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124-469: On November 18, 2019, the plant ceased commercial generation. Full decommissioning of the site was projected to take approximately three years. On December 18, 2020, the three smokestacks were demolished. In the 1950s and 1960s, there was a need for new electric generation in the Southwest to supply power to growing populations in southern California, Arizona and Nevada. The US Bureau of Reclamation also needed

248-853: A "Reasonable Progress Alternative to BART" which was submitted by the Department of the Interior to the EPA on July 26, 2013, for consideration in development of a final rule: The Parties shall submit this Agreement to EPA and request that EPA: adopt the Reasonable Progress Alternative to BART set forth in Appendix B as the Final BART Rule; The agreement contains a commitment by the current owners of NGS to cease their operation of conventional coal-fired generation at NGS no later than December 22, 2044. NGS

372-503: A boiler, turbine, generator, closed-cycle cooling system, and environmental control equipment. The boilers were tangentially fired , balanced draft, reheat type steam generators, supplied by Combustion Engineering . Designed for supercritical operation, each boiler supplied up 5,410,000 pounds of steam per hour to the turbines at 3500 psi (241 bar) and 1000 °F (537 °C). The main turbines are General Electric (GE) tandem compound reheat turbines, each directly coupled to

496-457: A change of one deciview being a just noticeable change.) In 2012, a fish consumption advisory was issued for striped bass in lower Lake Powell, raising concerns about mercury emissions from the plant. NGS emissions, however, were found to contribute less than 2% of atmospheric deposition of mercury on the Colorado River watershed. Atmospheric deposition, furthermore, accounts for only a part of

620-609: A coalition of environmental groups which promoted construction of a thermal or nuclear power plant as an alternative. As a result, the proposed dams were abandoned in favor of the Navajo Power Project, consisting of the Navajo Generating Station (NGS) along with the Kayenta mine , Black Mesa & Lake Powell (BM&LP) Railroad, and 800 miles (1,300 km) of 500 kV transmission lines. The site selected for

744-762: A generator and designed to rotate at 3600 rpm. Steam discharged from the turbines entered a condenser where water circulating through tubes cools and condensed it, producing a vacuum that maximized the pressure drop across the turbine. The heat picked up by the circulating water was removed by evaporation in six induced-draft cross flow cooling towers (two per unit). The plant used about 26,000 acre-feet (32,000,000 m) of water per year from Lake Powell, or about 1/2 gallon (1.9L) per kWh, mainly for cooling water and scrubber operation; see section #Wastewater handling . The plant consumed about 8 million tons of low sulfur bituminous coal each year, supplied by Peabody Energy 's Kayenta Mine near Kayenta, Arizona . The coal

868-462: A gross basis. On January 4, 2013, Department of the Interior , the EPA, and Department of Energy announced plans to jointly develop a plan for the future of the plant that maintains its energy, water, and economic benefits. The plan would outline short term investments in the plant to meet environmental goals, and long term plans for transitioning to cleaner energy options, such that short term and long term plans work together. On January 17, 2013,

992-531: A large oasis at the western end of the El Paso-Tucson corridor. The region between the two cities is a major transportation trunk with settlements serving both highway and railway needs. There are also large mining operations, ranches, and agricultural oases. Both El Paso and Tucson have large military installations nearby; Fort Bliss and White Sands Missile Range north of El Paso in New Mexico, and, near Tucson,

1116-578: A large source of power for running the pumps of the planned Central Arizona Project (CAP). A number of power projects were considered to fill these needs, including Bridge Canyon and Marble Canyon hydroelectric dams on the Colorado River . However, the proximity of the proposed dams to the Grand Canyon raised opposition, initially from the National Park Service and then more vigorously from

1240-440: A net heat rate of 34% or 2.95 kWh/kWh (10,060 Btu/kWh). In 2014, generation fell to 72% of capacity, and to 61% in 2016. In the first 11 months of 2016, the plant consumed 32.7  TWh (111.6 × 10 Btu) and produced 10.7  TWh of power, giving 33% efficiency. Fly ash particulate was removed from the flue gas by hot-side electrostatic precipitators (ESPs) and SO 2 scrubbers. The ESPs, constructed as part of

1364-466: A number of hurdles to retrofitting SCRs in the allotted time. Before the plant's owners could invest in SCRs, they will have to resolve the site lease, rights-of-way for the railroad, transmission and water lines, and the coal supply agreement. One participant – LADWP – cannot invest in the improvements due to California law prohibiting long term investment in coal-fired power plants, and plans to sell its share in

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1488-577: A result of the amount of energy it produced. In the same year, however, its CO 2 emissions per unit of energy generated were lower than 75% of all U.S. coal fired power plants. The plant's low CO 2 emissions per electric output, compared to other coal fired plants, were attributable to a relatively low heat rate combined with exclusive use of bituminous coal, which creates less CO 2 per heat output than other types of coal. Mercury emissions in 2011 were 586 pounds (266 kg) or 3.4  pounds per 10 Btu ( 5.3 kg/ TWh ). Northern Arizona and

1612-578: A settlement in Arizona in 1599, but were turned back by inclement weather. In 1610, Santa Fe was founded, making it the oldest capital in United States. In 1664 Juan Archuleta led an expedition into what is now Colorado, becoming the first European to enter. A second Spanish expedition was led into Colorado by Juan Ulibarrí in 1706, during which he claimed the Colorado territory for Spain. From 1687 to 1691

1736-454: A sub-region of the South , which some consider southwestern in the general framework of the original application, meaning the "Western South." This is an area containing the basic elements of Southern history , culture , politics , religion , and linguistic and settlement patterns, yet blended with traits of the frontier West. While this particular Southwest is notably different in many ways from

1860-490: A system that injects a powdered sorbent such as trona to absorb the acid mist - and the addition of baghouses and booster fans to capture the resulting particulate. SCRs without baghouses are expected to cost about $ 600 million to construct and about $ 12 million per year to operate and maintain. SCRs with baghouses would cost about $ 1.1 billion to construct and about $ 20 million per year to operate and maintain. The SCRs by themselves would need about 15 MW to operate, requiring

