 6 86 Sufficient navigational aids on Lake Powell 171 1.5 71 19 6 2 3 88 Conflicts with others for beach space 177 1.5 69 15 10 4 2 89 Adequate toilet facilities at landings 179 1.5 72 16 7 4 3 88 Confusion about rules and regulations 176 1.5 70 18 7 3 2 91 Lack of National Park Service presence on the lake 

172 1.5 75 10 9 4 2 87 

Too many commercial tour boats 180 1.4 81 8 7 3 2 89 Evidence of livestock 174 1.3 84 8 5 1 3 88 Too much light on lake at night 179 1.2 91 6 1 2 1 91 Noise from airplanes 180 1.2 90 6 3 1 1 90 Too much light at the marinas at night 171 1.1 92 5 2 0 1 87 Evidence of mining operations 170 1.1 95 3 1 1 1 86 
FINAL 

ENVIRONMENTAL MPACT ISTATEMENT 325

Percent of All Respondents 

by Response Categorya

Persona

Watercra

Operator

Experience N Meanb

No 

Problem 

Slight 

Problem 

Moderate 

Problem 

Serious 

Problem 

Very 

Serious 

Problem N M

Enough ranger-led activities 127 1.1 94 2 3 1 1 64 Source: Mail-back survey, Question 7. a. Responses based on a 5-point scale:  1 = no problem  2 = slight problem  3 = moderate problem  4 = serious problem  5 = very serious problem. b. Rank ordered by mean scores of total sample.c. Bold font = differences between groups are statistically significant at the p<0.05 level. 
326 GLEN CANYON NATIONAL RECREATION AREA

TABLE D.2.4: RESPONSE TO: “GIVEN THE CONDITIONS IN THE 

GLEN 

CANYON 

NATIONAL 

RECREATION 

AREA, 

TO WHAT EXTENT DO YOU OPPOSE EACH POSSIBLE MANAGEMENT ACTION” 

Percent of All Respondents 

by Response Categorya

Pers

Wate

Oper

Management Actionb N Mean Strongly Oppose Oppose 

Neither 

Support 

nor 

Oppose Support 

Strongly 

Support N 

Provide more information to visitors about appropriate behavior 

186 4.0 3 3 19 43 33 91 

Aggressively enforce safety rules and regulations on lake 

185 3.7 5 7 22 41 24 90 

Provide visitors with natural history information about the area 

184 3.7 2 3 34 46 16 91 

Use management controls to prevent damage to the environment by visitors 

184 3.7 7 5 22 42 24 91 

Provide more toilet facilities at landings 183 3.7 2 3 32 44 19 91 Provide more park rangers on the lake to educate visitors about appropriate behavior 

185 3.6 5 7 30 40 18 90 

Improve public access to the lake 184 3.3 11 18 24 27 21 90 Expand the number of marina slips 185 3.3 7 12 38 29 15 91 Use management controls to prevent conflicts between lake users 

181 3.3 6 12 39 35 9 91 

Establish “off-limit” zones to protect sensitive resources 

184 3.2 17 11 19 37 16 90 

Require visitors to learn about appropriate behavior on the lake (e.g., watch a short video presentation) 

181 3.0 13 20 32 22 13 90 

Prohibit drinking alcoholic beverages on the lake 

185 2.8 31 17 14 15 23 91 

Restrict personal watercraft use to designated areas only 

183 2.7 31 20 12 19 19 89 

Restrict further facility development and expansion 

184 2.7 19 24 33 17 7 90 

Close area to pets 186 2.7 24 18 32 15 11 91 Zone the waters to provide specific uses at specific places 

184 2.7 31 20 19 21 10 90 

Limit number of personal watercraft allowed 186 2.6 34 19 18 17 11 91 
FINAL 

ENVIRONMENTAL MPACT ISTATEMENT 327

Percent of All Respondents 

by Response Categorya

Pers

Wate

Oper

Management Actionb N Mean Strongly Oppose Oppose 

Neither 

Support 

nor 

Oppose Support 

Strongly 

Support N 

on lake at any one time Limit number of boats allowed on lake 181 2.4 31 27 21 16 6 88 Limit number of houseboats allowed on lake at any one time 

184 2.4 33 23 24 14 6 91 

Limit number of motorized watercraft allowed on lake at any one time 

184 2.4 35 25 22 14 4 91 

Limit number of non-motorized watercraft allowed on lake at any one time 

185 2.3 41 28 25 5 2 91 

Restrict number of people using lake at any one time 

185 2.0 40 30 20 10 1 91 

Limit number of people per group allowed on lake 

185 2.0 42 30 17 9 3 91 

Prohibit personal watercraft on the lake 185 1.9 52 24 14 4 5 91 Prohibit non-motorized watercraft on the lake 184 1.7 52 32 11 3 2 90 Prohibit motorized watercraft on the lake 184 1.4 70 21 9 1 0 91 Source: Mail-back survey, Question 11. a. Rank ordered by mean scores of total sample. b. Responses based on a 5-point scale:  1 = strongly oppose  2 = oppose  3 = neither support nor oppose  4 = support  5 = strongly support.
328 GLEN CANYON NATIONAL RECREATION AREA

APPENDIX E 

METHOD USED TO CALCULATE BOAT USE DAYS 

ASSUMPTIONS 

The purpose of the following is estimate the amount of boat use specifically personal watercraft use on Lake 

Powell during calendar year 2001. This use was broken down into two broad categories: 

All boats except personal watercraft, and 

Personal watercraft 

The following definitions apply through this analysis: 

Data – Rental, and slip and buoy data used in this analysis was obtained from ARAMARK, a concessioner for 

Glen Canyon National Recreation Area. Entry data was obtained from monthly use data, principally entry gate 

counts or trailer counts. 

Boat days – All figures used in the analysis were reduced to boat days. A boat day equals one watercraft on the 

lake for a 24-hour period. For example, a single boat that enters Glen Canyon National Recreation Area and 

stays for 14 days would equate to 14 boat days. 

Monthly summaries – All use approximations were developed on a monthly basis to give a reasonable 

approximation of the seasonal nature of use. In addition, both ARAMARK and the National Park Service 

provide data on a monthly basis. 

Entry – Entry was assumed to mostly occur through established entry gates at Wahweap, Lone Rock, Antelope 

Point, Bullfrog, Halls Crossing, and Hite. 

Miscellaneous access – Two sources of lake access were considered sufficiently significant to estimate for the 

analysis. These sources were after-hour access at the Bullfrog and Halls Crossing developed areas, as well as 

Bullfrog north and south undeveloped areas. 

ENTRY DETERMINATIONS 

Entry numbers were based on actual entry gate counts when the gates were open. Trailer counts were used to 

estimate entry numbers when gate counts were not available. 

Entry gate and trailer counts were used at the following locations and times for analysis: 

Entry Location Gate Counts Trailer Counts 

Wahweap April – November December – March 

Lone Rock April – October November – March 

Bullfrog April – October November – March 

Halls Crossing May – October November – April 

Hite No entry gate January – December 

Entry gate numbers – Entry gate numbers were converted to boat days with the following formula: 
Method Used to Calculate Boat Use Days 

FINAL ENVIRONMENTAL IMPACT STATEMENT 329

AB = Entry gate monthly AB total time the average length of stay (ALS) for all boats 

personal watercraft = Entry gate monthly personal watercraft total time the average length of stay for 

personal watercraft 

where the ALS is the following: 

Time Period ALS for personal 

watercraft1

ALS for AB1

Winter (January – March) 5.12 6.52 

Spring (April – June) 7.6 9.0 

Summer (July – September) 5.0 4.1 

Fall (October – December) 5.1 6.5 

 

1. ALS determined by James et al. 2001 

2. No data for winter ALS assumed to be same as fall ALS

Trailer count numbers – Trailer count numbers were converted to AB and personal watercraft boat days using 

the following formula: 

AB = Trailer count – personal watercraft 

personal watercraft = Trailer count multiplied by a seasonal adjuster1

 

where the seasonal adjuster1

 is the following: 

Time Period Adjuster1

October through April 0.035 

May 0.25 

June through August 0.47 

September 0.21 

 

1. Adjuster determined by AB/personal watercraft ratio from 

gate figures 

Miscellaneous access – Access after hours at Bullfrog and accessing the lake at Bullfrog north and south beaches 

was assumed to account for additional numbers given the following formula: 

Bullfrog entry numbers times 20 

Where 20 is the estimated amount of after hour and ungated access 

RENTALS 

Rental numbers were derived directly from the figures (days out) provided by ARAMARK. 
APPENDIX E 

330 GLEN CANYON NATIONAL RECREATION AREA

SLIPS AND BUOYS 

Total slip and buoy numbers (estimated days out on the lake) were provided to the National Park Service by 

ARAMARK. Percent personal watercraft and AB were calculated using the following two formulas: 

AB (on Lake Powell) = Total monthly slip and buoy number (days out) reported by ARAMARK times a 

Seasonal Adjuster2

where seasonal adjuster2

 accounts for boats taken out of a slip or buoy but not on Lake Powell (provided 

by Dan Cordesen of ARAMARK) and is the following: 

Time period Adjuster2

December through February 0 

March .25 

April .50 

May through September 1 

October .50 

November .25 

personal watercraft = AB times 0.44 or 0.10 (the average # of personal watercraft/boat in a slip or buoy) 

times seasonal adjuster3

 

where the average number of personal watercraft per slip or buoy is 

0.44 at Wahweap, Bullfrog, and Halls Crossing (359/809) and 

0.10 at Hite (5/50) 

and seasonal adjuster3

 (accounting for decreased use of personal watercraft during the cold period) was 

assumed as the following: 

Month Adjuster3

December through March 0.2 

April and November 0.4 

May 0.6 

October 0.8 

June through September 1.0 

DRY STORAGE 

It was assumed that ARAMARK dry storage would not be counted by the entrance gate or the trailer counts. 

Dry storage numbers were derived using the monthly summary numbers (days out) provided to the National Park 

Service by ARAMARK. 

Percent AB and personal watercraft for a particular month were calculated using the following formula: 

AB = Total monthly dry storage days out number from ARAMARK minus personal watercraft days out 

number 
Method Used to Calculate Boat Use Days 

FINAL ENVIRONMENTAL IMPACT STATEMENT 331

personal watercraft = Total monthly dry storage days out number from ARAMARK times 0.075 where 

0.075 is the average number of personal watercraft in ARAMARK dry storage
332 GLEN CANYON NATIONAL RECREATION AREA

APPENDIX F 

TEN-YEAR VISITATION CHANGE (1991–2001) 

53 SELECTED NATIONAL PARKS INCLUDING 

PERSONAL WATERCRAFT RULEMAKING PARKS 

Parks were generally selected based on one or more of the following characteristics: 

• Personal Watercraft Rule 

• Water-based, National Recreation Area reservoirs, National Seashores 

• Large National Parks - for general comparison 

• Western parks 

Park 

Average Annual 

Growth – 1991–2001 

Average Annual 

Growth in Personal 

Watercraft Use in 

Parks 

Amistad National Recreation Area -0.3% -0.3% 

Apostle Islands National Landmark 3.8% 

Arches National Park 0.9% 

Assateague Island National Seashore -0.8% -0.8% 

Badlands National Park -4.0% 

Bandelier National Monument 0.1% 

Big Bend National Park 1.8% 

Big South Fork National River and Recreation Area 0.8% 

Big Thicket National Preserve 7.7% 7.7% 

Bighorn Canyon National Recreation Area -4.8% -4.8% 

Black Canyon of the Gunnison National Park -4.7% 

Blue Ridge Parkway 1.9% 

Buffalo National River -0.8% 

Canaveral National Seashore 2.0% 

Cape Cod National Seashore -2.0% -2.0% 

Cape Hatteras National Seashore 2.2% 

Cape Lookout National Seashore 9.2% 9.2% 

Capitol Reef National Park -0.8% 

Chaco Culture National Historic Park 1.0% 

Chattahoochee River National Recreation Area 6.3% 

Chickasaw National Recreation Area 1.2% 1.2% 

Crater Lake National Park 0.1% 

Curecanti National Recreation Area -2.0% -2.0% 

Death Valley National Park 3.5% 

Delaware Water Gap National Recreation Area 1.2% 1.2% 

Dinosaur National Monument -3.2% 

Everglades National Park -1.5% 

Fire Island National Seashore 1.9% 1.9% 

Gateway National Recreation Area 4.7% 4.7% 

Glacier National Park -1.1% 
Ten-Year Visitation Change (1991–2001) 53 Selected National Parks Including Personal Watercraft Rulemaking Parks 

FINAL ENVIRONMENTAL IMPACT STATEMENT 333

Park 

Average Annual 

Growth – 1991–2001 

Average Annual 

Growth in Personal 

Watercraft Use in 

Parks 

Glen Canyon NRA -2.6% -2.6% 

Golden Gate NRA -0.8% 

Great Smoky Mountains National Park 1.3% 

Guadalupe Mountains National Park 1.4% 

Gulf Islands National Seashore 2.5% 2.5% 

Indiana Dunes National Landmark -1.7% -1.7% 

Lake Chelan National Recreation Area -1.5% 

Lake Mead National Recreation Area 0.1% 0.1% 

Lake Meredith National Recreation Area 0.3% 0.3% 

Lake Roosevelt National Recreation Area -1.3% -1.3% 

Mount Rainier National Park -1.2% 

New River Gorge National River 5.0% 

Ozark National Scenic Riverways -3.7% 

Padre Island National Seashore -2.8% -2.8% 

Pictured Rocks National Landmark -4.5% -4.5% 

Point Reyes National Seashore -0.6% 

Rainbow Bridge National Monument -0.3% 

Ross Lake National Recreation Area 2.2% 

Saint Croix National Scenic River -4.3% 

Sleeping Bear Dunes National Landmark -0.8% 

Voyageurs National Park 0.4% 

Whiskeytown-Shasta-Trinity National Recreation Area -0.9% -0.9% 

Yellowstone National Park 2.5% 

 

Overall Average Annual Change 0.251% 0.261% 
334 GLEN CANYON NATIONAL RECREATION AREA

APPENDIX G 

APPROACH TO EVALUATING SURFACE WATER QUALITY IMPACTS 

FROM THE USE OF PERSONAL WATERCRAFT 

OBJECTIVE 

Using simplifying assumptions, estimate the minimum (threshold) volume of water in a reservoir or lake below 

which concentrations of gasoline constituents from personal watercraft or outboards would be potentially toxic 

to aquatic organisms or humans. Using the estimated threshold volumes, and applying knowledge about the 

characteristics of the receiving waterbody and the chemical in question, estimate if any areas within the 

waterbody of interest may present unacceptable risks to human health or the environment. 

OVERALL APPROACH 

Following are the basic steps in evaluating the degree of impact a waterbody (or portion of a water body) would 

experience based on an exceedence of water quality standards / toxicity benchmarks for personal watercraft and 

outboard engine -related contaminants. 

