(wind whistles faintly) (somber ringing music) - Well, I hate to break it to you folks.

This is the Colorado River, at least what's left of it.

Where did all the water go?

(melancholy orchestral music) (light ethereal music) This feels like Arrakis, not a river.

Whew.

(exhales) Whew.

It's time to solve the case.

Who killed the Colorado River?

(light electronic music) The Colorado River.

For centuries, it's been the lifeblood of the American Southwest, carving canyons and bringing life to an arid land.

A river so vast, it could fill 300 million Olympic-sized swimming pools each year.

Born in the snow-capped Rocky Mountains of Colorado, the Colorado River traces a spectacular course through five U.S. states, carving its way through 1,450 miles of rugged Western landscape, before emptying into the Gulf of California in Mexico.

At least that's how it's supposed to work.

This is the delta where the Colorado River meets the ocean, or rather, what's left of it.

Since the early 1960s, one of America's great waterways almost never actually reaches the sea.

- Right now, this is the original river bed of the Colorado River.

It used to be a forest, and if you look back south, 70 miles, you'll reach eventually the delta, the original delta, and the upper Gulf of California.

- Where this river used to flow.

- It used to flow and connect there and create another great ecosystem of marshes, estuarine ecosystems for totoaba, vaquita, and many species flourish in this space, which no longer exists.

- [Joe] The Colorado is part of a troubling global trend.

The Yellow River in China, the Indus River.

More and more rivers around the world are drying up before they reach their final destination.

Rivers flow to the sea.

That's their whole deal.

What happened?

- Well, we happened.

- So here's the problem.

In recent times, around four trillion gallons of water flow through the Colorado River every year, but we are allowed to take out around five trillion gallons of water every year.

Now, I'm no mathematician, but that doesn't add up.

So, where is it all going?

Well to solve this mystery, we need to go on a hunt for some suspects, and our first stop takes us back to 1922.

Representatives from seven Southwestern states gathered in a Santa Fe mountain retreat to divvy up the Colorado River's water.

The result was the Colorado River Compact, an agreement for who gets water and how much.

Their goal was clear, help settlers gain a foothold through irrigation and development.

In doing so, they were deciding the fate of a river.

Notably absent from that meeting, Mexico, despite sharing this river with the United States, and not a single representative from the Native American tribes who have long called this region home.

And almost no consideration for the river itself, or the ecosystems and wildlife that depended on it.

Here's the thing.

They overestimated the river's flow, and ignored warnings about future water shortages.

The Colorado Compact divvied up 15 million acre feet of water every year, based on an assumed annual flow of 16.4 million acre feet.

Just one problem.

The river's actual flow in recent decades has averaged just 12.4 million acre feet each year, leading to a situation where we are promising far more water than the river can actually deliver.

So the Colorado Compact was less of a master plan, and more of a disaster plan.

That's our first suspect, shortsighted water management.

But the plot thickens.

It's time to meet our second suspect.

(soft somber music) This is the Imperial Dam, completed in 1938.

It wasn't the first, and it certainly wasn't the last.

Between 1905 and 1970, 15 major dams were built along the Colorado River.

These river fortresses provide flood control, hydroelectricity, and a steady water supply for millions.

But, all this control comes at a cost.

These dams have not only significantly altered the river's course, they have altered entire ecosystems.

But more significantly, 11% of the river's flow evaporates every year in the reservoirs.

That's a lot of water evaporating into thin air, in a region where every drop is like liquid gold.

The vast surface area of these reservoirs exposes more water to the air than a flowing river would.

Plus the still water in these reservoirs gives the sun plenty of time to work its evaporative magic, unlike in a fast-moving river.

(dark strident music) Okay, we've got outdated water laws and thirsty dams, but this water mystery is far from over.

It's time to meet our next suspect.

(light electronic music) This may look like a giant lazy river at an amusement park or something, and honestly, right now I kinda wish it was one.

But this is actually suspect number three in "Who Killed the Colorado River," the Central Arizona Project.

Picture this, a massive canal system stretching over 330 miles, gulping down nearly one trillion gallons of water from the Colorado River.

This thirst quenching marvel is like a giant straw, sucking up water on behalf of cities like Phoenix, which is more than 70 miles to the east, holding more than 1.6 million humans, who are thirsty, and so are their lawns and golf courses.

And like a straw, this water doesn't flow downhill.

No, it's pushed uphill by 14 pumping plants, climbing nearly 3,000 vertical feet along its path.

That's two-and-a-half Empire State Buildings, stacked on top of each other.

And Arizona's not the only ones sipping from this river cocktail.

Los Angeles, Denver, Albuquerque, and Salt Lake City are all taking their fair share too.

In fact, cities and industry are responsible for slurping up 18% of all the water consumed from the Colorado.

You might think that millions of people living in and around some of the driest land in North America would cause some problems with water, but apparently this is not obvious at all.

All right, we've seen how dams and canals are siphoning off this river, but there's more to this story.

I think our next stop might surprise you.

