Penn State NASA

The Growing Battle Over Water


The Growing Battle Over Water

Even in regions where desalinization has the potential to add water and strict management practices are underway, water is such a vital commodity that water rights of communities, cities, and even states are often contested in court. Such legal battles sometimes stem from old agreements about the distribution of rivers and groundwater between municipalities that were drawn up before substantial growth occurred. With population growth requiring water for drinking, domestic use, agriculture, and industry, the value of water has increased substantially, and old agreements are often extremely prohibitive to growth. Some of the most bitter water disputes occur in the western US, where, as we have seen, southern California relies heavily on water derived via aqueducts from the Colorado River to the east and the Owens Valley in the Sierra Nevada Mountains to the north.

California Aqueducts

Owens Valley

The City of Los Angeles has had brutal showdowns with farmers and environmentalists in the Owens Valley, from where it derives about half of its water. The city built the first of two aqueducts from the valley between 1908 and 1913 and the second in 1970. These aqueducts substantially lowered water levels in Mono and Owens Lake and the Owens River and took a terrible toll on farming in the Owens Valley. The impact was so negative that farmers used dynamite to breach the aqueduct and temporarily return the flow to the Owens River. After the second aqueduct was built, a series of litigation began between municipalities in the Owens Valley and ultimately the Sierra Club. The net result has been rulings in favor of the Owens Valley, and some increases in water levels in bodies such as Mono Lake, but ultimately southern California continues to withdraw water at a faster rate than it is being replenished, so the conflict is by no means over.

The Colorado River Compact

To the east of Los Angeles, water rights for the Colorado River were defined by the Colorado River Compact of 1922, which divided states bordering the river into upper basin states (in the Rocky Mountains) and lower basin states (in the plains to the west). The compact appropriated the annual amount of water each group of states could withdraw from the river with the upper basin states receiving the same amount as the lower basin states.

Today forty million people from Wyoming to Mexico receive water from the Colorado River, so the river is vital to communities small and large and for residential and agricultural use. Since the compact was developed, the lower basin states (Arizona, California, Nevada) have developed especially rapidly and now use a lot more water than they did in 1922. Cities such as Phoenix and Las Vegas have experienced some of the most rapid growth in the country.

The compact was modified when the Hoover Dam was constructed, at which time the lower basin states were allocated annual withdrawal amounts. These amounts have led to fierce litigation between Arizona and California, which changed the appropriations in Arizona’s favor. For a long time, only California has completely utilized its quota each year and its surplus was guaranteed by the Secretary of the Interior until 2016. By that time, surging development in Arizona and southern Nevada required full use of their quotas from the Colorado so that the surplus was no longer available to California.

Two major reservoirs exist in the lower Colorado River basin, Lake Mead and Lake Powell, bounded by the Hoover Dam and the Glenn Canyon Dam, respectively. These reservoirs were designed for water management, but both have been drying up recently. The situation is dire in both reservoirs, as the images below show. Let’s start with Lake Powell. This reservoir provides water and electricity generated through turbines in the Glen Canyon Dam to millions of people. The level in Lake Powell is lower than it has ever been. As of June 2023, the level was at 3580 feet with the normal level being 3700 feet. If the level drops below 3490 feet (a level known as “dead pool”), water cannot flow downstream to the lower basin states from the reservoir. In addition, the dam would not be able to generate electricity, potentially cutting off power to millions.

Lake Mead’s issues may be even more pressing, as the lake provides 90 percent of nearby Las Vegas’s water. The largest reservoir in the country had a level of 1049 feet in May 2022 which was 170 feet below the maximum capacity. The level was so low that sunken boats resurfaced and an intake valve (for pumping to Las Vegas and other communities) was exposed. Las Vegas was taking water from the lower intake valves, which were installed to retrieve water at lower lake levels. Fortunately, there was a massive amount of snow in the mountains in the winter of 2022-2023 and the level has risen somewhat. But regardless, Las Vegas is planning for a future when low water supply is the new normal and frequent dead pool” events when no water flows out of Lake Mead. Fortunately, a third intake valve and pumping station for Las Vegas’s water has been installed below the dead pool level, so the city will still receive water, but the city is already imposing severe water restrictions including banning grass in yards and strictly limiting watering of grass on golf courses. The city also recycles a lot of its water. These and other measures have been successful in reducing the demand for water: over the last twenty years the population has grown by 49% but water use has shrunk by 26%. Regardless, the future looks bleak as the decades long drought in the area is forecasted to continue.

So, the situation is dire for both Lake Mead and Lake Powell, and recently in 2023 the US government brokered a temporary deal whereby the lower basin states (California, Arizona and Nevada) must lower their water extraction from the Colorado by 13 percent. However, a longer term deal must be reached by 2027 and this will likely involve some tough negotiation. Essentially, the original 1922 compact was developed at a very wet time in the west, and the upper basin states (Colorado, Wyoming and New Mexico) can’t afford to give 50% of the water to the lower basin states when they need the water to fuel growth in cities such as Denver and Albuquerque as well as provide the water farmers and ranchers desperately need.

A sign of the times to come, Phoenix just imposed restrictions on development in the fastest growing suburbs where the supply comes from groundwater. The new rules say that no new development can take place without an alternate source of surface or recycled water. Such controls are likely in all of the southwestern cities in the future as climate change leads to even lower water supplies.

