Santa Ana water resource basin

Santa Ana water resource basin (HUC 180702) is one of three hydrologic basins within the Southern California Coastal water resource subregion and is one of approximately 2,200 water resource basins in the United States hydrologic unit system. The Santa Ana water resource basin is a third-level subdivision of the United States hydrologic unit system.

The Santa Ana basin is approximately 2680 mi2 and includes the drainage into the Pacific Ocean from the San Gabriel boundary to the Moro Canyon drainage boundary near Laguna Beach. The Santa Ana basin is composed of four fourth-level hydrological units called water resource subbasins (formerly known as water resource cataloging units), each with its own 8-digit hydrologic unit code. The Santa Ana water resource basin is home to approximately 6 million people. The Santa Ana Integrated Regional Water Management Region and Santa Ana Watershed Project Authority oversee water systems in the basin. The most significant water feature is the basin is the Santa Ana River. Secondary features include Lake Perris and Lake Elsinore.