1984-589: A third of Colorado, and small portions of Kansas, Oklahoma, and Wyoming. Texas current borders were set in the Compromise of 1850 , where Texas ceded land to the federal government in exchange for $ 10 million, which would go to paying off the debt Texas had accumulated in its war with Mexico. Following the Mexican Cession, the lands of what had been the Mexican territory of Alta California were in flux: portions of what

2108-737: Is bordered to the south by the Mogollon Rim and the Sonoran Desert, to the west by the Mojave Desert, and to the east by the Rocky Mountains , the Rio Grande Rift valley, and the Llano Estacado . The Plateau is characterized by a series of plateaus and mesas, interspersed with canyons. The most dramatic example is the Grand Canyon . But that is one of many dramatic vistas included within

2232-596: Is from the Mojave Desert in California in the west (117° west longitude) to Carlsbad, New Mexico , in the east (104° west longitude); another says that it extends from the Mexico–United States border in the south to the southern areas of Colorado, Utah, and Nevada in the north (39° north latitude). In another definition, the core Southwestern U.S. includes only the states of Arizona and New Mexico; others focus on

2356-529: Is now New Mexico were claimed, but never controlled, by Texas. With the Compromise of 1850, the states of Texas and California were created (Texas as a slave state, and California as a free state), as well as the Utah Territory and New Mexico Territory . The New Mexico Territory consisted of most of Arizona and New Mexico (excluding a strip along their southern borders), a small section of southern Colorado, and

2480-462: Is projected to continue operating at least until 2044. EPA is proposing to require NGS to achieve a nearly 80 percent reduction of its current overall NO X emission rate. Our analysis indicates that installation of controls to achieve this reduction would result in significant visibility improvement that is well-balanced with the cost of those controls. For a number of reasons, including the importance of NGS to numerous Indian tribes located in Arizona and

2604-680: Is the saguaro cactus , which is unique to the desert. It is bounded on the northwest by the Mojave Desert, to the north by the Colorado Plateau and to the east by the Arizona Mountains forests and the Chihuahuan Desert. Aside from the trademark saguaro, the desert has the most diverse plant life of any desert in the world, and includes many other species of cacti, including the organ-pipe, senita, prickly pear, barrel, fishhook, hedgehog, cholla, silver dollar, and jojoba. The portion of

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2728-405: Is the smallest, driest and hottest desert within the United States. The Mojave gets less than 6 in (150 mm) of rain annually, and its elevation ranges from 3,000 to 6,000 feet (900 to 1,800 meters) above sea level. The most prolific vegetation is the tall Joshua tree , which grow as tall as 40 ft (12 m), and are thought to live almost 1000 years. Other major vegetation includes

2852-617: The American Southwest or simply the Southwest , is a geographic and cultural region of the United States that includes Arizona and New Mexico , along with adjacent portions of California , Colorado , Nevada , Oklahoma , Texas , and Utah . The largest cities by metropolitan area are Phoenix , Las Vegas , El Paso , Albuquerque , and Tucson . Before 1848, in the historical region of Santa Fe de Nuevo México as well as parts of Alta California and Coahuila y Tejas , settlement

2976-690: The Ancestral Pueblo people , the Hohokam , and the Mogollon , all of which existed among other surrounding cultures including the Patayan . Maize began to be cultivated in the region sometime during the early first millennium BC, but it took several hundred years for the native cultures to be dependent on it as a food source. As their dependence on maize grew, Pre-Columbian Indians began developing irrigation systems around 600 CE . According to archeological finds,

3100-599: The Arizona Organic Act , which officially created the U.S. Territory of Arizona , splitting the New Mexico Territory at the 107th meridian. Utah, as shown above, evolved out of the Utah Territory, as pieces of the original territory created in 1850 were carved out: parts were ceded to Nevada, Wyoming, and Colorado in 1861; another section to Nevada in 1862; and the final section to Nevada in 1866. In 1890,

3224-538: The Davis-Monthan Air Force Base . About 70 miles (110 km) to the southeast are the research facilities at Fort Huachuca . These military installations form a kind of hinterland around the El Paso-Tucson region, and are served by scientific and residential communities such as Sierra Vista , Las Cruces , and Alamogordo . El Paso's influence extends north into the Mesilla Valley , and southeast along

3348-632: The EPA , Salt River Project and other entities cooperated in visibility studies to assess possible effects that NGS emissions might have on those areas. The series of studies culminated in the Winter Haze Intensive Tracer Experiment (WHITEX) and the Navajo Generating Station Visibility Study (NGSVS). Those studies indicated that controlling sulfur dioxide (SO 2 ) emissions might improve winter visual range in

3472-579: The Gadsden Purchase in 1853. In 1851, San Luis became the first European settlement in what is now Colorado. Of the states of which at least a portion make up the Southwest, Texas was the first to achieve statehood. On December 29, 1845, the Republic of Texas was annexed, bypassing the status of becoming a territory, and immediately became a state. Initially, its borders included parts of what would become several other states: almost half of New Mexico,

3596-468: The Intermountain West . Coconino County, with the highest occurrences, averages less than two unhealthy days per year, these occurring between March and June, suggesting a correlation with spring stratospheric ozone intrusions. NGS emissions are unlikely to have contributed to high ozone occurrences, as the plant is located at the northern border of Coconino County, and prevailing southwesterly winds in

3720-658: The Narváez expedition (1528–36) who had crossed eastern Texas on their way to Mexico City, led an expedition to discover the Seven Golden Cities of Cíbola. The 1582–3 expedition of Antonio de Espejo explored New Mexico and eastern Arizona; and this led to Juan de Oñate 's establishment of the Spanish province of Santa Fe de Nuevo México in 1598, with a capital founded near Ohkay Oweenge Pueblo , which he called San Juan de los Caballeros. Oñate's party also attempted to establish

