Geology topics

Research about Lake Mead National Recreation Area

Source-linked reports with geographic coverage including Lake Mead National Recreation Area.

14 recordsLinked to original sources

USGS2018

Sperm quality biomarkers complement reproductive and endocrine parameters in investigating environmental contaminants in common carp (Cyprinus carpio) from the Lake Mead National Recreation Area

Lake Mead National Recreational Area (LMNRA) serves as critical habitat for several federally listed species and supplies water for municipal, domestic, and agricultural use in the Southwestern U.S. Contaminant sources and concentrations vary among the sub-basins within LMNRA. To investigate whether exposure to environmental contaminants is associated with alterations in male common carp ( Cyprinus carpio ) gamete quality and endocrine- and reproductive parameters, data were collected among sub-basins over 7 years (1999–2006). Endpoints included sperm quality parameters of motility , viability, mitochondrial membrane potential, count, morphology, and DNA fragmentation; plasma components were vitellogenin (VTG), 17ß-estradiol, 11-keto-testosterone, triiodothyronine, and thyroxine. Fish condition factor, gonadosomatic index, and gonadal histology parameters were also measured. Diminished biomarker effects were noted in 2006, and sub-basin differences were indicated by the irregular occurrences of contaminants and by several associations between chemicals (e.g., polychlorinated biphenyls, hexachlorobenzene , galaxolide, and methyl triclosan) and biomarkers (e.g., plasma thyroxine, sperm motility and DNA fragmentation). By 2006, sex steroid hormone and VTG levels decreased with subsequent reduced endocrine disrupting effects. The sperm quality bioassays developed and applied with carp complemented endocrine and reproductive data, and can be adapted for use with other species.

Lake Mead National Recreation Area↗

USGS2016

Foraging at the wildland–urban interface decouples weather as a driver of recruitment for desert bighorn sheep

A growing number of ungulate populations are living within or near the wildland–urban interface. When resources at the interface are of greater quality than that of adjacent natural habitat, wildlife can be attracted to these developed areas. Little is known about how use of the wildland–urban interface by wildlife may affect vital rates. Under natural conditions, recruitment by desert bighorn sheep ( Ovis canadensis nelsoni ) correlates with variation in the timing and amount of rainfall that initiates and enhances growth of annual plant species. However, for populations that forage in developed areas, this relationship may become decoupled. In the River Mountains of Nevada, USA, desert bighorn sheep have been feeding in a municipal park at the wildland–urban interface since its establishment in 1985. Approximately one-third of the population now uses the park during summer months when nutritional content of natural forage is low. We hypothesized that use of this municipal area, with its abundant vegetation and water resources, may have decoupled the previous relationship between precipitation and lamb recruitment. We assessed variables known to affect lamb recruitment before (1971–1986) and after (1987–2006) establishment of the park using linear regression models. Our top candidate model for the pre-park period indicated that total November precipitation was the greatest driver of lamb recruitment in this population. After park establishment, this relationship became decoupled because lamb recruitment was no longer driven by weather variables. These results raise questions about the effects of decoupling drivers of population growth and maintaining natural populations near urban areas.

Nevada↗

USGS2012

Introduction and summary of findings

Lakes Mead and Mohave, which are the centerpieces of Lake Mead National Recreation Area (LMNRA), provide many significant benefits that have made the modern development of the Southwestern United States possible. Lake Mead is the largest reservoir by volume in the nation and it supplies critical storage of water supplies for more than 25 million people in three Western States (California, Arizona, and Nevada). Storage within Lake Mead supplies drinking water and the hydropower to provide electricity for major cities including Las Vegas, Phoenix, Los Angeles, Tucson, and San Diego, and irrigation of more than 2.5 million acres of croplands (National Park Service, 2010). Lake Mead is arguably the most important reservoir in the nation because of its size and the services it delivers to the Western United States (Holdren and Turner, 2010).

