It happens without you even noticing  — you walk into your bathroom or kitchen, you turn on your faucet, and water flows. But have you ever thought about where that water actually comes from? It’s an important question to explore, especially considering the prolonged drought Southern California has been experiencing for most of the last decade.

Despite the way in which it’s generally depicted in popular culture, Los Angeles is not really a desert. It’s one of seven places in the world that can claim a Mediterranean climate, characterized by hot, dry summers and cool, wet winters. A robust array of native plants ranging from chaparral to sycamore trees grows here, and all need water to grow and thrive.

Today, most of that water comes from sources outside of the County’s borders – almost 60% of our freshwater is imported. But that wasn’t always the case. At one point in time, Los Angeles had enough local water for its resident animals, plants, and people.

Prior to the arrival of European settlers, indigenous peoples in the area relied on the Los Angeles River for their household and agricultural needs. Seasonal melting of the eastern Sierra Nevada Mountain snowpacks sent a steady flow of water into the river. Large underground reservoirs provided an additional year-round supply of groundwater that could be pumped or drawn out of wells.

A significant population increase in the 19th century created the need for large-scale infrastructure to deliver water to the area, and we needed to create agencies to handle distribution and supply. Many of the initial utility providers were privately-owned companies that varied in size and distribution area. Today, we still rely on hundreds of different municipal water agencies to manage supply.

Los Angeles Aqueduct OpenedAs the city grew even larger, residential and commercial demands for water increased. Despite local government and utility providers encouraging conservation, water consumption increased by almost four million gallons per day in one year. The depleting Los Angeles river was no longer a sufficient water source.

Construction of the Los Angeles Aqueduct, a large canal-like conduit for transferring water, began in the early 1900s. Led by William Mulholland, the aqueduct delivered much-needed water to Los Angeles from the Owens River, located about 200 miles to the north.

Land in the Owens Valley was predominantly agricultural, with several small farms scattered around the river. The purchasing process was complex and riddled with controversy – according to most historical accounts, the strategies used by the water companies were unilaterally unfair to the small farm owners of the region.

In the end, over 260,000 acres of land were purchased for $21 billion ($219 billion in 2003 dollars), increasing Los Angeles’ water by 400 percent. Later, the aqueduct was expanded to the Mono Basin, north of the Owens Valley.

In 1928, California established the Metropolitan Water District to construct the Colorado River Aqueduct to deliver water from the Central California Valley rivers. In the mid to late 1900s, the California State Water Project developed a pipeline from the Sacramento-San Joaquin Valley Delta to Southern California.

The Colorado Aqueduct and the San Joaquin Valley Delta continue to account for a significant portion of Los Angeles’ water supply today – almost sixty percent. The Los Angeles aqueduct provides about thirty percent. And local groundwater stored in underground aquifers accounts for another ten percent of our freshwater.

In more recent years, water agencies and sanitation departments have treated wastewater and made it available for re-use. Pepperdine University in Malibu, for example, uses recycled wastewater from the West Basin Municipal Water District to irrigate over 139 acres of its campus.

The Los Angeles County joint water pollution control plant, one of the largest wastewater treatment plants in the world, is currently working with the Metropolitan Water District on a project to move significant amounts of treated wastewater back into the potable water system for reuse.

Santa Monica Urban Runoff Water agencies are also turning to stormwater capture projects to augment local water supplies and divert polluted water before it ends up in our oceans and rivers. Agencies are partnering with schools and others to construct multi-benefit projects; for instance, playing fields that also provide underground stormwater capture capabilities or “green streets” that incorporate bioswales to naturally clean polluted stormwater and capture it for reuse.

In the Third District, the Santa Monica Urban Runoff recycling facility treats over 500,000 gallons of stormwater generated in Santa Monica and parts of Los Angeles, and is a great example of of the kinds of projects we should be building all over the County. Indeed, recaptured stormwater projects could potentially provide enough water for almost one-third of the County’s residents.

It is becoming increasingly important to get creative when we think about options for sourcing water to Los Angeles. Climate change will continue to be a threat to our water availability and will also increase the likelihood of natural disasters that can damage the delivery infrastructure. Focusing on local sources of water will be one way to reduce our reliance on external reservoirs and potentially recycle more of our own storm and wastewater.