3844-518: The Phoenix metropolitan area . The city of Phoenix is the largest urban center, and located in the approximate center of the area that includes Tempe , Mesa , and many others. Meinig calls the third subregion "El Paso, Tucson, and the Southern Borderlands." While El Paso and Tucson are distinctly different cities, they serve as anchor points to the hinterland between them. Tucson occupies

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3968-536: The San Luis Valley of southern Colorado to south of Socorro and including the Sandia-Manzano Mountains , with an east–west breadth in the north stretching from the upper Canadian River to the upper San Juan River . The area around Albuquerque is sometimes called Central New Mexico . "Central Arizona" is a vast metropolitan area spread across one contiguous sprawling oasis, essentially equivalent to

4092-537: The 1930s and 1940s, many definitions of the Southwest included all or part of Texas, Oklahoma, New Mexico, Arizona, California, Colorado, and Utah. As time has gone on, the definition of the Southwest has become more solidified and more compact. For example, in 1948 the National Geographic Society defined the American Southwest as all of California, Nevada, Utah, Arizona, Colorado, and New Mexico, and

4216-477: The American Southwest as parts of Arizona, Colorado, Kansas, New Mexico, Oklahoma, Texas, and Utah. From this perspective, almost all of the region's physiographical traits, geological formations, and weather are contained within a box between 26° and 38° northern latitude, and 98° 30' and 124° western longitude. When looking at the fauna of the region, there is a broader definition of the American Southwest. The Southwestern Center for Herpetological Research defines

4340-463: The Ancestral Pueblo people, also known as the "Anasazi" (although that term is viewed by modern Pueblo people as derogatory and is becoming more and more disused), began settling in the area in approximately 1500 BC. Eventually, they would spread throughout the entire northern section of the Southwest. This culture would go through several different eras lasting from approximately 1500 BC through

4464-650: The Ancestral Puebloans, while the Akimel O'odham and Tohono O'odham claim descent from Hohokam. The area previously occupied by the Mogollon was taken over by an unrelated tribe, the Apache . While it is unclear whether any of the modern Indian tribes are descended from the Mogollon, some archeologists and historians believe that they mixed with Ancestral Puebloans and became part of the modern Hopi and Zuni tribes. Prior to

4588-801: The Canyonlands section just to its north; the Navajo section is bordered to the south by the Grand Canyon section, which of course is dominated by the Grand Canyon; and the southeasternmost portion of the Plateau is the Datil section, consisting of valleys, mesas, and volcanic formations. Albuquerque is the most populous city often considered at the edge of this portion contained in the Southwest region, but Santa Fe, New Mexico and Flagstaff, Arizona, are also significant population centers. Phoenix , Tucson, and Las Vegas dominate

4712-701: The City of Tucson was founded when the Presidio San Augustin del Tucson was created, relocating the presidio from Tubac. In 1776, two Franciscan priests, Francisco Atanasio Domínguez and Silvestre Vélez de Escalante, led an expedition from Santa Fe heading to California. After passing through Colorado, they became the first Europeans to travel into what is now Utah. Their journey was halted by bad weather in October, and they turned back, heading south into Arizona before turning east back to Santa Fe. In 1804 Spain divided

4836-852: The Clean Air Act for pollution sources which might cause haze in a "Federal Class 1 area". An example of such a source is the Navajo Generating Station in Page, Arizona which could affect visibility in Grand Canyon National Park . BART provisions were included in the "Clean Air Visibility Rule," published by the United States Environmental Protection Agency (EPA) in 1999, and amended in 2005. The Clean Air Act defines Best available retrofit technology: ... in determining best available retrofit technology

4960-464: The Colorado Plateau have consistently met National Ambient Air Quality Standards (NAAQS) established to protect public health. The EPA's Air Quality Index (AQI), showing air quality on a daily basis, lists no unhealthy days for the general population in all of northern Arizona and southern Utah counties. Unhealthy days for ozone-sensitive groups – those with asthma or lung disease – are also rare in these counties despite high natural background levels in

5084-714: The EPA proposed a BART ruling to further reduce NO x emissions: The Environmental Protection Agency (EPA) is proposing a source-specific federal implementation plan (FIP) requiring the Navajo Generating Station (NGS), located on the Navajo Nation, to reduce emissions of oxides of nitrogen (NO X) under the Best Available Retrofit Technology (BART) provision of the Clean Air Act (CAA or Act) in order to reduce visibility impairment resulting from NGS at 11 National Parks and Wilderness Areas. NGS, which

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5208-569: The Exploration of the Columbia River of the West and Its Tributaries , which was later republished as The Exploration of the Colorado River and Its Canyons . In 1877 silver was discovered in southeastern Arizona. The notorious mining town of Tombstone, Arizona was born to service the miners. The town would become immortalized as the scene of what is considered the greatest gunfight in the history of

5332-469: The Grand Canyon by 2% to 7%, which prompted the EPA to propose a rule requiring NGS to reduce SO 2 emissions by 70%. NGS and environmental groups, however, negotiated an approach that would achieve a greater degree of improvement at lower cost. They agreed to, and recommended a requirement of a 90% reduction in SO 2 emissions based on an annual average, with installation to be completed in 1999. The EPA accepted

5456-531: The Grand Canyon. Nitrogen dioxide (NO 2 ) levels in the Page area average about 3 ppb, 94 percent lower than the NAAQS standard of 53 ppb. Carbon monoxide (CO) levels have also been far below the standards. Fine particulate (PM2.5) levels in the Grand Canyon region have been among the lowest in the nation since before NGS completed installation of SO 2 scrubbers and low NO x -SOFA burners. Annual mean levels for PM2.5 in

5580-634: The Jesuit priest Eusebio Kino established several missions in the Santa Cruz River valley; and Kino further explored southern and central Arizona in 1694, during which he discovered the ruins of Casa Grande. Beginning in 1732, Spanish settlers began to enter the region, and the Spanish started bestowing land grants in Mexico and the Southwest US. In 1751, the O'odham rebelled against the Spanish incursions, but

