Grand Canyon National Park Research Articles

Small-Bodied Fish Surveys Demonstrate Native Fish Dominance Over 300 Kilometers of the Colorado River Through Grand Canyon, Arizona

The Colorado River in Grand Canyon is highly regulated, with hypolimnetic releases that are generally unfavorable for endemic native fishes. However, both long-term drought and changes in dam operations have led to changes in river conditions, including the addition of approximately 125 km of riverine environment due to the contraction of Lake Mead. Through sampling of small-bodied fish, we were able to describe the Grand Canyon fish community and define the current native fish distribution from near Bright Angel Creek downstream to Pearce Ferry. Beginning in 2014 and continuing through 2018, we sampled the fish community via seining and documented a fish community that was dominated (>95%) by native fish through approximately 300 km of river. Nonnative species that were once commonly captured, such as Red Shiner Cyprinella lutrensis, Common Carp Cyprinus carpio, and Channel Catfish Ictalurus punctatus, were rarely encountered in Grand Canyon during this more recent sampling, which makes the Colorado River in Grand Canyon National Park a rare contemporary example of native fish populations regaining dominance over invasive fishes in the desert southwest.

Geochemical Variability in Karst-Siliciclastic Aquifer Spring Discharge, Kaibab Plateau, Grand Canyon

ABSTRACT The source area of groundwater for springs discharging from lithologically variably perched aquifers is essential to understand when establishing baseline aquifer characteristics. Stratigraphic data from hydrostratigraphic outcrops and geochemical data from springs were used to characterize the hydrogeology of a remote, data-poor aquifer. This study focuses on the hydrogeological variability within the shallow karst-siliciclastic Coconino (C) aquifer on the Kaibab Plateau, north of Grand Canyon National Park. Stratigraphic data were collected from 8 locations, and 22 C aquifer springs were sampled for 18 months. Stable isotope analyses indicate that groundwater is biased to winter recharge in the form of snow and shows similar isotopic signature for groundwater storage areas for all C aquifer springs. Stratigraphic analyses show that the primary water-bearing unit in the C aquifer thins dramatically from south to north and has evaporite lithofacies directly above the unit. Principal component analysis (PCA) indicates that the hydrogeochemistry is influenced by SO42−, Cl−, Mg2+, Ca+, specific conductivity, alkalinity, and δD variability. The stratigraphic variability influences geochemistry at multiple locations and has geochemical variabilities that correlate with changing lithology. Based on the PCA results, groundwater sub-basins were delineated based on geochemical variability. This study provides new analytical tools for land managers and karst hydrogeologists to evaluate lithologically complex aquifers by evaluating the stratigraphy and with high-resolution data. Cost-effective stratigraphic analyses and high-resolution spring sampling can and should be used to evaluate lithologically complex aquifers in remote, data-poor regions.

Natural and anthropogenic processes affecting radon releases during mining and early stage reclamation activities, Pinenut uranium mine, Arizona, USA

Radon (Rnair) was monitored in open air in publicly accessible areas surrounding the Pinenut uranium (U) mine during mining and reclamation activities in 2015–16 to address concerns about mining related effects to areas surrounding Grand Canyon National Park (GCNP) in Arizona, USA. During July 2015, Rnair concentrations associated with the ore storage pile monitoring site were larger than those at the mine vent monitoring site and likely resulted from the relatively large amount of ore stored on site during this period. Higher wind velocities at the ore pile monitoring site generally resulted in lower Rnair concentrations; however, wind velocity did not appear to be an important factor in controlling Rnair concentrations at the mine vent monitoring site. Physical disturbances of the ore pile by heavy equipment did not coincide with elevated Rnair concentrations at the ore storage pile or mine vent monitoring sites. The relative size of the ore storage pile showed a positive trend with the daily mean Rnair concentration measured at the ore pile monitoring site. Principal component analysis (PCA) was applied to the ore pile and mine vent multivariate data sets for simultaneous comparison of all measured variables during 230 days of the study period. A significant positive coefficient for Rnair was associated with a significant negative coefficient for wind speed for principal component (PC) 2ore pile. Significant, positive PC2mine vent coefficients included Rnair, wind direction, and relative ore pile size indicating that Rnair variations at the mine vent monitoring site may be affected by Rn sourced from the ore pile. The ore pile is located about 200 m south of the mine vent Rn monitor with the prevalent wind direction coming from the south. All data generated during the field study and laboratory verification tests were published by Naftz et al. (2018) and are available online at: https://doi.org/10.5066/F79Z946T.

