Blue Mountains (Pacific Northwest)
The Blue Mountains are a mountain range in the western United States, located in northeastern Oregon and stretching into southeastern Washington. The range has an area of 4,060 square miles, stretching east and southeast of Pendleton, Oregon, to the Snake River along the Oregon-Idaho border; the Blue Mountains cover seven counties in Washington. They are home to fungal mycelial mat, the Armillaria ostoyae; the Blue Mountains were so named due to thick smoke from the fires which engulf the area. The Blues are uplift mountains. Geologically, the range is a part of the larger rugged Columbia River Plateau, located in the dry area of Oregon and Washington east of the Cascade Range; the highest peak in the range is Rock Creek Butte in Baker County, Oregon at 9,106 feet, on Elkhorn Ridge. Other ranges in the Blue Mountains physiographic section include the Wallowa Mountains, the Elkhorn Mountains, the Strawberry Mountains; the river valleys and lower levels of the range were occupied by indigenous peoples for thousands of years.
Historic tribes of the region included the Walla Walla, Cayuse people and Umatilla, now acting together as the Confederated Tribes of the Umatilla Indian Reservation, located in Umatilla County, Oregon. The southern portion of the Blue Mountains were inhabited by several different bands of the Northern Paiute, a Great Basin culture. Native American tribes migrated to the Blue Mountains for hunting and salmon runs; the Natives used to purposefully burn parts of the forest or allow campfires to burn over wide areas. In the mid-1800s, the Blue Mountains were a formidable obstacle to settlers traveling on the Oregon Trail and were the last mountain range American pioneers had to cross before either reaching southeast Washington near Walla Walla or passing down the Columbia River Gorge to the end of the Oregon Trail in the Willamette Valley near Oregon City; the range is traversed by Interstate 84, which crosses the crest of the range at a 4,193 feet summit, from south-southeast to north-northwest between La Grande and Pendleton.
The community of Baker City is located along the south-eastern flank of the range. U. S. Route 26 crosses the southern portion of the range, traversing the Blue Mountain Summit and reaching an elevation of 5,098 feet. Elk The Washington Blue Mountains, in 1989, regulated elk hunting with a spike-only general hunting season; this was in response to a decline in the elk population creating a heavy female biased population. By the mid 1990s the area became known for its mature males and trophy hunting. During winter months elk will prefer to use "moderately steep south slopes" rather than northern slopes because of the southern slopes being warmer and containing less snow. Throughout the Blue Mountains physiographic section, foresters have been, nearly a century, attempting to create a regulated, scientific forest, in a process referred to as restoration. Much of the range is included in the Malheur National Forest, Umatilla National Forest, Wallowa–Whitman National Forest. Several wilderness areas encompass remote parts of the range, including the North Fork Umatilla Wilderness, the North Fork John Day Wilderness, the Strawberry Mountain Wilderness, the Monument Rock Wilderness, all of which are in Oregon.
The Wenaha–Tucannon Wilderness sits astride the Oregon–Washington border. The range is drained by several rivers, including the Grande Ronde and Tucannon, tributaries of the Snake, as well as the forks of the John Day and Walla Walla rivers, tributaries of the Columbia; the southernmost portion of the Blue Mountains is drained by the Silvies River, in the endorheic Harney Basin. "Blue Mountains". Getty Thesaurus of Geographic Names. 2004. Retrieved 2007-07-28
Prairie City, Oregon
Prairie City is a city in Grant County, United States. The population was 909 at the 2010 census; the community was incorporated by the Oregon Legislative Assembly on February 23, 1891. Prairie City grew out of the former mining camp of Dixie, established in 1862 about 3 miles up Dixie Creek from the John Day River. Prairie City, at the mouth of the creek, was chosen after placer mining rendered Dixie unsuitable for a townsite; the new city's post office was established in 1870 with Jules Le Bret as postmaster. A narrow gauge line, the Sumpter Valley Railway, ran 80 miles from Baker City west to Sumpter and on to its western terminus at Prairie City, which it reached in 1907, it carried passengers as well as freight shipped by ranchers, mining interests, timber companies until its piecemeal abandonment in the 1930s. In the 21st century, a heritage railway operates on a segment of the original line between Sumpter and McEwen. Prairie City is in eastern Oregon at the upper end of the John Day River valley.