5704-531: The LDS church issued the 1890 Manifesto , which officially banned polygamy for members of the church. It was the last roadblock for Utah entering the Union, and on January 4, 1896, Utah was officially granted statehood, becoming the 45th state. In 1869, John Wesley Powell led a 3-month expedition which explored the Grand Canyon and the Colorado River. In 1875, he would publish a book describing his explorations, Report of

5828-807: The Mojave Desert. Bordered on the south by the Sonoran Desert and the east by the Colorado Plateau, its range within the region makes up the southeast tip of Nevada, the southwestern corner of Utah and the northwestern corner of Arizona. In terms of topography, the Mojave is very similar to the Great Basin Desert, which lies just to its north. Within the region, Las Vegas is the most populous city; other significant population centers include Laughlin and Pahrump in Nevada, St. George and Hurricane in Utah, and Lake Havasu City , Kingman , and Bullhead City in Arizona. The Mojave

5952-434: The Mojave and Colorado deserts in California. Other individuals who focus on Southwest studies who favored a more limited extent of the area to center on Arizona and New Mexico, with small parts of surrounding areas, include Erna Fergusson , Charles Lummis (who claimed to have coined the term, the Southwest), and cultural geographer Raymond Gastil , and ethnologist Miguel León-Portilla . Geographer D. W. Meinig defines

6076-429: The Native American (especially Apache , Pueblo , and Navajo ), Hispano , Mexican American , and frontier cowboy . The geography of the region is mainly made up of four features: the Mojave , Sonoran , and Chihuahuan Deserts , and the Colorado Plateau ; although there are other geographical features as well, such as a portion of the Great Basin Desert . The deserts dominate the southern and western reaches of

6200-427: The Old West, the Gunfight at the O.K. Corral . Copper was also discovered in 1877, near Bisbee and Jerome in Arizona, which became an important component of the economy of the Southwest. Production began in 1880 and was made more profitable by the expansion of the railroad throughout the territory during the 1880s. The early 1880s also saw the completion of the second transcontinental railroad, which ran through

6324-406: The Page area are about 3 micrograms/cubic meter (μg/m) – one-quarter of the NAAQS standard of 12 μg/m and as low or lower than the cleanest U.S. cities listed by the World Health Organization. Visibility in the Grand Canyon region has also been among the best in the nation since before NGS installed scrubbers and low NO x -SOFA burners. Within Coconino County, visibility is generally better in

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6448-407: The Page/Glen Canyon area at the north end of the county than at the Grand Canyon and areas further south (Sunset Crater, Walnut Canyon, Wupatki National Monuments). Visibility in the Page/Glen Canyon area averages 3.5 deciviews above natural background conditions, within less than one deciview of the best visibility listed in the contiguous U.S. (The DV scale is near zero for a pristine atmosphere, with

6572-406: The Parry saltbush and the Mojave sage, both only found in the Mojave, as well as the creosote bush. The Colorado Plateau varies from the large stands of forests in the west, including the largest stand of ponderosa pine trees in the world, to the Mesas to the east. Although not called a desert, the Colorado Plateau is mostly made up of high desert. Within the Southwest U.S. region, the Colorado

6696-471: The Pecos, north of the [Mexican] Border, south of the Mesa Verde and the Grand Canyon, and east of the mountains which wall off Southern California and make it a land in itself." Texas has long been the focal point of this dichotomy, and is often considered, as such, the core area of "the South's Southwest." While the Trans-Pecos area is generally acknowledged as part of the desert Southwest , most of Texas and large parts of Oklahoma are often placed into

6820-466: The Plateau, which includes spectacular lava formations, "painted" deserts, sand dunes, and badlands. One of the most distinctive features of the Plateau is its longevity, having come into existence at least 500 million years ago. The Plateau can be divided into six sections, three of which fall into the Southwest region. Beginning with the Navajo section forming the northern boundary of the Southwestern United States, which has shallower canyons than those in

6944-427: The Provincia de las Californias, creating the province Alta California , which consisted primarily of what would become California, Nevada, Arizona, Colorado, Utah and New Mexico. In 1821 Mexico achieved its independence from Spain and shortly after, in 1824, developed its constitution , which established the Alta California territory, which was the same geographic area as the earlier Spanish province. In 1825, Arizona

7068-404: The Rio Grande into the Trans-Pecos region of Texas. The fourth subregion Meinig calls the "Northern Corridor and Navajolands," a major highway and railway trunk which connects Albuquerque and Flagstaff . Just north of the transportation trunk are large blocks of American Indian land. As the US expanded westward , the country's western border also shifted westward, and consequently, so did

7192-411: The Sonora Desert which lies in the Southwestern United States is the most populated area within the region. Six of the top ten major population centers of the region are found within its borders: Phoenix, Tucson , Mesa , Chandler , Glendale , and Scottsdale , all in Arizona. Also within its borders are Yuma and Prescott, Arizona . The most northwest portion of the American Southwest is covered by

7316-405: The Sonoran Desert to the west. The Chihuahuan Desert spreads across the southeastern portion of the region, covering from southeastern Arizona, across southern New Mexico, and the portion of western Texas included in the Southwest. While it is the second largest desert in the United States, only a third of the desert is within the United States, with the rest in Mexico. El Paso and Albuquerque are

7440-410: The Southwest as being only the states of Arizona, New Mexico, with parts of California, Nevada, Texas, and Utah; although they include all of those six states in their map of the region, solely for ease of defining the border. Lawrence Clark Powell, a major bibliographer whose emphasis is on the Southwest, defined the American Southwest in a 1958 Arizona Highways article as, "the lands lying west of

7564-411: The Southwest became embroiled in the Mexican–American War , partly as a result of the United States' annexation of Texas. On August 18, 1846, an American force captured Santa Fe, New Mexico. On December 16 of the same year, American forces captured Tucson, Arizona, marking the end of hostilities in the Southwest United States. When the war ended with the Treaty of Guadalupe Hidalgo on February 2, 1848,

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7688-407: The Southwest began to decline for unknown reasons, although severe drought and encroachment from other peoples have been postulated. By the end of the 15th century, all three cultures had disappeared. The modern Puebloan tribes of the Isleta , Sandia , Cochiti , Kewa , Santa Ana , Taos , Jemez , Acoma , Laguna , and Zia , as well as the Hopi and Zuni peoples , trace their ancestry back to

