Great Basin Water: Polluted Or Pristine?

The Great Basin is the largest area of contiguous endorheic watersheds in North America, meaning it has no outlets to the ocean. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California. The region is defined by its dramatic geography, wildlife, plant life, culture, industry, travel, and ways of life, which are all influenced by the unique hydrographic nature of the landform. The Great Basin's water situation is complex, with river systems, lakes, and basins all playing a role in the region's hydrology. So, how polluted is the water in this vast and diverse area?

The Great Basin's water never reaches the ocean

The Great Basin is the largest area of contiguous endorheic watersheds in North America, meaning it is a region with no outlets to the ocean. The region is bounded by the Wasatch Mountains to the east, the Sierra Nevada and Cascade Ranges to the west, and the Snake River Basin to the north. The Great Basin includes most of Nevada, half of Utah, and substantial portions of Oregon, California, and small areas of Idaho, Wyoming, and Baja California, Mexico.

The hydrographic nature of the Great Basin has been described as "having no connection to the ocean". This definition is the most commonly used and is the only one with a definitive border. The Great Basin is characterised by its arid climate and basin and range topography, with elevations ranging from the North American low point at Badwater Basin in Death Valley to the highest point of the contiguous United States at Mount Whitney.

The Great Basin's longest and largest river is the Bear River, which stretches for approximately 350 miles (560 km). Most of the precipitation in the region is in the form of snow, and the water that neither evaporates nor is extracted for human use sinks into groundwater aquifers. Lake Tahoe, North America's largest alpine lake, is part of the Great Basin's central Lahontan subregion.

The Great Basin is home to diverse flora and fauna, with the types of plants and animals varying depending on the elevation. For example, Utah juniper and single-leaf pinyon are found in the southern regions, while mountain mahogany is more common in the northern regions. The World Wildlife Fund has designated the mountains of the Great Basin desert as their own ecoregion, known as the Great Basin montane forests, due to the unique forest ecosystem found there.

The Great Basin's water eventually evaporates or seeps into the ground

The Great Basin is the largest area of contiguous endorheic watersheds in North America. Endorheic refers to a body of water with no outlets to the ocean, meaning that any water in the Great Basin will either evaporate or sink into the ground.

The Great Basin is bounded by the Wasatch Mountains to the east, the Sierra Nevada and Cascade Ranges to the west, and the Snake River Basin to the north. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California. The region includes several deserts, such as the Mojave and Colorado Deserts, and the Great Basin Desert.

Most of the precipitation in the Great Basin is in the form of snow. The water that doesn't evaporate or get extracted for human use will sink into groundwater aquifers. As water flows through the basin, it can form tributaries that change the structure of the land. The soil type will determine how much water reaches the river, with sandy soils being more permeable and clay soils causing more runoff.

The Great Basin is also a drainage basin, which is an area of land where all flowing surface water converges to a single point, such as a river mouth or another body of water. Drainage basins are important in ecology because they can pick up nutrients, sediment, and pollutants, which are then transported to the outlet of the basin, affecting the ecological processes along the way. In endorheic bodies of water, like the Great Basin, evaporation is the primary means of water loss, and the water is typically more saline than the oceans.

The Great Basin's water flows into salty basins and lakes

The Great Basin is a vast region in the United States that includes most of Nevada, half of Utah, and substantial portions of Oregon, California, and small areas of Idaho, Wyoming, and Baja California in Mexico. The region is characterised by its unique hydrological characteristics, where water flows into salty basins and lakes.

The Great Basin is bounded by the Wasatch Mountains to the east, the Sierra Nevada and Cascade Ranges to the west, and the Snake River Basin to the north. The region is known for its aridity, with most areas experiencing a semi-arid or arid climate. The western areas of the basin tend to be drier due to the rain shadow of the Sierra Nevada.

The term "Great Basin" is slightly misleading as the region comprises many small basins. These basins collect water from precipitation, which either evaporates or sinks underground, and eventually flows into lakes that are mostly saline. The Great Salt Lake, Pyramid Lake, and the Humboldt Sink are some of the "drains" in the Great Basin. The Great Salt Lake, for example, is all that remains of the ancient Lake Bonneville, which formed about 32,000 years ago.