Determine concentrations of polycyclic aromatic hydrocarbons, benzene, and methyl tertiary-butyl ether 

in gasoline (convert from weight percent to mg/L, as needed) and polycyclic aromatic hydrocarbons in 

exhaust. The half-life of benzene in water is 5 hours at 25°C (Verschueren 1983; EPA 2001). 

Estimate loading of polycyclic aromatic hydrocarbons, benzene, and methyl tertiary-butyl ether for 

various appropriate personal watercraft-hour levels of use for one day (mg/day) 

Find/estimate ecological and human health toxicity benchmarks (risk-based concentrations [RBCs]) 

(μg/L) for polycyclic aromatic hydrocarbons, benzene, and methyl tertiary-butyl ether. 

Divide the estimated loading for each constituent (μg) by a toxicity benchmark (μg/L) to determine the 

waterbody threshold volume (L) below which toxic effects may occur (convert liters to acre-feet). 

Estimated hydrocarbon emissions from personal watercraft and outboards will be significantly reduced in the 

near future, based on regulations issued by the Environmental Protection Agency and California Air Resources 

Board (CARB). 

ASSUMPTIONS AND CONSTANTS 

Several assumptions must be made to estimate waterbody threshold volumes for each hydrocarbon evaluated. 

Each park unit should have specific information that can be used to modify these assumptions or to qualitatively 

assess impacts in light of park unit-specific conditions such as mixing and stratification, and the characteristics 

of the chemicals themselves. The assumptions are as follows: 

Benzene, toluene, ethyl benzene, and xylenes (benzene, toluene, ethyl benzene, and xylene) are volatile 

and do not stay in the water column for long periods of time. Because benzene is a recognized human 

carcinogen, it is retained for the example calculations below and should be considered in each 

environmental assessment or environmental impact statement (Verschueren 1983; EPA 2001c). 

Methyl tertiary-butyl ether volatilizes slightly and is soluble in water. Methyl tertiary-butyl ether may 

accumulate in water from day to day, but this is not factored into the calculation and should be considered 

qualitatively in the assessment. 
Approach to Evaluating Surface Water Quality Impacts from the Use of Personal Watercraft 

FINAL ENVIRONMENTAL IMPACT STATEMENT 335

Polycyclic aromatic hydrocarbons volatilize slightly (depending on structure and molecule size) and may 

adhere to sediment and settle out of the water column or float to the surface and be photo-oxidized. They 

may accumulate in water from day to day, but this is not factored into the calculation and should be 

considered qualitatively in the assessment. 

The toxicity of several polycyclic aromatic hydrocarbons increases (by several orders of magnitude) when 

polycyclic aromatic hydrocarbons are exposed to sunlight. This was not incorporated because site-specific 

water transparency is not known, and should be discussed qualitatively. 

The threshold volume of water will mix vertically and aerially with contiguous waters to some extent, but 

the amount of this mixing will vary with location in the lake, reservoir, or river. Therefore, although the 

threshold volume calculation assumes no mixing with waters outside the “boundary” of the threshold 

volume of water, this should be discussed in the assessment after the threshold volume is calculated. The 

presence or absence of a thermocline should also be addressed. 

Volume of the waterbody, or portion thereof, is estimated by the area multiplied times the average depth. 

In addition to these assumptions, several constants required to make the calculations were compiled from 

literature and agency announcements. Gasoline concentrations are provided for benzene, methyl tertiary-butyl 

ether and those polycyclic aromatic hydrocarbons for which concentrations were available in the literature. 

Constants used are: 

Gasoline emission rate for two-stroke personal watercraft: 3 gallons per hour at full throttle (CARB 

1998a) 

Gasoline emission rate for two-stroke outboards: estimated at approximately the same as for personal 

watercraft for same or higher horsepower outboards (80–150 hp); approximately twice that of personal 

watercraft for small (e.g., 15 hp) outboards. (Note: Assume total hours of use for the various size 

boats/motors, and that smaller 15 hp motors that exhaust relatively more unburned fuel would probably be 

in use for a much smaller amount of time than the recreational speedboats and personal watercraft). This 

estimate is based on data from Allen et al. 1998 (Fig. 5). It is noted that other studies may show different 

results, e.g. about the same emissions regardless of horsepower, or larger horsepower engines having 

more emissions than smaller engines (e.g., CARB 2001a); the approach selected represents only one 

reasonable estimate. 

1 gallon = 3.78 liters 

Specific gravity of gasoline: 739 g/L 

1 acre-foot = 1.234 × 106

 liters 

Concentration of benzo(a)pyrene (B[a]P) in gasoline: 2.8 mg/kg (or 2.07 mg/L) (Gustafson et al. 1997) 

Concentration of naphthalene in gasoline: 0.5% or 0.5 g/100 g (or 3,695 mg/L) (Gustafson et al. 1997) 

Concentration of 1-methyl naphthalene in gasoline: 0.78% or 0.78 g/100 g (or approx. 5,760 mg/L) 

(estimated from Gustafson et al. 1997) 

Concentration of benzene in gasoline: 2.5% or 2.5 g/100 g (or 1.85 × 104

 mg/L) (Hamilton 1996) 

Concentration of methyl tertiary-butyl ether in gasoline: 15% or 15 g/100 g (or approx. 1.10 × 105

 mg/L) 

(Hamilton 1996). (Note: methyl tertiary-butyl ether concentrations in gasoline vary from state to state. 

Many states do not add methyl tertiary-butyl ether.) 
APPENDIX G 

336 GLEN CANYON NATIONAL RECREATION AREA

Estimated emission of B(a)P in exhaust: 1080 μg/hr (from White and Carroll 1998), using weighted 

average B(a)P emissions from two-cylinder, carbureted two-stroke liquid cooled snow mobile engine 

using gasoline and oil injected Arctic Extreme injection oil, 24-38:1 fuel:oil ratio. Weighted average 

based on percentage of time engine was in five modes of operation, from full throttle to idle. 

Estimated amount of B(a)P exhaust emissions retained in water phase = approximately 40% (based on 

value for B(a)P from Hare and Springier 1973). 

TOXICITY BENCHMARKS 

A key part of the estimations is the water quality criterion, standard, or toxicological benchmark for each 

contaminant evaluated. There are no Environmental Protection Agency water quality criteria for the protection of 

aquatic life for the personal watercraft-related contaminants (EPA 1999a). There are, however, a limited number 

of Environmental Protection Agency criteria for the protection of human health (via ingestion of water and 

aquatic organisms). Chronic ecotoxicological and human health benchmarks for contaminants were acquired 

from various sources. 

Ecological benchmarks for benzo(a)pyrene, naphthalene, and benzene are from Toxicological Benchmarks for 

Screening Potential Contaminants of Concern for Effects on Aquatic Biota: 1996 Revision (Suter and Tsao 1996) 

and from the Arizona Administrative Code (for benzene concentration in a warm water fishery). The ecological 

benchmarks for benzo(a)pyrene (0.014 μg/L) and benzene (71 μg/L) are Tier II Secondary Chronic Values in 

table 1 of Suter and Tsao (1996), which were calculated using methods in the Great Lakes Water Quality 

Initiative (EPA 1993). The ecological benchmark for naphthalene (62 μg/L) is the Environmental Protection 

Agency Region 4 chronic screening value (table 3 of Suter and Tsao 1996). This screening value was chosen for 

use as a conservative mid-range value considering the wide range of chronic values for naphthalene (12–

620 μg/L) shown in Suter and Tsao (1996) The ecological benchmarks for 1-methyl naphthalene (19 and 

34 μg/L) are based on LC50 values of 1,900 and 3,400 μg/L for the marine invertebrate, Dungeness crab (Cancer 

magister), and the fresh water/estuarine fish, sheepshead minnow (Cyprinodon variegatus) (U.S. Fish and 

Wildlife Service 2000). The methyl tertiary-butyl ether benchmark 51,000 μg/L is for fresh water and is based 

on the preliminary chronic water quality criteria presented in Mancini et al. (2001). 
Approach to Evaluating Surface Water Quality Impacts from the Use of Personal Watercraft 

FINAL ENVIRONMENTAL IMPACT STATEMENT 337

TABLE G.1: TOXICITY BENCHMARKS FOR SELECTED CONSTITUENTS OF GASOLINE

Chemical 

Ecological 

Benchmark (μg/L) Source 

Human Health 

Benchmarka

(μg/L) Source 

Benzo(a)pyrene 0.014 Suter and Tsao 1996 0.0044a 

0.049b

EPA 1999a 

Naphthalene 62 Suter and Tsao 1996 — — 

1-methyl naphthalene 19–34c U.S. Fish and Wildlife 

Service 2000 

— 

Benzene 71 Arizona 

Administrative Code 

1996 

1.2a 

71b

EPA 1999aa

methyl tertiary-butyl etherd 18,000 

51,000 

Mancini et al. 2002 13e — 

 

a. Based on the consumption of water and aquatic organisms. 

b. Based on the consumption of aquatic organisms only. 

c. Based on LC50s of 1,900 μg/L and 3,400 μg/L for Dungeness crab and sheepshead minnow, respectively (34 μg/L used for freshwater 

calculations; 19 μg/L used for marine and estuarine calculations).

d. Ecological benchmarks considered preliminary chronic water quality criteria for marine and freshwater, respectively. Human health 

toxicological information for methyl tertiary-butyl ether is currently under review. There is no Environmental Protection Agency human health 

benchmark. 

e. California primary drinking water standard (shown for informational purposes).

EXAMPLE CALCULATIONS 

Calculations of an example set of waterbody volume thresholds are provided below for the chemicals listed 

above together with their concentrations in gasoline and available toxicity benchmarks. 

Loading to Water 

Loadings of the five contaminants listed above are calculated for one day assuming 10 personal watercraft 

operate for four hours (40 personal watercraft-hours), each discharging 11.34 L gasoline per hour and having 

concentrations in fuel or exhaust as listed. 

Benzo(a)pyrene (from the fuel): 40 personal watercraft-hrs × 11.34 L gas/hr × 2.07 mg/L = 939 mg 

Benzo(a)pyrene (from the gas exhaust): 40 personal watercraft-hrs × 1080 μg/hr × 1/1000 mg/μg × 0.40 = 

17 mg 

Total B(a)P = 956 mg 

Naphthalene: 40 personal watercraft-hrs × 11.34 L gas/hr × 3695 mg/L = 1.68 × 106

 mg 

1-methyl naphthalene: 40 personal watercraft-hrs × 11.34 L gas/hr × 5764 mg/L = 2.62 × 106

 mg 

Benzene: 40 personal watercraft-hrs × 11.34 L gas/hr × 1.85 × 104

 mg/L = 8.39 × 106 mg 

methyl tertiary-butyl ether: 40 personal watercraft-hrs × 11.34 L gas/hr × 1.10 × 105

 mg/L = 4.99 ×

107 mg 
APPENDIX G 

338 GLEN CANYON NATIONAL RECREATION AREA

Loadings of contaminants from two-stroke outboards should be estimated based on the estimated loading based 

on the horsepower of the outboards involved (see “Assumptions and Constants” above) and the estimated hours 

of use, based on the types of boats and the pattern of use observed. 

Threshold Volumes 

Threshold volumes of water (volume at which a personal watercraft or outboard engine-related contaminant 

would equal the thresholds listed above) are calculated by dividing the estimated loadings (mg of contaminant) 

for the number of operational hours (e.g., 40 personal watercraft-hours) by the listed toxicity benchmark 

concentrations (μg/L), correcting for units (1 mg = 103

 μg), and converting from liters to acre-feet (1 acre-foot = 

1.234 × 106 L): 

Protection of Aquatic Organisms 

Benzo(a)pyrene: 956 mg B(a)P × 103 μg/mg / 0.014 μg/L = 6.8 × 107

 L or 55 acre-feet 

Naphthalene: 1.68 × 106

 mg naphthalene × 103 μg/mg / 62 μg/L = 2.71 × 107 L or 22 acre-feet 

1-methyl naphthalene: 2.62 × 106

 mg 1-methyl naphthalene. × 103 μg/mg / 34 μg/L = 7.69 × 107 L or 

62 acre-feet 

Benzene: 8.39 × 106

 mg benzene × 103 μg/mg / 71 μg/L = 6.45 × 107 L or 96 acre-feet 

methyl tertiary-butyl ether (acute): 4.99 × 107

 mg methyl tertiary-butyl ether × 103 μg/mg / 51,000 μg/L = 

9.42 × 105

 L or 0.79 acre-feet 

Based on these estimates and assumptions, 1-methyl naphthalene appears to be the contaminant (of those 

analyzed) that would be the first to accumulate to concentrations potentially toxic to aquatic organisms (i.e., it 

requires more water [62 acre-feet] to dilute the contaminant loading to a concentration below the toxicity 

benchmark); however, the threshold volumes are very similar for 1-methyl naphthalene, benzo(a)pyrene, and 

benzene. 

Protection of Human Health 

Benzo(a)pyrene: 956 mg B(a)P × 103 μg/mg / 0.0044 μg/L = 2.17 × 108

 L or 176 acre-feet 

Benzene: 8.39 × 106

 mg benzene × 103 μg/mg / 1.2 μg/L = 6.99 × 109 L or 5,670 acre-feet 

Using the numbers provided above, benzene would be the first personal watercraft-related contaminant in these 

example calculations that would reach unacceptable levels in surface water; however, volatilization of benzene 

from water to air was not included in the calculation. If human health water quality criteria for ingestion of 

aquatic organisms only were used for benzo(a)pyrene and benzene (0.049 μg/L and 71 μg/L, respectively), the 

corresponding threshold volumes would be 15.8 acre-feet and 95.8 acre-feet, respectively. 

As a result of the estimated reductions in hydrocarbon emissions (from the unburned fuel) in response to 

Environmental Protection Agency regulations (listed above), additional personal watercraft and/or outboards 

may be used in the parks without additional impacts on water quality. For example, based on the expected 

overall reductions from the Environmental Protection Agency (1996, 1997), up to 75% additional personal 

watercraft/ outboards may be used in a given area in 2025 without additional impacts on water quality over 
Approach to Evaluating Surface Water Quality Impacts from the Use of Personal Watercraft 

FINAL ENVIRONMENTAL IMPACT STATEMENT 339

current levels. Effects on noise levels, physical disturbance, or hydrocarbon emissions that are products of 

combustion (e.g., B(a)P) may not be similarly reduced by the reduced emission regulations. 

APPLICATION OF APPROACH 

Use of the approach described above for evaluating possible exceedence of standards or other benchmarks must 

be adapted to the unique scenarios presented by each park unit, personal watercraft use, and waterbody being 

evaluated. 

Factors that would affect the concentration of the contaminants in water must be discussed in light of the specific 

site conditions. These factors include varying formulations of gasoline (especially for methyl tertiary-butyl 

ether); dilution due to mixing (e.g., influence of the thermocline), wind, currents, and flushing; plus loss of the 

chemical due to volatilization to the atmosphere (Henry’s Law constants can help to predict volatilization to air; 

see Yaws et al. 1993); adsorption to sediments and organic particles in the water column (e.g., polycyclic 

aromatic hydrocarbons), oxidation, and biodegradation (breakdown by bacteria). Toxicity of phototoxic 

polycyclic aromatic hydrocarbons may be of concern in more clear waters, but not in very turbid waters. 

