The water crisis in the American Southwest – Watt?

Guest post by Kip Hansen — December 28, 2024 — 1800 words — many images

The reservoir is simple. They can be thought of as a rain barrel, with a spout providing water inlet (such as from the roof), a spigot near the bottom of the barrel for extracting water from the barrel, and some overflow device.

Great Salt Lake – a model

One of the iconic geographical features of the American West is the Great Salt Lake (GSL). Now the GSL is not a reservoir, but it can teach us lessons about reservoirs in the American Southwest.

A recent letter from a subscriber to The Salt Lake Tribune rightly accused the newspaper and Utah Public Radio of misrepresenting GSL's plight in a recent three-part series. Reader Maria Archibald wrote succinctly:

“…Snowpack (or lack thereof) is not even the primary cause of lake decline. Sedimentation cannot solve problems that it did not cause, and to assert otherwise would be both incorrect and dangerous. Of course, additional snow [winter 2022 and 2023] Provided temporary respite for the Great Salt Lake and may have delayed its collapse by a few years, but humans continue to consume one million acre feet more than our water systems can sustain…”

Archibald was absolutely right. Weather affecting precipitation (primarily snowpack in the GSL) is not the reason why lake levels are low, get lower, or stay low. When I wrote about this issue last year, I found the same thing to be true. I recommend Andy May’s recent article on drought in the greater Southwest to answer this question.

For the Great Salt Lake, only inflow and evaporation (This is outflow). The amount of water in a lake at any one time (measured by its surface level) depends almost entirely on how much water is allowed into the lake. Evaporation varies with weather (mainly temperature) but is not a controllable variable. In our GSL bucket example, water is directed from downspouts—all streams and rivers that naturally flow into the GSL—for human use for drinking water and agricultural irrigation. These uses divert 2.1 million acre feet (MAF) of water per year that would otherwise enter the lake, leaving the lake with a water deficit (overall loss) of 1.2 million acre feet per year. As a result, the lake cannot be restored to the size that conservationists and environmentalists had hoped [pdf].

notes: That deficitin words, that is Thirty-nine billion one hundred and thirty thousand gallons of water.

To many, water in the Southwest means the Colorado River system

Two weeks ago, I wrote an article about the water crisis in the Northeastern United States, including New York City and Philadelphia. Today I want to discuss the region most associated with water scarcity in the eyes of most citizens and the mainstream media—the Great Southwest.

This region of the United States is generally arid, with nearly all areas considered by most people to be deserts (although not strictly so in Köppen's classification).

[ click here for full sized continental image ]

Yellow, beige, and brown are arid areas…purple is snow-covered mountains in winter. The green areas of Arizona and Southern California are warm temperate climate types with hot dry/warm summers – they are not the lush green areas that the color suggests. These are climate types – the same for hundreds or even thousands of years.

Typically, arid areas are sparsely populated, and residents must grow crops and graze livestock. Agriculture and livestock farming also require water. Less water = less food. But sometimes things don't work that way. As the map shows, the true desert Southwest is home to one of the fastest-growing populations in the country. As civilization advanced, humans found ways to survive in challenging environments—even the American Southwest.

Added to this image, the Los Angeles/San Diego metropolitan area occupies the entire coast west of the desert (shown in blue on the California map). Today, the Los Angeles/South Dakota metropolitan population is approximately 23 million people. Los Angeles is partially supplied by the Colorado River.

Where did these people get their water from? “The mighty Colorado River serves 40 million people in seven states and two Mexican states. It also irrigates 5.5 million acres of agricultural land, including 15 percent of U.S. agriculture and about 90 percent of the country's winter vegetables. These 40 million people 12% of the U.S. population.

So, as is the case in the Northeastern United States, some precipitation (such as rain or snow) is stored in reservoirs and slowly supplied to consumers.

So, what’s all the fuss about?

Lake Mead, formed by Hoover Dam, is the primary reservoir for Colorado River water and can be used to determine the amount of water available in the Southwest. Water levels have been falling for nearly 25 years, since the turn of the century. Officially in “shortage situation 2” – well below drought conditions. As we'll see in the image below, at the top of the system, the main reservoir is Lake Powell, located behind Glen Canyon Dam. Powell feeds Lake Mead.