Tracking the Grand Canyon’s Mysterious Springs

Improved modeling will help protect a crucial drinking water source for both rims of Grand Canyon National Park.

Estimating Bedload From Suspended Load and Water Discharge in Sand Bed Rivers

AbstractEstimates of fluvial sediment discharge from in situ instruments are an important component of large‐scale sediment budgets that track long‐term geomorphic change. Suspended sediment load can be reliably estimated using acoustic or physical sampling techniques; however, bedload is difficult to measure directly and can consequently be one of the largest sources of uncertainty in estimates of total load. We propose a physically informed predictive empirical model for bedload sand flux as a function of variables that are measured using existing acoustic or physical sampling techniques. This model depends on the assumption that concentration and grain size in suspension are in equilibrium with reach‐averaged boundary conditions. Bayesian inference is used to fit model parameters to data from eight sand‐bed rivers and to simulate bedload flux over the available gage record at one site on the Colorado River in Grand Canyon National Park. We find that the cumulative bedload flux during the 9 year period from 2008 to 2016 was 5% of the cumulative suspended sand load; however, instantaneous bedload flux ranged from as little as 1% of instantaneous suspended sand load to as much as 75% of instantaneous suspended sand load due to fluctuations in flow strength and sediment supply. Changes in bedload flux at a constant discharge are indicative of short‐term sediment supply enrichment and depletion. Long‐term average bedload flux cannot be expected to remain constant in the future as the river adjusts to changes in sediment runoff and the dam‐regulated discharge regime.

Establishment of a Reproducing Population of Endangered Humpback Chub through Translocations to a Colorado River Tributary in Grand Canyon, Arizona

AbstractTranslocations, defined herein as the human‐assisted movement of individuals from a source population to other waters within their historical range, are prevalent in recovery plans for endangered fishes. Many translocations fail to establish new populations, however, and outcomes are often poorly documented. Endangered Humpback Chub Gila cypha persist as a self‐sustaining population in Grand Canyon, Arizona, despite threats from introduced nonnative competitors and predators and modified flow, thermal, and sediment regimes due to river regulation. In the decades following the completion of Glen Canyon Dam, the Grand Canyon population has been primarily sustained through reproduction in a single Colorado River tributary, the Little Colorado River (LCR). To establish population redundancy and aid in recovery, we annually translocated between 243 and 509 juvenile Humpback Chub from the LCR to Havasu Creek, a smaller Colorado River tributary in Grand Canyon National Park. Juvenile Humpback Chub were collected from the wild and reared in a hatchery for 8–12 months prior to the translocations. Through biannual mark–recapture sampling in Havasu Creek, we estimated annual abundance for all of the translocated cohorts and found that apparent survival and growth rates met or exceeded the demographic rates that are published for the LCR. We observed reproductively mature adults each year in May, beginning in 2012, and untagged juvenile Humpback Chub beginning in the following year and every year thereafter, with results that indicated successful reproduction. Beginning in 2016, we noted recruitment to maturity of fish that were produced in situ and the population's abundance increased through 2018, indicating potential for the establishment of a self‐sustaining population. As an example of the successful translocation of an endangered species that demonstrates the potential importance of tributaries in the recovery of large‐river fishes, our study may help to inform future recovery planning.

Ecosystem management applications of resource objective wildfires in forests of the Grand Canyon National Park, USA

Forest managers of the western United States are increasingly interested in utilising naturally ignited wildfires to achieve management objectives. Wildfires can accomplish a range of objectives, from maintenance of intact ecological conditions, to ecosystem restoration, to playing vital natural disturbance roles; however, few studies have carefully evaluated long-term effectiveness and outcomes of wildfire applications across multiple forest types. We remeasured monitoring plots more than 10 years after ‘resource objective’ (RO) fires were allowed to burn in three main south-western forest types. Results showed minimal effects and effective maintenance of open conditions in an intact pine-oak site. Higher-severity fire and delayed mortality of larger and older trees contributed to reductions in basal area and canopy cover at the mixed-conifer and spruce-fir sites. Species dominance shifted towards ponderosa pine in both the mixed-conifer and spruce-fir sites. Although fires resulted in 46–68% mortality of smaller trees initially, substantial ingrowth brought tree density to near pre-fire levels in all forest types after 12 years. Overall, the 2003 RO fires were broadly successful at maintaining or creating open and heterogeneous conditions and resulted in fire- and drought-tolerant species composition. These conditions are likely to be resilient to changing climate, at least in the short term. Substantial mortality of large trees and continuing loss of basal area, however, are a concern, given further climate warming.

