Oroville Dam

• Location


  Lake Oroville lies east of the city of Oroville, 112 km north of Sacramento, California.Construction of the dam began in 1962, and opened in 1967. The dam is built on the Feather River, a tributary of the Sacramento River
• Size


  The lake is the second-largest reservoir in the state, at 210 m deep and has the capacity to store 4.3 billion cubic metres of water. The dam itself is about 230 m high. The Hoover Dam on the border of Nevada and Arizona is 221 m
• Why was it built

  The dam was built by the California Department of Water Resources,and is one of the key features of the California State Water Project (SWP). The purpose of the project was to provide water for arid Southern California, whose local water resources and share of the Colorado River were insufficient to sustain the region's growth.

  Since its completion in 1968, the Oroville Dam has allocated the flow of the Feather River from the Sacramento-San Joaquin Delta into the SWP's California Aqueduct. It provides a major supply of water for irrigation in the San Joaquin Valley, as well as municipal and industrial water supplies to coastal Southern California. It has also prevented large amounts of flood damage to the area—more than $1.3 billion between 1987 and 1999.
• Environmental impacts of dam construction: People

  Areas they live are inundated by water so they have to move homes and are often not compensated for their losses. People who used to farm or fish may be relocated far away from the river and then have to try and get a new job.
• Environmental impacts of dam construction: Plants and animals

  upstream of the dam the river is flooded to make a reservoir, the nature of the river flow downstream is changed and the dam can hold back sediment that normally finds its way downstream. When the river valley is inundated with water animals have to leave and plants and trees are killed. Dams can form a barrier to fish that migrate i.e. salmon.
• Environmental impacts of dam construction: Sedimentation

  rivers slow down when they enter reservoirs meaning sediment is deposited on the reservoir bed. This builds up over time meaning there is less space for water to be stored. Also sediment does not get carried downstream as it normally would changing the natural balance of the river downstream. Farm land is deprived of silt and its nutrient
• Environmental impacts of dam construction: Water quality

  Quality of water in a reservoir can deteriorate. River water contains dissolved oxygen that maintains animal and plant life and prevents chemical reactions that form unwanted pollution. Organic material decomposition, depth of water, temperature and flow can all affect oxygen levels. If farmland was inundated there may be pesticides in the water.
• Environmental impacts of dam construction: Historical sites


  Throughout history people have built their communities in river valleys meaning many archaeological sites, historical buildings and monuments are often in these areas. These heritage sites can be lost when the area is inundated to create a dam.
• Environmental impacts of this dam: impact on wildlife


  deterioration of natural habitats along the river bank

  sediment is trapped by the dam leading to the degradation of habitats downstream.

  fish can't travel down the river - the Chinook salmon and steelhead trouts migration is blocked by the dam
• Environmental impacts of this dam: spillway failure

  erosion in the concrete needed to be repaired but high inflows to the river forced the spillway to be used regardless causing additional damage

  11th feb 2017 - emergency spillway used for the first time and it overflowed into a parking lot

  Feb 2017 the main and emergency spillways threatened to fail leading to the evacuation of 188,000 living near the dam

  the main spillway was reconstructed by Nov 1st 2018
• Benefits: Reduced flooding


  prevented large amounts of flood damage to the area - more than $1.3 billion between 1987 and 1999

  Lake Oroville is required to have 1/5th of the reservoirs storage capacity available for flood control

  Dam is operated to maintain an objective flood control release of 150,000ft3

  December 1964: partially completed dam 70 miles north of Sacramento checked major flooding
• Benefits: Hydroelectric power


  Edward Hyatt power plant is the largest hydroelectric facility in the State water system and has the capacity to generate 819 megawatts.
• Climate change and the future

  drought can cause the plant to be taken offline

  happened for the first time in august 2021

  as climate change causes more droughts it is likely to go offline many more times