It is about 50 miles southwest of Baker City by highway and 13 miles east of John Day along U. S. Route 26 in Grant County. Strawberry Mountain in the Strawberry Mountain Wilderness of the Malheur National Forest is directly south of the city. According to the United States Census Bureau, the city has a total area of 0.99 square miles, all land. As of the census of 2010, there were 909 people, 402 households, 257 families residing in the city; the population density was 918.2 inhabitants per square mile. There were 476 housing units at an average density of 480.8 per square mile. The racial makeup of the city was 94.6% White, 0.1% African American, 1.3% Native American, 0.1% Asian, 0.2% Pacific Islander, 0.3% from other races, 3.3% from two or more races. Hispanic or Latino of any race were 3.1% of the population. There were 402 households of which 24.9% had children under the age of 18 living with them, 53.7% were married couples living together, 7.2% had a female householder with no husband present, 3.0% had a male householder with no wife present, 36.1% were non-families.
32.1% of all households were made up of individuals and 17% had someone living alone, 65 years of age or older. The average household size was 2.18 and the average family size was 2.69. The median age in the city was 49.8 years. 20.4% of residents were under the age of 18. The gender makeup of the city was 49.3% male and 50.7% female. At the census of 2000, the median income for a household in the city was $31,354, the median income for a family was $35,893. Males had a median income of $31,771 versus $24,500 for females; the per capita income for the city was $16,278. About 10.6% of families and 14.7% of the population were below the poverty line, including 17.4% of those under age 18 and 9.4% of those age 65 or over. The economy includes ranching, retail stores, a wood-fueled power plant, public services. Prairie Wood Products, a mill that produces fine-grained studs from timber from nearby forests, is in Prairie City. Prairie City School in Prairie City serves children from kindergarten through 12th grade.
Architectural features in Prairie City include historic stone buildings and the former railway depot. The ground floor of the depot consists of a waiting room, railway station agent's office, baggage room, freight office; the second floor, once the home of the station agent and his family, houses the Dewitt Museum, with pioneer artifacts, tools and memorabilia, as well as rocks and minerals from the surrounding area. The depot was listed on the National Register of Historic Places in 1976. Bates State Park, built on the site of a former lumber mill, is northeast of Prairie City at Bates, near Austin Junction at the intersection of U. S. Route 26 and Oregon Route 7. City of Prairie City Entry for Prairie City in the Oregon Blue Book Grant County Chamber of Commerce entry for Prairie City Weather statistics for Prairie City from The Weather Channel
The Snake River is a major river of the greater Pacific Northwest region in the United States. At 1,078 miles long, it is the largest tributary of the Columbia River, in turn the largest North American river that empties into the Pacific Ocean; the Snake River rises in western Wyoming flows through the Snake River Plain of southern Idaho, the rugged Hells Canyon on the Oregon–Idaho border and the rolling Palouse Hills of Washington, emptying into the Columbia River at the Tri-Cities, Washington. The Snake River drainage basin encompasses parts of six U. S. is known for its varied geologic history. The Snake River Plain was created by a volcanic hotspot which now lies underneath the Snake River headwaters in Yellowstone National Park. Gigantic glacial-retreat flooding episodes that occurred during the previous Ice Age carved out canyons and waterfalls along the middle and lower Snake River. Two of these catastrophic flooding events, the Missoula Floods and Bonneville Flood affected the river and its surroundings.
Prehistoric Native Americans lived along the Snake starting more than 11,000 years ago. Salmon from the Pacific Ocean spawned by the millions in the river, were a vital resource for people living on the Snake downstream of Shoshone Falls. By the time Lewis and Clark explored the area, the Nez Perce and Shoshone were the dominant Native American groups in the region. Explorers and fur trappers further changed and used the resources of the Snake River basin. At one point, sign language used by the Shoshones representing weaving baskets was misinterpreted to represent a snake, giving the Snake River its name. By the middle 19th century, the Oregon Trail had become well established, bringing numerous settlers to the Snake River region. Steamboats and railroads moved agricultural products and minerals along the river throughout the 19th and early 20th centuries. Starting in the 1890s, fifteen major dams have been built on the Snake River to generate hydroelectricity, enhance navigation, provide irrigation water.