The chemical composition of gasoline will vary by source of crude oil, refinery, and distillation batch. No two 

gasolines will have the exact same chemical composition. For example, B(a)P concentrations may range from 

0.19 to 2.8 mg/kg, and benzene concentrations may range from 0% to 7% (2% to 3% is typical). Methyl tertiarybutyl ether concentrations will vary from state to state and season to season, with concentrations ranging from 

0% to 15%. The composition of gasoline exhaust is dependent on the chemical composition of the gasoline and 

engine operating conditions such as temperature, revolutions per minute, and oxygen intake. If site-specific 

information is available on gasoline and exhaust constituents, they should be considered in the site-specific 

evaluation. If additional information on the toxicity of gasoline constituents (e.g., methyl tertiary-butyl ether) 

become available, they should be considered in the site-specific evaluation. 
APPENDIX G 

340 GLEN CANYON NATIONAL RECREATION AREA

REFERENCES CITED 

Allen, B.C., J.E. Reuther, C.R. Goldman, M.F. Fiore, and G.C. Miller 

1998 “Lake Tahoe Motorized Watercraft Report — An Integration of Water Quality, Watercraft Use 

and Ecotoxicology Issues.” Preliminary draft report prepared for the Tahoe Regional Planning 

Agency. 

California Air Resources Board 

1998 “Proposed Regulations for Gasoline Spark-Ignition Marine Engines, Draft Proposal 

Summary.” Mobile Resources Control Division. 

1999 “Fact Sheet – New Regulations for Gasoline Engines.” Available at <www.arb.ca.gov/msprog/ 

marine/marine.htm>. 

2001 “Outboard Engine and Personal Watercraft Emissions to Air and Water: A Laboratory Study.” 

Prepared by Mobile Source Control Division and Monitoring and Laboratory Division. 

California Department of Health Services 

2002 “MTBE in California Drinking Water.” Prevention Services, Division of Drinking Water and 

Environmental Management. Available at <www.dhs.ca.gov/ps/ddwem/chemicals/ 

MTBE/mtbeindex,htm> (latest update: August 7, 2002). 

Gustafson, J.B., J.G. Tell, and D. Orem 

1997 “Selection of Representative TPH Fractions Based on Fate and Transport Considerations.” 

Final draft. Vol. 3. TPH Criteria Working Group, Fate and Transport Technical Action Group. 

Amherst Scientific Publishing. 

Hamilton, Bruce 

1996 “FAQ: Automotive Gasoline.” 4 parts. Available at <www.faqs.org/faqs/autos/gasoline-faq>. 

Hare, C.T., and K.J. Springier 

1973 “Exhaust Emissions from Uncontrolled Vehicles and Related Equipment Using Internal Combustion Engines.” Final Report. Part Two: “Outboard Motors.” Prepared for the U.S. 

Environmental Protection Agency by Southwest Research Institute, San Antonio, TX. 

Available at <http://www.nalms.org/bclss/impactsoutboard.htm>. 

Mancini, E.R., A. Steen, G.A. Rausina, D.C.L. Wong, W.R. Arnold, F E. Gostomski, T. Davies, J.R. Hockett, 

W.A. Stubblefield, K.R. Drottar, T.A. Spring, and P. Errico 

2002 “MTBE Ambient Water Quality Criteria Development: A Public/Private Partnership.” 

Environmental Science and Technology 36: 125–29. 

Mastran, Trina A., Andrea M. Dietrich, Daniel J. Gallagher, and Thomas J. Grizzard 

1994 “Distribution of Polyaromatic Hydrocarbons in the Water Column and Sediments of a 

Drinking Water Reservoir with Respect to Boating Activity.” Water Resources 28 (11): 

2353–66. 

National Park Service, U. S. Department of the Interior 

1999 “Water Quality Concerns Related to Personal Watercraft Usage,” by M. VanMouwerik and 

M. Hagemann. Technical paper. Water Resources Division, Fort Collins, CO. 
Approach to Evaluating Surface Water Quality Impacts from the Use of Personal Watercraft 

FINAL ENVIRONMENTAL IMPACT STATEMENT 341

Ortis, J.T., A.C. Hatch, J.E. Weinstein, R.H. Findlay, P.J. McGinn, S.A. Diamond, R. Garrett, W. Jackson, G.A. 

Burton, B. Allen 

1998 “Toxicity of Ambient Levels of Motorized Watercraft Emissions to Fish and Zooplankton in 

Lake Tahoe, California/Nevada, USA.” Poster 3E-P005, presented at the 8th Annual Meeting 

of the European Society of Environmental Toxicology and Chemistry, April 14–18, 1998, 

University of Bordeaux, Bordeaux, France. 

Suter, G.W., and C.L. Tsao 

1996 Toxicological Benchmarks for Screening Potential Contaminants of Concern for Effects on 

Aquatic Biota. Rev. ES/ER/TM-96/R2. Oak Ridge National Laboratory, TN. 

Tahoe Regional Planning Agency 

1999 Environmental Assessment for the Prohibition of Certain Two-Stroke Powered Watercraft.

U.S. Environmental Protection Agency (EPA) 

1993 Great Lakes Water Quality Initiative Criteria: Documents for the Protection of Aquatic Life in 

Ambient Water. Draft. PB93-154656. National Technical Information Service. Springfield, 

VA. 

1994 “The Effects of Marine Engine Exhaust Emissions on Water Quality: Summary of Findings of 

Various Research Studies.” Office of Air and Radiation. 

1995 “Final Water Quality Guidance for the Great Lakes System; Final Rule.” Federal Register, 60 

(Mar. 23): 15366–425. 

1996a “Air Pollution Control; Gasoline Spark-Ignition Marine Engines; New Nonroad CompressionIgnition and Spark-Ignition Engines, Exemptions; Rule.” Federal Register 61 (Oct. 4): 52087–

106. 

1996b “Emission Standards for New Gasoline Marine Engines.” EPA 420-F-96-012. EPA 

Environmental Fact Sheet. Office of Mobile Sources, Ann Arbor, MI. 

1996c Regulatory Impact Analysis: Control of Air Pollution Emission Standards for New Nonroad 

Spark-Ignition Marine Engines. ANR-443. Office of Air and Radiation, Office of Mobile 

Sources, Engine Programs and Compliance Division, Ann Arbor, MI 

1997 “Control of Air Pollution; Amendment to Emission Requirements Applicable to New Gasoline 

Spark-Ignition Engines.” Federal Register 62 (April 2): 15805–08. 

1998 “National Recommended Water Quality Criteria.” Federal Register 63 (Dec. 10): 68353–64. 

1999a “National Recommended Water Quality Criteria — Correction.” EPA822-Z-99-001. Office of 

Water. 

1999b “Power Boating and America’s Waters.” Available at 

<http://www.epa.gov/CEIS/atlas/ohiowaters/ uses/power_boating_and_america.htm>. 

2000a Lake Superior Lakewide Management Plan 2000. Lake superior Binational Program. 

2000b “Recreational Vehicles, Marine Engines.” Region III, Air Protection Division. Available at 

<http://www.epa.gov/reg3artd/vehicletran/vehicles/recreational_vehicles.htm>. 

2001 “National Primary Drinking Water Regulations: Technical Fact Sheet on Benzene.” Office of 

Water. Available at <www.epa.gov/ogwdw000/dwh/t-voc/benzene.htm>. 
APPENDIX G 

342 GLEN CANYON NATIONAL RECREATION AREA

United States Fish and Wildlife Service, U.S. Department of the Interior 

1987 “Polycyclic Aromatic Hydrocarbon Hazards to Fish, Wildlife, and Invertebrates: A Synoptic 

Review,” by R. Eisler. Biological Report 85; Contaminant Hazard Reviews Report 11. Laurel, 

MD. 

U.S. Geological Survey, U.S. Department of the Interior 

2001 “Occurrence and Potential Adverse Effects of Semivolatile Organic Compounds in Streambed 

Sediment, United States, 1992-1995,” by T. J. Lopes and E. T. Furlong, USGS, Carson City, 

NY. Available from USGS Denver Federal Center, Denver, CO 80225-0046. 

Verschuren, K. 

1983 Handbook of Environmental Data on Organic Chemicals. 2nd ed. New York: Van Nostrand 

Reinhold Company. 
FINAL ENVIRONMENTAL IMPACT STATEMENT 343

APPENDIX H 

CONSULTATION LETTERS 

H.1: State Historic Preservation Officers 

H.2: Advisory Council on Historic Preservation 

H.3: U.S. Fish and Wildlife Service Section 7 Consultation 

H.4: Arizona Game and Fish Department 

H.5: Utah Division of Wildlife Resources 

H.6: Tribal Consultation 
APPENDIX H 

344 GLEN CANYON NATIONAL RECREATION AREA

H.1: State Historic Preservation Officers 
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 345

H.1: State Historic Preservation Officers (continued) 
APPENDIX H 

346 GLEN CANYON NATIONAL RECREATION AREA

H.1: State Historic Preservation Officers (continued) 
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 347

H.1: State Historic Preservation Officers (continued) 
APPENDIX H 

348 GLEN CANYON NATIONAL RECREATION AREA

H.1: State Historic Preservation Officers (continued) 
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 349

H.2: Advisory Council on Historic Preservation 
APPENDIX H 

350 GLEN CANYON NATIONAL RECREATION AREA

H.2: Advisory Council on Historic Preservation (continued) 
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 351

H.3: U.S. Fish and Wildlife Service Section 7 Consultation 
APPENDIX H 

352 GLEN CANYON NATIONAL RECREATION AREA

H.3: U.S. Fish and Wildlife Service Section 7 Consultation (continued) 
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 353

H.3: U.S. Fish and Wildlife Service Section 7 Consultation (continued) 
APPENDIX H 

354 GLEN CANYON NATIONAL RECREATION AREA

H.4: Arizona Game and Fish Department 
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 355

H.4: Arizona Game and Fish Department (continued) 
APPENDIX H 

356 GLEN CANYON NATIONAL RECREATION AREA

H.4: Arizona Game and Fish Department (continued) 
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 357

H.5: Utah Division of Wildlife Resources 
APPENDIX H 

358 GLEN CANYON NATIONAL RECREATION AREA

H.6: Tribal Consultation 
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 359

H.6: Tribal Consultation (continued) 
APPENDIX H 

360 GLEN CANYON NATIONAL RECREATION AREA

H.6: Tribal Consultation (continued)
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 361

H.6: Tribal Consultation (continued)
APPENDIX H 

362 GLEN CANYON NATIONAL RECREATION AREA

H.6: Tribal Consultation (continued)
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 363

H.6: Tribal Consultation (continued)
APPENDIX H 

364 GLEN CANYON NATIONAL RECREATION AREA
Consultation Letters 

FINAL ENVIRONMENTAL IMPACT STATEMENT 365

References and Index

Divider 

This page to be removed 

(Needs to be an odd page) 
APPENDIX H 

366 GLEN CANYON NATIONAL RECREATION AREA

Back of Divider 

This page to be removed 
FINAL ENVIRONMENTAL IMPACT STATEMENT 367

REFERENCES 

U.S. PUBLIC LAWS, CODES, FEDERAL REGULATIONS, STATUTES, AND ACTS 

All U.S. Public Laws, Codes, Federal Regulations, and Statutes can be found at the Office of the 

Federal Register, U.S. Government Printing Office, Washington, DC. Many can be found on the 

Internet at http://www.gpo.gov. 

American Indian Religious Freedom Act (AIRFA) 42 United States Code 1996—1996a; Public Law 

95-341, 103-344. 

Antiquities Act of 1906 16 United States Code 431—433; June 8, 1906, ch. 3060, 34 Stat. 225. 

Archaeological Resources Protection Act of 1979 (ARPA) 16 United States Code 470aa—470mm; 

Public Law 96-95. 

Architectural Barriers Act of 1968 42 United States Code 4151—4157; Public Law 90-480. 

Bald Eagle Protection Act of 1940 (16 United States Code 668-668d, 54 Stat. 250) as amended. 

Approved June 8, 1940. 

Clean Air Act 42 United States Code 7401—7671q; Public Law 88-206. 

Endangered Species Act of 1973 16 United States Code 1531—1544; Public Law 93-205. 

Farmland Protection Policy Act (Public Law 97-98; 7 United States Code 4201 et seq.).

Federal Water Pollution Control Act (commonly known as the Clean Water Act) 33 United States 

Code 1251—387; Public Law 92-500, 95-217. 

Fish and Wildlife Coordination Act of 1934 as amended; March 10, 1934, ch 55, Sec. 1, 48 Stat. 401. 

Historic Sites, Buildings and Antiquities Act 16 United States Code 461—467; Aug. 21, 1935, 

ch. 593, 49 Stat. 666. 

Migratory Bird Treaty Act of 1918 (16 United States Code 703-712; Chapter 128; July 13, 1918; 

40 stat. 755) as amended. 

National Environmental Policy Act of 1969 (National Environmental Policy Act) 42 United States 

Code 4321—4370d; Public Law 91-190. 

National Historic Preservation Act (NHPA) 16 United States Code 470—470x-6; Public Law 89-665, 

96-515. 

National Parks Omnibus Management Act of 1998 16 United States Code 5901—60116; Public Law 

105-391. 

National Park Service Concessions Management Improvement Act of 1998 16 United States Code

5951—5966; Public Law 105-391 (title IV). 
REFERENCES AND INDEX

368 GLEN CANYON NATIONAL RECREATION AREA 

National Park Service Organic Act 16 United States Code 1—4; Aug. 25, 1916, ch. 408, 39 Stat. 535. 

National Park System General Authorities Act 16 United States Code 1a-1 et seq. 7; Public Law 91-

383, 94-458, 95-. 

Native American Graves Protection and Repatriation Act (NAGPRA) 25 United States Code 3001—

3013; Public Law 101-601. 

Wild and Scenic Rivers Act 16 United States Code 1271—1287; Public Law 90-542. 

Wilderness Act 16 United States Code 1131—1136; Public Law 88-577 10. 

REFERENCES CITED 

Albers, Peter H. 

2000 “Sources, Fate, and Effects of PAHs in Shallow Water Environments.” In Impacts of 

Motorized Boats on Shallow Water Systems, Science Workshop Abstracts, November 

7–8, 2000, Douglass College Center, Rutgers, the State University of New Jersey. 

Rutgers, NJ. 

Allen, B.C., J.E. Reuther, C.R. Goldman, M.F. Fiore, and G.C. Miller 

1998 “Lake Tahoe Motorized Watercraft Report - An Integration of Water Quality, 

Watercraft Use and Ecotoxicology Issues.” Preliminary draft report prepared for the 

Tahoe Regional Planning Agency. 

American Academy of Pediatrics 

2000 “Policy Watercraft Use by Children and Adolescents.” Policy Statement. Pediatrics 

105 (no. 2): 452–53. 

