Water Information

Water is an essential resource. Without it, taps run dry, streams stop flowing, businesses suffer and crops die.

California relies on an elaborate network of water storage and delivery systems to supply cities, farms, businesses and the environment with adequate water year-round. The systems are necessary because California’s Mediterranean-style climate means we receive little or no rain for months at a time. The ability to store and move water has made it possible for California to grow and prosper.

Precipitation varies from place to place, season to season, and year to year. Most of the state’s rain and snowfall occurs in the northern part of the state, while most of the demand for water is along the coast and in the valleys to the south of Sacramento. California receives most of its rain and snowfall between October and April, though the highest demand for water is in the hot, dry summer months.

California’s water system was developed to address that variability. Two important projects in that system are the State Water Project (SWP) and the federal Central Valley Project (CVP). The SWP and the CVP bring water from Northern California through the Sacramento-San Joaquin River Delta for delivery to users in the San Joaquin Valley, parts of the San Francisco Bay Area and Southern California.

The California Department of Water Resources California Water Plan 2013 breaks down how available water is used throughout the state for environmentalagricultural and urban purposes. 

Challenges to our water supply system

Though this system has served California well in the past, it faces a number of challenges that threaten the reliability of its water supplies.

Ecological problems in the Delta

The Sacramento-San Joaquin Delta, the hub of our state’s water system, is in an ecological collapse that has triggered major cutbacks in water deliveries for many areas of the state and continues to threaten the state’s economy and species such as salmon and Delta smelt.

Growing pressure on our water delivery system

Constructed primarily in the mid-20th century, the state’s water infrastructure is struggling to keep up with the state’s population growth as well as new environmental requirements to protect species and habitats.

Climate change

Experts agree that long-term climate change is occurring and that it is already affecting California’s water resources. Warming temperatures, changing rain and snowfall patterns and rising sea levels will profoundly affect the state’s ability to manage water supplies and other natural resources.

Dry conditions

California is prone to frequent dry spells, including our current record-breaking drought. California’s water year 2014 – which ended Sept. 30 – will go down as one of the driest years in the state’s recorded history, resulting in a dismally low 5% of water deliveries from the State Water Project and thousands of acres of cropland idled, according to figures from the California Department of Water Resources.


Proposition 1 – the Water Quality, Supply and Infrastructure Improvement Act of 2014 – is a $7.5 billion general obligation bond measure placed on the November 4 ballot by a near-unanimous, bipartisan vote by the Legislature and the signature of Gov. Jerry Brown. Voters overwhelmingly passed the measure in November 2014 with a 67% - 33% margin. Proposition 1 will help fund investments in water projects and programs as part of a statewide, comprehensive water plan for California.

In addition to funding programs from water conservation to recycling to groundwater cleanup to water storage, Proposition 1 is intended to leverage additional local and regional funds to provide a total investment of $25 billion to $30 billion to address California’s water needs.

The package puts California on a path to long-term solutions, but many of its elements will take years to implement.

Local water agencies also continue to invest to local and regional programs such as water conservation, water recycling, groundwater storage and other strategies to diversify water sources and improve reliability.