What does surface water in California primarily consist of?

Surface water in California primarily consists of water from rivers and reservoirs. This is because surface water refers to any water that collects on the surface of the ground, including rivers, lakes, and reservoirs, where water is stored for various uses such as irrigation, drinking, and recreational activities. California has a complex system of rivers and reservoirs that manage the state's water supply, particularly given the state’s varying climate and seasonal droughts.

While rainwater runoff does contribute to surface water, it is not the sole component, and surface water is more explicitly categorized through its collection in rivers and man-made reservoirs. Groundwater aquifers are an entirely different category, sourced from below the ground, and although stormwater management systems play a role in managing surface runoff, they do not directly represent the primary sources of surface water. Therefore, the most accurate characterization of surface water in California is indeed the water collected and flowing in rivers and stored in reservoirs.