Colorado River: The River That Built the American West

Podcast Transcript

Over 1,400 miles, the Colorado River has carved some of the most dramatic landscapes on Earth and enabled life across the American Southwest.

It shaped canyons, powered cities, irrigated farms, and became the center of one of the most important water disputes in modern history.

From the Rocky Mountains to the Gulf of California, the Colorado has shaped almost every aspect of society for everyone who uses it.

Learn more about the Colorado River on this episode of Everything Everywhere Daily.

There are few places on Earth as impressive as the geologic formations created by the Colorado River and its drainage basin. The Grand Staircase of the Lower Colorado Plateau is home to Zion, Bryce Canyon, Canyonlands, Capital Reef, and Arches National Parks.

A bit further downstream, you’ll find the majestic Grand Canyon.

Geological evidence suggests that shifting tectonic plates triggered geologic uplift approximately 70 million years ago, elevating the Colorado Plateau.

This uplift allowed rivers, including the Colorado and Virgin, to cut through the sedimentary rocks, forming the canyons that have come to define the region.

The rivers were well fed by summer rains, as the intense heat limits vegetation and the rocky, dry ground limits absorption, allowing rainfall to cascade down into the rivers.

Surprisingly, the region is also home to monsoonal rainfall. The North American Monsoon, also known as the Southwest monsoon, is a seasonal weather pattern that occurs when intense summer heat pulls moisture from the ocean into the desert, triggering sudden, strong afternoon thunderstorms across the Colorado Plateau.

Although these heavy rains matter to the Colorado River, nearly 90% of its water actually comes from spring snowmelt in the Rocky Mountains, reinforcing the River’s dependence on mountain sources.

The Colorado River erodes the surrounding rock as it falls more than 12,000 feet from its source, acting like a fast-moving mix of sediment that carves through the Colorado Plateau.

Rio Colorado was chosen as the name for the lower river between Lee’s Ferry, Arizona, and the border of Mexico, because it means “reddish” in Spanish.

Colorado was a perfect name for the river, chosen by the Spanish explorers, who saw the reddish hue of iron oxide in the surrounding landscape and in its muddy water. North of the Grand Canyon, however, it was called the Grand River.

The entire river wasn’t called the Colorado River until 1921, when Edward Taylor, a Colorado Congressman, convinced Congress to use one name for the entire river.

Today, the name Colorado seems odd, given its color is now a deep blue-green. Dam construction removed most of the river’s sediment and eliminated the reddish tint seen by early explorers.

Beyond its physical presence, the Colorado River continues to shape the American Southwest in ways that cannot be overstated.

Arguably, the greatest contribution of the Colorado River has been to the millions of people who live along its basin.

Today, the river and its tributaries provide water to more than 30 million people. The river also supports major metropolitan areas, such as Denver, Los Angeles, Phoenix, Salt Lake City, and Las Vegas.

Although the river supports major metropolitan areas, municipal use is relatively small compared to the almost 3 million acres of farmland which use nearly 80% of the river’s yearly flow.

The Colorado River and the people who rely on it in the Southwest have a problem. A really big problem. A megadrought over the past 25 years has caused water scarcity never seen before.

Tree-ring data from the past 800 years show this is the driest period ever recorded.

The two main reservoirs, Lake Powell and Lake Mead, are losing water at a critical rate. Lake Powell is now at 23% capacity, while Lake Mead is at 31%. Those visiting either reservoir will notice a remarkable sight: a prominent “bathtub ring” carved into the cliffs and rock formations along the shore caused by lower water levels.

Given the river’s essential role, its widespread use has led to numerous arrangements and covenants governing its distribution, setting the stage for ongoing legal conflicts.

The complicated system controlling the river’s use is called the “Law of the River”. This complex set of compacts, regional water traditions, decrees, regulations, and court cases has led to so much water being taken from the Colorado River that it no longer reaches the Gulf of California.

The earliest attempt to regulate the river’s use was the Colorado River Compact of 1922. Negotiated by the seven states that share the Colorado River Basin, the compact defined the relationship between the upper- and lower-basin states.

Water usage presents a complicated problem: the upper basin is where the water originates, while the lower basin has greater water needs, which is the root of the ongoing debate over allocation.

The upper basin states were also concerned that their use of the water would be limited by the planned construction of several prominent dams, foremost among them, the Hoover Dam.

Unable to reach an agreement in the negotiations, the Secretary of Commerce and the dam’s namesake, Herbert Hoover, was tasked with brokering peace.

Hoover’s solution was to formally partition the region into an upper basin and a lower basin and to allow each section to use 7.5 million acre-feet of river water annually.

