Temperance Flat Dam facts for kids
Quick facts for kids Temperance Flat Dam |
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Map showing reservoir outline of the proposed reservoir at RM 274, at elevation 985 ft (300 m). The reservoir would partially inundate both Millerton and Kerckhoff reservoirs.
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| Country | United States |
| Location | Fresno / Madera counties, near Auberry, California |
| Coordinates | 37°02′03″N 119°37′45″W / 37.0342°N 119.6293°W |
| Status | Proposed |
| Construction began | 2021 (projected) |
| Opening date | 2030 (projected) |
| Construction cost | $2.5–3.3 billion |
| Owner(s) | U.S. Bureau of Reclamation |
| Dam and spillways | |
| Type of dam | Roller-compacted concrete gravity arch |
| Height | 665 ft (203 m) |
| Length | 1,600 ft (490 m) |
| Spillway type | Uncontrolled ogee crest |
| Spillway capacity | 145,000 cu ft/s (4,100 m3/s) |
| Reservoir | |
| Creates | Temperance Flat Reservoir |
| Total capacity | 1,260,000 acre⋅ft (1,550,000 dam3) |
| Catchment area | 1,600 sq mi (4,100 km2) |
| Surface area | 5,700 acres (2,300 ha) |
| Power station | |
| Type | Conventional |
| Turbines | 3 |
| Installed capacity | 160 MW |
| Annual generation | 84 GWh |
The Temperance Flat Dam is a proposed project for a new dam on the San Joaquin River in California. It would be built west of Auberry, California. The main goal of this dam is to hold more water in the upper San Joaquin River area. If built, it would more than double the amount of water that can be stored there.
This project is quite debated. Many people are concerned because it would flood beautiful canyons and important historical places along the river. It would also affect how much hydroelectricity (power from water) is made upstream. The government agency in charge, the Bureau of Reclamation, thinks it will cost between $2.5 billion and $2.6 billion to build. Other groups estimate the cost could be even higher. At 665 feet tall, Temperance Flat Dam would be the second tallest dam in California. It would also be the fifth tallest dam in the entire United States.
In 2014, a politician named Representative Jim Costa suggested a law to allow the dam to be built. The Bureau of Reclamation then shared a report about how the dam might affect the environment. This dam is one of three big water storage projects that could get money from a special water bond. People voted on this bond in November 2014.
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What the Dam Would Do
The U.S. Bureau of Reclamation is the agency that would build and run the Temperance Flat Dam. They have looked at different places to build the dam along the San Joaquin River. They also considered different types of dams, like those made of rock or concrete. These dams could be different heights and hold different amounts of water.
Dam Location and Size
The Bureau of Reclamation decided that the best place for the dam is at a spot called River Mile (RM) 274. This spot is in the upper part of Millerton Lake, which is the reservoir for Friant Dam. This means some of the new water storage would replace water already in Millerton Lake. Also, a very tall dam could flood Kerckhoff Lake upstream.
Water Storage Benefits
The Temperance Flat Dam would help California by catching a lot of water from winter and spring rains. This water often flows downstream and is lost because there isn't enough space to store it. Experts believe the dam could save between 165,000 and 183,000 acre-feet of water each year. By having more surface water from the San Joaquin River, farmers in the San Joaquin Valley would not need to pump as much water from underground. This helps protect underground water supplies.
Power Generation
The new dam would also have a larger system to make hydroelectric power. This system could produce 160 megawatts (MW) of electricity. This is important because the new reservoir would flood some existing power plants.
Impact on Fish
The Bureau of Reclamation also looked at how the dam might affect chinook salmon. These fish are important to the river's ecosystem. They estimated that the dam could lead to a small increase in the number of spring-run chinook salmon over time. However, in some situations, the number of salmon could actually decrease.
Concerns About the Dam
Building the Temperance Flat Dam would have some serious negative effects. Many groups are worried about what the dam would change.
Loss of Hydroelectric Power
If the Temperance Flat Reservoir fills up too high, it would flood several power plants that are part of the Big Creek Hydroelectric Project. These plants currently make a lot of electricity. This means the Temperance Flat Dam project could actually cause a net loss of hydroelectric power. Even with the new power system at Temperance Flat, it might only replace 81% to 91% of the power that would be lost. Even if more power is made at Friant Dam, there would still be less power overall. For example, another dam of similar size, New Bullards Bar Dam, makes almost 16 times more power each year than the proposed Temperance Flat Dam.
Environmental and Cultural Impacts
The Bureau of Reclamation has stated that building the dam would have "unavoidable and/or disproportionately high and adverse" impacts. This means there would be very serious negative effects on many things:
- Air Quality: The air might get worse during construction.
- Water Quality: Measures to improve water quality downstream of Millerton Lake were removed from the plans.
- Fish and Wildlife: The dam would harm fish and other animals that live in the river and surrounding areas. This includes bald eagles, several types of bats, ringtails, American badgers, and San Joaquin pocket mice. Western pond turtles and the California tiger salamander are also found here.
- Plants and Wetlands: Important plants and wet areas would be affected.
- Climate Change: The project would contribute to greenhouse gas emissions.
- Cultural Sites: The proposed reservoir would flood many important historical and cultural sites. Local Native American tribes have found 30 sensitive sites in the area, and one is considered sacred.
- Agricultural Resources: Farming areas could be impacted.
- Noise and Visuals: There would be more noise and changes to the natural views.
River and Habitat Changes
The proposed reservoir would cover about 18 miles of the San Joaquin River. This area includes beautiful canyons and exciting whitewater rapids. The dam would also reduce the amount of water flowing to a sensitive area called the Sacramento–San Joaquin River Delta. Less water flow could harm the places where salmon lay their eggs and where young salmon grow.
Concerns About Effectiveness
Some environmental groups, like Friends of the River, are not sure if the Temperance Flat project is a good way to solve California's water needs. They call it "an expensive and ineffective solution." Also, building the dam at RM 274 would reduce the amount of water that Millerton Lake can hold by 75,000 acre-feet. This is a significant amount of water.
