Where Does My Water Come From?


Most of the water we drink is actually snowmelt from the Sierras and Rockies. Photo Credit: Chris Barton

When you turn on your kitchen faucet to fill up a pot for spaghetti dinner, it’s hard to imagine that the water you are using fell as snow at the top of America’s two largest mountain ranges—the Sierra Nevadas and the Rocky Mountains. Perhaps some of it spent the winter clinging to a pine tree or even a sequoia, nevertheless, most of the water we use in Southern California comes from snowmelt.

As spring arrives, melting snow from the Sierra Nevadas makes its way down the mountains and into the Bay Delta (up in the northern part of the state). Some of that snowmelt  it is sent south, pumped over the Tehachapi Mountains, purified, and finally sent to the homes of just about everyone living between Bakersfield and Santa Monica (to the east and west), and Santa Barbara and San Diego (to the north and south). Similarly, snowmelt from the Rocky Mountains travels to the Colorado River and the Hoover Dam, where it’s sent to people living in Southern California, Arizona, and Nevada.



Since they are underground, it’s impossible to take a picture of an aquifer. However, they are essentially lakes beneath out feet. Photo Credit: Joost J. Bakker

We don’t just rely on snowmelt from mountains, though. Many of us who live in the Inland Empire are lucky enough to have giant lakes of water underground that we can use during dry years. We pump up the water using wells, clean it, and then mix it with the water from the Sierras and the Rockies, and deliver it to homes and businesses.

Ground water is becoming more and more important in our plans to supply our area with water through dry years. Having underground aquifers means that we can store imported water during wet years for use during droughts – just like the way we save money in banks. Not all cities have access to ground water or the ability to store water underground, so they are completely dependant on rain water and imported water – which means that they are very vulnerable during droughts. Atlanta is one of those cities. In the past, it has had more rain than even Seattle, but since there are no natural underground aquifers, all of the rain water washes south to Alabama and Florida. That put Atlanta in the situation of nearly running out of water for the city a few years ago. That is why it is so important that we protect the our groundwater from pollution – we can count on needing it in the future.



It’s now possible to take salt out of water, but it’s very expensive to do it. Photo Credit: Dubravko Sorić

The ocean isn’t the only place to find saltwater. Some of it can actually be found in our underground lakes in the Inland Empire. The technical term for this ground water is “brackish,” but we treat it just as we would ocean water.

It is now possible to take the salt out of water, and Australia is already doing it on a large scale to combat a decade of severe drought (imagine having a river the size of the Mississippi dry up – that’s what they’re facing). We use the same method – reverse osmosis – to take the salt out of our inland brackish ground water. The drawback of “desal,” as it’s called, is that it takes an enormous amount of energy, so doing it on a large scale like the Australians only makes sense if most other options literally dry up.

Desal is extremely expensive, so it is important to keep our groundwater from becoming too salty. That is why the five SAWPA member agencies pooled their resources to build and maintain the “brine line.” The brine line is a series of large pipes that take used water from industrial operations in the IE, extracts the excess salt and sends it out to sea.