The compact encountered difficulties, creating a byzantine structure that governed the divide between the upper-basin states of Colorado, Utah, New Mexico, and Wyoming and the lower-basin states of Arizona, California, and Nevada.

A complex framework of principles and assumptions governs the water distribution and the division between the two basins. Flow patterns from the early 20th century established many of the primary benchmarks for water usage on the Colorado River.

This last piece is crucial to the story

The period when the compact was developed, the first quarter of the 20th century, was notably among the wettest on record. This historical rainfall is completely different from the megadrought that has characterized the past quarter-century.

According to the Rockies Project Research Team, which has been studying the water issue on the Colorado: The Colorado River Compact of 1922, which set the annual average as 15.0 million acre-feet and divided this amount up between the basin states, was created during the wettest recorded ten-year period of the last 100 years. This was from 1914 to 1923, in which the annual average was 18.8 million acre-feet.

The 18 million acre-feet per year meant the water originally scheduled to be taken from the basin was less than the amount replenishing it.

Over the last 10 years, however, the basin has averaged approximately 13 million acre-feet per year of rainfall, so the water taken from the basin has put the river in deficit.

Another problem is that the lower basin may increase its allocation when agricultural and industrial needs arise. This made conflict inevitable, as the lower basin contains a far greater share of nearly every quantifiable data point than the upper basin.

The lower basin states hold a 3:1 population advantage and a 3:1 advantage in nearly every agricultural, industrial, and economic factor. The lower division was always going to be able to claim more than its 50/50 split.

Adding to the turmoil were provisions guaranteeing water deliveries regardless of weather conditions.

This arrangement puts the upper basin states in a bind, as the flow begins there, and they have often found themselves more aggressively restricting water flows than their lower-basin counterparts.

Since 2015, the upper-basin states have averaged 4.5 million acre-feet of water per year, while the lower-basin states continue to use their full allocations.

Complicating the situation was a provision that Mexico would be added to the compact and would also get a significant share of the water. An amendment to the deal in 1944, granted Mexico an additional 1.5 million acre-feet of water per year.

Mexico currently gets next to nothing because most of the water is gone by the time it reaches the border.

In 1928, the Federal Government passed the Boulder Canyon Act, which authorized funding for the construction of the Hoover Dam near Las Vegas. One of the primary challengers to the various water agreements has been California.

California is the largest single user of the Colorado River, despite flowing adjacent to California only as its border with Arizona, a distance of 1/8 of the river’s overall length.

California’s oversized withdrawals from the river are largely used for agriculture in Southern California, with approximately 80% of the total allocation providing irrigation water for the Imperial Valley.

Nowhere is this situation more confusing and problematic than among the indigenous communities that live along the basin. Among the 34 established reservations that rely on the system, all have implied water rights, but the system is rife with conflicts between reservations and tribes over water use.

Some reservations expected a water increase under an agreement reached with federal officials, only to learn that an adjacent agreement with a different group nullified it.

The incentives for agriculture in the region are also counterproductive to conserving water. They created a powerful incentive to use as much water as possible. In many western states, if farmers did not fully use their allocated water, they risked losing part of their claim under the principle of “use it or lose it.”

As a result, conserving water could actually work against a farmer’s long-term interests. Many agricultural users continued flood irrigation or grew extremely water-intensive crops such as alfalfa, cotton, and hay in desert regions because maintaining high water consumption protected their valuable legal rights.

Because water prices for many irrigation districts are heavily subsidized and disconnected from actual scarcity, there has historically been little financial pressure to modernize irrigation systems or switch crops. In some areas, water is effectively more valuable than the crops themselves.

As previously mentioned, the state of the Colorado River is most visible at the two major reservoirs. When full, they can hold approximately 25 million acre-feet of water.

The conditions in the two reservoirs are nothing short of concerning. Limited snowpack in the upper basin has placed the reservoir system in crisis.

According to Shannon Mullane, who covers water rights for the Colorado Sun, the challenges to the reservoirs extend far beyond water volume, as she notes: If the water level at Lake Powell falls too low, it can endanger critical infrastructure in the dam and stop hydroelectric power generation, which helps supply communities across the West with affordable, renewable energy.

The core problem with water rights on the Colorado River is that the legal system governing the river was created during an unusually wet period in the early 20th century, when policymakers dramatically overestimated how much water the river could reliably provide.

The agreements that followed, especially the 1922 Colorado River Compact, divided up more water than the river normally produces in most years.

Few rivers have been studied, dammed, diverted, and argued over more than the Colorado. Even so, it continues to sustain tens of millions of people and shape some of the most remarkable landscapes on Earth. The river’s future may depend on whether the people who rely on it can finally learn to live within its limits.