However, these dams blocked salmon migration above Hells Canyon and have led to water quality and environmental issues in certain parts of the river. The removal of several dams on the lower Snake River has been proposed, in order to restore some of the river's once-tremendous salmon runs. Formed by the confluence of three tiny streams on the southwest flank of Two Oceans Plateau in Yellowstone National Park, western Wyoming, the Snake starts out flowing west and south into Jackson Lake, its first 50 miles run through Jackson Hole, a wide valley between the Teton Range and the Gros Ventre Range. Below the tourist town of Jackson, the river turns west and flows through Snake River Canyon, cutting through the Snake River Range and into eastern Idaho, it receives the Hoback and Greys Rivers before entering Palisades Reservoir, where the Salt River joins at the mouth of Star Valley. Below Palisades Dam, the Snake River flows through the Snake River Plain, a vast arid physiographic province extending through southern Idaho south-west of the Rocky Mountains and underlain by the Snake River Aquifer, one of the most productive aquifers in the United States.
Southwest of Rexburg, the Snake is joined from the north by Henrys Fork. The Henrys Fork is sometimes called the North Fork of the Snake River, with the main Snake above their confluence known as the "South Fork". From there it turns south, flowing through downtown Idaho Falls past the Fort Hall Indian Reservation and into American Falls Reservoir, where it is joined by the Portneuf River; the Portneuf River Valley is an overflow channel that in the last glacial period carried floodwaters from pluvial Lake Bonneville into the Snake River altering the landscape of the Snake River Plain through massive erosion. From there the Snake resumes its journey west, it is interrupted by several major cataracts, the largest being 212-foot Shoshone Falls, which marked the upriver limit of migrating salmon. A short distance downstream. Near Twin Falls, the Snake approaches the southernmost point in its entire course, after which it starts to flow west-northwest; the Snake continues through its canyon, receiving the Malad River from the east near Bliss and the Bruneau River from the south in C.
J. Strike Reservoir, it passes through an agricultural valley about 30 miles southwest of Boise and flows west into Oregon, before turning north to define the Idaho–Oregon border. Here the Snake River doubles in size as it receives several major tributaries – the Owyhee from the southwest the Boise and Payette rivers from the east, further downstream the Malheur River from the west and Weiser River from the east. North of Boise, the Snake enters Hells Canyon, a steep, rapid-strewn gorge that cuts through the Salmon River Mountains and Blue Mountains of Idaho and Oregon. Hells Canyon is one of the most rugged and treacherous portions of the course of the Snake River, posing a major obstacle for 19th-century American explorers. Here the Snake is impounded by Hells Canyon and Brownlee Dams, which together make up the Hells Canyon Hydroelectric Project. At the halfway point in Hells Canyon, in one of the most remote and inaccessible sections of its course, the Snake River is joined from the east by its largest tributary, the Salmon River.
From there, the Snake begins to form the Washington–Idaho border, receiving the Grande Ronde River from the west before receiving the Clearwater River from the east at Lewiston, which marks the head of navigation on the Snake. The river leaves Hells Canyon and turns west, winding through the Palouse Hills of eastern Washington; the Lower Snake River Project's four dams and
National Wild and Scenic Rivers System
The National Wild and Scenic Rivers System was created by the Wild and Scenic Rivers Act of 1968, enacted by the U. S. Congress to preserve certain rivers with outstanding natural and recreational values in a free-flowing condition for the enjoyment of present and future generations; the Act is notable for safeguarding the special character of these rivers, while recognizing the potential for their appropriate use and development. It encourages river management that crosses political boundaries and promotes public participation in developing goals for river protection; the Act, signed into law by President Lyndon B. Johnson in the height of the United States environmental era, states:"It is hereby declared to be the policy of the United States that certain selected rivers of the Nation which, with their immediate environments, possess outstandingly remarkable scenic, geologic and wildlife, cultural or other similar values, shall be preserved in free-flowing condition, that they and their immediate environments shall be protected for the benefit and enjoyment of present and future generations.
The Congress declares that the established national policy of dams and other construction at appropriate sections of the rivers of the United States needs to be complemented by a policy that would preserve other selected rivers or sections thereof in their free-flowing condition to protect the water quality of such rivers and to fulfill other vital national conservation purposes." The Act established the National Wild and Scenic Rivers System to protect and enhance rivers found to be regionally and nationally significant. Rivers may be designated by Congress or, if certain requirements are met, the Secretary of the Interior; each designated river is administered by either a federal, state, or tribal agency, or as a partnership between any number of these government entities and local NGOs. Designated segments need not include the entire river and may include headwaters and tributaries. For federally administered rivers, the designated boundaries average one-quarter mile on either bank in the lower 48 states and one-half mile on rivers outside national parks in Alaska in order to protect river-related values.
