Why is the Colorado River running dry?

From the article:

The problem at hand is clear: Somehow we need to find water to refill the reservoirs. We can’t control the amount of precipitation that falls within the Colorado River watershed, but we can control how we use the water that’s available. If we use less, there will be more to store in the reservoirs.

The river supplies 40 million people, the large majority living in cities, and you’d think this is where we could conserve a large amount of water. But it turns out that the cities—all the homes and lawns and golf courses and public parks and even the celebrity swimming pools—account for only 12 percent of what’s drawn from the river. Industry, such as factories and power plants and data centers, uses another 8 percent. And the rest, 79 percent of what we take from the river, goes to agriculture.

This seems like a lot of water being used for farming, but it’s actually a normal percentage compared with other river systems around the world; it takes a lot of water to grow food. What’s not normal about the Colorado River, however, is that an enormous portion, as much as 70 percent, of the water devoted to agriculture goes to just two crops—alfalfa and grass—to make hay. When you do the math, this means that more than half the water siphoned from the Colorado River is used to grow food for beef and dairy cattle, as well as for some sheep and horses.