7812-494: The Southwest in a very similar fashion to Reed: the portion of New Mexico west of the Llano Estacado and the portion of Arizona east of the Mojave - Sonoran Desert and south of the "canyon lands" and also including the El Paso district of western Texas and the southernmost part of Colorado. Meinig breaks the Southwest down into four distinct subregions. He calls the first subregion " Northern New Mexico ," and describes it as focused on Albuquerque and Santa Fe . It extends from

7936-494: The Southwest. Around AD 1100 their culture began to develop in the Four Corners area of the region. The Navajos migrated from northwestern Canada and eastern Alaska , where the majority of Athabaskan speakers reside. The Ute were found over most of modern-day Utah and Colorado, as well as northern New Mexico and Arizona. The Paiutes roamed an area which covered over 45,000 square miles of southern Nevada and California, south-central Utah, and northern Arizona. The Hopi settled

8060-420: The State (or the Administrator in determining emission limitations which reflect such technology) shall take into consideration the costs of compliance, the energy and nonair quality environmental impacts of compliance, any existing pollution control technology in use at the source, the remaining useful life of the source, and the degree of improvement in visibility which may reasonably be anticipated to result from

8184-446: The United States gained control of all of present-day California, Nevada and Utah, as well as the majority of Arizona, and parts of New Mexico and Colorado (the rest of present-day Colorado, and most of New Mexico had been gained by the United States in their annexation of the Republic of Texas). The final portion of the Southwestern United States came about through the acquisition of the southernmost parts of Arizona and New Mexico through

8308-565: The ancestral Puebloans. The modern-day Zuni established a culture along the Zuni River in far-eastern Arizona and western New Mexico. Both major tribes of the O'odham tribe settled in the southern and central Arizona, in the lands once controlled by their ancestors, the Hohokam. The first European intrusion into the region came from the south. In 1539, a Jesuit Franciscan named Marcos de Niza led an expedition from Mexico City which passed through eastern Arizona. The following year Francisco Vázquez de Coronado , based on reports from survivors of

8432-414: The area, namely the Animas , San Andres , and Doña Ana Mountains in New Mexico; and the Franklin , Hueco , and Davis Mountains in Texas. It also reaches up into the foothills of the higher ranges such as the Black Range and Oscura Mountains in New Mexico. High above the desert, these forest-covered and sometimes snow-capped mountains form sky islands , with radically different flora and fauna than

8556-408: The area, while the plateau (which is largely made up of high desert) is the main feature north of the Mogollon Rim . The two major rivers of the region are the Colorado River , running in the northern and western areas, and the Rio Grande , running in the east, north to south. Formed approximately 8000 years ago, the Chihuahuan Desert is a relatively dry desert, although it is slightly wetter than

8680-420: The area. The Chihuahuan Desert is considered the "most biologically diverse desert in the Western Hemisphere and one of the most diverse in the world," and includes more species of cacti than any other desert in the world. The most prolific plants in this region are agave , yucca and creosote bushes , in addition to the ubiquitous presence of various cacti species. When people think of the desert southwest,

8804-403: The arrival of Europeans, the Southwestern United States was inhabited by a very large population of American Indian tribes. The area once occupied by the ancestral Puebloans became inhabited by several American Indian tribes, the most populous of which were the Navajo , Ute , Southern Paiute , and Hopi. The Navajo, along with the Hopi, were the earliest of the modern Indian tribes to develop in

8928-438: The atmosphere to form sulfate and nitrate aerosols. NGS combined permit limits for these precursors has been 0.34 pounds per million British thermal units (0.53  kg / MWh ), lower than 94% of all U.S. coal steam units, while the actual NGS rate in 2011 was 0.29 pounds per million British thermal units (0.45 kg/MWh). Carbon dioxide (CO 2 ) emissions from NGS were seventh highest of all U.S facilities in 2015, largely

9052-405: The burning of an additional 50,000 tons of coal per year and increasing CO 2 emissions by 125,000 tons per year. If baghouses are also needed, the systems would need about 30 MW to operate, requiring an additional 100,000 tons of coal per year and increasing CO 2 emissions by 250,000 tons per year. The operation would also consume some 40,000 pounds of anhydrous ammonia daily. The plant faced

9176-492: The classic "Old South" or Southeast , these features are strong enough to give it a separate southwestern identity quite different in nature from that of the interior southwestern states to the west. Best Available Retrofit Technology Best Available Retrofit Technology ( BART ) is a pollution control standard in the United States Clean Air Act . A BART review is required by sections 169A and 169B of

9300-570: The command of Lt. Colonel John Robert Baylor forced the surrender of the small Union garrison stationed at Fort Fillmore , near Mesilla, New Mexico . On August 1, 1861, Baylor declared the creation of the Arizona Territory , and claimed it for the Confederacy, with Mesilla as its capital. The territory, which had been formed by the portion of the existing New Mexico Territory below the 34th parallel, became official on February 14, 1862. Nevada

9424-789: The environmental assessments are expected to take about five years to complete. After the EPA issued a proposed BART rule it solicited input from stakeholders: the Department of the Interior , the Central Arizona Project , the Navajo Nation , the Gila River Indian Community , the Salt River Project , the Environmental Defense Fund , and Western Resources Advocates who as a technical working group negotiated

9548-530: The establishment of Alta Ski Area , Utah's skiing began to be developed. Due to the ski conditions in the state, during WWII, the 10th Mountain Division established Camp Hale in Colorado to train elite ski troops. While this article deals with the core definition for the American Southwest, there are many others. The various definitions can be broken down into four main categories: Historical/Archeological; Geological/Topographical; Ecological; and Cultural. In

9672-525: The federal government's reliance on NGS to meet the requirements of water settlements with several tribes, EPA is proposing an alternative to BART that would provide flexibility to NGS in the schedule for the installation of new control equipment. We also describe other compliance schedules for consideration and comment. We recognize that there may be other approaches that could result in equivalent or better visibility benefits over time and that there may be changes in energy demand, supply or other developments over

