Nevada

C

Rivers, Lakes, and Reservoirs

Two areas in Nevada do have drainage to the sea. In the northeast, Salmon Falls Creek, the Bruneau River, the East and South forks of the Owyhee River, and the Little Owyhee River drain into the Snake River and reach the Pacific Ocean through the Columbia River. The Muddy River, Meadow Valley Wash, and the Virgin River run into Lake Mead on the Colorado River, which drains into the Gulf of California.

The principal rivers of Nevada are the Humboldt, Truckee, Carson, Walker, Owyhee, and Colorado. The Humboldt River, Nevada’s longest, is located entirely within the state. It begins in the desert ranges of the northeast and flows west from one basin to another until it finally ends in Humboldt Sink. The flow of this river constitutes about one-fifth of the state’s water runoff.

The Truckee, Carson, and Walker rivers flow out of the Sierra Nevada, thread their way around several of the desert ranges, and also end in closed basins. Because these three streams flow constantly, the lakes into which they empty never dry up. The Colorado River is Nevada’s most voluminous river. However, because of its position along the state’s southern boundary and the fact that its waters are shared by several states, the river has not been of primary importance to Nevada until recently. Today, the Colorado provides nearly all the water supply for Las Vegas and nearby communities. Lake Mead, a vast reservoir, was created by damming the Colorado River near Las Vegas, along the Nevada-Arizona Border (see Hoover Dam).

Nevada’s other permanent lakes include Washoe Lake, a few tiny lakes in the higher mountains, and Lake Tahoe. Lake Tahoe is located along the state boundary with California, at 1,897 m (6,225 ft) above sea level, in the Sierra Nevada.

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Thousands of years ago a large lake called Lake Lahontan covered a substantial area in northwestern Nevada. The level of its waters stood as high as 160 m (530 ft) above the present level of Pyramid Lake, as shown by wave-cut terraces on the mountainsides. Walker, Carson, and other lakes are mere remnants of the former lake. Black Rock Desert and Smoke Creek Desert were also once occupied by the lake.

D

Climate

Nevada has an arid climate and receives less precipitation than any other state. Skies are clear, sunshine is abundant, and relative humidity is low. There are wide ranges of temperature between day and night throughout Nevada because the clear dry air permits both the rapid gain of heat in the day and its rapid loss after dark. The climate pattern, however, is complicated by differences in elevation. Mountainous areas are far damper and cooler than low-lying areas.

D

1

Temperature

Mean annual temperatures vary greatly within Nevada because of the comparatively long distance from north to south within the state. In the south, summers are extremely hot and winters are short and mild. The average July temperature at Las Vegas is 32°C (90°F), and the highest temperature ever recorded there was 48°C (118°F). Las Vegas’ January average high temperature is in the lower 10°s C (lower 50°s F), and average lows are near freezing. The growing season, the period from the last killing frost in spring to the first in fall, in this area averages more than 230 days per year.

In the northeast, winters are long and cold and summers short and hot. San Jacinto’s average temperature in January is -4°C (24°F), but it has recorded readings as low as -46°C (-50°F) in the winter. The July average at San Jacinto is 19°C (66°F), and the average growing season is about 80 days per year. Reno, in the west-central part of the state, has mean temperatures that fall between the averages at San Jacinto and Las Vegas. The growing season is about 155 days. Night-to-day temperature changes are sharp throughout Nevada because the clear dry air permits both the rapid gain of heat in the day and its rapid loss after dark.

D

2

Precipitation

Most of the precipitation comes in winter, and in the mountains much of it is snow. Summer rainfall is generally slight. However, heavy thunderstorms occasionally occur, bringing cloudbursts that in a few minutes drench an area with as much rain as would normally fall over a period of several months.

Precipitation over the state as a whole averages less than 230 mm (9 in) annually. It is lowest in west central and southern Nevada, where the average drops to less than 100 mm (4 in) a year in some localities. Mountain areas above 1,800 to 2,100 m (6,000 to 7,000 ft) receive more than 380 mm (15 in) of precipitation annually. The greatest annual precipitation, 690 mm (27 in), occurs at Marlette Lake, on the lee slope of the Sierra Nevada.

The scarcity of precipitation in Nevada is due largely to the state’s location on the eastern side of the Sierra Nevada, which is a barrier to moisture-laden air. Nevada is said to lie in the rain shadow of the Sierra Nevada. As warm, moisture-laden air from the Pacific Ocean moves eastward and rises against the Sierra Nevada, it cools, and most of its moisture falls on the western slopes in California. Major storms may cross the Sierra, however, and some summer storms come from the Gulf of California up the east side of the Sierra. They occasionally produce large rainfalls.

E

Soils

For the most part the soils of Nevada are so-called gray desert soils, developed from material washed down into the valleys from the mountains. Where the desert vegetation is thin, the ground often has a layer of gravel and small stones, called desert pavement. However, in the low areas of the basins and along the rivers there are narrow belts of alluvial soils that are of finer texture. The better of these soils, such as Fallon fine sandy loam, are farmed successfully under irrigation. Others, such as Lahontan silty clay loam, are too salty to be used for agriculture, although they produce brush and grass suitable for grazing. In southern Nevada the soils are pinkish in color and are known as red desert soils. The mountains contain much rough and stony land without soil covering. Almost all Nevada soils are low in nitrogen and organic matter.

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