American Watercraft Association (AWA) 

2001 “The Advocate Action Kit: Personal Watercraft and the Environment.” Burbank, CA. 

American Watercraft Association. 

Anderson, F.E. 

2000 “Effects of Wave-Wash from Personal Watercraft on Salt Marshes.” Science 

workshop abstract for Impacts of Motorized Boats on Shallow Water Systems 

Conference, prepared by T. O’Connor, Rutgers, NJ: Department of Earth Sciences, 

University of New Hampshire. 

ARAMARK Sports and Entertainment Services, Inc. 

n.d. Spill Prevention Control and Countermeasure Plan for Lake Powell Resort and 

Marinas. Lake Powell, Utah. 

Arfsten, D.P., D.J. Schaeffer, and D.C. Mulveny 

1996 “The Effects of Near Ultraviolet Radiation on the Toxic Effects of Polycyclic 

Aromatic Hydrocarbons in Animals and Plants: A Review.” Ecotoxicology and 

Environmental Safety 33:1–24. 
References 

FINAL ENVIRONMENTAL IMPACT STATEMENT 369

Arizona Administrative Code 

1996 Arizona Administrative Code, Title 18. Environmental Quality, Chapter 11, 

Department of Environmental Quality Water Quality Standards. Available on the 

Internet @ http://www.sosaz.com/public_services/Tite_18/18-11.htm. 

2002 Information extracted from “2002 Air Quality Report,” Arizona Administrative Code 

Title 18, Article 2. Phoenix, AZ. Available on the Internet @ 

http://www.sosaz.com/public_services/Title_18/18-

02.htm#ARTICLE%201.%20GENERAL. 

Arizona Department of Environmental Quality (ADEQ) 

1999 “Report on Methyl Tertiary Butyl Ether (methyl tertiary-butyl ether).” Available on 

the Internet @ 

http://www.adeq.state.az.us/environ/waste/ust/download/1001mtbe.pdf. 

no date “BADCT Guidance Document for Domestic and Municipal Wastewater Treatment. 

Draft.” Water Quality Division, Aquifer Protection Program, Phoenix, Arizona. 

Arizona Game and Fish Department 

2001 Arizona Game and Fish Laws and Rules 2000-2001. Phoenix AZ: Reprinted from the 

Arizona Revised Statutes (2000 Edition) and the Arizona Administrative Code, 

Supplement 00-4. 

2002 Personal communication from Dave Harris, Lake Ranger, Glen Canyon National 

Recreation Area, Page, AZ, to Parsons, Denver, April. 

Asplund, Tim, R. 

2000 “The Effects of Motorized Watercraft on Aquatic Ecosystems.” Publication PUBLSS-948-00. Wisconsin Department of Natural Resources and University of Wisconsin, 

Madison. 

Axel, Anne 

2002 Electronic mail message from Axel, The Natural Heritage Program, Utah Division of 

Wildlife Resources, Salt Lake City, UT, to Connie Chitwood, Parsons, Denver, 

April 15. 

BCS International 

1998 Draft Summary of Measurement Results, Cal Black Memorial Airport. Produced for 

the Federal Aviation Administration, BCS International. 

Blakeslee, Sandra 

2002 “Dam Project May Steer Nature.” The New York Times, June 14, 2002. 

Bluewater Network 

2001 “Jet Ski Position Paper.” Available on Internet @ 

http://www.earthisland.org/bw/jetskipos.html. 

Branche, C.M., J.M. Conn, and J.L. Annest 

1997 “Personal Watercraft-Related Injuries: a Growing Public Health Concern.” Journal of 

the American Medical Association 278(8): 663-665. 
REFERENCES AND INDEX

370 GLEN CANYON NATIONAL RECREATION AREA 

Bureau of Land Management, U.S. Department of the Interior 

2002 Letter from S. Berkenfield, Supervisory Recreation Planner, Monticello, UT, to 

Parsons, Denver, May. 

Burger, J. 

1998 “Effects of Motorboats and Personal Watercraft on Flight Behavior over a Colony of 

Common Terns.” The Condor 100:528-534. 

2000 “Managing Personal Watercraft around Tern Colonies.” In Impacts of Motorized 

Boats on Shallow Water Systems. Science Workshop Abstracts, November 7 – 8, 

2000, Douglass College Center, Rutgers, the State University of New Jersey. Rutgers, 

NJ. 

California Environmental Protection Agency, Air Resources Board 

1998a “Draft Proposed Summary, Proposed Regulations for Gasoline Spark-Ignition Marine 

Engines.” Available on the Internet @ 

http://www.arb.ca.gov/msprog/marine/workdoc2.pdf. 

1998b News Release: Air Board Acts to Reduce Marine Engine Pollution. Sacramento, CA, 

December 10. Available on the Internet at 

http://www.arb.ca.gov/newsrel/nr121098.htm. 

1999a “Fact Sheet -- New Regulations for Gasoline Engines.” Available on the Internet at 

http://www.arb.ca.gov/msprog/marine/marine.htm. 

1999b News Release: First Personal Watercraft Certified to ARB 2001 Standards. 

Sacramento, CA, April 13. Available on the Internet at 

http://www.arb.ca.gov/newsrel/nr041399.htm. 

2001 “Outboard Engine and Personal Watercraft Emissions to Air and Water: A Laboratory 

Study.” Prepared by Mobile Source Control Division and Monitoring and Laboratory 

Division. 

Census Bureau, U.S. Department of Commerce 

2000 “People Quick Facts, 2000 Census of Population and Profiles of General 

Demographics.” Available on the Internet @ www.fedstats.gov. 

Collaboration in Science and Technology, Inc. 

1990 Ambient Sound Monitoring Program for Colorado Plateau Parks. Produced under 

contract to the National Park Service, Collaboration in Science and Technology, Inc. 

Council on Environmental Quality, Executive Office of the President 

1978 “Regulations for Implementing the Procedural Provisions of the National 

Environmental Policy Act.” Code of Federal Regulations Title 40, Parts 1500-1508. 

1980 “Analysis of Impacts on Prime and Unique Agricultural Lands in Implementing 

National Environmental Policy Act.” Federal Register 45: 59189. 
References 

FINAL ENVIRONMENTAL IMPACT STATEMENT 371

Devlin, E.W., J.D. Brammer, and R.L. Puyear 

1982 “Acute Toxicity of Toluene to Three Age Groups of Fathead Minnows (Pimephales 

promelas).” Bulletin of Environmental Contamination Toxicology 29:12-17. 

Douglas, A.J. and D.A. Harpman 

no date Nonmarket Values and Management Alternatives at Lake Powell: CVM Estimates of 

Recreation Benefits. On file at Glen Canyon National Recreation Area, Page, AZ. 

Douglas, A.J., M. Lee, and A. Sleeper 

no date Visitors and Activities at Lake Powell: A Study of Recreation Users. On file at Glen 

Canyon National Recreation Area, Page, AZ. 

Executive Orders 

1994 Executive Order 12898: Federal Actions to Address Environmental Justice in 

Minority Populations and Low-Income Populations, February. 

Federal Highway Administration 

1998 FHWA Traffic Noise Model Version 1.0: Technical Manual. By C.W. Menge, C.F. 

Rossano, G.S. Anderson, and C.J. Bajdek. Report No. FHWA-PD-96-010. 

Forest Service, U.S. Department of Agriculture 

1980 Predicting Impact of Noise on Recreationists. by Robin T. Harrison, Roger N. Clark 

and George H. Stankey. Forest Service Equipment Development Center. San Dimas, 

CA: INT-4901. 

1999 “National Distribution of Biomonitoring Sites – 1999.” Available on the Internet @ 

http://www.na.fs.fed.us/spfo/fhm/ozonetrng/biozone.htm. 

2002 Personal communication from Roger Boyer, Forest Health Biomonitoring Program, 

Ogden, UT, to Parsons, Denver, June. 

Foster Wheeler Environmental Corporation 

1997 Prepared for Project Oversight Group Duwamish Brownfields/TPH Project. 

Brownfields/TPH Project Phase 2, Task 4, Subtask 4.2.1 Technical Memorandum 

Preliminary Selection of Candidate Petroleum Hydrocarbons as Surrogates for 

Ecological Risk Evaluation of TPH. 

Grand Canyon Monitoring and Research Center 

2002 Personal communication from Susan Hueftle, Limnologist, Flagstaff, AZ, to Jacklyn 

Bryant, Parsons, Denver, April 30. 

Grubb, T., W. Robinson, and W. Bowerman 

2002 “Effects of watercraft on bald eagles nesting in Voyageurs National Park, Minnesota.” 

Wildlife Society Bulletin 2002, 30(1):156-161. 

Gustafson, J.B., J.G. Tell, and D. Orem 

1997 “Selection of Representative TPH Fractions Based on Fate and Transport 

Considerations.” Final draft. Vol. 3. TPH Criteria Working Group, Fate and Transport 

Technical Action Group. Amherst Scientific Publishing. 
REFERENCES AND INDEX

372 GLEN CANYON NATIONAL RECREATION AREA 

Gustaveson, Wayne 

2002 Electronic mail message from Gustaveson, Utah Department of Natural Resources, 

Division of Wildlife Resources, Page, AZ, to Mark Norman, Parsons, Denver, May 5. 

Hamilton, Bruce 

1996. “FAQ: Automotive Gasoline.” 4 parts. Available on the Internet @ 

www.faqs.org/faqs/autos/gasoline-faq. 

Hagler Bailly 

1999 Final Report: Watercraft Use Study, Nevada Lakes. Madison, WI. 

Hare, C.T., and K.J. Springier 

1973 “Exhaust Emissions from Uncontrolled Vehicles and Related Equipment Using 

Internal Combustion Engines Final Report. Part Two: Outboard Motors,” prepared for 

the U.S. Environmental Protection Agency by Southwest Research Institute, San 

Antonio, TX. Available on the Internet @ 

http://www.nalms.org/bclss/impactsoutboard.htm. 

Harris Miller Miller & Hanson Inc. 

2002 Draft Technical Report on Noise: Personal Watercraft and Boating Activities at Glen 

Canyon National Recreation Area. Produced under contract to National Park Service. 

Harris Miller Miller & Hanson Inc. 

Henderson, Norm 

2002 Electronic mail message from Henderson, National Park Service, Glen Canyon 

National Recreation Area, Page, AZ, to Mark Norman, Parsons, Denver, April 19. 

Hibbs, P. 

2002 Electronic mail message from Hibbs, Downlake District Ranger, National Park 

Service, Glen Canyon National Recreation Area, Page, AZ, to Timberley Belish, 

Parsons, Denver, April 26. 

James, E.B., D.H. Anderson, C.A. Warzecha, and J.L. Thompson 

2001a Final Report: Visitor Use at Glen Canyon National Recreation Area, Comparison of 

personal watercraft Users and Nonusers, Summer 2000 Data Collection. St. Paul 

MN: University of Minnesota, College of Natural Resources. 

2001b Personal Watercraft Use in Glen Canyon National Recreation Area: Visitor 

Characteristics and Perceptions Across Three Study Seasons. Research Summary, 

No. 21. St. Paul, MN: University of Minnesota, College of Natural Resources, 

Cooperative Park Studies Program. 

Kado, Norman Y., Paul A. Kuzmicky, and Robert A. Okamoto 

2001 Environmental and Occupational Exposure to Toxic Air Pollutants from Winter 

Snowmobile Use in Yellowstone National Park. University of California Davis, 

California Air Resources Board. 
References 

FINAL ENVIRONMENTAL IMPACT STATEMENT 373

Kado, Norman Y., Robert F. Okamoto, John Karim, and Paul A. Kuzmicky 

2000 “Airborne Particle Emissions from two-stroke and four-stroke Outboard Marine 

Engines: Polycyclic Aromatic Hydrocarbon and Bioassay Analyses.” Environmental 

Science & Technology 34(13): 2714–20. 

Kang, D., V.P. Aneja, R.G. Zika, C. Farmer, and J.D. Ray 

2001 “Nonmethane Hydrocarbons in the Rural Southeast U.S. National Parks.” Journal of 

Geophysic Resources, 106:3133-3155. 

Komanoff, Charles and Howard Shaw 

2000 Drowning in Noise: Noise Costs of Jet Skis in America. A Report for the Noise 

Pollution Clearinghouse. Available on the Internet @ 

http://www.nonoise.org/library/drowning/drowning.htm. 

Krausman, Paul R., Mark Wallace, Mara Weisenberger, Donald DeYoung, and O. Maughan 

1996 “Effects of Simulated Jetcraft Noise on Heart Rate and Behavior of Desert 

Ungulates.” Journal of Wildlife Management 60 (1): 52-61. 

Landrum, P.F., J.P. Geisy, J.T. Oris, and P.M. Allred 

1987 “Photoinduced Toxicity of Polycyclic Aromatic Hydrocarbons to Aquatic 

Organisms.” In Oil in Freshwater: Chemistry, Biology, Countermeasure Technology, 

edited by J.H. Vandermeulen and S.E. Hrudey, 304–18, Ontario, Canada: Pergamon 

Press. 

Law Engineering and Environmental Sciences, Inc. 

2003 Economic Analysis of Personal Watercraft Regulations in Glen Canyon National 

Recreation Area. Prepared for the National Park Service by Law Engineering and 

Environmental Sciences, Inc., Kennesaw, GA, with assistance from Arcadis JSA, and 

RTI. 

Mancini, E.R., A. Steen, G.A. Rausina, D.C.L. Wong, W.R. Arnold, F.E. Gostomski, T. Davies, J.R. 

Hockett, W.A. Stubblefield, D.R. Drottar, T.A. Spring, and P. Errico 

2001 “Methyl tertiary-butyl ether Ambient Water Quality Criteria Development: A 

Public/Private Partnership.” Environmental Science and Technology, 36: 125-29. 

Mayer, Mike 

2002 Electronic mail message from Mayer, Assistant Chief Ranger, National Park Service, 

Glen Canyon National Recreation Area, Page, AZ, to Timberley Belish, Parsons, 

Denver, April 19. 

Mekenyan, O.G., G.T. Ankely, G.D. Veitt, and D.J. Call 

1994 “QSARs for Photoinduced Toxicity: I. Acute Lethality of Polycyclic Aromatic 

Hydrocarbons into Daphnia Magna.” Chemosphere 28:56782. 

Menge, C.W., C.F. Rossano, G.S. Anderson, and C.J. Bajdek 

1998 FHWA Traffic Noise Model Version 1.0: Technical Manual. Report No. FHWA-PD96-010. 
REFERENCES AND INDEX

374 GLEN CANYON NATIONAL RECREATION AREA 

Millard, J 

2003 Electronic mail message from J. Millard, Utah Department of Motor Vehicles, to 

Parsons, Denver, April 10. 

Mueller, Gordon, and Catherine A. Karp 

2002 “Razorback Sucker Movements and Habitat Use in the San Juan River Inflow, Lake 

Powell, Utah 1995-1997.” Reprinted from, Western North American Naturalist. 

