This issue brief examines urban, agricultural, and environmental water use trends in California using the most recent statewide data and publicly available information. California’s population and economy have grown dramatically since the 1960s, while total urban and agricultural water use has increased only modestly, reflecting a dramatic decoupling of water use from growth. Water dedicated to or remaining within the environment is a critical part of the state’s overall water system, but important questions remain about how it should be defined, categorized, and accounted for. Through this brief, we aim to provide a clear understanding of how water is allocated and used statewide and to equip researchers, policymakers, advocates, and other stakeholders with the information they need to drive meaningful policy and implementation change. 

• Environmental flows are a critical part of California’s water system, but determining how much water is truly dedicated to environmental purposes is difficult due to limited direct measurement, reliance on assumptions, and inconsistent or unclear definitions. 

• Environmental flow trends closely mirror precipitation patterns and vary significantly across the state, with most dedicated environmental flows concentrated in the North Coast region while population is concentrated in coastal and southern parts of the state. 

• California’s population more than doubled and the economy grew sixfold since the 1960s, while total urban and agricultural water use increased by less than 20%, reflecting a clear decoupling of water use from growth. 

• Total urban and agricultural water use peaked at 46.5 million acre-feet in 2007 and declined to 39.1 million acre-feet by 2022. Agricultural water use accounts for about 80% of total water use. Urban water use has declined across all hydrologic regions.

• Much of the available water use data is based on modeled estimates rather than direct measurement. Strengthening statewide measurement and reporting systems and improving terminology and classification would help inform more effective decision-making.