What are groundwater basins in California?

Groundwater basins in California refer to underground layers of water-bearing rock, also known as aquifers, that store significant amounts of water. These basins are crucial for supplying water to many regions in California, especially during times of drought or when surface water supplies are low. The geology of California includes various formations that can hold groundwater, making these basins essential for agricultural, municipal, and industrial water use.

The other options describe different aspects of water management and natural water systems. Surface rivers do not pertain to groundwater basins, as they refer to above-ground water flow. Wetlands play a significant role in ecological filtering functions but are not classified as groundwater basins. Similarly, reservoirs, while important for collecting and storing surface runoff and rainwater, do not represent the underground systems that groundwater basins exemplify. Understanding the role and function of groundwater basins is vital for effective water resource management in California, given the state's complex water needs and challenges.