Volume 62, No. 1 January 2002. 106-111. 

National Association of State Boating Law Administrators 

2001 The Futures Forum on Recreational Boating. Presented at the Futures Forum, 

April 1-3, 2001, St. Petersburg, FL. 

National Marine Manufacturers Association 

2000 1999 U.S. Recreational Boat Registration Statistics. Chicago, IL. 

2001a “Boating 2001 – Facts and Figures at a Glance.” Available on the Internet @ 

http://www.nmma.org/facts/boatingstats/2001. 

2001b Information extracted from “2001 Population Estimates.” Available on the Internet @ 

http://nmma.org/facts/boatingstats/2001/files/populationestimates.asp. 

National Park Service, U.S. Department of the Interior 

1979a Glen Canyon National Recreation Area / Arizona-Utah: Proposed General 

Management Plan, Wilderness Recommendation, Road Study Alternatives, and Final 

Environmental Impact. Page, AZ: Glen Canyon National Recreation Area. 

1979b Proposed Management Plan for Glen Canyon National Recreation Area, Arizona and 

Utah. Page, AZ: Glen Canyon National Recreation Area. 

1986 Natural Resources Management Plan and Environmental Assessment for Glen 

Canyon National Recreation Area. Glen Canyon National Recreation Area and Rocky 

Mountain Regional Office. Page, AZ. 

1987a Glen Canyon National Recreation Area, Arizona/Utah: Water Resources Management 

Plan and Environmental Assessment. Page, AZ: Glen Canyon National Recreation 

Area. 

1987b The Carrying Capacity of Lake Powell A Management Analysis of Capacity for 

Boater Recreation Glen Canyon National Recreation Area Arizona/Utah. Page, AZ: 

Rocky Mountain Region. 

1988a Environmental Assessment and Management/Development Concept Plans for Lake 

Powell’s Accessible Shorelines. Denver, CO: Rocky Mountain Regional Office. 

1988b Glen Canyon Environmental Studies Final Report. D-43. 

1994 “Everglades National Park Special Regulations.” Federal Register 59(36):1024. 
References 

FINAL ENVIRONMENTAL IMPACT STATEMENT 375

1995a “A Survey and Classification of the Riparian Vegetation in Side Canyons around Lake 

Powell, Glen Canyon National Recreation Area, Draft Final Report,” by John Spence. 

On file at Glen Canyon National Recreation Area, Page, AZ. 

1995b The Secretary of the Interior’s Standards for the Treatment of Historic Properties 

With Guidelines for the Treatment of Cultural Landscape. Washington, DC. 

1996a Ethnographic Resource Inventory and Assessment for the Burr Trail, Capitol Reef 

National Park, Utah and Glen Canyon National Recreation Area, Utah, in 

Cooperation with the Hopi Tribe, by Rosemary J. Sucec. Denver, CO: National Park 

Service, Rocky Mountain Regional Office. 

1996b Ethnographic Resource Inventory and Assessment for the Burr Trail, Capitol Reef 

National Park, Utah and Glen Canyon National Recreation Area, Utah, in 

Cooperation with the Kaibab Paiute Tribe, the Kanosh and Koosharem Bands of the 

Paiute Indian Tribe of Utah, and the San Juan Southern Paiute, by Rosemary J. 

Sucec. Denver, CO: National Park Service, Rocky Mountain Regional Office. 

1996c “Flora of Glen Canyon,” by John Spence. On file at Glen Canyon National Recreation 

Area, Page, AZ. 

1996d Director’s Order #28: Cultural Resource Management. Washington, DC. 

1996e “Field Checklist of the Birds of Glen Canyon National Recreation Area.” On file at 

Glen Canyon National Recreation Area, Page, Arizona. 

1997 Information extracted from “Benzene, Naphthalene and 1-Methyl-Naphthalene 

chapters” in “Environmental Contaminants Encyclopedia.” By R. J. Irwin, M. L. 

Vanmouwerik, L. Stevens, M.D. Seese, and W. Basham, Water Resources Division, 

Fort Collins, Colorado. Available on the Internet @ 

http://www.nature.nps.gov/toxic/list.html. 

1998a Director’s Order #2: Park Planning. [Washington, DC]. 

1998b “Lake Waterfowl,” by J. Spence, on file at Glen Canyon National Recreation Area, 

Page, AZ. 

1998c “Proposed Rule on Personal Watercraft Use within the NPS System.” Available on the 

Internet at <http://www.nps.gov/refdesk/1pwcrule.html>. 

1998d Spill Prevention Control and Countermeasures (SPCC) Plan. Prepared by the 

Hazardous Waste Management and Pollution Prevention Team, April 27. 

1999a Grazing Management Plan Glen Canyon National Recreation Area. National Park 

Service. Glen Canyon National Recreation Area. Page, AZ. 

1999b Planners’ Sourcebook: Director’s Order 2: Park Planning, Framework for NPS Park 

Planning and Decision Making, Reference Manual 2. [Washington, DC]. 
REFERENCES AND INDEX

376 GLEN CANYON NATIONAL RECREATION AREA 

1999c “Water Quality Concerns Related to Personal Watercraft Usage,” by Vanmouwerik 

and M. Hagemann. Technical paper. Water Resources Division, Fort Collins, CO. 

2000a Director’s Order #9: Law Enforcement Program. [Washington, DC]. 

2000b “Director’s Order #47: Soundscape Preservation and Noise Management.” 

[Washington, DC]. Available on the Internet @ 

http://www.nps.gov/refdesk/DOrders/DOrder47.html. 

2000c Draft Environmental Impact Statement for the Implementation of the Lake Mead 

Management Plan, 122 pp. Boulder City, NV: Lake Mead National Recreation Area. 

2000d Management Policies 2001. NPS D1416. [Washington, DC]. 

2000e Personal watercraft use within the NPS system: final rule. Federal Register 65(55): 

15077-15090. 

2000f Reference Manual 9: Law Enforcement Program. [Washington, DC]. 

2000g Strategic Plan for Glen Canyon National Recreation Area and Rainbow Bridge NM, 

October 1, 2000 - September 30, 2005. 21 pp. 

2001a “Air Quality Study at Glen Canyon National Recreation Area Related to personal 

watercraft and boating Activity,” by J. Ray, National Park Service Air Resources 

Division. On file at Glen Canyon National Recreation Area, Page, AZ. 

2001b Director’s Order #12 and Handbook: Conservation Planning, Environmental Impact 

Analysis, and Decision Making. [Washington, DC]. 

2001c “Glen Canyon National Recreation Area Cases on Lake Powell,” by S. Schulman and 

N. Henderson. On file at Glen Canyon National Recreation Area, Page, AZ. 

2001d “Glen Canyon National Recreation Area Personal Watercraft and Other Vessels boat 

days on Lake Powell per month by use zone in 2001.” Glen Canyon National 

Recreation Area. Unpublished data on file at Glen Canyon National Recreation Area, 

Page, AZ. 

2001e “Glen Canyon Lake Powell accident data by location and month.” Unpublished data. 

On file at Glen Canyon National Recreation Area, Page, AZ. 

2001f “Glen Canyon National Recreation Area Special-Status Terrestrial Species and 

Communities of Glen Canyon National Recreation Area,” by John Spence. On file at 

Glen Canyon National Recreation Area, Page, AZ. 

2001g “Lake Powell Pure – Now and Forever.” Available on the Internet @ 

http://www.nps.gov/glca/pp.htm. 

2001h Memo from M. Vanmouwerik, Restoration Case Officer, Natural Resource 

Stewardship and Science Office, Fort Collins, CO, to the Superintendent of Glen 

Canyon National Recreation Area, Page, AZ, July 16. 
References 

FINAL ENVIRONMENTAL IMPACT STATEMENT 377

2001i “Personal Watercraft Use, Environmental Impact Statement, Glen Canyon National 

Recreation Area, Arizona and Utah.” Federal Register 66(148):39789. 

2001j ARAMARK Rental Fleet by Marina – 2001. Unpublished data on file at Glen Canyon 

National Recreation Area, Page, AZ. 

2002a Antelope Point EA, Glen Canyon National Recreation Area, Arizona/Utah. Page, AZ: 

National Park Service. 

2002b “Bald Eagle Surveys at Glen Canyon,” by John Spence and others. On file at Glen 

Canyon National Recreation Area, Page, AZ. 

2002c Draft Superintendent’s Compendium for Glen Canyon National Recreation Area and 

Rainbow Bridge National Monument. Page, AZ: Glen Canyon National Recreation 

Area. 

2002d “Glen Canyon and National Boating Accident Date Comparison.” On file at Glen 

Canyon National Recreation Area, Page, AZ. 

2002e Personal communication from Mark Anderson, Aquatic Ecologist, Glen Canyon 

National Recreation Area, Page, AZ, to Parsons, Denver, April. 

2002f Personal communication from Glenn Gossard, Acting Chief of Interpretation, Glen 

Canyon National Recreation Area, Page, AZ, to Parsons, Denver, April. 

2002g Personal communication from Paul Henderson, Information Officer, Glen Canyon 

National Recreation Area, Page, AZ to Parsons, Denver, April. 

2002h Personal communication from Norm Henderson, Natural Resource Specialist, Glen 

Canyon National Recreation Area, Page, AZ, to Parsons, Denver, May. 

2002i Personal communication from P. Hibbs, District Ranger, Glen Canyon National 

Recreation Area Downlake, Page, AZ, to Parsons, Denver, April. 

2002j Personal communication from S. Hueftle, Grand Canyon Monitoring and Research 

Center, Flagstaff, AZ, to Parsons, Denver, April. 

2002k Personal communication from Mike Mayer, Assistant Chief Ranger, Glen Canyon 

National Recreation Area, Page, AZ, to Parsons, Denver, April. 

2002l Personal communication from Rosenlieb, Water Resources Division, Ft. Collins, CO, 

to Parsons, Denver, June. 

2002m Personal communication from John Spence, Natural Resource Specialist, Glen 

Canyon National Recreation Area, Page, AZ, to Parsons, Denver, April. 

2002n Personal communication from John Spence, Natural Resource Specialist, Glen 

Canyon National Recreation Area, Page, AZ, to Parsons, Denver, May. 
REFERENCES AND INDEX

378 GLEN CANYON NATIONAL RECREATION AREA 

2002o Personal communication from Cheryl Schreier, Concessions Assistant, Glen Canyon 

National Recreation Area, Page, AZ, to Timberley Belish, Parsons, Denver, June 11. 

2002p Personal communication from M. Vanmouwerik, Contaminants Specialist, Water 

Resources Division, Fort Collins, CO, to Parsons, Denver, May. 

2002q Personal Watercraft Use Draft Environmental Assessment, Big Thicket National 

Preserve. 158 pp. 

2002r “Air Quality Study at Glen Canyon National Recreation Area Related to personal 

watercraft and Boating Activity,” Draft report by J. Ray, National Park Service Air 

Resources Division. On file at Glen Canyon National Recreation Area, Page, AZ. 

2002s “State of Arizona Boating Regulations and Summary-State of Utah Boating 

Regulations.” Available on the Internet @http://www.nps.gov/glca/actindx.htm. 

2003a Personal communication from B. Rossman, Soundscape Specialist, Fort Collins, CO, 

to Parsons, Denver, April 10. 

2003b Personal communication from Mark Anderson, Aquatic Resource Specialist, Glen 

Canyon National Recreation Area, Page, AZ, to Parsons, Denver, April. 

No date “How to Apply the National Register Criteria for Evaluation.” National Register 

Bulletin # 15. Available on the Internet @ 

http://www.cr.nps.gov/nr/publications/bulletins/nr15_toc.htm. 

National Research Council, National Academies of Science 

2002 Oil in the Sea III: Inputs, Fates, and Effects. Washington, DC: National Academy 

Press. 

National Transportation Safety Board 

1998 Personal Watercraft Safety: Safety Study. Washington, DC: National Transportation 

Safety Board/SS-98/01. 

Navajo Nation 

2002 Personal communication from Ron Maltonado, Program Manager, Navajo Tribe 

Cultural Resource Compliance Section, to Diane Rhodes, Parsons, Denver, April 29. 

Neff, J.M. and W.A. Stubblefield 

1995 “Chemical and Toxicological Evaluation of Water Quality Following the Exxon 

Valdez Oil Spill.” in Exxon Valdez Oil Spill: Fate and Effects in Alaskan Waters, 

ASTM STP 1219, pp. 141-177, edited by Peter G. Wells, James N. Butler, and Jane S. 

Hughes, Eds. Philadelphia: PA: American Society for Testing and Materials. 

Ocean Studies Board, Marine Board, and Transportation Research Board 

2002 Oil in the Sea III: Inputs, Fates, and Effects. National Academy Press. Available on 

the Internet @ http://books.nap.edu/books/0309084385/html. 
References 

FINAL ENVIRONMENTAL IMPACT STATEMENT 379

Oregon Department of Environmental Quality 

1999 “Carbureted 2-stroke Marine Engines. Impacts on the Environment and Voluntary 

Policy Options to Encourage Their Replacement.” Prepared by Mindy Correll, 

Pollution Prevention Team. Portland, OR. 

Oris, J.T., A.C. Hatch, J.E. Weinstein, R.H. Findlay, P.J. McGinn, S.A. Diamond, R. Garrett, W. 

Jackson, G.A. Burton, and B. Allen 

1998 “Toxicity of Ambient Levels of Motorized Watercraft Emissions to Fish and 

Zooplankton in Lake Tahoe, California/Nevada, USA.” Poster number 3E-P005, 

presented at the 8th Annual Meeting of the European Society of Environmental 

Toxicology and Chemistry, April 14-18, at University of Bordeaux, Bordeaux, France. 

Personal Watercraft Industry Association 

2002a PWIA correspondence to NPS, May 28, 2002: comment on Lake Mead National 

Recreation Area Lake Management Plan and Draft Environmental Impact Statement. 

2002b PWIA email to NPS dated September 23, 2002. 

Platania, Steve P., K.R. Bestgen, M.A. Moretti, D.L. Propst, and J.E. Brooks 

1991 “Status of Colorado Squawfish and Razorback Sucker in the San Juan River, 

Colorado, New Mexico, and Utah” in Southwestern Naturalist 36:147-149. 

Radle, A.L. 

no date “The Effect of Noise on Wildlife: A Literature Review” for the World Forum for 

Acoustic Ecology, University of Oregon. Available on the Internet @ http:// 

www.interact.uoregon.edu/MediaLt/wfae/readings/radle.html. 

Rodgers, J. Jr. and S.T. Schwikert 

2002 “Buffer zone distances to protect foraging and loafing waterbirds from disturbance by 

personal watercraft and outboard-powered boats.” Conservation Biology, 16(1):216-

224. 

Scholik, A.R. and H.Y. Yan 

2002a “Effects of Boat Engine Noise on the Auditory Sensitivity of the Fathead Minnow, 

Pimephales promelas.” Environmental Biology of Fishes Journal, 63: (2) 203-209. 