Classic Rock Tours 3. Grand Canyon Geology, One Hundred and Fifty Years after John Wesley Powell: A Geology Guide for Visiting the South Rim of Grand Canyon National Park

Classic Rock Tours 3. Grand Canyon Geology, One Hundred and Fifty Years after John Wesley Powell: A Geology Guide for Visiting the South Rim of Grand Canyon National Park

Eastern Virgin Hinterlands: Formative Period (AD 700–AD 1225) Settlement Practices in Grand Canyon National Park

Grand Canyon National Park encompasses a large portion of the southeastern extent of the Virgin Ancestral Puebloan tradition. From AD 700 to 1225, the region also bounded the Kayenta Ancestral Puebloan and the Cohonina traditions. This paper examines variation in settlement practices between these three traditions in this ecologically diverse locale. The analyses provide new insights and settlement models for the Formative Period in Grand Canyon National Park.

Grand Canyon National Park Research Library

This article is written by Edward M. (Ted) McClure. Ted is the Librarian at the Grand Canyon National Park Research Library in Arizona. In this article, Ted details the history, collection scope, public services, and unique challenges of operating a research library at the Grand Canyon National Park.

Cover Image

Description of Graphic on the cover of the July issue of JEE (108:3)Our sacred, foundational knowledge of Art, Science, Technology, Engineering and Mathematics are embedded in our homes of timber, packed with earth; ceremonially we gather in this sacred place, under these sacred forms, welcoming the rising sun's abundance; structured to hold family and warmth; kept cool by the air moving through and up, like the smoke of our ceremonies.From these walls, we hold and share the story of these lands.The four, Navajo‐centered categories, Application, Strategy, Purpose, and Behavior are represented by the four colors, jet, white shell, turquoise, and abalone colored smoke. As the smoke rises, it blends to unify in the night sky; this is the moment innovation is naturally conceived.Dawn is representative of the rising hope stimulated by the Navajo Nation youth seeking to strengthen their communities, creating economic opportunities and improving the lives of their tribe.Dusk is representative of maturing and the reflection of foundational development for culturally‐contextualized engineering design. It is held in the understanding and acceptance of similarities and differences that the Navajo culture and practicing Navajo Engineers experience.Walk in beauty, balance within harmony and the goodness of all things physical and spiritual. “Hózhó náhásdlíí' Hózhó náhásdlíí' Hózhó náhásdlíí' Hózhó náhásdlíí'.”Eunique's BiosketchEunique Yazzie is Diné (Navajo) from Canyon de Chelle, Arizona. She is Naaneesht'ézhi Táchii'nii born for Mą 'íí deeshgíízhíníí. Her maternal grandfather is Tódích'íi'nii and her paternal grandfather is Kinyaa'áanii. She lives in Phoenix, AZ with her 11 year old son running a small business as a Creative influencer and Designer within the arts and cultural community. She is a poet and storyteller, as well as working as a System Administrator for a national corporate enterprise.Brian's BiosketchBrian Skeet is an Indigenous (Diné) designer from Tuba City, AZ and was raised at the Grand Canyon National Park. Skeet has a Bachelor of Science in Industrial Design and a Bachelor of Arts in Design Management. He specializes in Industrial/Product Design and Graphic Design. Skeet strives to be a designer that focuses on inclusivity, pushing innovation and empowering community engagement through design.

Modeling Temperature Regime and Physical Habitat Impacts from Restored Streamflow.

