California Water Challenge

The California Water Challenge is a simulation of some of the tough choices Californians face in seeking to meet the increasing demands on its limited water supplies. The California Water Challenge lets you decide how to bring the state's water supply and demand into balance.
Current Issues: After you take the California Water Challenge, weigh in on current issues such as fines for overuse and mandatory reductions
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Scroll down for a highly visual overview with California Water Facts

How much water do we use?
An average california family of 4 uses around286,000gallons per yearThe average californian uses
196 gallons per day
The US consumes more water per capitathan any other country
California has
per capita
in the nation
9-12 gallons
per shower
25 gallons
for each load of laundry
300 gallons
to water the lawn once
Who uses water?
Used by agriculture:80,500 total farms750,000 acres of land
Used by Residents and Businesses
This displays human water use and not the water that is left untouched in the environment, which represents about half of the water California receives each year.
How do we measure water?
One acre/foot
Enough water to flood an acre with12in of water
Enough water to flood a football field with 9in of water
Annual water usage of two households
Where does my water come from?
In an average year, 200 million acre-feet of precipitation provides the Golden State with its water supply, though this varies widely from year to year.
65% of this is lost through evaporation and other natural events
The remaining 35% stays in the state's system as runoff
30% of this runoff flows into the Pacific Ocean or other salt sinks
The rest is used by agricultural, urban, and environmental purposes
Water is supplied to households, businesses and farms from:
State and Federal Water Projects
Aqueduct from the Mountains
Colorado River
Ground Water
Where water comes from and who uses it has been an important subject since California's inception as a state.

About 75% of the annual precipitation falls north of Sacramento, while more than 75% of the demand for water is south of the capital city.

Most of the rain and snowfall occurs between October and April, while demand is highest during the hot and dry summer months.

Seven major systems of aqueducts and associated infrastructure exist today to capture and deliver water within the state. Two of the most important projects are the federal Central Valley Project and the State Water Project.

In an average year the State Water Project accounts for 4% and the Central Valley Project for 9% of dedicated water supplies via an extensive network of dams, pumping stations, and canals.

Regional suppliers transport water hundreds of miles from the Sierra Nevada's watershed to urban areas in Los Angeles and the San Francisco Bay Area.

The Colorado River and local water projects account for 30% of dedicated water supplies.

Groundwater serves as a critical buffer against drought and climate change.
Locally owned groundwater wells typically account for 30-40% of the state's water supplies.
Overall, groundwater provides about 40-60% of the state's water.
Does water use energy?

Yes! Household use along with pumping, treating and transporting water is energy intensive, using 20% of California’s electricity, 30% of the state’s natural gas not used by power plants, and 88 million gallons of diesel fuel.

This is not surprising, given that millions of gallons are transported hundreds of miles from the natural point of origin in the northern and eastern parts of the state to users in the coastal and southern regions. Understanding the relationship between water and energy is crucial to reducing water-related energy consumption, which not only lowers the cost of water but also provides additional environmental benefits such as reducing the greenhouse gas emissions associated with producing that energy.

Do we have enough water?

By 2030, the Bureau of Reclamation estimates that California will have an annual unmet water demand (or water gap) of almost 4.9 million acre-feet (1.5 trillion gallons) in an average year and more in a dry year. This long-term water gap is one focus of the California Water Challenge, however, this is a simplified take on water in California, as each region has its own water supply and demand that is not connected to other regions or the state as a whole.

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"(21) Miramar Reservoir" by Oleg Bozhenko aka MrGALL - Own work. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons - (modified to black and white) "FoggDam-NT “- Own work (Original text: “I (Bidgee) created this work entirely by myself.”). Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons - (modified to black and white) “PivotWithDrops” - Gene Alexander, USDA Natural Resources Conservation Service, (modified to black and white)