2002b Information extracted from “The Effects of Underwater Noise on Auditory Sensitivity 

of Fish,” Thomas H. Morgan School of Biological Sciences, University of Kentucky, 

Lexington, Kentucky. Available on the Internet @ 

http://biology.uky.edu/Yan/Yanresearch2.htm. 

Schmidt, M. 

2001 Personal Communication, September 4, 2001. 

Schulman, S. 

2002a Electronic mail message from S. Schulman, National Park Service, Glen Canyon 

National Recreation Area, Page, AZ, to Parsons, Denver, April 23. 

2002b Electronic mail message from S. Schulman, National Park Service, Glen Canyon 

National Recreation Area, Page, AZ, to Parsons, Denver, April 24. 
REFERENCES AND INDEX

380 GLEN CANYON NATIONAL RECREATION AREA 

Sea-Doo 

2001a “Bombardier Announces Revolutionary New O.P.A.S. System.” Available on the 

Internet at <http://www.seadoo.com/usa/seadoo_today/news/010827.html>. 

2001b “The New 155 hp, 1494 cc 4-TEC, Four-Stroke.” Available on the Internet at 

<http://www.seadoo.com>. 

Secretary of the Interior 

1992 Secretary of the Interior’s Standards and Guidelines for Archeology and Historic 

Preservation. Washington, DC. 

1996 The Secretary of the Interior’s Standards for the Treatment of Historic Properties 

with Guidelines for the Treatment of Cultural Landscapes. Washington, DC. 

Spectrum Laboratories 

no date Information extracted from “Chemical Fact Sheet #90120 “1-methylnaphthalene.” By 

Spectrum Laboratories. Available on the Internet @ 

http://www.speclab.com/compound/c90120.htm. 

Spence, John 

2002a Electronic mail message from Spence, National Park Service, Glen Canyon National 

Recreation Area, Page, AZ, to Mark Norman, Parsons, Denver, April 19. 

2002b Electronic mail message from Spence, National Park Service, Glen Canyon National 

Recreation Area, Page, AZ, to Connie Chitwood, Parsons, Denver, May 30. 

Stevenson, J.C. and W.C. Dennison 

2000 “The Potential Impacts of Recreational Boating on Submersed Aquatic Vegetation in 

Upper Chesapeake Bay.” Abstract prepared by T. O’Connor for Impacts of Motorized 

Boats on Shallow Water Systems Conference, Science Workshop, Rutgers, NJ. 

Sucec, Rosemary J. 

1996a Ethnographic Resource Inventory and Assessment for the Burr Trail, Capitol Reef 

National Park, Utah and Glen Canyon National Recreation Area, Utah, in 

Cooperation with the Hopi Tribe. Denver, CO: National Park Service, Rocky 

Mountain Regional Office. 

1996b Ethnographic Resource Inventory and Assessment for the Burr Trail, Capitol Reef 

National Park, Utah and Glen Canyon National Recreation Area, Utah, in 

Cooperation with the Kaibab Paiute Tribe, the Kanosh and Koosharem Bands of the 

Paiute Indian Tribe of Utah, and the San Juan Southern Paiute. Denver, CO: National 

Park Service, Rocky Mountain Regional Office. 

Suter, G. W., and C. L. Tsao 

1996 Toxicological Benchmarks for Screening Potential Contaminants of Concern for 

Effects on Aquatic Biota. Rev. ES/ER/TM-96/R2. TN: Oak Ridge National 

Laboratory. 
References 

FINAL ENVIRONMENTAL IMPACT STATEMENT 381

Tahoe Regional Planning Agency 

1998 Lake Tahoe Motorized Watercraft Report — An Integration of Water Quality, 

Watercraft Use and Ecotoxicology Issues. Preliminary draft report prepared for the 

Tahoe Regional Planning Agency. 

1999 Environmental Assessment for the Prohibition of Certain Two-Stroke Powered 

Watercraft. Zephyr Cove, NV. Available on the Internet at 

http://www.trpa.org/Boating/MWC%20EA.pdf /. 

2003 "Environmental Assessment of the Impact of PAH in Lake Tahoe and Donner Lake," by 

G. C. Miller, C. Hoonhout, E. Sufka, S. Carroll and V. Edirveerasingam, University of 

Nevada Reno; B. Allen and J. Reuter, University of California Davis; J. Oris, Miami 

University of Ohio, and M. Lico, U.S. Geological Survey. Prepared for Tahoe 

Regional Planning Agency, Zephyr Cove, NV. Unpublished Document. 

U.S. Coast Guard 

2001 Boating Statistics. Available on the Internet at 

http://www.uscgboating.org/statistics/accident_stats.htm 

U.S. Court of Appeals 

1991 “Michigan United Conservation Clubs v. Lujan.” 949 F.2d 202 (6th Cir. 1991). 

1996 “Bicycle Trails Council of Marin v. Babbitt.” No. 94-16920 D.C. No. CV-93-00009-

EFL; 82 F.3d 1445, 1452 (9th Cir. 1996). 

U.S. Department of Energy 

2002 “Controversial Additive, MTBE, is Gradually Phased Out by States,” National 

Biomass Coordination Office, U.S. Department of Energy, Energy Efficiency and 

Renewable Energy (EERE). Available on the Internet at www.bioproductsbioenergy.gov/news/displayrecentarticle.asp?idarticle=13. 

U.S. Environmental Protection Agency (EPA) 

1993 Great Lakes Water Quality Initiative. Available on the Internet at 

http://www.epa.state.oh.us/dsw/gli/. 

1994 “The Effects of Marine Engine Exhaust on Water Quality: Summary of Findings of 

Various Research Studies.” Memorandum from J.M. Revelt to Public Docket No. A92-28, 15November. 

1996a “Control of Air Pollution; Final Rule for New Gasoline Spark-Ignition Marine 

Engines; Exemptions for New Nonroad Compression-Ignition Engines at or Above 37 

Kilowatts and New Nonroad Spark-Ignition Engines at or Below 19 Kilowatts.” 

Federal Register 61: 52087–52169. 

1996b “Environmental Fact Sheet: Emission Standards for New Gasoline Marine Engines.” 

EPA420-F-96-012. Office of Mobile Sources, Ann Arbor, Michigan. 

1997a “Control of Air Pollution: Amendment to Emission Requirements Applicable to New 

Gasoline Spark-Ignition Engines.” Federal Register 62 (April 2): 15805-08. 
REFERENCES AND INDEX

382 GLEN CANYON NATIONAL RECREATION AREA 

1997b Conversion Factors for Hydrocarbon Emission Components. Washington DC: Report 

No. NR-002. 

1997c Fact Sheet Drinking Water Advisory: Consumer Acceptability Advice and Health 

Effects Analysis on Methyl Tertiary-Butyl Ether (MtBE). EPA-822-F-97-009. Office 

of Water, Washington, District of Columbia. 

1998 “National Recommended Water Quality Criteria.” Federal Register 63 (Dec. 10): 

68353–64. 

1999a “National Recommended Water Quality Criteria – Correction.” EPA822-Z-99-01. 

Office of Water. 

1999b Exhaust and Emission Factors for Non Road Engine Modeling. Washington DC: 

Report No. NR-010b. 

2001a “Naphthalene.” Available on the Internet @ 

http://www.epa.gov/ttn/atw/hlthef/haphthal.html. 

2001b Methyl Tertiary Butyl Ether (methyl tertiary-butyl ether) Overview. Available on the 

Internet @ http://epa.gov/mtbe/faq.htm. 

2001c National Primary Drinking Water Regulations: Technical Fact Sheet on Benzene.” 

Office of Water. Available on the Internet@ http://www.epa.gov/ogwdw000/dwh/tvoc/benzene.htm. 

2001d “Water Quality Standards.” 40 Code of Federal Regulations, Volume 18:131. 

2002a National Recommended Water Quality Criteria: 2002. Office of Water. EPA-822-R02-047. November. 

2002b Personal communication from Karen Hamilton, EPA Region VIII, to Jacklyn Bryant, 

Parsons, Denver, April 10. 

2002c Technical Factsheet on: Polycyclic Aromatic Hydrocarbons (polycyclic aromatic 

hydrocarbons). Available on the Internet @ http://www.epa.gov/OGWDW/dwh/tsoc/pahs.html. 

n.d. a Information extracted from “Surf Your Watershed,” Colorado River above Lake 

Powell impairment information. Available on the Internet @ 

http://www.epa.gov/iwi/303d/14030005_303d.html. 

n.d. b Information extracted from “Surf Your Watershed,” Dirty Devil impairment 

information. Available on the Internet @ 

http://www.epa.gov/iwi/303d/14070004_303d.html. 

n.d. c Information extracted from “Surf Your Watershed.” Escalante River impairment 

information. Available on the Internet @ 

http://www.epa.gov/iwi/303d/14070005_303d.html. 
References 

FINAL ENVIRONMENTAL IMPACT STATEMENT 383

n.d. d Information extracted from “Surf Your Watershed” website. Available on the Internet 

@ http://www.epa.gov/surf. Hardcopy available at Glen Canyon National Recreation 

Area. 

U.S. Fish and Wildlife Service, U.S. Department of the Interior 

1994 “Endangered and Threatened Wildlife and Plants: Determination of Critical Habitat 

for Four Colorado River Endangered Fishes; Final Rule.” Federal Register 50:13374-

13400. 

2000 “Polycyclic Aromatic Hydrocarbon Hazard to Fish, Wildlife, and Invertebrates: A 

Synoptic Review,” by R. Eisler. Biol. Report No. 85 (1.11), Contaminant Hazard 

Report No. 11, Laurel, Maryland. 

2001 Letter from D.C. Harlow, Field Supervisor, Phoenix, Arizona to N. Henderson, 

National Park Service, Glen Canyon National Recreation Area, Arizona, 

December 10. 

2002a Letter from H.R. Maddux, Field Supervisor, West Valley, Utah to N. Henderson, 

National Park Service, Glen Canyon National Recreation Area, Page, AZ, May 9. 

2002b Letter from Utah Field Supervisor, West Valley, Utah to Kitty Roberts, National Park 

Service, Glen Canyon National Recreation Area, Page, AZ, November 14. 

U.S. Geological Survey 

2002 Information extracted from “Water Quality Data: Water Quality Samples for Utah,” 

Available on the Internet @ http://waterdata.usgs.gov/ut/nwis/qwdata. 

no date Examination of Native Fish Recruitment and Description of the Fish Communities 

found in the San Juan and Colorado River Interface Zones of Lake Powell, Utah. 

Open File Report 01-159 On file at U.S. Geological Survey, Denver. 

Utah Code – Statutes and Constitution 

2001 Utah Code. Salt Lake City, Utah. Available on the Internet @ 

http://www.le.state.ut.us/~code/title23/title23.htm 

Utah Department of Environmental Quality 

2001 Information extracted from “Utah LUST Cleanup Levels as listed in the Utah Certified 

Laboratories approved for UST Environmental Sample Analysis for Aromatic 

Volatiles and Oil & Grease,” Available on the Internet @ 

http://www.deq.state.ut.us/EQERR/ust/ust_cert/labs.pdf, 

2002a Information extracted from “Total Maximum Daily Loads.” Available on the Internet 

@ http://www.deq.state.ut.us/eqwq/tmdl/tmdlweb.htm#publicomm 

2002b Personal communication from B. Moellmer, Division of Water Quality, Salt Lake 

City, UT, to Parsons, Denver, April. 

2002c Personal communication from Brandy Taylor, Division of Environmental Response 

and Remediation, Salt Lake City, UT, to Parsons, Denver, April. 
REFERENCES AND INDEX

384 GLEN CANYON NATIONAL RECREATION AREA 

2003a Personal Communication from B. Moellmer, Division of Water Quality, Salt Lake 

City, UT, to Parsons, Denver, January. 

2003b Personal communication with Pherson, Water Quality Division, April. 

Utah Division of Parks and Recreation 

2002 Unpublished data regarding personal watercraft and traditional boating accidents 

between 1992 and 2001, Salt Lake City Utah, faxed to Parsons, Denver, June 11. 

2003 Personal communication with T. Wooley, Boating Coordinator, Salt Lake City, UT, to 

B. Wright, Glen Canyon National Recreation Area, Page, AZ, April. 

Utah Division of Wildlife Resources 

1988 Information extracted from “Inventory of Sensitive Species and Ecosystems in Utah: 

Endemic and Rare Plants of Utah An Overview of Their Distribution and Status.” 

Available on the Internet @ 

http://www.utahcdc.usu.edu/ucdc/ViewReports/plantrpt.pdf. 

1996 Fish Management Plan, Glen Canyon National Recreation Area, by Utah Division of 

Wildlife Resources, Arizona Game and Fish Department and the National Park 

Service. Page, AZ. 

1998 “Reclamation Mitigation and Conservation Commission Mitigation and Conservation 

Plan,” Utah Sensitive Species List. 49 pp. 

2002a Information extracted from State of Utah Department of Natural Resources, Division 

of Wildlife Resources website. Available on the internet@ 

http://www.utahcdc.usu.edu/rsgis2/Search/Display.asap?FINm=saurobes. 

2002b Personal communication from W. Gustaveson, Fisheries Biologist, Page, AZ, to 

Connie Chitwood, Parsons, Denver, April 10. 

2003 Personal communication from Bradwisch, Wildlife Resource Specialist, Salt Lake 

City, UT, to Glen Canyon National Recreation Area staff, Page, AZ, April 2003 

Vanmouwerik, Mark and M. Hagemann 

1999 “Water Quality Concerns Related to Personal Watercraft Usage.” Technical paper. 

Water Resources Division, Fort Collins, CO. 

Verschueren, K. 

1983 Handbook of Environmental Data on Organic Chemicals. 2nd ed. New York: 

VanNostrand Reinhold Company. 

Vlasich, Brian 

1998 “Personal Watercraft: Environmental Effects of a ‘Thrill-Craft.’” In Claremont 

Environmental Policy Briefs, Student Edition. Roberts Environmental Center, 

Claremont, CA: Claremont McKenna College. 

Wagner, K.J. 

1994 “Of Hummocks and Horsepower: the Noise Issue at Lakes.” Lakeline (1492):24-28. 
References 

FINAL ENVIRONMENTAL IMPACT STATEMENT 385

Waring, G.L. 

1992 A Study of Developing Riparian Communities Along the Shoreline of Lake Powell, 

Arizona and Utah. Final Report. Glen Canyon National Recreation Area, Page, AZ: 

Contract No. CA-1463-5-0001. 

Warrington, P. 

1999 Information extracted from “Impacts of Recreational Boating on the Aquatic 

Environment,” Available on the Internet @ http://www.nalms.org/bclss/impacts 

recreationboat.htm. 

Washington DC Circuit Court 

1986 “National Rifle Association of America v. Potter.” Case No. 02-0581 Washington DC. 

1995 “Personal Watercraft Industry Association v. Department of Commerce.” 48 F.3d 540. 

Washington DC. 

White, Michael J. 