9796-448: The flow of waste water to the system. The plant sold about 500,000 tons of fly ash per year for use in the manufacture of concrete and Flexcrete insulating block building product. Bottom ash and gypsum, a byproduct of the scrubber operation, are dewatered in the removal process; and, along with any fly ash not sold, were landfilled on-site as solids. Southwestern United States The Southwestern United States , also known as

9920-595: The heart of the Southwest, called the "Santa Fe Route." It ran from Chicago, down through Topeka, then further south to Albuquerque, before heading almost due west through northern Arizona to Los Angeles. The repeal of the Sherman Silver Purchase Act in 1893 led to the decline of the silver mining industry in the region. In 1901, the Santa Fe Railroad reached the South Rim of the Grand Canyon, opening

10044-527: The installation of Selective Catalytic Reduction (SCR) equipment. The SCRs would need to reduce NO x by about 15,000 tons per year. Along with the existing Low-NO x burners, the total reduction would be about 29,000 tons per year below 2008 levels. The SCRs would use a catalyst and ammonia to react with NO x to form diatomic nitrogen and water. SCRs would also increase sulfuric acid mist levels by causing SO 2 to oxidize to SO 3 . The high sulfuric acid levels could require dry sorbent injection (DSI) –

10168-539: The land within the old Spanish and Mexican borders of the Nuevo México Province or the later American New Mexico Territory . Distinct elements of the Western lifestyle thrive in the region, such as Western wear and Southwestern cuisines , including Native American , New Mexican , and Tex-Mex , or various genres of Western music like Indigenous , New Mexico , and Tejano music styles. Likewise with

10292-699: The lands of the central and western portions of northern Arizona. Their village of Oraibi , settled in approximately AD 1100, is, along with Acoma Sky City in New Mexico, one of the oldest continuously occupied settlements in the United States. The Mogollon area became occupied by the Apaches and the Zuni. The Apache migrated into the American Southwest from the northern areas of North America at some point between 1200 and 1500. They settled throughout New Mexico, eastern Arizona, northern Mexico, parts of western Texas, and southern Colorado. The Zuni count their direct ancestry through

10416-413: The landscape of the Sonoran Desert is what mostly comes to mind. The Sonoran Desert makes up the southwestern portion of the Southwest; most of the desert lies in Mexico, but its United States component lies on the southeastern border of California, and the western 2/3 of southern Arizona. Rainfall averages between 4 and 12 in (100 and 300 mm) per year, and the desert's most widely known inhabitant

10540-407: The last of the 48 contiguous United States on February 14, 1912. The 1930s saw the beginning of the ski industry in the Southwest. Resorts were established in Colorado in areas such as Estes Park , Gunnison , and on Loveland Pass . New Mexico's oldest ski area is Sandia Peak Ski Area at the eastern edge of Albuquerque , which opened to skiers in 1936. At the end of the decade, in 1939, with

10664-402: The late 1990s after being replaced by larger diameter stacks of the same height, resulting in the plant having up to six stacks visible for a time. The new stacks were required to accommodate cooler flue gas saturated with water vapor that resulted when wet SO 2 scrubbers were added. The plant had a net nameplate capacity of 2250 MW or 750 MW net per unit, the rated power output leaving

10788-763: The location of the Southwestern and Northwestern United States . In the early years of the United States, newly colonized lands lying immediately west of the Appalachian Mountains were detached from North Carolina and given the name Southwest Territory . During the decades that followed, the region known as "the Southwestern United States" covered much of the Deep South east of the Mississippi River. However, as territories and eventual states to

10912-645: The major US cities in this desert, with other smaller cities being Las Cruces and Roswell in New Mexico and Willcox in Arizona. The elevation in the Chihuahuan varies from about 1,750 to 6,000 feet (500 to 1,800 meters), as there are several larger mountain ranges, such as the Organ Mountains , the Guadalupe Mountains , and the Chiracahua Mountains , plus many smaller mountain ranges contained in

11036-560: The mercury loading, much of it coming from natural geological deposits. The natural weathering of rock in the Green River catchment, for example, alone contributes about 40% of the mercury loading in Lake Powell. The EPA's Mercury and Air Toxics Standard (MATS) that took effect in 2015 required that the plant reduce mercury emissions to 1.2  pounds per 10 Btu ( 1.9 kg/ TWh ) or 0.013 pounds per gigawatt-hour (5.9 kg/TWh) on

11160-689: The middle of the 15th century AD: the Basketmaker I , II , and III phases followed by the Pueblo I , II , III , and IV . As the Puebloans transitioned from a nomadic lifestyle to one based on both dry land and irrigated agriculture, their first domiciles were pithouses. The Mogollon culture developed later than the Puebloan, arising in the eastern area of the region at around 300 BC. Their range would eventually extend deep into what would become Mexico, and dominate

11284-420: The new power plant was about six miles (10 km) east of Glen Canyon Dam and three miles (5 km) south of Lake Powell on 1,786 acres (723 ha) of land leased from the Navajo Nation. The site was close to a source of competitively priced fuel and a reliable source of surface water for cooling. The nearby city of Page and U.S. Highway 89 provided infrastructure to support construction and operation of

11408-442: The next several decades that may change electricity generation on the Navajo Nation. EPA encourages a robust public discussion of our proposed BART determination and alternative, the additional alternatives described herein, and other possible approaches. EPA is prepared to issue a supplemental proposal if approaches other than the proposed BART determination or proposed alternative articulated in this notice are identified as satisfying

11532-682: The original plant, removed 99% of particulate. Scrubbers removed an additional 50% of what remained in the flue gas after passing through the ESPs. Sulfur dioxide (SO 2 ) emissions were controlled by forced oxidation wet scrubbers. The scrubbers consisted of two countercurrent–flow absorber vessels on each unit, using limestone slurry sprays to remove more than 92% of SO 2 from the flue gas. The three scrubbers in total consumed about 24 MW of power, and used 130,000 tons of limestone and 3,000 acre-feet (3,700,000  m ) of water per year, producing 200,000 tons of gypsum per year. Prior to installation of

