“Law of the River”: 7 Things (2024) You Must Know

The Colorado River is the sixth-longest river in the United States, and without it, several states would crumble – which is why we have the law of the river.

Beginning in the Rocky Mountains and ending near the Gulf of Mexico, the river flows through some of the nation’s most arid landscapes that are desperate for its water.

But who should be allowed to access it?

Well, a hundred years ago, seven states came together to hash out that exact question and created the Colorado River Compact of 1922.

Since then, there have been various additions and amendments to help protect the river and ensure the states that need its water have adequate access to it.

These rules and regulations have become known as the Law of the River.

Like every law, there are those who agree with it and those who don’t, but, as of now, it’s the best system in place to monitor the usage of the river.

In order to better understand the Law of the River, we’re going to take a deep dive into the most important regulations, decrees, and court decisions and also look more closely at the Colorado River and how it has changed over time.

So, get ready to spend a day at the river, and let’s get into it!

1. What is the Law of the River?

In the western part of the United States, water is scarce.

The Colorado River is a lifeline for seven key states: Arizona, California, Nevada, Colorado, Utah, New Mexico, and Wyoming.

In 1922, these states came together to make the first compact, allocating certain sections of the river for each state–the agreement was the beginning of the Law of the River.

The Law of the River is now made up of compacts between seven states, an international treaty, federal laws, court decisions, contracts, and other regulatory guidelines that manage the waters of the Colorado River.

Without these rules, regulations, and agreements, harnessing the river’s water and energy potential would be a free for all, doing harm to the environment and making it difficult for certain states to receive the water needed to supply their populations.

The Law of the River also gives certain rights to Mexico (where the Colorado River ends); however, climate change and over-use issues threaten Mexico’s and the seven’s states’ access to its water.

2. Why Is the Colorado River so Important?

The Colorado River sustains life in the west and has made the development of cities like Los Angeles and Las Vegas possible.

Today, around 40 million people rely on the river, which is about 12% of the entire United States population.

The river also supplies water for 5.5 million acres of land, 11 National Parks, 7 National Wildlife Refuges, and 22 federally recognized tribes.

So, calling the Colorado River important is an understatement; it’s a lifeline.

If parts of it begin drying up, which is a growing concern, it could trigger a water crisis unlike anything the United States has experienced before.

3. What Does the Law of the River Include?

Since the first compact of 1922, a lot has changed.

Cities were developed, dams were built, and the importance of the Colorado River grew more and more.

As a result, the Law of the River now contains several key rulings and agreements, and discussions for alterations and new additions are constantly underway.

So, let’s check out the key elements that make up the Law of the River to better understand how it controls water usage.

bullet The Colorado River Compact of 1922

The Colorado River Compact of 1922 was the first time the seven Colorado River Basin States came together to discuss accessibility to the river.

The Upper Basin States were concerned that the water demands and developments in the Lower Basin States would disrupt the natural flow of the river.

When the seven states couldn’t come to an agreement, President Hoover devised a plan that separated the Colorado River Basin into an upper and lower half, giving 7.5 million acre feet per year of river water to each section.

The Upper Basin States include New Mexico, Utah, Colorado, Wyoming, and a sliver of northern Arizona.

The Lower Basin States include Nevada, Arizona, and California.

bulletThe Boulder Canyon Project Act of 1928

The Boulder Canyon Project Act of 1928 permitted the construction of the Hoover Damn and the All-American Canal.

Building the dam created a massive water reservoir, Lake Mead, and greatly increased the Lower Basin States’ access to water (the act also divided water accessibility between the Lower Basin States).

The All-American Canal, an 80-mile-long aqueduct, was created to deliver water to the Imperial Valley in California, which is now the region’s primary access to water.

bulletCalifornia Seven Party Agreement of 1931

California faced internal conflicts between different districts that demanded certain rights over the Colorado River water.

The California Seven Party Agreement of 1931 officially declared how much water each district would get and how it would be delivered.

Here are the primary water districts the agreement impacted:

  • Palo Verde Irrigation District
  • Yuma Project
  • Imperial Irrigation District
  • Coachella Valley Irrigation District
  • Metropolitan Water District
  • City and County of San Diego

bulletThe Mexican Water Treaty of 1944

The Mexican Water Treaty of 1944 committed 1.5 million acre-feet of water to Mexico.

It also specified that, under special circumstances, additional or restricted amounts of water would be delivered.

For example, Mexico would be allotted an additional 200,000 acre-feet of water in the case of a surplus; during a drought, Mexico’s uses would be cut at the same proportions that the United States experienced.

bulletUpper Colorado River Basin Compact of 1948

In 1948, the Upper Basin States created the Upper Colorado River Basin Compact to determine how much of the 7.5 million acre-feet of water each state would be allotted.

Here are the percentages of the Basin each state was assigned:

  • Colorado: 52%
  • Utah: 23%
  • Wyoming: 14%
  • New Mexico: 11%

The Upper Colorado Basin Compact also allotted 50,000 acre-feet of water to northern Arizona annually (northern Arizona is just above the border marking the Lower Basin territory).

bulletColorado River Storage Project of 1956

The Colorado River Storage Project of 1956 detailed water resource development plans for the Upper Basin States.

It also authorized the development of four dams: Glen Canyon, Flaming Gorge, and Navajo dams (in addition to a few other projects).

These projects were devised to help regulate the river, create hydroelectricity, and support irrigation efforts.

The Glen Canyon Dam, which is responsible for creating Lake Powell, was the most ambitious of the projects, producing power for all the Upper Basin states.

bulletThe Arizona v. California U.S. Supreme Court Decision of 1964

Conflicts between Arizona and California began almost immediately after water was divided between the Lower Basin States.