Here are the historical inflows to Lake Powell:

There are up years and there are down years – the last three years were the trough, followed by strong growth in 2023, and this year, with a month to go, is slightly below average.

Note the difference between the top of the barrel inflow and the water level in the barrel (Lake Mead).

The flow out of Lake Powell at Lee's Ferry (considered the inflow to Lake Mead) looks like this:

Let's take a look at the entire system:

Here we have a map of the Colorado River Basin…both delineated on the east by the Continental Divide. For our purposes—the water crisis in the southwestern United States—the most important parts are the Upper and Lower Basin above Yuma, Arizona. Let’s take a look at the reservoir:

The four lakes, named for their relative importance, provide water to 40 million people – their homes, businesses, crops and livestock.

As we found with reservoirs northeast of New York City, some supply inflow water to downstream reservoirs. Here we see that the North Branch of the Colorado River, the Green River, and the San Juan River (and their tributaries) all have dams that divert some of the water and send the rest ultimately downstream to Lake Powell, which itself will Water is transported through the Grand Canyon area to Lake Mead to feed Lake Mohave, which in turn feeds Lake Havasu and its southern portion.

Northwest Utah lies outside the Colorado River Basin and is the watershed of the Great Salt Lake.

In southern Arizona, the Salt and Gila rivers flow north of Yuma, feeding the All-American Canal, which in turn supplies the Imperial Valley's fertile farmland, whose runoff flows into the Salton Sea. Recently, water conservation efforts in the Imperial Valley have limited runoff that threatens the existence of the Salton Sea.

This map shows the mighty Colorado River flowing happily into the Gulf of California. That is, neither good nor bad is true. Google Earth reveals:

The USGS describes the area seen in the satellite photo above:

“…This NASA Earth Observatory satellite photo from September 2000 shows that irrigation and urban water demands now prevent the river from reaching its final destination. Instead, the Colorado River simply disappears into the desert. …The river is in the northwest corner of the image Colorful farmland ends to the south and then fans out at the foothills of the Juárez Mountains. Only about 10% of the water that flows into the Colorado River reaches Mexico, and most of it is used by the Mexican people for agriculture.

The thin gray line in the photo is the official boundary formed by the Colorado River (if there is water in it).

Bottom line:

1. The American Southwest is a generally dry region. Unsuitable for dense populations and lacking the technology needed to store and transport large quantities of clean fresh water for drinking and agriculture.

2. Between 1910 and 1970, the U.S. federal government built most of the major dams and aqueducts on the Colorado River. [and the Rio Grande] It is now considered one of the most controlled and litigated river systems in the world. Since 1960, the area's population has tripled.

3. Too many people – not enough water. This simple fact is well known to all levels of government in the South West – there are numerous committees, treaties and agreements – none of which create more water but only allocate the available water slightly differently to each new demand.

4. Despite the lack of new water sources, towns and cities in the Southwest continue to grow, with thousands of new homes being built and businesses moving into the region. Some cities, such as Phoenix, have begun denying building permits for housing developments that do not have adequate pre-planned water sources.

5. Farther north, in California, the Sacramento River, which flows into the Pacific Ocean via San Francisco Bay, is also drying up due to the demands of central California cities. In wet years, the opposite happens—too much water flows through the delta into the bay.

6. The suggestion that the water crisis in the American Southwest is due to “climate change” is simply false – the climate there has not experienced any noticeable or significant changes – and it has been dry for a long time now. The weather has become drier.

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Author comments:

I grew up in Los Angeles, Southern California. Dry, hot summers with occasional storms now known as atmospheric rivers wash down the houses from the steep hillsides. In college, I worked as a volunteer with hundreds of other students fighting floods and mudslides. Southern California politics have often been overwhelmed by the California water wars.

Just recently, California began moving forward with construction of a new reservoir, the Settles Reservoir, the first in decades – possibly decades too late – but was met with controversy by various so-called conservation and environmental groups active opposition.

There is no shortage of water on Earth, but there is not always enough fresh water where it is needed or wanted.

Thank you for reading.

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