What uses most of California’s water supply?

Editor’s note: This story has been updated to correct that the environment uses the most water in the state.

SAN DIEGO (FOX 5/KUSI) — Even following a water year like 2023 and historic flooding events in recent months, California continues to see the need to conserve water.

A water year, or a “wet year,” according to the United States Geological Survey, is defined as a 12-month period in which precipitation levels are measured. Generally, it takes place between October 1 and September 30 in the northern hemisphere.

According to the California Department of Water Resources, while California gets 75% of its rain and snow from the watersheds in the northern portion of the state, 80% of water demand comes from the southern two-thirds of the sate.

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Residential water use by urban, suburban and rural communities is highest in the San Francisco Bay Area and the southern coast, which includes San Diego County, but in general, per-capita water use has been falling. Statewide, the average monthly residential water usage has dropped since 2021.

This follows an agreement last year made between California and six other states that rely on the Colorado River to cut back on water usage over the next three years.

In its analysis of water year 2023, the DWR says the Colorado River Basin benefited from the wet winter and saw improved amounts of water in Lake Mead and Lake Powell, the two largest reservoirs in the United States.

The latest data from the State Water Resources Control Board shows statewide, the daily average monthly residential gallons per capita in 2023 was 83 gallons. That’s compared to 92 in 2022 and 101 in 2021.

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The south coast region followed that downward trend, dropping to a daily average of 73 gallons last year from 85 in 2022 and 90 in 2021.

Since 2018, the State Water Resources Control Board has been trying to push for regulation that manages urban water use by creating a water budget for water agencies in California, but urban water use only makes up a small portion of how much water the state actually consumes.

According to the Public Policy Institute of California, communities only use 10% of the state’s water.

Half of all water in California is used by the environment, followed by agriculture which uses 40%. However, agriculture uses about 80% of the state’s developed water (water that is controlled and managed).

The California Department of Food and Agriculture says California grows over a third of the country’s vegetables and about three-quarters of fruits and nuts. The agribusiness of growing 400 different commodities would not be possible without irrigation.

Imagine 31 million football fields covered with a foot of water. That’s how much water the DWR says it takes to irrigate approximately 9.6 million acres.

While last year’s wet months gave California some needed reprieve from previous years of drought, water conservation requires a strong collaborative effort between residents, businesses, water managers and farmers to ensure the state’s available water supply keeps up with statewide demand.

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