11656-649: The plant by 2015. NV Energy announced it also intends to pull out of participation in the plant, planning to divest its interest by 2019. Extension of the plantsite lease with the Navajo Nation requires the approval of the Secretary of the Interior , who cannot approve it until environmental assessments required by the National Environmental Policy Act (NEPA) and the Endangered Species Act (ESA) are completed. The current lease expired in 2019 and

11780-468: The plant through the transmission lines. The gross capacity was 2409.3 (MW) or 803.1 MW per unit, the rated power output at the generator that includes power used internally in the operation of the plant. Annual net energy generation in 2011 was 16.9 terawatt-hours ( TWh ), with a net capacity factor of 86%. Annual gross generation was 18.3 TWh. Fuel consumed ( primary energy ) in 2011 provided 50.0  TWh (170.5 × 10 Btu) of heat input, resulting in

11904-476: The project in 2016. After the rise of shale gas in the United States , natural gas power prices ($ 32/MWh) fell under the cost of coal power for NGS ($ 38/MWh), and NGS production decreased. The owners require a potential new owner (such as the Navajo Nation) to assume responsibility of future cleanups. The plant had three identical 750 MW steam electric generating units. Major components of each unit included

12028-447: The project. The contract for engineering and construction was awarded to Bechtel Corporation , which began construction in April, 1970. Generating units 1, 2, and 3 were completed in 1974, 1975, and 1976 respectively at a total cost of about $ 650 million. Between 1977 and 1990, following Clean Air Act amendments for assessing and protecting visibility in national parks and wilderness areas,

12152-407: The recommendation and implemented those conditions in its final rule. The technology selected for flue gas desulfurization (FGD) were wet SO 2 scrubbers with forced oxidation. Stone & Webster , the architect-engineering firm for the scrubber project, began construction in 1994 and completed the work on Units 3, 2, and 1 in 1997, 1998, and 1999 respectively. The cost of the scrubber project

12276-499: The requirements of the Clean Air Act and meeting the needs of the stakeholders. EPA is committed to continuing to engage with stakeholders to develop a final FIP that maintains benefits to tribes and the regional economy while improving visibility in many of our nation's most treasured National Parks and Wilderness Areas. The ruling would require the plant to reduce NO x emissions to no more than 0.055 pounds per million British thermal units (85  g / MWh ) by 2023, necessitating

12400-472: The revolt was unsuccessful. In fact, it had the exact opposite effect, for the result of the rebellion was the establishment of the presidio at Tubac , the first permanent European settlement in Arizona. In 1768, the Spanish created the Provincia de las Californias , which included California and the Southwest US. Over approximately the next 50 years, the Spanish continued to explore the Southwest, and in 1776

12524-555: The scrubbers, SO 2 emissions were about 71,000 tons per year. Nitrogen oxide emissions were controlled in the combustion process by the use of low-NO x SOFA burners. Prior to 2009 when installation of the new burners began, NOx emissions were about 34,000 tons per year. The new burners reduced NO x emissions by about 14,000 tons per year, or more than 40%. Fine particulate measuring 2.5 micrometers or less ( PM2.5 ), of concern for its potential effect on health and visibility, primarily results from reactions of SO 2 and NO x in

12648-402: The sought-after Southwestern architectural styles in the region inspired by blending Pueblo and Territorial styles, with Mediterranean Revival , Spanish Colonial architecture , Mission Revival architecture , Pueblo Deco , and Ranch-style houses in the form of the amalgamated Pueblo Revival and Territorial Revival architectures. This is due to the region's caballero heritage of

12772-460: The south the 37th parallel . In 1862 Nevada's eastern border shifted to the 38th meridian west from Washington , and finally to its current position at the 37th meridian west from Washington in 1866. The boundary modification in 1866 also included adding the southern triangular tip of the present-day state, taken from the Arizona Territory. From July 24–27, 1861 a Confederate force under

12896-402: The southeastern portion of the Southwest. Their settlements would evolve over time from pit-dwellings through pueblos and finally also incorporating cliff-dwellings. The Hohokam were the last of these ancestral cultures to develop, somewhere around AD 1, but they would grow to be the most populous of the three by AD 1300, despite being the smallest of the three in terms of area, covering most of

13020-487: The southernmost sections of Oregon, Idaho, and Wyoming, as well as parts of southwest Nebraska, western Kansas, Oklahoma, and Texas. By 1977, the Society's definition had narrowed to only the four states of Utah, Arizona, Colorado, and New Mexico; and by 1982 the portion of the Southwest in the United States, as defined by the Society, had shrunk to Arizona and New Mexico, with the southernmost strip of Utah and Colorado, as well as

13144-500: The southwest portion. Beginning in approximately AD 600, the Hohokam began to develop an extensive series of irrigation canals; of the three major cultures in the Southwest, only the Ancestral Puebloans of the Chaco culture and the Hohokam developed irrigation as a means of watering their agriculture. Not long after the Hohokam reached the height of their culture, all three major cultures in

13268-429: The spring blow toward counties to the north and east, which have not reported any days with unhealthy ozone levels. Moreover, Coconino County's two ozone monitoring sites – Grand Canyon Hance Camp and Page – show significant differences within the county (the sites being 70 miles apart). During periods when ozone readings have been highest, peak concentrations in Page were noted to be more than 10 percent lower than those at

13392-591: The surrounding desert below. The sky islands also supply the surrounding desert foothills with flowing water during the spring runoff and after the summer storms of the New Mexican monsoon season . The Chihuahuan is a "rain shadow" desert, formed between two mountain ranges (the Sierra Madre Occidental on the west and the Sierra Madre Oriental on the east) which block oceanic precipitation from reaching

13516-456: The use of such technology; A BART review may take into account the interests of stakeholders associated with the source. In the case of Navajo Generating Station, EPA solicited input from stakeholders: the Department of the Interior , the Central Arizona Project , the Navajo Nation , the Gila River Indian Community , the Salt River Project , the Environmental Defense Fund , and Western Resources Advocates. A technical working group negotiated