(light pensive music) (door closes) This oasis in the desert is one of many wetland areas near Yuma, Arizona.

It is beautiful, but it's also suspect number four.

Wetlands like this are a bustling metropolis of flora and fauna.

They prove there's more to this river than just quenching our human thirsts.

But these lush green oases are also secret water guzzlers.

Believe it or not, a whopping 19% of all water consumed from the Colorado gets taken up by these river ecosystems.

Nature, it turns out, is pretty thirsty too.

That's a lot of water, but these wetlands are also the unsung heroes of the Colorado River.

These natural areas are like nature's Swiss Army Knife.

They're flood control experts, soaking up excess water like a sponge.

They also purify the water as it flows through, and they are biodiversity hotspots for migrating birds, as well as mammals and invertebrates.

So while these wetlands may be thirsty customers, they are working overtime to keep the whole ecosystem in balance.

So we've seen how cities, dams, even wetlands are draining the Colorado River, but we are about to meet our heavyweight champion of water consumption, our number one most wanted when it comes to draining a river dry.

And it might make you think twice about what's on your plate.

(light contemporary music) Welcome to the Imperial Valley of California, our prime suspect in the case of the vanishing Colorado River.

Well, it's not just the Imperial Valley, but what happens here is a perfect example of how agriculture, at least the way that we do it now, is drinking our rivers dry.

These green seas in the middle of the desert gulp down 52% of the Colorado's water.

That's right, more than half of the river's water goes to agriculture.

Now, you might be thinking, we're looking at fruits and vegetables destined for your dinner table, but here's the twist.

Most of what you're seeing isn't for us at all.

This is alfalfa, one of the thirstiest crops out there, and this is not for feeding humans.

This is for feeding cows.

We are using most of our precious river water to essentially grow steaks and hamburgers.

And about 20% of this alfalfa is shipped overseas to places like the Middle East and Asia.

So in essence, we're taking our already scarce river water resources, and exporting them in the form of cattle food.

And this isn't just about thirsty crops, it's also about a use it or lose it water rights system.

Farmers who don't use their full water allotment risk losing those rights in the future.

So we end up with wasteful water practices like flood irrigation, where fields are essentially submerged just to ensure those water rights aren't lost.

It incentivizes using every drop, whether it's needed or not.

In a region where water's becoming increasingly scarce, this outdated policy is like leaving the tap running full blast in the middle of a drought.

And all that wasted water has had some weird effects.

Exhibit A, the Salton Sea.

This massive body of water that you see behind me, it should be a dry lake bed, but instead it's filled with agricultural runoff from the Colorado River.

So who killed the Colorado River?

The truth is there's no single culprit.

It's a perfect storm of outdated water laws, dams, urban development, nature itself, and of course, our prime suspect, agriculture.

So it's no wonder that by the time the Colorado River reaches Mexico, it's nearly dry.

But, this story is not over.

There are some bright spots, or green spots.

Back on the Mexican side of the border, today we see dry, cracked earth where there was once a broad river delta that supported rich marshlands and forest ecosystems.

But a dedicated team of environmental organizations has been working hard to restore pieces of this landscape to what they once were.

Through binational agreements, they've secured regular water releases into the delta area where this river once flowed into the sea.

This careful management is bringing life back to areas once thought lost.

- So if you are outside in the desert, you can see dunes or dry landscape like in the "Mad Max" movie.

It's really dry, no vegetation, and when you come here, inside the forest, you feel really different.

It's a fresh place.

You can hear the birds, you can smell plants, you can smell flowers.

You can have the shadow of the trees.

Oh, it's amazing.

- [Joe] This dramatic transformation is also having a measurable impact on local wildlife.

- The group of birds are good indicators of health of the ecosystems, and the health of the restoration sites.

So we're monitoring periodically the abundance and the diversity of the rivers.

When we compare restored sites with non-restored sites, we can see that there are 70% more birds, and there is 30% more bird diversity in these sites.

- We record and saw a lot of animals here from the beaver, the bobcat, coyote, raccoons.

So it's a lot of species that we saw here.

- [Joe] The success of these restoration efforts is challenging local perceptions about what's possible in this region.

- The people actually think that no water is the natural condition, because they have no record of that ancient times.

- With just few drops of water, you can generate a forest like this.

- [Joe] While the Colorado River still faces significant challenges, these restoration efforts offer a glimmer of hope for the future.

- It's been almost 100 years since the river doesn't flow here naturally in Mexico, in through the delta.

In the desert like this, the life depends of the water.

So that's why you can hear it.

You put some water and this is what you can do.

- For me, all this work, all this restoration is important because we are recovering something that we lost in the past.

It's a river crossing the desert.

If you do not have that, maybe you miss all the benefits, all the beauty that the Colorado River brings to this area.

- It's about so much more than just saving a river.

It's a reminder to reconsider our entire relationship with water in this changing world.

The Colorado's story isn't over, it's evolving.

And with continued effort and cooperation, maybe one day the mighty Colorado River will reach the sea once again.

(light orchestral music)