1994 Estimating Attenuation and Propagation of Noise Bands from a Distant Source using 

the Lookup Program and Database. Champaign, IL. U.S. Army Corps of Engineers 

Construction Engineering Research Laboratories, Technical Report EC-94/12. 

White, J.J. and J.N. Carroll 

1998. “Emissions from Snowmobile Engines Using Bio-Based Fuels and Lubricants.” Final 

Report. Prepared for Montana Department of Environmental Quality, Helena, MT. 

Wiedemeier, Todd H., Hanadi S. Rifani, Charles J. Newell, and John T. Wilson 

1999 Natural Attenuation of Fuels and Chlorinated Solvents in the Subsurface. New York, 

NY: John Wiley & Sons, Inc. 

Winebrake, J.J., M.Q. Wang, and D. He 

2001 “Toxic Emissions from Mobile Sources: A Total Fuel-Cycle Analysis for 

Conventional and Alternative Fuel Vehicles.” Journal of the Air & Waste 

Management Association 51:1073-1086. 

Wong, D.C.L., W.R. Arnold, G.A. Rausina, E.R. Mancini, and A.E. Steen 

2001. “Development of a Freshwater Aquatic Toxicity Database for Ambient Water Quality 

Criteria for Methyl Tertiary-Butyl Ether.” Environmental Toxicology and Chemistry

20 (5): 1125–32. 

Wu, C.Y. and G.C. Pratt 

2001 “Analysis of Air Toxics Emission Inventory: Inhalation Toxicity-Based Ranking.” 

Journal of the Air and Waste Management Association 51:1129-1141. 

Yaws, C.L., Pan Xiang, and Lin Xiaoyin 

1993. “Water Solubility Data for 151 Hydrocarbons. Chemical Engineering, 100 (n.2): 108–11. 
REFERENCES AND INDEX

386 GLEN CANYON NATIONAL RECREATION AREA 

EXECUTIVE ORDERS CITED IN THE TEXT 

Executive Order No. 11644 (Use of Off-Road Vehicles on Public Lands) Feb. 8, 1972, 37 Federal 

Register 2877, as amended by Executive Order No. 11989, May 24, 1977, 42 Federal Register

26959; Executive Order No. 12608, Sept. 9, 1987, 52 Federal Register 34617 [42 United States 

Code 4321]. 

Executive Order No. 11988 (Floodplain Management) May 24, 1977, 42 Federal Register 26951, as 

amended by Executive Order No. 12148, July 20, 1979, 44 Federal Register 43239 [42 United 

States Code 4321]. 

Executive Order No. 11990 (Protection of Wetlands) May 24, 1977, 42 Federal Register 26961, as 

amended by Executive Order No. 12608, Sept. 9, 1987, 52 Federal Register 34617 [42 United 

States Code 4321]. 

Memorandum on Government-to-Government Relations with Native American Tribal Governments 

April 29, 1994, 59 Federal Register 22951 [25 United States Code 450]. 

Executive Order No. 13006 (Locating Federal Facilities on Historic Properties in Our Nation’s Central 

Cities) May 21, 1996, 61 26071 [40 United States Code 601a]. 

Executive Order No. 13007 (Indian Sacred Sites) May 24, 1996, 61 Federal Register 26771 [42 

United States Code 1996]. 

Executive Order No. 13031 (Federal Alternative Fueled Vehicle Leadership) Dec. 13, 1996, 61 66529 

[42 United States Code 13212]. 

Executive Order No. 13175 (Consultation and Coordination with Indian Tribal Governments) 

November 6, 2000, 65 Federal Register 67249 [25 United States Code 450]. 

PUBLIC LAWS CITED IN THE TEXT 

Public Law 92-593, Oct. 27, 1972, 86 Stat. 1312, Title 16, Chapter 1, Subchapter LXXXVIII – Glen 

Canyon National Recreation Area. 

Public Law 92-593, Oct. 27, 1972, 86 Stat. 1312, Title 16, Chapter 1, Subchapter LXXXVIII, Section 

460dd-3– Administration, Protection, and Development; Statutory Authorities for Conservation 

and Management of Natural Resources; Glen Canyon Dam and Reservoir. 

TEXT CITATIONS 

FROM THE CODE OF FEDERAL REGULATIONS AND FEDERAL REGISTER 

“Navigation and Navigable Waters.” 33 Code of Federal Regulations, Volume 3:1-199. 

“Regulation of Personal Watercraft.(personal watercraft)” in Parks, Forests, and Public Property, 

Chapter 1, Part 3. Boating and Water Use Activities; Section 3.24, 36 Code of Federal 

Regulations, Volume 1:324. 

“Protection of Environment.” 40 Code of Federal Regulations (24):790 to end. 
References 

FINAL ENVIRONMENTAL IMPACT STATEMENT 387

“Wildlife and Fisheries.” 50 Code of Federal Regulations-99. 

Air Quality Related Value. Federal Register 43:15016. 

“Everglades National Park Special Regulations.” Federal Register 59:1024-AB10. 

“Air Pollution Control; Gasoline Spark-Ignition Marine Engines; New Nonroad Compression-Ignition 

and Spark-Ignition Engines, Exemptions; Rule.” Federal Register 61:52087-52169. 

Control of Air Pollution; Amendment to Emission Requirements Applicable to New Gasoline SparkIgnition Marine Engines; Final Rule. 40 Code of Federal Regulations Part 91 FRL 5805-7; 

Federal Register 62:15805-15808. 

“Personal Watercraft Use within the National Park Service System: Proposed Rule.” Federal Register

63:49312-49317. 

“Endangered and Threatened Wildlife and Plants; Final Rule to Remove the Peregrine Falcon from the 

Federal List of Endangered and Threatened Wildlife, and to Remove the Similarity of 

Appearance Provision for Free-Flying Peregrines in the Coterminous United States; Final 

Rule.” Federal Register 64:46542. 

“Personal Watercraft Use Within the National Park Service System: Final Rule” Federal Register