Water infrastructure updates at Grand Canyon National Park (GRCA) provide an opportunity to restore natural flow to Bright Angel Creek, adding an additional ~20% to baseflow. This creek provides habitat for endangered humpback chub (Gila cypha) and invasive brown trout (Salmo trutta). We assess how increased flow may alter habitat and how that change may impact native and nonnative species using physical habitat modeling and statistical analysis of stream temperature data. We used System for Environmental Flow Analysis to calculate the change in habitat area for both species in the lower 2.1 km of the creek before and after the increased flow. Results indicate a slight increase in available habitat for juveniles of both species and a slight decrease for spawning brown trout. We used regression modeling to relate daily average air temperature to stream temperature and periods of increased discharge during water system maintenance were used to model the temperatures during likely future conditions. Both high and low stream temperature were dampened due to the added water resulting in fewer days with suitable spawning temperature and more days with suitable growth temperature for humpback chub. Fewer suitable days for growth upstream but more suitable days downstream, were predicted for brown trout. Compared to other streams that sustain populations of humpback chub, flow conditions for Bright Angel Creek provide fewer days throughout the year with suitable temperatures, particularly during the winter months. Juvenile humpback chub rearing may improve through the restoration of flow however the presence of predatory brown trout complicates the net beneficial impact.

Assessing the Relationship between Forest Structure and Fire Severity on the North Rim of the Grand Canyon

While operational fire severity products inform fire management decisions in Grand Canyon National Park (GRCA), managers have expressed the need for better quantification of the consequences of severity, specifically forest structure. In this study we computed metrics related to the forest structure from airborne laser scanning (ALS) data and investigated the influence that fires that burned in the decade previous had on forest structure on the North Rim of the Grand Canyon in Arizona. We found that fire severity best explains the occurrence of structure classes that include canopy cover, vertical fuel distribution, and surface roughness. In general we found that high fire severity resulted in structure types that exhibit lower canopy cover and higher surface roughness. Areas that burned more frequently with lower fire severity in general had a more closed canopy and a lower surface roughness, with less brush and less conifer regeneration. In a random forests modeling exercise to examine the relationship between severity and structure we found mean canopy height to be a powerful explanatory variable, but still proved less informative than the three-component structure classification. We show that fire severity not only impacts forest structure but also brings heterogeneity to vegetation types along the elevation gradient on the Kaibab plateau. This work provides managers with a unique dataset, usable in conjunction with vegetation, fuels and fire history data, to support management decisions at GRCA.

Which visibility indicators best represent a population’s preference for a level of visual air quality?

ABSTRACTSeveral studies have been carried out over the past 20 or so years to assess the level of visual air quality that is judged to be acceptable in urban settings. Groups of individuals were shown slides or computer-projected scenes under a variety of haze conditions and asked to judge whether each image represented acceptable visual air quality. The goal was to assess the level of haziness found to be acceptable for purposes of setting an urban visibility regulatory standard. More recently, similar studies were carried out in Beijing, China, and the more pristine Grand Canyon National Park and Great Gulf Wilderness. The studies clearly showed that when preference ratings were compared to measures of atmospheric haze such as atmospheric extinction, visual range, or deciview (dv), there was not a single indicator that represented acceptable levels of visual air quality for the varied urban or more remote settings. For instance, using a Washington, D.C., setting, 50% of the observers rated the landscape feature as not having acceptable visual air quality at an extinction of 0.19 km−1 (21 km visual range, 29 dv), while the 50% acceptability point for a Denver, Colorado, setting was 0.075 km−1 (52 km visual range, 20 dv) and for the Grand Canyon it was 0.023 km−1 (170 km visual range, 7 dv). Over the past three or four decades, many scene-specific visibility indices have been put forth as potential indicators of visibility levels as perceived by human observers. They include, but are not limited to, color and achromatic contrast of single landscape features, average and equivalent contrast of the entire image, edge detection algorithms such as the Sobel index, and just-noticeable difference or change indexes. This paper explores various scene-specific visual air quality indices and examines their applicability for use in quantifying visibility preference levels and judgments of visual air quality.Implications: Visibility acceptability studies clearly show that visibility become more unacceptable as haze increases. However, there are large variations in the preference levels for different scenes when universal haze indicators, such as atmospheric extinction, are used. This variability is significantly reduced when the sky–landscape contrast of the more distant landscape features in the observed scene is used. Analysis suggest that about 50% of individuals would find the visibility unacceptable if at any time the more distant landscape features nearly disappear, that is, they are at the visual range. This common metric could form the basis for setting an urban visibility standard.

