How is Water Used in California?


No California resident can claim ignorance of the current drought conditions: things are bad, and they'll probably stay that way for a while. Governor Jerry Brown called for statewide water restrictions earlier this year, and news coverage of dwindling suppliesdry rivers and sinking farmland have flooded the local and national media for months. While the drought is on every Californian’s mind in some way, it can still be hard to imagine the sheer physical extent of our water: where it comes from, and how exactly we use it. Making drought conditions tangible can be difficult for anyone, in or out of California. In the final week of Archinect’s open call for submissions to our Dry Futures competition, we’ve compiled some helpful stats and figures for better understanding water use in California. These are basic numbers, intended to be used as a framing context for how water flows through the state. But first, let’s clarify some water-based terminology, courtesy of the US Geological Survey

  • aqueduct: a pipe, conduit, or channel designed to transport water from a remote source, usually by gravity.
  • aquifer: a geologic formation(s) that is water bearing. Use of the term is usually restricted to those water-bearing formations capable of yielding water in sufficient quantity to constitute a usable supply for people's uses.
  • greywater: wastewater from clothes washing machines, showers, bathtubs, hand washing, lavatories and sinks.
  • groundwater: water that is held underground, in soil or rock. Wells are dug to access repositories of groundwater, down to the level of the water table.
  • riparian*: relating to the area adjacent to rivers / streams (ie river banks, wetlands)
  • runoff: That part of the precipitation, snow melt, or irrigation water that appears in uncontrolled surface streams, rivers, drains or sewers.
  • watershed: the land area that drains water to a particular stream, river, or lake. It is a land feature that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge.
  • surface water: water that is on the Earth's surface, such as in a stream, river, lake, or reservoir.
  • water table: the top of the water surface in the saturated part of an aquifer.

Now, let’s take a trip back to elementary school and revisit this diagrammatic gem: The Water Cycle. How does water move around our planet and atmosphere?

So, where does California’s water come from?

In California, all water used for human consumption comes from four major sources, originating both within the state and elsewhere. Those sources are: The San Francisco Bay delta, groundwater, the Colorado River, and the Russian River. Any given resident may get water from more than one of these sources, depending on the water's use.

The confluence of the Sacramento and San Joaquin rivers in the San Francisco Bay Delta provide the vast majority of water to the state – around two-thirds of Californians get their water from here, while most of it flows to farming in the Central Valley.

Roughly half of California residents get water from groundwater sources, the largest aquifers of which are found in the Central Valley. About the same proportion of Californians are serviced from the Colorado River, a source also relied upon heavily by other states, Mexico, and Native American communities. California has historically drawn more than its fair share from the Colorado River, going so far as to temporarily reroute its flow in the early 20th century, ultimately creating the Salton Sea.

The final major water source in California is the Russian River, serving citizens mostly in Marin and Sonoma counties. Additional sources providing comparatively minimal supplies, such as desalination plants, may be pulled on more in the imminent future, should conservation and more efficient management not fulfill our water needs.

How does California use its water?

When considering how all of California’s water is distributed across the state, much of it, by ecological necessity, is not destined for human hands or mouths. Roughly half of California’s water is fulfilling some environmental role and can’t be “developed” for human consumption. That covers water needed to maintain aquatic habitats, in federally or state-protected “wild and scenic” rivers, in wildlife preserves, etc. Of the other half of California’s water, the half intended for human use, 80% is used for farming operations, while the remaining 20% goes to urban use.*

How is water distributed throughout California?

Wrangling the water from its source and into systems for human manipulation is managed through a wide range of federal, state and municipal entities, as well as some private organizations, too wonky to get into here. But generally, it’s done through seven major distribution systems: the All-American Canal (at the Mexico border), the State Water Project (statewide), the Central Valley Project, Colorado River delivery systems, the Los Angeles Aqueduct, the Tuolumne River/Hetch Hetchy system in Yosemite, and Mokelumne Aqueduct outside the Bay Area in the Central Valley.

From there, who uses the water, for what, and how much it costs also plays a role in who ultimately dispenses and controls the water. But many of these rules governing water distribution and sale aren’t up to date or efficient, and sometimes they don’t even exist. For example, California laws governing individual well-digging to access groundwater reservoirs aren’t very well developed, leading to some well-wars in the Central Valley, to see who can dig deeper and suck out the most water.

How much water does an individual use in a day?

On average, a person uses 80-100 gallons of water per day. By activity, here’s a rough breakdown of how much of that water is used to:

  • stay hydrated: Men typically need 3 liters (~0.8 gallons), and women 2.2 liters (~0.6 gallons) of water (or whatever watery beverage you prefer) per day.
  • run a dishwasher: The typical dishwasher uses 10 gallons per load, but energy efficient ones use only 5.
  • shower: the typical shower head dispenses 5 gallons per minute, with more efficient models using only 2 GPM. Average showers last about 11 minutes – so anywhere from 22 - 55 gallons are used per shower.
  • flush a toilet: anywhere from 3.5 to 7 gallons of water per flush (GPF), although federal standards now demand that new models only use 1.6 GPF. A typical, hydrated adult with a healthy bladder will go to the bathroom 6-7 times per day, so unless you let the yellow mellow, that’s anywhere from 21 to 49 gallons of water every day, just to go to the bathroom. If you’re using the most efficient toilet model, then you’ll flush only 9.6 gallons per day.
  • wash clothes: High-efficiency clothes washers use 14-25 gallons, but the old-school ones can use up to 40-45 per wash.

Estimate your own daily usage with USGS's handy calculator.

OK, but what about agricultural use?

How much water does it take to grow crops? Will almonds suck California dry? The Los Angeles Times published an incredibly handy infographic, comparing how thirsty commonly grown crops are in California. Keep in mind that a significant portion of the crops grown in California go to feeding livestock, which in turn consume their own direct supply of water. View the full interactive graphic here.

And how much does water cost?

As with deciding any utility’s price, it’s complicated. To better serve conservation efforts, some municipalities have begun proposing alternative rate-structures, such as setting prices based on peak demand times (the more people are using water at a given time, the more it costs), or on total volume, so that rates increase exponentially instead of linearly. Determining exactly how much water costs is a bit too complicated to dig fully into here, but the short answer is: probably not enough.

For those interested, here are some deeper dives into water rate deliberations from the Los Angeles Times, the Wall Street Journal, and the Sacramento Bee.

This is all to say…

Water – where it comes from, how we use it, how much it costs – is a complex ecological and economic system. None of the numbers detailed here should be taken for granted, and are open to fluctuate given new technologies, shifting policies and cultural expectations. Before we throw billions of dollars at desalinating oceans or cloud-seeding, there’s lots we can do to make water use more efficient and strategic, and ultimately resilient in the face of inevitable future droughts.

cynthia hirschhornwater