California’s Water Resources Chapter 13A, Section 2

California’s Water Supply The main sources of California’s freshwater supply are precipitation, surface water, and groundwater California receives an average of about 58 cm of precipitation per year Northern CA and mountains receive most of the precipitation Some of CA’s precipitation flows back into the lakes, rivers, and streams that make up the state’s drainage basins; supplies half of the freshwater needs for the year One of CA’s major sources of fresh water is the Colorado River Some precipitation seeps into the ground to become groundwater; accounting for 30% of fresh water used Most groundwater is used in the area from which the water is withdrawn Desalination – removal of salt from ocean water to obtain fresh water

California’s Average Annual Precipitation

California’s Drainage Basins

Concept Check What is desalination? Desalination is the removal of salt from ocean water to obtain fresh water.

California’s Water Projects To meet freshwater needs throughout the state, California has an intricate network of water storage and distribution systems, or water projects Aqueduct – pipe, or channel, through which water flows from a higher elevation to a lower elevation The Los Angeles Aqueduct carries water 359 km from the Owens River east of the Sierra Nevada, providing L.A. with water since 1913 California’s State Water Project (SWP) is one of the nation’s largest water distribution systems, transporting water from northern CA to southern The federal government has also constructed major water projects in CA

California’s Water Projects Yellow = Federal Green = Local Red = State

Water Needs Most of California’s water supply is used to grow crops The rest is used in homes, businesses, and industries, or has been set aside for recreation or wildlife use About 80% of fresh water used each year goes toward irrigating crops Think of all the ways you use water, this adds up to about 380 liters per person per day The major use of water in industry is as a coolant—either to cool products or the equipment used to make products CA preserves some streams and rivers as fisheries and as recreation zones, not diverting the water from these areas

Assignment Read Chapter 13A, Section 2 (pg. CA 13-CA 19) DO Section 13A.2 Assessment #1-7 (pg. CA 19)