Observational Study of Grand Canyon Rim-to-Rim Day Hikers: Determining Behavior Patterns to Aid in Preventive Search and Rescue Efforts

Grand Canyon National Park has seen an increase in visitors traversing the canyon from rim to rim (R2R) in a single day. R2R hikers travel over 33.8 km (21 mi) over 3300 m (11,000 ft) of elevation change and endure large temperature changes. Grand Canyon emergency medical service providers provide emergency medical services to over 1100 visitors annually. Direct guidance by Preventive Search and Rescue rangers has improved safety. The objective of this study was to examine visitors attempting an R2R traverse and to enhance PSAR rangers' anticipatory guidance. We conducted an observational study of R2R hikers in the spring and fall of 2015. Hikers consented to study inclusion and were interviewed at the starting trailhead, canyon bottom, and exit trailhead. We performed a survey and collected biometric data. We enrolled 617 visitors with a median age of 43 y (interquartile range [IQR] 33-53); 65% were male and 46% had hiked the R2R a median number of 3 times previously (IQR 2-7). Hydration strategies included water bottle only (20%), hydration bladder only (31%), and both water bottle and hydration bladder (48%). R2R crossers had an average start time of 0530 (SD 1.3 h) and median crossing time of 11.9 h (IQR 10.7-13.3). Crossing time and self-reported fatigue were negatively correlated with prior R2R experience (P=0.02). Crossing R2R in a day is hazardous and associated with risk of injury and illness. The results of this study can be used by Preventive Search and Rescue to reduce these risks by educating hikers.

Quantifying geomorphic and vegetation change at sandbar campsites in response to flow regulation and controlled floods, Grand Canyon National Park, Arizona

AbstractSandbars along the Colorado River in Grand Canyon National Park, USA, are an important recreational resource used as campsites by over 25,000 river runners and hikers annually. The number and size of campsites decreased following the completion of Glen Canyon Dam in 1963 due to reductions of sediment that replenish sandbars and increases in vegetation cover caused by flow regulation. Campsite area continues to decrease despite the use of controlled floods to rebuild sandbars. We quantify the relative magnitude of factors that contribute to changes in campsite size, such as fluvial deposition and erosion, gullying, and vegetation expansion with analysis of four‐band aerial imagery and digital elevation models. Campsite area declined by 37% between 2002 and 2016 (an average of 161 m2 per site at long‐term monitoring sites). Two drivers contributed to campsite area change: (a) short‐term gains and losses associated with controlled floods and flood‐deposit erosion and (b) long‐term one‐directional loss of campsite area caused by vegetation encroachment. There was more erosion and slope change at sites in critical reaches—sections of river where campsites are infrequent or in high demand—than in noncritical reaches. Vegetation continues to expand at campsites under flow regulation, particularly in noncritical reaches. Although controlled floods have contributed to short‐term increases in sandbar size, long‐term increases in campsite area have not occurred because of sandbar erosion between controlled floods and vegetation expansion. Manual vegetation removal may need to be considered in future management strategies.

Vulnerability and fragility risk indices for non-renewable resources.

Protected areas are tasked with mitigating impacts to a wide range of invaluable resources. These resources are often subject to a variety of potential natural and anthropogenic impacts that require monitoring efforts and management actions to minimize the degradation of these resources. However, due to insufficient funding and staff, managers often have to prioritize efforts, leaving some resources at higher risk to impact. Attempts to address this issue have resulted in numerous qualitative and semi-quantitative frameworks for prioritization based on resource vulnerability. Here, we add to those methods by modifying an internationally standardized vulnerability framework, quantify both resource vulnerability, susceptibility to human disturbance, and fragility, susceptibility to natural disturbance. This modified framework quantifies impacts through a six-step process: identifying the resource and management objectives, identifying exposure and sensitivity indicators, define scoring criteria for each indicator, collect and compile data, calculate indices, and prioritize sites for mitigations. We applied this methodology to two resource types in Grand Canyon National Park (GRCA): caves and fossil sites. Three hundred sixty-five cave sites and 127 fossil sites in GRCA were used for this analysis. The majority of cave and fossil sites scored moderate to low vulnerability (0-6 out of 10 points) and moderate to low fragility for fossils. The percentage of sites that fell in the high-priority range was 5.5% for fossils and 21.9% for caves. These results are consistent with the known state of these resources and the results present a tool for managers to utilize to prioritize monitoring and management needs.