13640-471: The very southern tip of Nevada; while the Utah Territory consisted of Utah, most of Nevada, and portions of Wyoming and Colorado. The New Mexico Territory was expanded along its southern extent, to its current border, with the signing of the Gadsden Purchase Treaty on December 30, 1853, which was ratified by the U.S. Congress, with some slight alterations, in April 1854. The Colorado Territory

13764-474: The very southernmost part of Utah, southwestern Colorado, the very tip of west Texas, and triangle formed by the southern tip of Nevada. This will be the defined scope that is used in this article unless otherwise specified in a particular area. Parts of the other states make up the various areas that can be included in the Southwest, depending on the source. The Learning Center of the American Southwest (LCAS) does not rely on current state boundaries, and defines

13888-448: The way for a tourism boom, a trend led by restaurant and hotel entrepreneur Fred Harvey . The last two territories within the Southwest to achieve statehood were New Mexico and Arizona. By 1863, with the splitting off of the Arizona Territory, New Mexico reached its modern borders. They became states within forty days of one another. On January 6, 1912, New Mexico became the 47th state in the Union. Arizona would shortly follow, becoming

14012-564: The west to Las Vegas, New Mexico in the East. Reed's definition is roughly equivalent to the western half of the Learning Center of the American Southwest's definition, leaving out any portion of Kansas and Oklahoma, and much of Texas, as well as the eastern half of New Mexico. Since this article is about the Southwestern United States, the areas of Sonora and Chihuahua in Mexico will be excluded. The portion left includes Arizona and western New Mexico,

14136-539: The west were added after the Mexican–American War , the geographical "Southwest" expanded, and the relationship of these new acquisitions to the South itself became "increasingly unclear." However, archeologist, Erik Reed, gives a description which is the most widely accepted as defining the American Southwest, which runs from Durango, Colorado in the north, to Durango, Mexico, in the south, and from Las Vegas, Nevada in

14260-506: The westernmost metropolitan areas in the Southwest, while Albuquerque - Santa Fe and El Paso - Las Cruces dominate the easternmost metropolitan areas. Human history in the Southwest begins with the arrival of the Clovis culture , a Paleo-Indian hunter-gatherer culture which arrived sometime around 9000 BC. This culture remained in the area for several millennia. At some point they were replaced by three great Pre-Columbian Indian cultures:

14384-487: Was about $ 420 million. During spring overhauls in 2003 through 2005, the electrostatic precipitators were completely gutted and rebuilt for reliability and optimum performance. The original collecting plates and weighted wire electrodes were replaced with improved collecting plates and rigid discharge electrodes. Control equipment was replaced with upgraded automatic voltage controls and rappers. In 2007, an analysis of nitrogen oxide (NO x ) emissions and control options

14508-423: Was admitted to the Union on October 31, 1864, becoming the 36th state. This was followed by the admittance to the Union of Colorado, which became the 38th state on August 1, 1876. Confederate Arizona was short-lived, however. By May 1862, Confederate forces had been driven out of the region by union troops. That same month a bill was introduced into the U.S. Congress, and on February 24, 1863 Abraham Lincoln signed

14632-459: Was almost non-existent outside of Nuevo México's Pueblos and Spanish or Mexican municipalities . Much of the area had been a part of New Spain and Mexico until the United States acquired the area through the Treaty of Guadalupe Hidalgo in 1848 and the smaller Gadsden Purchase in 1854. While the region's boundaries are not officially defined, there have been attempts to do so. One such definition

14756-482: Was built over 35 years ago, is the largest coal-fired power plant in the West in terms of generating capacity. It is central to the economies of the Navajo Nation and Hopi Tribe and supplies power to the states of Arizona, Nevada, and California. Electricity produced by NGS is also used to power the Central Arizona Project, which supplies surface water to three counties and numerous Indian tribes in Arizona. NGS

14880-468: Was built with one of the first zero liquid discharge (ZLD) systems in a power plant, recovering all cooling tower blow-down and runoff from developed areas of the site. The waste water is processed through three brine concentrators and a crystallizer, which remove the solids and produce distilled water for re-use within the plant. Several lined ponds are used in conjunction with the ZLD system to capture and regulate

15004-725: Was conducted for SRP in support of Clean Air Act regional haze reduction efforts, although there were no (NO x ) reduction requirements on NGS at the time. The analysis concluded that Low NO x burners with separated overfire air (SOFA) would provide the Best Available Retrofit Technology (BART) alternative in accordance with EPA BART guidelines. Consequently, the plant voluntarily installed low NO x -SOFA burners on units 3, 2, and 1 during eight-week outages in February through March 2009, 2010, and 2011 respectively. The Los Angeles Department of Water and Power withdrew from

15128-587: Was hauled 75 miles from mine silos to the plant by the Black Mesa and Lake Powell Railroad that is owned and operated by the plant. Characteristics of the coal in 2011 included a sulfur content of 0.64%, an ash content of 10.6%, and higher heating value (HHV) of 10,774 Btu/lb. The plant had three 775 ft (236 meter) tall flue gas stacks , listed among the tallest structures in Arizona . The stacks were constructed of reinforced concrete, supporting an internal metal liner. The plant's original stacks were demolished in

15252-481: Was organized on February 28, 1861, created out of lands then currently in the Utah, Kansas, Nebraska, and New Mexico territories. The Nevada Territory was also organized in 1861, on March 2, with land taken from the existing Utah Territory. Initially, only the western 2/3 of what is currently the State of Nevada was included in the territory, with its boundary to the east being the 39th meridian west from Washington , and to

15376-550: Was visited by its first non-Spanish Europeans, English trappers. In 1836, the Republic of Texas , which contained the easternmost of the Southwest United States, won its independence from Mexico. In 1845 the Republic of Texas was annexed by the United States and immediately became a state, bypassing the usual territory phase. The new state still contained portions of what would eventually become parts of other states. In 1846,

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