Data Sources: United States Geological Survey (USGS)

National Water Information System
USGS’ National Water Information System (NWIS) webpages provide access to water-resource data collected for surface water, groundwater, water quality, and water use throughout the United States, territories, and protectorates. The USGS investigates the occurrence, quantity, quality, distribution, and movement of surface and underground waters, and provides data to the public via the NWIS. Additional information and access to USGS’s NWIS may be found at USGS NWIS.

California Water Science Center
USGS' California Water Science Center works with state and federal agencies to conduct studies that provide water managers the knowledge needed to effectively allocate water resources. Additional information and data on surface water, groundwater, and water quality may be found at USGS Water Science Center.