Arizona, Nevada↗

USGS2012

A synthesis of aquatic science for management of Lakes Mead and Mohave

Lakes Mead and Mohave, which are the centerpieces of Lake Mead National Recreation Area, provide many significant benefits that have made the modern development of the Southwestern United States possible. Lake Mead is the largest reservoir by volume in the nation and it supplies critical storage of water supplies for more than 25 million people in three Western States (California, Arizona, and Nevada). Storage within Lake Mead supplies drinking water and the hydropower to provide electricity for major cities including Las Vegas, Phoenix, Los Angeles, Tucson, and San Diego, and irrigation of more than 2.5 million acres of croplands. Lake Mead is arguably the most important reservoir in the nation because of its size and the services it delivers to the Western United States. This Circular includes seven chapters. Chapter 1 provides a short summary of the overall findings and management implications for Lakes Mead and Mohave that can be used to guide the reader through the rest of the Circular. Chapter 2 introduces the environmental setting and characteristics of Lakes Mead and Mohave and provides a brief management context of the lakes within the Colorado River system as well as overviews of the geological bedrock and sediment accumulations of the lakes. Chapter 3 contains summaries of the operational and hydrologic characteristics of Lakes Mead and Mohave. Chapter 4 provides information on water quality, including discussion on the monitoring of contaminants and sediments within the reservoirs. Chapter 5 describes aquatic biota and wildlife, including food-web dynamics, plankton, invertebrates, fish, aquatic birds, and aquatic vegetation. Chapter 6 outlines threats and stressors to the health of Lake Mead aquatic ecosystems that include a range of environmental contaminants, invasive species, and climate change. Chapter 7 provides a more detailed summary of overall findings that are presented in Chapter 1; and it contains a more detailed discussion on associated management implications, additional research, and monitoring needs.

Arizona, Nevada↗

USGS2012

Environmental setting of Lake Mead National Recreation Area: Chapter 2 in A synthesis of aquatic science for management of Lakes Mead and Mohave

Lakes Mead and Mohave provide opportunities for millions of regional, national, and international visitors to enjoy a wide array of water-based recreation in a spectacular desert setting. The national significance of the site’s recreational opportunities and scientific values led to its designation as the nation’s first National Recreation Area in 1964. The stark contrast of the deep blue lakes with spacious open water basins against a backdrop of mountain and canyon scenery creates a diversity of landscapes inviting recreation from the active to the contemplative (Maxon, 2009). The quality of the setting as a backdrop for the recreational experience has resulted in designation of approximately 200,000 acres of lands surrounding the lakes as wilderness (National Park Service, 2005).

Circular↗

USGS2012

Hydrology and management of Lakes Mead and Mohave within the Colorado River Basin: Chapter 3 in A synthesis of aquatic science for management of Lakes Mead and Mohave

The Colorado River Basin covers parts of seven States: Colorado, Wyoming, Utah, New Mexico, Nevada, Arizona, and California; at 1,450 mi (2,333.5 km) in length, the Colorado River is the seventh longest river in the United States (fig. 3-1). The Bureau of Reclamation has the responsibility for management of this system, in coordination with the seven basin States, within a complex framework of law, regulations, compact, treaty, and policies often referred to collectively as the “Law of the River.” Lake Mead is a critical component of the overall Colorado River management, providing the capacity to store almost 2 years of the average runoff of the river.

Circular↗

USGS2012

Lake water quality: Chapter 4 in A synthesis of aquatic science for management of Lakes Mead and Mohave

Given the importance of the availability and quality of water in Lake Mead, it has become one of the most intensely sampled and studied bodies of water in the United States. As a result, data are available from sampling stations across the lake (fig. 4-1 and see U.S. Geological Survey Automated Water-Quality Platforms) to provide information on past and current (2012) water-quality conditions and on invasive species that influence—and are affected by—water quality. Water quality in Lakes Mead and Mohave generally exceeds standards set by the State of Nevada to protect water supplies for public uses: drinking water, aquatic ecosystem health, recreation, or agricultural irrigation. In comparison to other reservoirs studied by the U.S. Environmental Protection Agency (USEPA) for a national lake assessment (U.S. Environmental Protection Agency, 2010), Lake Mead is well within the highest or ‘good’ category for recreation and aquatic health (see U.S. Environmental Protection Agency National Lakes Assessment and Lake Mead for more details). While a small part of the lake, particularly Las Vegas Bay, is locally influenced by runoff from urbanized tributaries such as Las Vegas Wash, contaminant loading in the lake as a whole is low compared to other reservoirs in the nation, which are influenced by runoff from more heavily urbanized watersheds (Rosen and Van Metre, 2010).

Circular↗

USGS2012

Wildlife and biological resources: Chapter 5 in A synthesis of aquatic science for management of Lakes Mead and Mohave

The creation of Lakes Mead and Mohave drastically changed habitats originally found along their region of the historical Colorado River. While still continuing to provide habitat conditions that support a rich diversity of species within the water, along shorelines, and in adjacent drainage areas, the reservoirs contain organisms that are both native and non-native to the Colorado River drainage (fig. 5-1). The diversity of species within these lakes continues to change with time due to changing habitat conditions, the invasion of non-native species, and extirpations of native species. From the bottom of the food web to the top predators, all organisms within the ecosystem are interconnected in food webs or food-chain networks. As non-native invasive species continue to be introduced into the lakes, alterations to the food web, species competition, and species predation likely will continue to change the ecosystem and populations of native organisms. Following an overview of the food web, this chapter summarizes information on aquatic and aquatic-dependent wildlife at Lakes Mead and Mohave and their relationships within the food web from members of lower trophic levels to the highest: phytoplankton, invertebrates, including zooplankton, and macroinvertebrates; fishes; and birds. The following sections describe the biological diversity, limiting factors, and ecological functions of these groups in Lake Mead, and to a lesser extent, in Lake Mohave.