Remote sensing of tamarisk beetle (Diorhabda carinulata) impacts along 412 km of the Colorado River in the Grand Canyon, Arizona, USA

Tamarisk (Tamarix spp.) is an invasive plant species that is rapidly expanding along arid and semi-arid rivers in the western United States. A biocontrol agent, tamarisk beetle (Diorhabda carinulata), was released in 2001 in California, Colorado, Utah, and Texas. In 2009, the tamarisk beetle was found further south than anticipated in the Colorado River ecosystem within the Grand Canyon National Park and Glen Canyon National Recreation Area. Our objectives were to classify tamarisk stands along 412 km of the Colorado River from the Glen Canyon Dam through the Grand Canyon National Park using 2009 aerial, high spatial resolution multispectral imagery, and then quantify tamarisk beetle impacts by comparing the pre-beetle images from 2009 with 2013 post-beetle images. We classified tamarisk presence in 2009 using the Mahalanobis Distance method with a total of 2500 training samples, and assessed the classification accuracy with an independent set of 7858 samples across 49 image quads. A total of 214 ha of tamarisk were detected in 2009 along the Colorado River, where each image quad, on average, included an 8.4 km segment of the river. Tamarisk detection accuracies varied across the 49 image quads, but the combined overall accuracy across the entire study region was 74%. Using the Normalized Difference Vegetation Index (NDVI) from 2009 and 2013 with a region-specific ratio of >1.5 decline between the two image dates (2009NDVI/2013NDVI), we detected tamarisk defoliation due to beetle herbivory. The total beetle-impacted tamarisk area was 32 ha across the study region, where tamarisk defoliation ranged 1–86% at the local levels. Our tamarisk classification can aid long-term efforts to monitor the spread and impact of the beetle along the river and the eventual mortality of tamarisk due to beetle impacts. Identifying areas of tamarisk defoliation is a useful ecological indicator for managers to plan restoration and tamarisk removal efforts.

Identifying cost-effective invasive species control to enhance endangered species populations in the Grand Canyon, USA

Recovering endangered species populations when confronted with the threat of invasive species is an ongoing natural resource management challenge. While eradication of the invasive species is often the optimal economic solution, it may not be a feasible nor desirable management action in other cases. For example, when invasive species are desired in one area, but disperse into areas managed for endangered species, managers may be interested in persistent, but cost-effective means of managing dispersers rather than eradicating the source. In the Colorado River, a nonnative rainbow trout (Oncorhynchus mykiss) sport fishery is desired within Glen Canyon National Recreation Area, however, dispersal downriver into the Grand Canyon National Park is not desired as rainbow trout negatively affect endangered humpback chub (Gila cypha). Here, we developed a bioeconomic model incorporating population abundance goals and cost-effectiveness analyses to approximate the optimal control strategies for invasive rainbow trout conditional on achieving endangered humpback chub adult population abundance goals. Model results indicated that the most cost-effective approach to achieve target adult humpback chub abundance was a high level of rainbow trout control over moderately high rainbow trout population abundance. Adult humpback chub abundance goals were achieved at relatively low rainbow trout abundance and control measures were not cost-effective at relatively high rainbow trout abundance. Our model considered population level dynamics, species interaction and economic costs in a multi-objective decision framework to provide a preferred solution to long-run management of invasive and native species.

Visibility Protection Under the Clean Air Act

The Clean Air Act’s (CAAs) visibility protection program was created in 1977 and expanded in 1990. It applies to states with sources of air emissions that impact 156 Federal Class I areas, which include national parks and wilderness areas. Such states are required to develop haze implementation plans (SIPs) to control emissions in order to restore natural visibility in Class I areas. Initially, large stationary sources that began operating between 1962 and 1977 were to install the Best Available Retrofit Technology (BART) based on regulations issued by EPA. This process resulted in complex rules, litigation, and political maneuvering. Subsequently, the CAA was expanded to include a regional haze program that requires haze SIPs to provide for reasonable progress using a phased approach to visibility protection. The requirements apply to nearly all pollution-emitting stationary sources. For some states, the regulations provide an alternative approach to BART requirements. If a state does not develop a haze SIP that receives EPA’s approval, EPA must promulgate a federal implementation plan (FIP). This article covers the regulatory development of this program and the litigation that has helped shape the program. It discusses the efforts to protect the visibility in the Grand Canyon National Park. It discusses the State of Utah’s efforts to comply with the CAA’s visibility requirements. It concludes with a discussion of the many obstacles that make the achievement of the visibility goals problematic. This article was written in December 2017. It was accepted for publication by the George Washington Journal of Energy and Environmental Law in January 2018 for publication in the summer of 2018, volume 9. The article was updated in the spring of 2018 and again in the summer of 2018. As of the end of July 2019, it has not yet been published.