The primary conflict stemmed from the Central Arizona Project, which would bring water from one of the Colorado River’s tributaries to irrigated agricultural land areas in Arizona.

California believed Arizona would be unjustly impacting the flow of the Colorado River.

In 1964, the U.S. Supreme Court decided in Arizona’s favor and reiterated that states were allowed to use the flow of tributaries before they linked with the Colorado River.

bulletThe Colorado River Basin Project Act of 1968

The Colorado River Basin Project Act was signed in by President Johnson in 1968.

The law’s primary function was to authorize the Central Arizona Project, which had been disputed by California for years.

The Central Arizona Project cost over $800 million and now delivers water to around six million people, including Indian and non-Indian agricultural areas and metropolitan areas in Phoenix and Tucson.

Here are the counties that receive water from the Central Arizona Project.

  • Pima
  • Pinal
  • Maricopa

bulletThe Criteria for Coordinated Long-Range Operation of Colorado River Reservoirs of 1970

The Criteria for Coordinated Long-Range Operation of Colorado River Reservoirs set guidelines for water releases from  Lake Powell and Lake Mead.

It also determines how much water should be stored in the two reservoirs and specifies the circumstances that dictate the amount.

In 2005, after the Colorado River Basin States consulted with each other, several modifications were made to the original text.

bulletMinute 242 of the U.S-Mexico International Boundary and Water Commission of 1973

In the 1960s, the portion of the Colorado River that flowed through Mexico had an increase in salinity concentration.

The excess salt severely affected agricultural productivity and damaged parts of the land.

Minute 242 was established to address Mexico’s salinity problem, and it now requires the United States to actively take steps to reduce salinity concentration levels before delivering water to Mexico through the Morelos Dam (the water can only be a certain level over the annual salinity average).

bulletThe Colorado River Basin Salinity Control Act of 1974

In order to desalinate the water flowing into Mexico and also parts of the United States, the Colorado River Basin Salinity Control Act was passed to construct the necessary desalination plants, intake pumping plant systems, power transmission facilities, product waterline, and other permanent operating facilities.

In total, the act allotted $155.5 million to construct everything required.

4. How Has the Law of the River Changed the Colorado River over Time?

Since states began tapping into the Colorado River for a source of water and energy, a lot has changed about the river.

These changes are partly due to climate change and partly due to human intervention.

Two of the most significant changes came from the Hoover Dam and Glen Canyon Dam.

These dams are responsible for creating Lake Mead and Lake Powell, the two largest reservoirs in the United States, which completely changed the landscapes around them.

Within a matter of years of the dams being built, environments were flooded, and the flow of the river was became determined by man.

In the last 30 years, environmentalists have found that the annual flow of the river has dropped by 20%; most of the reduction is attributed to the rising temperatures in the Basin–temperatures that are only predicted to increase.

On top of climate change, all the dams and diversions have taken a major toll on ecosystems that once thrived.

There has been a steep drop in marine life populations, and biologists are struggling to find a way to bring numbers back up.

5. Does the Colorado River Still Reach the Ocean?

During the Colorado River’s glory days, it once ran from the Rocky Mountains to the Gulf of California (northwestern Mexico).

But that’s no longer the case today.

When the Glen Canyon Dam was completed in the 1960s, resulting in Lake Powell, it stopped the river from regularly flowing into the gulf.

Today, it almost always stops miles short; however, there have been special circumstances that temporarily bring the river back to its pre-dam state.

In 2014, the river reached the sea for the first time since the 1990s, thanks to a surprise surge.

As temperatures in the Basin continue to rise and states continue to overuse the water, it’s unlikely the river will ever flow into the gulf without the help of another powerful surge.

6. Will There Be Water Cutbacks in the Colorado River?

Droughts have been plaguing the Basin States for years, and it has reached the point where political leaders are recognizing that something has to be done.

The Interior Department requested that the seven states who claim water from the Colorado River create and agree upon a plan that would cut back the amount of water each state takes.

These states had until January 31st, 2023, to make a plan.

Well, on the day of the deadline, there was no plan and no agreeance.

Are you surprised?

Probably not.

There are very few officials who believe a voluntary agreement will ever be made between the states, which means the Federal Government may have to step in and take control of the situation.

However, without a voluntary agreement, we can expect to see an onslaught of legal challenges from states that feel they were given the short end of the stick.

7. What Would Happen if the Colorado River Dried Up?

The likelihood of the Colorado River completely drying up are slim.


The chances that the flow of the river will reduce to extremely low levels are quite high if things continue the way they are going.

But what would happen if the river did, in fact, dry up?

Well, California, Arizona, Nevada, New Mexico, Colorado, Utah, and Wyoming would lose one of their major sources of water.

Serious changes would have to be implemented if they couldn’t find another source,

Residents of these states would likely have to follow new water restrictions.

Although the Colorado River is currently crucial for seven states, that doesn’t mean we can’t live without it as long as people are willing to alter their lifestyles and habits.

Final Thoughts

The Colorado River is one of the most important rivers in the country.

It supplies power and water to millions of people and countless agricultural areas.

In order to divide access to the river in a just manner, the seven Basin States have been relying on the Law of the River to make things fair.

As the river’s water levels decline and climate change becomes more of a pressing issue, we will likely see new additions or amendments to the Law of the River in the coming decades.

But for now, the current rules and regulations in place are the best we have to supply water to arid regions and protect the environment.

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Erika Gokce Capital

Disclaimer: we are not lawyers, accountants or financial advisors and the information in this article is for informational purposes only. This article is based on our own research and experience and we do our best to keep it accurate and up-to-date, but it may contain errors. Please be sure to consult a legal or financial professional before making any investment decisions.


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