As of August 2018, the National System protects over 12,700 miles of 209 rivers in 40 states and the Commonwealth of Puerto Rico. By comparison, more than 75,000 large dams across the country have modified at least 600,000 miles, or about 17%, of American rivers; the National Wild and Scenic Rivers Act was an outgrowth of the recommendations of a Presidential commission, the Outdoor Recreation Resources Review Commission. Among other things, the commission recommended that the nation protect wild rivers and scenic rivers from development that would change their free-flowing nature and values. At this time, the country was experiencing rapid degradation of its water resources due to municipal and industrial effluent being released into the nation's rivers. Many waterways and the fish in them were toxic. Populations of aquatic species were declining and people were being relocated from their communities due to rampant dam building. All across the country people were writing letters imploring the President and First lady to protect their beloved rivers.
The act was sponsored by Sen. Frank Church and signed into law by President Lyndon B. Johnson on October 2, 1968. A river, or river section, may be designated by the U. S. Congress or the Secretary of the Interior. In 1968, as part of the original act, eight rivers were designated as National Wild and Scenic Rivers; as of November 2018, 209 rivers, totaling 12,754 miles of river in 40 states and Puerto Rico, have Wild and Scenic status. By comparison, more than 75,000 large dams across the country have modified at least 600,000 miles, or about 17%, of American rivers. Selected rivers in the United States are preserved for possessing Outstandingly Remarkable Values that fall into the 8 categories: Scenic, Geologic, Wildlife, Culture, or Other similar values; these values can be considered synonymous with ecosystem services, or those goods and services that nature provides and that benefit society. Rivers so designated are set out for protection and enhancement in perpetuity by preserving their free-flowing condition from dams and development that would otherwise diminish the quality of their remarkable values.
National Wild and Scenic designation vetoes the licensing of new dams on, or directly affecting the designated section of river. It provides strong protection against federally funded bank and channel alterations that adversely affect river values, protects riverfront public lands from new oil and mineral development, creates a federal reserved water right to protect flow-dependent values such as fish habitat. Designation as a Wild and Scenic River is not the same as a national park designation, does not confer the same protections as a Wilderness Area designation. Wild and Scenic designation protects the free-flowing nature of rivers in both federal and non-federal areas, something the Wilderness Act and other federal designations cannot do. Despite misplaced fears, WSR designation does not alter private property rights. Federally administered National Wild and Scenic Rivers are managed by one or more of the four principal land-managing agencies of the federal government. Of the 209 National Wild an
The United States of America known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U. S. is the third most populous country. The capital is Washington, D. C. and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico; the State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean; the U. S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The diverse geography and wildlife of the United States make it one of the world's 17 megadiverse countries.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago. European colonization began in the 16th century; the United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies following the French and Indian War led to the American Revolution, which began in 1775, the subsequent Declaration of Independence in 1776; the war ended in 1783 with the United States becoming the first country to gain independence from a European power. The current constitution was adopted in 1788, with the first ten amendments, collectively named the Bill of Rights, being ratified in 1791 to guarantee many fundamental civil liberties; the United States embarked on a vigorous expansion across North America throughout the 19th century, acquiring new territories, displacing Native American tribes, admitting new states until it spanned the continent by 1848. During the second half of the 19th century, the Civil War led to the abolition of slavery.
By the end of the century, the United States had extended into the Pacific Ocean, its economy, driven in large part by the Industrial Revolution, began to soar. The Spanish–American War and World War I confirmed the country's status as a global military power; the United States emerged from World War II as a global superpower, the first country to develop nuclear weapons, the only country to use them in warfare, a permanent member of the United Nations Security Council. Sweeping civil rights legislation, notably the Civil Rights Act of 1964, the Voting Rights Act of 1965 and the Fair Housing Act of 1968, outlawed discrimination based on race or color. During the Cold War, the United States and the Soviet Union competed in the Space Race, culminating with the 1969 U. S. Moon landing; the end of the Cold War and the collapse of the Soviet Union in 1991 left the United States as the world's sole superpower. The United States is the world's oldest surviving federation, it is a representative democracy.