65:15077-15090. 
388 GLEN CANYON NATIONAL RECREATION AREA

INDEX 

1-methyl naphthalene, 83, 86, 89, 90, 91, 169, 171, 

172, 176, 180, 223, 335–338 

accident, x, xviii, 19, 28, 63, 136–138, 154, 254, 257, 

258, 306 

adverse impacts, xiii, xv, 14, 58, 60, 157, 159, 183, 

190, 192, 194, 196, 198, 208, 216, 218, 220–222, 

224, 225, 231, 232, 234, 239, 242, 244, 245, 254, 

266, 271, 272, 282, 284, 286 

air quality standards, xiii, 31, 58, 93–95, 181, 183, 

186, 187, 189, 190, 192, 193, 196, 198 

air quality, viii, ix, xii, xiii , 8, 15, 17, 21, 23, 24, 31, 

53, 58, 66, 93–95, 180–184, 186–198, 283, 287 

alcohol, 39, 44, 82, 184, 255 

alternative A, x–xix, 10, 35–47, 51–54, 56, 58–64, 

66, 169–171, 173–179, 184, 188–194, 196–198, 

204, 206–208, 210, 211, 219, 222, 224–226, 231, 

233, 235–237, 241–245, 248–252, 255–258, 

265–271, 274, 275, 280–282, 284, 286 

alternative B, vii, xi–xix, 10, 35, 36, 47–53, 57–64, 

66, 67, 169, 175–178, 184, 192–194, 195, 196, 

204, 210, 211, 225, 226, 235–238, 243, 244, 250, 

251, 256, 257, 269, 270–272, 275, 281–283, 286 

alternative C, xi–xix, 10, 35, 36, 55, 56, 58–64, 67, 

159, 165, 169, 178, 179, 184, 196–198, 204, 208, 

211–213, 217, 226, 237, 238, 244, 245, 247, 251, 

252, 257, 258, 270, 271, 275–277, 283–287 

amphibians, 106, 109, 114, 222 

analysis area, 113, 114, 117, 118, 159, 188, 189, 193, 

217, 229, 231, 233, 236, 241 

Antelope Point, 20, 28, 71, 72, 124, 128, 162, 224, 

225, 226, 234, 261, 311, 312, 328 

aquatic organisms, ix, 16, 21, 86, 88–90, 163, 334, 

336–338 

archeological resources, 21, 25, 28, 72, 140, 201, 

259, 260, 262, 263, 265, 266, 269, 271, 272 

Arizona Game and Fish Department, 31, 113, 133, 

150, 217, 228, 343, 354–356 

Arizona, v, 3, 20, 25, 30, 31, 37–39, 44, 46, 52–54, 

56, 71, 80, 81, 83, 86, 88–94, 101, 104, 107, 108, 

113, 116–118, 133–135, 144–148, 150, 164, 169, 

170, 175, 181, 184, 190, 199, 203, 205, 216, 217, 

228, 229, 239, 254–256, 258, 272, 274, 278–280, 

282, 306, 308, 336, 337, 343, 354–356 

assumption, 159, 164, 172, 183, 184, 189, 203, 204, 

211, 217, 228, 229, 240, 247, 260, 273, 279, 328, 

334, 335, 338 

bald eagle, xvi, 61, 114, 117, 118, 216, 229, 233, 

235–238 

beach, 37, 80, 81, 120, 121, 130, 135, 199, 204, 214, 

217, 223, 242, 305, 311, 324 

benzene, ix, 16, 82, 83, 85–87, 89–91, 163, 168, 169, 

171–176, 178, 180, 220, 223, 224, 313, 334–339, 

341 

benzo(a)pyrene, 83, 85, 86, 89–91, 169, 171, 172, 

176, 180, 335–338 

bighorn sheep, 106, 110, 112, 217, 220 

birds, ix, xvi, 7, 18, 61, 86, 96, 98, 104, 106, 107, 

110, 111, 114, 117, 118, 209, 214, 216, 217, 

221–234, 236, 238 

Bluewater Network, vii, viii, 8, 11, 23, 83, 253 

bonytail, 108, 113–115, 117, 229, 231, 235, 237 

Bullfrog Marina, 83, 174, 175, 178 

Bureau of Land Management, v, 3, 29, 30, 71, 122, 

128, 129 

Bureau of Reclamation, v, 12, 22, 28, 30, 71, 79, 83, 

116, 278 

California condor, 113, 114, 117 

Canyonlands, v, 3, 71, 128–130, 140, 250 

Capitol Reef, v, 3, 71, 332 

carbon monoxide, ix, xiii, 17, 25, 58, 93–95, 138, 

180, 182, 187, 189–198 
Index 

FINAL ENVIRONMENTAL IMPACT STATEMENT 389

Carl Hayden Visitor Center, 72 

carrying capacity, 39, 126, 180, 308 

Clayhills Crossing, 232 

Clean Air Act, 31, 53, 84, 93, 87, 88, 163, 181, 183, 

185 

Coconino County, 94, 113, 117, 148 

Colorado pikeminnow, 108, 113–115, 229, 231, 235 

Colorado Plateau, vi, 12, 13, 71, 94, 97, 164, 170, 

177, 210, 225, 231, 233, 235, 241–243, 250, 256, 

261, 266, 268, 269 

Colorado River, v, vi, xi, xii, 3, 12, 20, 28, 30, 36, 43, 

47, 51, 71, 75–79, 106–109, 111, 113, 115–118, 

121, 128–130, 141, 142, 303, 304 

cottonwood, 108, 117, 118, 121–123, 141, 233, 236 

cultural landscapes, 140, 141, 262, 264, 265, 267, 

272 

Cultural Zone, xiv, 59, 72, 99, 201, 203, 205, 206, 

208–213 

cultural, xii, xiv, xviii, 15, 21, 23, 25, 26, 29, 59, 63, 

66, 67, 72, 99, 124, 140–143, 152, 161, 162, 182, 

186, 188, 200, 201, 203, 205, 206, 208–213, 215, 

246, 253, 259–265, 267–273, 305, 320, 322 

Dangling Rope, 72, 81, 110, 112, 126, 128, 151 

Development Zone, 29, 72, 201, 205, 229 

Dirty Devil River, xi, 35, 36, 41, 43, 47, 48, 50, 71, 

76, 77, 111, 113, 115, 129, 135, 162, 177, 225, 

231, 242, 250, 256, 267, 304, 312 

drinking water, ix, 24, 76, 83, 87, 89, 90–92, 163, 

164, 170, 174, 175, 178, 337, 340, 341 

education, xiv, xvii–xix, 37, 40, 45, 52, 55, 56, 59, 

62–64, 67, 80, 104, 138, 139, 150, 210, 250, 251, 

253, 255–257, 269, 281–283, 310 

emission standards, xix, 17, 31, 35, 36, 47, 57, 64, 

182, 184, 190, 191, 195, 197, 283, 341 

enabling legislation, v, vi, viii, xv, 9, 10, 12, 15, 21, 

30, 57, 60, 188, 225, 226, 231, 247 

Endangered Species Act, 31, 113, 227, 228, 230–234, 

236, 237 

endangered species, xvi, 31, 61, 67, 113–115, 214, 

215, 217, 227–238 

enforcement, xiv, xix, 25, 39, 44, 45, 52, 55, 59, 64, 

80, 87, 88, 126, 135, 150–154, 202, 205, 210, 221, 

253, 255, 256, 258, 278–280, 282–285, 306, 310 

environmental consequences, xii, 15, 23, 57, 83, 155, 

223, 224, 282, 286, 319 

environmentally preferred alternative, xii, 66, 67 

Escalante River, viii, xi, xvi, xvii, 11, 36, 42, 43, 47, 

49, 51, 52, 61, 62, 66, 72, 76–78, 110, 117, 123, 

129, 141, 176–178, 192, 219, 225, 231, 235, 241, 

243, 244, 250, 256, 269, 304 

ethnographic resources, xviii, 63, 140, 142, 262, 264, 

265, 267, 269, 270–272 

ethylbenzene, ix, 16, 82, 85, 220, 222, 224 

Everglades National Park, vi, vii, 7, 332 

exotic, 120, 242 

fish, ix, xv, xvi, 7, 21, 24, 28, 29, 60, 61, 75, 77, 78, 

86–92, 106, 108–111, 113–119, 163, 214, 

216–218, 223–232, 234–238, 336, 337, 341–343, 

351–353 

Garfield County, 118, 149 

Glen Canyon Dam, viii, 11, 28, 30, 71, 72, 76, 78, 79, 

83, 106, 116, 118, 141, 144, 146, 148, 159, 170, 

175, 231, 261, 303 

Grand Canyon National Park, v, 3, 303 

Grand Staircase, v, 3, 71 

habitat(s), viii, ix, xv, xvi, 8, 18, 21, 23, 24, 29, 60, 

61, 106, 108–111, 113–118, 199, 200, 206, 214, 

215, 217–221, 223–238 

Halls Crossing, 20, 71, 72, 81, 94, 95, 97, 124, 126, 

128, 141, 151, 183, 232, 305, 312, 328, 330 

Havasupai, 142 
REFERENCES AND INDEX

390 GLEN CANYON NATIONAL RECREATION AREA 

historic, v, vi, 3, 12–14, 25, 26, 29, 66, 72, 77, 117, 

140, 141, 142, 181, 182, 200–202, 215, 216, 246, 

259–263, 265–269, 271, 272, 332, 343, 349, 350 

Hite, 20, 29, 37, 71, 72, 76, 77, 81, 83, 124, 126, 

128–130, 136, 150, 151, 162, 174, 232, 241, 250, 

305, 312, 328, 330 

Hualapai, 142 

humpback chub, 108, 113–116, 229, 231, 235, 237 

hydrocarbon(s), xiii, xv, 16, 17, 31, 35, 40, 53, 58, 

60, 82–86, 160, 163–165, 168, 171, 174, 178, 179, 

182, 184, 185, 189–198, 219, 222, 224, 225, 232, 

313, 334, 338, 342 

impact threshold(s), 158, 170, 173, 174, 186, 205, 

218, 230, 240, 247, 254, 262, 274, 279 

impact topic(s), viii, xiii, 21, 23, 26, 58 

impact(s), vii, viii, x, xii–xv, xviii, 8, 10, 11, 13–16, 

18, 21, 23, 26, 27, 57–60, 63, 72, 96–98, 118, 124, 

141, 157–162, 165, 168, 170, 173, 174, 179, 180, 

183–187, 190, 194, 200, 202–215, 217–219, 

221–223, 225, 226, 228–230, 232, 235, 236, 238, 

240, 242–244, 247, 252, 254, 255, 257, 261–266, 

268, 271–275, 279, 311, 334, 341 

impairment, xiii–xviii, 13, 14, 15, 58–63, 159, 161, 

170, 175, 177, 179, 187, 188, 192, 196, 198, 206, 

210, 211, 213, 216, 219, 225, 226, 231, 235, 237, 

238, 240, 243–245, 263, 264, 269, 270, 271, 286 

inflow areas, xvi, 53, 61, 108, 110, 115, 116, 227, 

235, 237, 238 

issues, viii, ix, x, 23, 25, 46, 129, 130, 139, 158, 163, 

180, 199, 200, 214, 227, 239, 246, 253, 258, 259, 

273, 278, 279, 310, 311, 340 

Kaibab Paiute, 142 

Kane County, 148, 149 

Kanosh, 142 

Knowles Canyon, 82, 83, 174, 312, 313 

Koosharem, 142 

lake management plan, xi, 11, 40, 46, 51, 54, 56, 57, 

67, 160, 255, 257, 311 

Lake Powell, v, vi, viii, ix, x, xiii, xvi–xviii, 3, 11, 

12, 20, 22, 26, 29–31, 39, 45–47, 52, 53, 55–58, 

61–63, 71, 72, 75–84, 87–92, 99, 100, 104, 

106–113, 115–120, 122, 124, 125, 128–131, 

133–140, 142–144, 146, 148, 154, 160, 162, 

164–180, 184, 188, 191, 198, 202, 205, 206, 210, 

211, 216, 218–220, 222–224, 226, 227, 229, 

231–235, 238, 239, 241, 244, 246–250, 252, 254, 

257, 258, 261, 268, 270, 275, 278, 280, 284, 287, 

304, 311, 313–317, 319, 320, 322, 324, 328, 330 

lake zone, 128 

legislation, 46, 161, 202, 263, 264 

livestock, ix, 30, 75, 89, 122, 242, 324 

mammals, 104, 106, 109, 114, 209, 220, 221 

management objectives, xii, 9, 47, 163, 164, 180, 

181, 199–201, 206, 214, 227, 239, 246, 253, 259, 

273, 278 

Mexican spotted owl, 113, 114, 117, 229 

monitoring, xix, 29, 40, 46, 53, 54, 56, 64, 80, 83, 94, 

95, 97, 116, 152, 158, 175, 183, 

186–190, 268, 272, 283, 312, 340 

Moqui Canyon, 82, 83, 174, 175, 312 

naphthalene, 83, 85, 86, 89–91, 169, 171, 172, 175, 

176, 180, 223, 335–338 

National Register of Historic Places, 25, 140, 142, 

260–266, 268, 272 

Natural Zone, x, 72, 99, 100, 104, 105, 201, 203, 204, 

206, 207, 209, 210, 213, 249, 252 

Navajo Nation, v, 3, 26, 71, 141, 268 

Navajo sedge, 113, 114, 118 

Neskahi Bay, 232 

nesting, ix, 18, 107, 110, 117, 118, 214, 217, 

221–223 

noise, ix, x, xii, xiv, xv, xvii, 8, 17, 18, 24, 25, 35, 39, 

40, 44, 46, 52, 53, 59, 60, 62, 66, 67, 96–101, 

103–106, 160, 199–214, 217, 219, 220, 222–227, 

232–236, 238, 246, 248, 249, 251, 252, 259, 267, 

269–271, 283, 286, 287, 309–311, 324, 339 
Index 

FINAL ENVIRONMENTAL IMPACT STATEMENT 391

Nokai Canyon, 232 

North Gulch, 312 

objectives, viii, 9, 11, 21, 28–30, 35, 46, 57, 66, 71, 

163, 202, 214, 219, 221, 227, 249, 253, 259, 278 

oil, 17, 81–83, 85, 86, 167, 174, 180, 222, 287, 336, 

339 

Organic Act, v, vii, 8, 12–14, 157, 161, 182, 183, 

200, 214, 215, 259, 260 

Paria Canyon, v, 3 

peregrine falcon, xv, xvi , 60, 61, 107, 111, 114, 118, 

225, 229, 231, 233, 235–238 

personal watercraft, vi–xix, 3, 7–12, 15–29, 31, 

35–40, 43–45, 47, 50–53, 55–64, 66, 67, 72, 

80–85, 88, 89, 95–106, 110, 112–114, 119, 

124–133, 135–140, 144–146, 150–154, 157–160, 

162–199, 201–227, 229–244, 246–260, 262, 

265–287, 303, 306–308, 311–313, 319, 320, 322, 

324, 326–332, 334–340 

pollution, 8, 16, 53, 80–82, 84, 88, 93, 94, 165, 166, 

173, 174, 176, 178, 179, 181, 183, 186, 223, 234, 

236–238, 279, 341 

preferred alternative, vii, xi, xii, xiii, 10, 36, 47, 58, 

66, 67, 175, 192, 193, 210, 225, 235, 250, 256, 

269, 275, 281 

public, v, vi, vii, xii, 3, 7, 8, 12, 13, 21, 23, 29, 30, 

35, 37, 51, 55, 57, 71, 89, 91–93, 135, 136, 151, 

158, 167, 181, 183, 200, 202, 215, 216, 228, 246, 

249, 253, 259, 260, 268, 273, 279, 280, 282, 305, 

312, 326, 340 

Rainbow Bridge, v, 3, 28, 44, 97, 98, 101, 104, 126, 

209, 215, 305, 333 

razorback sucker, 108, 113–116, 229, 231, 232, 235, 

237 

Recreation and Resource Utilization Zone, 20, 29, 57, 

72, 99, 104, 201, 203, 206–208, 210, 212, 213, 

229, 234, 242 

regulations, vi, vii, xiv, 7, 20, 25, 31, 37–40, 44, 45, 

52, 53, 55, 59, 66, 67, 81, 93, 101, 131, 132, 135, 

139, 144, 150, 151, 157, 158, 162–164, 167, 181, 

183, 188, 189, 200–203, 205, 210, 214–216, 227, 

228, 239, 246, 253–255, 

258–262, 272, 273, 276, 278–283, 303, 304, 306, 

308, 324, 326, 334, 338, 340, 341 

reptiles, 106, 109, 222 

resource management, xix, 21, 29, 30, 64, 110, 143, 

150, 152, 157, 229, 234, 259, 280, 282, 283 

restrict, restriction(s), vii, x–xiii, xvi, xix, 7, 10, 28, 

35–38, 44, 47, 51, 55, 57, 58, 61, 64, 66, 101, 106, 

121, 132, 135, 175–177, 184, 192, 193, 205, 210, 

225, 235–237, 242–244, 248, 250, 256, 269, 275, 

281–283, 304, 326, 327 

riparian vegetation, 106, 110, 121, 122, 241, 242, 243 

Rock Creek Bay, 312 

safety, x, xviii, xix, 8, 15, 18, 19, 25, 26, 38, 45, 46, 

50–53, 56, 63, 64, 66, 67, 79, 93, 131, 132, 135, 

137–139, 151, 158, 253–258, 281, 283, 303, 304, 

307, 310, 326 

sampling, 40, 46, 53, 56, 82, 86, 89, 90, 91, 95, 104, 

173–175, 179, 183, 209, 313 

San Juan County, 7, 115, 148, 149 

San Juan River, xi, xvii, 20, 36, 37, 43, 47, 50, 62, 

76, 77, 110–113, 115–118, 122, 129, 130, 135, 

142, 177, 225, 231, 232, 234, 235, 241, 244, 249, 

256, 271, 304, 305 

San Juan Southern Paiute, 142 

sanitation, 40, 45, 53, 56, 152, 304 

section 101, xii, 66 

section 106, 260–264, 271, 272 

section 176, 181 

section 213, 31, 213, 84 

section 313, 88 

section 7, 231–234, 236, 237, 279, 306, 307, 343, 

351, 352, 353 

Sheep Canyon, xi, 36, 47, 51, 129, 225, 243, 250, 256 
REFERENCES AND INDEX

392 GLEN CANYON NATIONAL RECREATION AREA 

socioeconomic(s), xix, 22, 23, 25, 64, 124, 144, 165, 

273–276 

soils, 106, 123, 266 

soundscape, ix, xiv, 46, 59, 96–99, 104, 105, 

199–213, 246, 286 

southwestern willow flycatcher, xvi, 61, 113, 114, 

117, 229, 231, 233, 235–238 

special-interest, xv, 60, 110, 112, 217, 221, 225 

species, xv, xvi, 21, 23, 24, 28–30, 60, 61, 89, 90, 94, 

106–123, 158, 199, 214, 216–221, 223, 225–238, 

241, 243 

State Historic Preservation Officer, 343–348 

strategic plan, v, viii, 12, 21, 28, 46, 56, 81, 231, 239, 

246, 278 

summary, v, 15, 24, 35, 36, 52, 57, 97, 135, 136, 147, 

153, 157, 164, 167, 262, 271, 330, 340, 341 

sustainability, 286 

toluene, ix, 16, 82, 85, 220, 222–224, 334 

unavoidable adverse impact, 286 

Utah Division of Wildlife Resources, 

Utah Division of Wildlife Resources, 77–79, 112, 

113, 115, 116, 119, 217, 227, 228, 229, 234, 241, 

343, 357 

Utah, v, xi, 3, 20, 25, 30, 31, 36–39, 44, 46, 47, 50, 

52–54, 56, 71, 75–83, 86, 88–94, 101, 102, 104, 

108, 112, 113, 115–119, 128, 130, 

133–135, 138, 141, 142, 144–148, 150, 164, 169, 

174, 175, 178, 181, 184, 190, 203, 205, 216, 217, 

227, 228, 229, 234, 239, 241, 254, 255, 256, 258, 

272, 274, 278, 279, 280, 282, 304, 306, 313, 343, 

357 

Ute ladies-tresses, 118 

Ute Mountain Ute, 142 

vegetation, vi, viii, ix, x, xvii, 7, 8, 18, 21, 23, 25, 29, 

62, 71, 93, 95, 98, 100, 104, 106, 108–111, 120–

122, 180, 186, 190, 209, 217, 220, 224, 227, 232, 

239, 240, 241, 242, 243, 244, 245, 265 

visibility, ix, xiii, 24, 38, 58, 93, 94, 180, 181, 186, 

187, 188, 191, 192, 194, 196, 198, 308 

visitor conflict, viii, x, xviii, 8, 23, 25, 29, 39, 46, 51, 

52, 63, 67, 135, 253, 254, 255, 256, 257, 258, 310, 

311 

visitor experience, ix, xvii, 21, 25, 50, 51, 62, 66, 96, 

199, 200, 203, 246, 247, 248, 249, 250, 251, 252, 

253, 254, 311 

visitor safety, viii, x, xi, xviii, 8, 21, 23, 25, 28, 44, 

47, 51, 57, 63, 67, 135, 151, 250, 253, 254, 255, 

256, 257, 258 

visitor(s), viii–xiii, xvii–xix, 8, 9, 11, 14, 18, 21, 23, 

25, 28, 29, 39, 40, 43–47, 50–58, 62–64, 66, 67, 

72, 81, 82, 96, 97, 100, 102, 106, 109, 111, 112, 

121, 122, 124–133, 135, 137–139, 144–146, 

150–152, 160, 161, 162, 165, 169, 175, 178, 179, 

180, 182, 184, 190, 191, 194, 197, 198, 199, 200, 

201, 202, 203, 204, 205, 206, 207, 210, 211, 212, 

215, 217, 219, 220, 224, 226, 234, 238, 241, 242, 

243, 244, 246, 247, 248, 249, 250, 251, 252, 253, 

254, 255, 256, 257, 258, 259, 261, 266, 267, 268, 

269, 270, 271, 272, 273, 274, 275, 276, 277, 279, 

280, 281, 282, 283, 284, 285, 286, 287, 303, 304, 

310–312, 319, 326 

Wahweap, 20, 71, 72, 80–82, 94, 95, 107, 111, 120, 

124, 126, 128, 150–152, 162, 177, 183, 224, 225, 

226, 232, 234, 241, 243, 245 

Wahweap, 310–313, 328, 330 

wakeless zone, 311 

water quality standards, 46, 80, 87–89, 92, 152, 164, 

166, 169, 170, 173, 174, 176, 178, 179, 334 

water quality, viii, ix, xii, xiii, 7, 8, 15, 16, 21, 23, 24, 

28, 45, 46, 53, 56, 58, 75–83, 85–92, 108, 109, 

113, 116–118, 130, 152, 158, 163, 164, 165, 166, 

167, 168, 169, 170, 173, 174, 175, 176, 177, 178, 

179, 223, 224, 225, 232, 234, 236, 238, 282, 304, 

312, 313, 324, 334, 336–338, 340, 341 

water supply, ix, 75, 88, 89, 120, 121 

wetlands, 23, 110, 111, 120, 122, 123, 216, 217, 239, 

240, 242 

wilderness, v, 3, 72, 75, 76, 100, 141, 181, 182, 202, 

246 
Index 

FINAL ENVIRONMENTAL IMPACT STATEMENT 393

wildlife, vii–x, xv, 7, 8, 14, 18, 21, 23, 24, 30, 60, 

88–90, 92, 98, 106, 107, 109–113, 116–118, 182, 

199, 200, 203, 206, 214, 215, 216, 217, 218, 219, 

220, 221, 222, 223, 224, 225, 226, 227, 228, 230, 

241, 336, 337, 342, 343, 351–353 

willow, xvi, 61, 108, 117, 118, 121, 122, 233, 236, 

238 

xylenes, ix, 16, 82, 85, 220, 224, 334 

yellow-billed cuckoo, xvi, 61, 114, 118, 229, 231, 

233, 235, 236, 237, 238