Circular↗

USGS2012

Threats and stressors to the health of the ecosystems of Lakes Mead and Mohave: Chapter 6 in A synthesis of aquatic science for management of Lakes Mead and Mohave

Ecosystem impacts from visitor activities or natural environmental change are important concerns in all units of the National Park system. Possible impacts to aquatic ecosystems at Lake Mead National Recreation Area (LMNRA) are of particular concern because of the designation of Lakes Mead and Mohave as critical habitat for the federally listed endangered razorback sucker (Xyrauchen texanus), the significance of the sport fishery, and the regional importance of its habitats to more than 90 documented species of waterbirds. Potential threats to shoreline habitats are of concern not only for their ecosystem values but also for maintaining the recreational setting. Many areas adjacent to the shorelines of Lakes Mead and Mohave are designated wilderness areas. For purposes of this document, stressors are any chemical, biological, or physical agent that has a detrimental effect on aquatic ecosystems at the organism, population, or community level. Human-made stressors at Lakes Mead and Mohave include direct effects of recreation on the lakes, like boating and fishing, as well as indirect effects of activities away from the lakes, such as growing population and increasing urbanization. Common natural environmental stressors include extended changes in climate (precipitation or temperature), or the erosion, transport, and loading of chemical constituents in rocks and sediments to aquatic environments. Human activity also can exacerbate natural stressors in a variety of ways.

Circular↗

USGS2012

Management implications of the science: Chapter 7 in A synthesis of aquatic science for management of Lakes Mead and Mohave

Lake Mead, particularly its Boulder Basin, is one of the most intensively monitored reservoirs in the United States. With its importance to societal needs and ecosystem benefits, interest in water quality and water resources of Lake Mead will remain high. A number of agencies have authorities and management interests in Lake Mead and maintain individual agency monitoring programs. These programs were enhanced on an interagency basis from 2004 to 2012 to facilitate intensive monitoring in all major basins of the lake. Recognition that increasing stressors and influences in individual basins can affect water quality throughout Lake Mead and gave rise to an even stronger effort towards the development of holistic and effective interagency approaches. In 2010, agency monitoring programs were used to develop a management plan for water-dependent resources at Lake Mead National Recreation Area (LMNRA). The Long-Term Limnological and Aquatic Resource Monitoring and Research Plan for Lakes Mead and Mohave (the Plan; National Park Service, 2010) documented key management questions to be addressed through monitoring and research, and identified interagency strategic objectives for water quality and water-dependent resources. Moreover, the Plan provides a framework for summarizing water quality and water resource information in five resource categories: water quality and limnology; fish and aquatic biota; sediments; birds; and riparian vegetation. The Plan also addresses three stressors to lake resources: contaminants, invasive species, and climate change. For each of these topics, the current (2012) state of knowledge is summarized for LMNRA (table 7-1), including key scientific questions and findings, management implications, and information needs. A more detailed discussion for each topic follows.

Circular↗

USGS1996

Geohydrologic reconnaissance of Lake Mead National Recreation Area: Las Vegas Wash to Virgin River, Nevada

This study is the last of a series of eight geohydrologic reconnaissance studies that were done in the Lake Mead National Recreation Area. The studies were done to evaluate the water resources in the recreation area and to identify areas having potential for the development of water supplies that would be adequate for marinas and campgrounds. The study area includes about 250 square miles north of Lake Mead from Las Vegas Wash to the Virgin River (Overton Arm), Nevada. Volcanic rocks, consolidated sedimentary rocks, and unconsolidated to semiconsolidated sedimentary rocks underlie the area. Surface-water sources include the Colorado River, Virgin River, Muddy River, and Las Vegas Wash. Elsewhere in the area, streamflow is meager and extremely variable. Ground water originates from four sources: (1) subsurface flow in local basins, (2) infiltration of water from Lake Mead into permeable rocks near the lake, (3) subsurface flow in valleys of perennial streams, and (4) subsurface flow in consolidated rocks of the Muddy Mountains. The quantity of water from Lake Mead that has saturated rocks adjacent to the lake probably is greater than the quantity of ground water from all the other sources. Rocks saturated by water from the lake probably extend less than 0.5 mile inland from the lake shore. The quality of virtually all the ground water in the area is not acceptable for drinking purposes. The most favorable areas for obtaining ground water are those underlain by the coarse-grained deposits of the older alluvium and the younger alluvium adjacent to Lake Mead. The least favorable areas are those underlain by the mudstone facies of the Muddy Creek Formation and fine-grained rocks of the Horse Spring Formation. Four areas identified as having potential for ground-water development are (1) near Overton Beach, (2) west of Callville Bay, (3) near Middle Point, and (4) in the lower Moapa Valley. Usable quantities of water probably can be obtained at these sites, but the quality of the water may not be acceptable for drinking purposes. Test drilling for potable water supplies should be considered only as exploration.

