Castaic Dam facts for kids
Quick facts for kids Castaic Dam |
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View from the northeast.
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| Location | Castaic, United States |
| Coordinates | 34°31′10″N 118°36′25″W / 34.5194°N 118.6070°W |
| Opening date | 1973 |
| Dam and spillways | |
| Type of dam | Earthfill |
| Impounds | Castaic Creek |
| Height | 340 ft (100 m) |
| Length | 5,200 ft (1,600 m) |
| Dam volume | 44,000,000 cu yd (34,000,000 m3) |
| Spillway type | Uncontrolled overflow |
| Reservoir | |
| Creates | Castaic Lake |
| Total capacity | 325,000 acre⋅ft (401,000,000 m3) |
| Catchment area | 153.7 sq mi (398 km2) |
| Surface area | 2,235 acres (904 ha) |
| Power station | |
| Installed capacity | 11 MW |
The Castaic Dam is a large earth-fill dam located in northwestern Los Angeles County, California. It sits near the town of Castaic. Even though it's built on Castaic Creek, most of the water in the lake behind it doesn't come from this creek. Instead, Castaic Lake is the end point for the West Branch of the California Aqueduct. This aqueduct is a big part of the California State Water Project, which moves water across the state.
The California Department of Water Resources finished building the dam in 1973. Castaic Lake can hold a huge amount of water, about 325,000 acre-feet (401,000,000 m3). This water is super important because it provides drinking water for many people in the western part of the Greater Los Angeles Area.
Contents
How Big is Castaic Dam?
Castaic Dam is an earth-fill dam. This means it's made mostly of compacted earth, rocks, and clay. Its outer surfaces are covered with large boulders and smaller cobble-sized rocks. This covering helps protect the dam from erosion caused by wind and water.
The dam stands about 340 feet (100 m) tall above the streambed. That's taller than a 30-story building! It stretches 5,200 feet (1,600 m) long, which is almost a mile. The base of the dam is very thick, about 2,350 feet (720 m) wide at its widest point.
When there's too much water, like during heavy rains, extra water can flow out through a special concrete overflow area called a spillway. This spillway is on the west side of the dam. The water then goes into a smaller pool called Castaic Lagoon. People often call Castaic Lagoon the "Lower Lake," while the main Castaic Lake is known as the "Upper Lake."
Castaic Lake can hold a total of 325,000 acre⋅ft (401,000,000 m3) of water. Most of this water, about 31,000 acre-feet (38,000,000 m3), is used regularly. A larger part, 294,000 acre-feet (363,000,000 m3), is kept as an "inactive" reserve. This reserve water is only used during very dry times or if water deliveries from other places are stopped. For example, it was used in 2014 during a drought. When the lake is full, its surface covers about 2,235 acres (904 ha), and it has about 29 miles (47 km) of shoreline. The smaller Castaic Lagoon holds 5,560 acre⋅ft (6,860,000 m3) and covers 200 acres (81 ha).
How Castaic Dam Works
Water Supply for Millions
Castaic Lake is one of the two main storage lakes for the West Branch of the California Aqueduct. This aqueduct is a huge system that brings water from the Sacramento–San Joaquin River Delta in northern California all the way south.
Here's how it works:
- Water travels down the San Joaquin Valley through the California Aqueduct.
- It's then pumped over the Tehachapi Mountains.
- After the mountains, the aqueduct splits into two main branches.
- The East Branch sends water to places like Riverside and San Bernardino.
- The West Branch supplies water to western Los Angeles and parts of Ventura County.
The water in the West Branch first enters Pyramid Lake. From there, it travels through a long tunnel, about 7.2-mile (11.6 km) long, called the Angeles Tunnel. This tunnel leads to the upper part of Castaic Lake. Together, Pyramid Lake and Castaic Lake can store about 505,000 acre⋅ft (623,000,000 m3) of water. This is roughly a year's supply for the areas they serve!
Normally, Castaic Lake acts like a giant water bank. It holds water from the California Aqueduct and releases it when people need it most, especially during busy times of the day. But the dam and lake also serve as an "emergency storage" pool. This means if water deliveries from northern California are stopped for any reason – like construction, equipment problems, or a severe drought – there's still a large supply of water available.
Most of the water released from Castaic Dam flows to Los Angeles through a system called the Foothill Feeder. This water travels about 20 miles (32 km) south through a very large pipeline, about 16.75-foot (5.11 m) wide. It goes to the Jensen Filtration Plant near San Fernando. Here, the water is cleaned and then connected to the city's water system. The pipeline is mostly underground and has very thick walls, almost 4 feet (1.2 m) thick!
Water from the Foothill Feeder is also stored in the smaller Los Angeles Reservoir in the San Fernando Valley. From there, it continues south through another pipeline, the Sepulveda Feeder, which is about 45-mile (72 km) long. This feeder provides water to Los Angeles and other cities in southern Los Angeles and Orange Counties. Many water agencies get their supply from this system. In total, up to 12 million people in these areas get all or some of their water from Castaic Lake and its feeder system.
A smaller amount of water is given out by the Castaic Lake Water Agency. This agency serves about 195 square miles (510 km2) in Ventura and northern Los Angeles counties. They provide water to about 287,000 people.
Generating Power with Water
Castaic Dam also helps make electricity! The 11 MW Foothill Feeder hydroelectric power plant is located right at the bottom of the dam. It creates electricity when water is released from the lake and flows towards Los Angeles. In 2009, this plant generated 49 million kilowatt hours of electricity.
There's an even bigger power plant called the Castaic Pumped-Storage Plant. This plant is located at the upper end of the west arm of Castaic Lake. A smaller dam, the Elderberry Forebay Dam, separates a part of Castaic Lake called the Elderberry Forebay. This forebay acts as the lower reservoir for the pumped-storage operation. Pyramid Lake, about 7.2 miles (11.6 km) away, serves as the upper reservoir.
Here's how pumped-storage works:
- When people need a lot of electricity, usually in the afternoon, water is released from Pyramid Lake.
- This water flows down to Castaic Lake, turning turbines to generate electricity.
- At night, when less electricity is needed, extra power is used to pump the water back up from Castaic Lake to Pyramid Lake.
This system helps the Department of Water Resources save money on electricity costs for running the California Aqueduct. In 2009, the Castaic pumped-storage plant generated a net 465 million KWh of electricity.
Images for kids
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View from the northeast.
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The Castaic Lake.