Video: 40 Million People Rely on the Colorado River, and Now It's Drying Up (9:32)

40 Million People Rely on the Colorado River, and Now It's Drying Up
Click here for transcript.

What a mess! What an absolute mess! I mean, each time you say, “Oh this is different than it was what's it going to be like in October what's going to be like next April. There isn't a lot about the Colorado river that Jack Schmidt doesn't know. He's been making research trips on it for decades, but he's never seen the river this low. Look at this. Yeah, you used to be able to back a truck in here right into the water. Is this new this year? Essentially, yeah, it's happened within the past six months. I am stunned by how horrible this is. The Colorado is the lifeline of the American Southwest. It runs nearly 1500 miles supplying water and electricity to seven states. In Mexico, some 40 million people rely on its resources. But 20 years of drought made worse by climate change have brought things to a moment of crisis. This part of the river was once the upper end of Lake Powell, one of the two main reservoirs Lake Powell filled for the first time in 1980. That concrete ramp was filled with houseboats, people backing in motorboats, people water skiing, and now look at that. Essentially 1999, 2000 was the last time the water was up at the base of that concrete ramp. And now, it's lower than it's ever been since it filled.

It's not only Powell, Lake Mead, the river's other major reservoir above the Hoover Dam is only about a third full. Unless things change, which they won't this month, officials will declare a tier-one shortage for the first time ever. That means next year major cutbacks are coming, starting with Arizona farmers. When that happens, a lot of farms will look like, Nancy K Woods, she relies on water from another river a tributary to the Colorado, but it got so low she was totally cut off in April. So, this out here, just looking at this, I mean is this, take a look. Is this dead? Now well we don't think it's going to green back up. What were you growing here? Alfalfa. See the seed lines and how it's just all dead?


Our dam has no water. We have no water period. [Music] so this is my granddad, and he bought the farm in about 1930, and here he's in the 40s. And he's listing a field getting ready to plant cotton it's an amazing photo. It's about the only picture I have of him on the farm. And this is our family. This was out in a cotton field it's really hot, everybody squinting, it was in august. What I’m struck by looking at this picture, you said it's august but you're standing in a bright green field, beautiful green and it's right over where that dead alfalfa is. Isn't that gorgeous? And that was taken in 2019. I feel like we've been talking about this moment as a future thing for a long time, this idea that there's going to be a time when we have to reduce water usage, we have to we have to pay attention to that, but being out here it feels like that moment's here. It's here. Here we are and there's no turning back. No, right now the population is not going to feel affected. Farmers are going to feel it. Does that create a little bit of a divide where farmers are in this place where you're, well you're taking the bear? To me, yeah. You know, yeah I think it does. There's a big push for land development here, encouraging industry to come in here. You know, new businesses, which means more homes and as that happens, they're going to be using water just like we are. The decisions over who loses water first were largely made back in 2019 as part of a drought contingency agreement between the states that used the river. It took six years to work out and was set to expire in seven. That means negotiators are already starting to worry about how they'll do it all again with many states still trying to build new pipelines and developments and even less water to go around. Tom Bushotzky is responsible for making Arizona’s case and navigating all of these tensions. Starting with the job contingency plan discussions in 2018, and 2019, we have been talking about climate change and the hotter and drier future, really putting that point out there to the water users that we have to be prepared for that. And I think a lot of what's going on with the Colorado river is the hotter drier future's already here. And it might get a little bit worse. Is it fair that farmers who ostensibly are doing something that's sort of essential, growing food for us to live, that they're having to cut back when other people are watering their lawns and not having to limit their shower length? That is a debate that has been growing. But the way the legal priority system works for water supplies, the farmers have that lower priority than the cities. Do you think as this gets harder over the coming years that the interstate negotiations are going to get trickier, so the harder it is in your state, the harder it will be between the states. So, the answer is clearly yes to that question. It remains to be seen what will happen. I know that we collectively will negotiate something. We will. What it's going to be, I don't know. When it's going to be, I don't know. But failure is not an option. It is because otherwise mother nature is going to take over. There are no easy answers for this are there? There are not. And in water, there never are.


Do you think we're at a critical point? I think we're at a point where the old ways will not suit us going forward. So, we are at a political critical point where we need to really have hard-nosed talks about where is the best place to use water to do the best good for human society. We have lived with the imagination that there is more water to develop and so we can increase development and it won't hurt anybody. But it is a zero-sum game. There's not any more extra water to develop.


Hoover Dam was the first major dam of its kind that was built. And at the time it was built it was the largest in the world. It impounded Lake Mead and downstream agriculture was the primary reason that it was built. We just recently passed a historic low in Lake Mead. It's now at the lowest level that it's been since it filled in the 1930s. In 2000 Lake Mead was at about 95, which was about 15 feet below that walkway right now, just 20 so years ago 2000. Wow that's kind of impossible to picture. Right now, standing here, it's dramatic. Do you expect it'll get back to that point? We need at least four or more years of consecutive good runoff into the upper basin, good snowpack for the reservoirs to be able to rebound completely. Can you talk me through what these structures are? These are intake towers. Water goes in, spins a turbine, which spins a generator and creates hydropower, which goes out to all of these power lines that you see. That's how Las Vegas is lit up at night. Las Vegas is lit up at night and Arizona, and California also receive power from Hoover Dam. I’m waiting to feel my ears pop. We produce our own power. These are little generators. There's one on the Nevada side too. And this is the power for the dam itself. The way it works as the reservoir level is high, there's more pressure pushing the water in to the pipes to the turbines. As it lowers, there's less pressure. Is there a lower limit to how little water there can be in here for them to still work? Elevation 950 is the lowest that we'd be able to go and still produce hydropower. The water level at Lake Mead is currently around 1067 feet. So, if the water level gets below 950, this dam will no longer really function as a generator of power. That is true. But we don't anticipate that happening. Right. Is it a little despairing for you to come out and see? It's concerning. I mean, all of us are concerned but I also have a lot of faith in the people that are working on the problem.

The following animation shows how Lake Powell has dried up since 1999.

Video: Earth 103: Water Level in Lake Powell (00:42) This video is not narrated.

Check Your Understanding