Nevada↗

USGS1981

Geohydrologic reconnaissance of Lake Mead National Recreation Area: Las Vegas Wash to Opal Mountain, Nevada

The study is a geohydrologic reconnaissance of about 170 square miles in the Lake Mead National Recreation Area from Las Vegas Wash to Opal Mountain, Nevada. The study is one of a series that describes the geohydrology of the recreation area and that indentifies areas where water supplies can be developed. Precipitation in this arid area is about 5 inches per year. Streamflow is seasonal and extremely variable except for that in the Colorado River, which adjoins the area. Pan evaporation is more than 20 times greater than precipitation; therefore, regional ground-water supplies are meager except near the Colorado River, Lake Mead, and Lake Mohave. Large ground-water supplies can be developed near the river and lakes, and much smaller supplies may be obtained in a few favorable locations farther from the river and lakes. Ground water in most of the areas probably contains more than 1,000 milligrams per liter of dissolved solids, but water that contains less than 1,000 milligrams per liter of dissolved solids can be obtained within about 1 mile of the lakes. Crystalline rocks of metamorphic, intrusive and volcanic origin crop out in the area. These rocks are overlain by conglomerate and mudstone of the Muddy Creek Formation, gravel and conglomerate of the older alluvium, and sand and gravel of the Chemehuevi Formation and younger alluvium. The crystalline rocks, where sufficiently fractured, yield water to springs and would yield small amounts of water to favorably located wells. The poorly cemented and more permeable beds of the older alluvium, Chemehuevi Formation, and younger alluvium are the better potential aquifers, particularly along the Colorado River and Lakes Mead and Mohave. Thermal springs in the gorge of the Colorado River south of Hoover Dam discharge at least 2,580 acre-feet per year of water from the volcanic rocks and metamorphic and plutonic rocks. The discharge is much greater than could be infiltrated in the drainage basin above the springs. Transbasin movement of ground water probably occurs , and perhaps the larger part of the spring discharge is underflow from Eldorado Valley. The more favorable sites for ground-water development are along the shores of Lakes Mead and Mohave and are the Fire Mountain, Opal Mountain to Aztec Wash, and Hemenway Wash sites. Wells yielding several hundred gallons per minute of water of acceptable chemical quality can be developed at these sites.

Nevada↗

USGS1980

Landsat wildland mapping accuracy

A Landsat-aided classification of ten wildland resource classes was developed for the Shivwits Plateau region of the Lake Mead National Recreation Area. Single stage cluster sampling (without replacement) was used to verify the accuracy of each class.

Arizona↗

USGS1977

Geohydrologic reconnaissance of Lake Mead National Recreation Area; Temple Bar to Grand Wash Cliffs, Arizona

The study is one of a series of geohydrologic reconnaissance studies being made in the Lake Mead National Recreation Area and covers about 200 square miles (520 square kilometers) from Temple Bar to the Grand Wash Cliffs. Streamflow in the drainages tributary to Lake Mead is meager and extremely variable. Ground water is derived from two principal sources: (1) infiltration into permeable rocks near Lake Mead and (2) ground-water underflow in the basins that drain to the lake. The volume of ground water derived from Lake Mead is much greater than that derived from the basins. In terms of potential groundwater development the rocks saturated by lake water probably extend less than 1 mile (1.6 kilometers) from the lake, whereas the basins that contribute underflow to the lake are of much larger areal extent. The most favorable sites for ground-water development are Grapevine Mesa, Sandy Point, Hualapai Wash, and the area near and south of Temple Bar; the permeable rocks include the conglomerate facies of the Muddy Creek Formation, the older alluvium, and the Chemehuevi Formation. The least favorable areas for ground-water development are those underlain by the mudstone facies of the Muddy Creek Formation. Seven sites are recommended for future ground-water development. Five sites are within 1 mile (1.6 kilometers) of Lake Mead and two sites are between 3 and 5 miles (5 and 8 kilometers) from the lake. The ground water contains less than 1, 500 milligrams per liter of dissolved solids in most of the area. Ground water on Grapevine Mesa contains less than 500 milligrams per liter of dissolved solids, and that from springs in the metamorphic and plutonic rocks contains more than 1, 500 milligrams per liter of dissolved solids.

Arizona↗