How Do Californians Get the Water They Need?

California Science Standard 3.e Students know the origin of the water used by their local communities.

Shasta Dam, California Where does the water in the Sacramento River come from? Is the water in the river fresh water or salt water? Why would a community consider building a dam?

Vocabulary Watershed – The area of land in which water runs off into a particular system of creeks and rivers.

Vocabulary Dam – A barrier across a river that controls the river’s flow.

Vocabulary Reservoir – A body of water stored for future use.

Vocabulary Aqueduct – A pipe or channel that is used to transport water.

Vocabulary Groundwater – Water that is in soil and rocks below Earth’s surface.

Water Resources Freshwater is vital to human health. It is also necessary for growing many kinds of plants that people rely on for food.

Water Resources Fresh water is vital to human health. It is also necessary for growing many kinds of plants that people rely on for food. What are some other ways that people use freshwater resources? What are some ways that people use saltwater resources?

Local Water Sources Most communities in California get their fresh water from lakes and rivers. These communities’ water supply depends on how much rain and snow falls during the year. When rain or snow falls it collects in a watershed. As snow melts from the top of a mountain, it flows down in small creeks. The creeks join to form rivers. The rivers join to form larger rivers. This system of creeks and rivers “drains” the watershed.

Local Water Sources A community may be able to take its water directly from the rivers of a watershed. The amount of water in a river changes from season to season. During spring, rivers may have plenty of water from melted snow. Dry seasons, the water level may be very low. There may not be enough water to meet the community needs.

Local Water Sources Many communities build dams to store water for dry seasons. In California, dams are often used to hold water. Water collects behind a dam to form a reservoir. This water is being stored for future use.

Local Water Sources If a community uses more water than is available from its watershed, it may need to bring in water from another watershed. The community would use an aqueduct, a pipe or channel, to transport water.

Local Water Sources Los Angeles uses two large aqueducts. The first aqueduct was built in the early 1900’s. As the city grew, so did it’s need for water. The second aqueduct was build in How has Los Angeles provided its citizens with water?

Groundwater Not all of California’s water supply is surface water. About 40% of California’s population uses groundwater. Groundwater is water under Earth’s surface located in the spaces between rocks and soil. Not all the rain that falls on land runs off into creeks and rivers. Some soaks in the soil and inside rocks.

Groundwater As water moves through these spaces, some of it sticks to soil particles, but most of the water continues moving downward. It soon reaches an area that is filled with water. This is called a water table.

Groundwater You can think of a water table as a line under the ground. The ground above the line has air gaps in it. The ground below the line is totally filled with water. The water table rises during wet season, and drops during dry seasons.

Groundwater Groundwater is can be found in rocks that have pores, or small openings. The pores and spaces allow water to pass between them. A rock layer can store a lot of water and let it flow through. This is called an aquifer. Water can be obtained from them by drilling wells.

Groundwater A well is drilled from the surface to a spot below the water table. A pump is used to bring the water to the surface. A well can supply a house, neighborhood, or even a city. If too much water is removed from a well, the water table will drop. This will cause the well to become dry. People should not use more well water than is replaced naturally by rainfall. Why?

Review Time