Do “40 million people” actually depend on water from the Colorado River?

No, they do not. While it’s technically true that 40 million people across seven states and Mexico have water systems that are supplied in part by the Colorado River, it’s misleading to imply that 40 million people depend on the Colorado River entirely. But the statement – which was taken out of context, has been repeated so often by the media and others that it’s now widely-accepted as a fact. It originated from a Bureau of Reclamation report that actually says, “Although agricultural users depend on 70 percent of Colorado River water, between 35 and 40 million people rely on the same water for some, if not all, of their municipal needs”.¹

The following towns are 100% dependent on water from the Colorado River: Yuma, Lake Havasu, Parker, Needles, Blythe, Bullhead City, Laughlin, and Green River, Wyoming. The total of their populations are 254,346 people.²

Top three reasons why the shortened “40 million” phrase is misleading

1. Agriculture consumes the vast majority of the Colorado River’s water, not individuals

The phrase implies that 40 million people rely on the river primarily for drinking, bathing, and basic survival. But in reality agricultural irrigation consumes roughly 75% to 80% of the river’s water. A massive portion of that goes specifically toward water-intensive cattle feed crops like alfalfa and hay. Domestic, household use accounts for only about 10% to 13% of the total supply. The narrative of “40 million thirsty citizens” masks the fact that the crisis is fundamentally an agricultural management problem rather than a residential population crisis. 

2. Metropolitan areas typically have a wide variety of water sources

Many of the 40 million people counted in this statistic live in large coastal or metropolitan cities—such as Los Angeles, San Diego, Denver, and Phoenix—that do not rely solely on the Colorado River. These cities utilize a diversified portfolio of water sources, including local groundwater, northern state aqueducts, state-wide recycling systems, and other local river basins. Saying they “depend” on the Colorado River implies total reliance, when it often provides only a fraction of their municipal supply. 

On average, the Colorado River only supplies roughly one-third of Southern California’s urban water.³ The rest comes from the State Water Project (or Northern California snowpack), local groundwater, and from water recycling programs, yet the Bureau of Reclamation counts all 19 million residents of this geographic area as being “dependent on Colorado River water”.

3. Aggressive water recycling and conservation has significantly reduced our dependence

Using the word “depend” creates a fatalistic narrative that if the river’s flow drops, 40 million people will run out of water. In practice, many of the urban centers counted in the 40 million figure are highly resilient due to aggressive wastewater recycling and conservation efforts. For example, Las Vegas and the state of Nevada recycle nearly 85% of their treated wastewater back into Lake Mead. Because these cities reuse the same water multiple times, their actual net depletion of the river is much lower than their gross population would suggest.

4. 1.8 million Cows use more Colorado River water than 40 million people

The Bureau of Reclamation should change their headline to: “1.8 Million Cattle depend on the Colorado River” because dairy and beef producing operations use more Colorado River water than people do. ³ Statistically metropolitan areas use 14 to 18% of the (total allocated) Colorado River water while beef and dairy production uses 32% when the growth of forage is included. ⁴