The United States is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, other international organizations. The United States is a developed country, with the world's largest economy by nominal GDP and second-largest economy by PPP, accounting for a quarter of global GDP; the U. S. economy is post-industrial, characterized by the dominance of services and knowledge-based activities, although the manufacturing sector remains the second-largest in the world. The United States is the world's largest importer and the second largest exporter of goods, by value. Although its population is only 4.3% of the world total, the U. S. holds 31% of the total wealth in the world, the largest share of global wealth concentrated in a single country. Despite wide income and wealth disparities, the United States continues to rank high in measures of socioeconomic performance, including average wage, human development, per capita GDP, worker productivity.
The United States is the foremost military power in the world, making up a third of global military spending, is a leading political and scientific force internationally. In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere America in honor of the Italian explorer and cartographer Amerigo Vespucci; the first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq. to George Washington's aide-de-camp and Muster-Master General of the Continental Army, Lt. Col. Joseph Reed. Moylan expressed his wish to go "with full and ample powers from the United States of America to Spain" to seek assistance in the revolutionary war effort; the first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, Virginia, on April 6, 1776. The second draft of the Articles of Confederation, prepared by John Dickinson and completed by June 17, 1776, at the latest, declared "The name of this Confederation shall be the'United States of America'".
The final version of the Articles sent to the states for ratification in late 1777 contains the sentence "The Stile of this Confederacy shall be'The United States of America'". In June 1776, Thomas Jefferson wrote the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence; this draft of the document did not surface unti
Floodgates called stop gates, are adjustable gates used to control water flow in flood barriers, river, stream, or levee systems. They may be designed to set spillway crest heights in dams, to adjust flow rates in sluices and canals, or they may be designed to stop water flow as part of a levee or storm surge system. Since most of these devices operate by controlling the water surface elevation being stored or routed, they are known as crest gates. In the case of flood bypass systems, floodgates sometimes are used to lower the water levels in a main river or canal channels by allowing more water to flow into a flood bypass or detention basin when the main river or canal is approaching a flood stage. Valves used in floodgate applications have a variety of design requirements and are located at the base of dams; the most important requirement is energy dissipation. Since water is heavy, it exits the base of a dam with the enormous force of water pushing from above. Unless this energy is dissipated, the flow can erode soil and damage structures.
Other design requirements include taking into account pressure head operation, the flow rate, whether the valve operates above or below water, the regulation of precision and cost. Fixed cone valves are designed to dissipate the energy from a water flow during reservoir discharge, they are a round pipe section with an adjustable sleeve cone at the discharge end. Flow is varied towards its cone seat; the design allows high pressure water from the base of a dam to be released without causing erosion to the surrounding environment. Fixed cone valves are able to handle heads up to 300 m. Hollow jet valves are a type of needle valve used for floodgate discharge. A cone and seat are inside a pipe. Water flows through an annular gap between the pipe and cone when it is moved downstream, away from the seat. Ribs support the bulb supply air for water jet stabilization. Ring jet valves are similar to fixed cone valves, but have an integral collar that discharges water in a narrow stream, they are suitable for heads up to 50 m.
Jet flow gate, similar to a gate valve but with a conical restriction prior to the gate leaf that focuses the water into a jet. They were developed in the 1940s by the United States Bureau of Reclamation to allow fine control of discharge flow without the cavitation seen in regular gate valves. Jet flow gates are able to handle heads up to 150 m. In order to do a simple calculation of the force on a rectangular flood gate one can use the following equation: F = p A where: F = force measured in the SI units kg·m·s−2, called the newton p = pressure = ρ g h measured in N/m2, called the pascal where: ρ is the density of fresh water. A = area = rectangle: length × height measured in m2where: length = the horizontal length of a rectangular floodgate measured in meters height = the height of a non-submerged flood gate from the bottom of the water column to the water surface measured in metersIf the rectangular flood gate is submerged below the surface the same equation can be used but only the height from the water surface to the middle of the gate must be used to calculate the force on the flood gate.