The Great Basin's water flows can have different fates depending on where they fall. For instance, on the eastern side of the Great Basin, the water flows eastward down the mountain, turns south at the confluence of the Green River, joins the mighty Colorado River, and eventually makes its way to the Sea of Cortez. In contrast, on the western side, water travels west, meandering between desert ranges, and eventually drains into the ground or evaporates from the surface of a salty desert hardpan.

The Great Basin has been the site of exploration and settlement by various European and American expeditions throughout the 18th and 19th centuries. The first non-indigenous settlement was in 1847 in the Great Salt Lake Valley, leading to the Mormon provisional State of Deseret in 1849. The region is also traversed by several rail lines and interstate highways, including Interstate 80 (I-80) and I-15.

The Great Basin's water is snow, which sinks into groundwater aquifers

The Great Basin is the largest area of contiguous endorheic watersheds in North America, spanning nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California. The region is characterised by its arid climate and basin and range topography. The Great Basin's water comes primarily from snow, which plays a crucial role in recharging the groundwater aquifers that supply the region's water needs.

As snow accumulates in the mountains and higher elevations of the Great Basin, it eventually melts during warmer periods. This meltwater then seeps into the ground, replenishing the underlying groundwater aquifers. The process by which water sinks into the soil or surface rock to become groundwater is known as recharge. Recharge areas are essential for sustaining groundwater basins, and the identification and protection of these areas are critical for water resource management.

The rate at which snow melts and the subsequent recharge of groundwater aquifers depend on various factors, including temperature and elevation and the permeability of the materials the water flows through. In the Great Basin, the climate and flora vary with elevation, with increasing precipitation and decreasing temperature at higher elevations. This unique relationship between elevation and climate influences the distribution of vegetation and the behaviour of water sources.

Groundwater movement from recharge areas to discharge areas, where it exits the aquifer, is influenced by the hydraulic gradient (slope) and the cross-sectional area of the aquifer. Natural discharge occurs primarily at springs and through seepage into stream channels, wetlands, and seasonal lakes, particularly in arid regions. Human activities, such as pumping groundwater from wells, can also contribute significantly to discharge rates.

The Great Basin's water supply is crucial for the region's ecology and the various species that inhabit it. The area is home to numerous rare and endemic species due to the isolation of the individual mountain ranges within the Great Basin desert. The health of these ecosystems and the biodiversity they support are closely tied to the availability and quality of water provided by the groundwater aquifers.

The Great Basin's water is influenced by its elevation and climate

The Great Basin, spanning nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California, is the largest contiguous endorheic watershed region in North America. Its water is influenced by a unique interplay of elevation and climate.

The Great Basin's climate is predominantly arid, with a basin and range topography. The region experiences a substantial diurnal temperature variation due to its high altitude and aridity. While the Great Basin has a temperate climate, with dry and hot summers and snowy, cold winters, its higher elevations exhibit unique characteristics. These higher areas, including some mountainous regions, tend to be cooler and receive more precipitation. Notably, freezing temperatures and snowfall can occur at any time of the year in these elevated regions.

The western areas of the Great Basin are typically drier than the eastern parts due to the rain shadow effect of the Sierra Nevada mountains. This rain shadow effect also influences the overall aridity of the Great Basin, contributing to its semi-arid or arid conditions. The region's climate is further characterised by moderate amounts of rainfall and/or snowfall throughout the year, setting it apart from hot deserts, which are typically associated with minimal precipitation.

The Great Basin encompasses multiple ecoregions, including both hot and cold deserts. The hot deserts, such as portions of the Mojave and Colorado Deserts, feature distinctive flora like the Joshua tree and creosote bush. In contrast, the cold deserts, generally located at higher elevations, have a more even spread of precipitation throughout the year. This elevation-driven variation in climate and vegetation leads to a diverse array of habitats and ecological boundaries within the Great Basin.

The elevation and climate of the Great Basin also influence the distribution of wildlife. For example, forests are more commonly found at higher elevations, with species such as Utah juniper, single-leaf pinyon, and mountain mahogany forming open pinyon-juniper woodlands on the slopes. The Great Basin's mountains, isolated from each other, constitute their own ecoregion, the Great Basin montane forests, harbouring many rare and endemic species.

Frequently asked questions