Flood barrier Tidal barrage Canal lock Thames Barrier Delta Works Oosterscheldekering US Army Corps of Engineers.. Engineering manual 1110-2-2607, Planning and Design of Navigation Dams, Chapter 5, Overview of gate types. Retrieved 2008-04-14. DeltaWorks. Org – project in the Netherlands on floodgates
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, the natural hazards that threaten it; the organization has four major science disciplines, concerning biology, geography and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility; the USGS is a bureau of the United States Department of the Interior. The USGS employs 8,670 people and is headquartered in Reston, Virginia; the USGS has major offices near Lakewood, Colorado, at the Denver Federal Center, Menlo Park, California. The current motto of the USGS, in use since August 1997, is "science for a changing world." The agency's previous slogan, adopted on the occasion of its hundredth anniversary, was "Earth Science in the Public Service." Since 2012, the USGS science focus is directed at six topical "Mission Areas", namely Climate and Land Use Change, Core Science Systems, Ecosystems and Minerals and Environmental Health, Natural Hazards, Water.
In December 2012, the USGS split the Energy and Minerals and Environmental Health Mission Area resulting in seven topical Mission Areas, with the two new areas being: Energy and Minerals and Environmental Health. Administratively, it is divided into six Regional Units. Other specific programs include: Earthquake Hazards Program monitors earthquake activity worldwide; the National Earthquake Information Center in Golden, Colorado on the campus of the Colorado School of Mines detects the location and magnitude of global earthquakes. The USGS runs or supports several regional monitoring networks in the United States under the umbrella of the Advanced National Seismic System; the USGS informs authorities, emergency responders, the media, the public, both domestic and worldwide, about significant earthquakes. It maintains long-term archives of earthquake data for scientific and engineering research, it conducts and supports research on long-term seismic hazards. USGS has released the UCERF California earthquake forecast.
As of 2005, the agency is working to create a National Volcano Early Warning System by improving the instrumentation monitoring the 169 volcanoes in U. S. territory and by establishing methods for measuring the relative threats posed at each site. The USGS National Geomagnetism Program monitors the magnetic field at magnetic observatories and distributes magnetometer data in real time; the USGS collaborates with Canadian and Mexican government scientists, along with the Commission for Environmental Cooperation, to produce the North American Environmental Atlas, used to depict and track environmental issues for a continental perspective. The USGS operates the streamgaging network for the United States, with over 7400 streamgages. Real-time streamflow data are available online. National Climate Change and Wildlife Science Center implements partner-driven science to improve understanding of past and present land use change, develops relevant climate and land use forecasts, identifies lands and communities that are most vulnerable to adverse impacts of change from the local to global scale.
Since 1962, the Astrogeology Research Program has been involved in global and planetary exploration and mapping. In collaboration with Stanford University, the USGS operates the USGS-Stanford Ion Microprobe Laboratory, a world-class analytical facility for U--Pb geochronology and trace element analyses of minerals and other earth materials. USGS operates a number of water related programs, notably the National Streamflow Information Program and National Water-Quality Assessment Program. USGS Water data is publicly available from their National Water Information System database; the USGS operates the National Wildlife Health Center, whose mission is "to serve the nation and its natural resources by providing sound science and technical support, to disseminate information to promote science-based decisions affecting wildlife and ecosystem health. The NWHC provides information, technical assistance, research and leadership on national and international wildlife health issues." It is the agency responsible for surveillance of H5N1 avian influenza outbreaks in the United States.
The USGS runs 17 biological research centers in the United States, including the Patuxent Wildlife Research Center. The USGS is investigating collaboration with the social networking site Twitter to allow for more rapid construction of ShakeMaps; the USGS produces several national series of topographic maps which vary in scale and extent, with some wide gaps in coverage, notably the complete absence of 1:50,000 scale topographic maps or their equivalent. The largest and best-known topographic series is the 7.5-minute, 1:24,000 scale, quadrangle, a non-metric scale unique to the United States. Each of these maps covers an area bounded by two lines of latitude and two lines of longitude spaced 7.5 minutes apart. Nearly 57,000 individual maps in this series cover the 48 contiguous states, Hawaii, U. S. territories, areas of Alaska near Anchorage and Prudhoe Bay. The area covered by each map varies with the latitude of its represented location due to convergence of the meridians. At lower latitudes, near 30° north, a 7.5-minute quadrangle contains an area of about 64 square miles.
At 49° north latitude, 49 square miles are contained within a quadrangle of that size. As a unique non-metric map scale, the 1:24,000 scale requires a separate and specialized romer scale for pl