New Bullards Bar Dam

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New Bullards Bar Dam
Bullards Bar Dam - face.jpg
Official name New Bullards Bar Dam
Location Yuba County, California
Opening date 1969
Operator(s) California
Dam and spillways
Impounds North Yuba River
Height 645 ft (197 m)[1]
Length 2,587 ft (789 m)[1]
Spillway type Concrete chute, 3x radial gates
Spillway capacity 160,000 cu ft/s (4,500 m3/s)
Reservoir
Creates New Bullards Bar Reservoir
Total capacity 969,600 acre·ft (1,196,000 dam3)[2]
Catchment area 489 sq mi (1,270 km2)[2]
Surface area 4,810 acres (1,950 ha)[2]
Power station
Hydraulic head 1,306 ft (398 m)[3]
Turbines 2x Pelton
Installed capacity 340 MW[3]
Annual generation 1,314 GWh[3]

New Bullards Bar Dam is a variable radius concrete arch dam in California on the North Yuba River. Located near the town of Dobbins in Yuba County, the dam forms the New Bullards Bar Reservoir, which can hold about 969,600 acre·ft (1,196,000 dam3) of water. The dam serves for irrigation, drinking water and hydroelectric power generation.

History[edit]

New Bullards Bar Dam was constructed by the Yuba County Water Agency. The agency was created through an act of the state legislature in 1959 specifically to construct a flood control reservoir in response to a flooding event in 1955. The bulk of the financing for the dam came from the issuance of revenue bonds. The dam was completed in 1969.

The dam is the fourth constructed on the Bullards Bar site, succeeding diversion dams built in 1899 and 1900 as well as a 200-foot (61 m) concrete arch dam built by the Yuba River Power Company and transferred to Pacific Gas and Electric in 1922. The dam generated power from 1924 until its inundation by the New Bullards Bar Reservoir in 1969. Although the 1899 diversion dam was washed away, the 1900 dam is still in place about a quarter mile (0.4 km) downstream from the present dam.

Operations[edit]

New Bullards Bar Reservoir provides flood control space between September 15 and May 31 of each year. There are 170,000 acre feet (210,000,000 m3) of flood control storage space between October 31 and March 31.

The reservoir controls water flows from the North Yuba River as well as from the Middle Yuba River and Oregon Creek via diversion tunnels. The Our House Diversion Dam is situated on the Middle Yuba about 8 miles (13 km) above its mouth and diverts water into a 5.5-mile (8.9 km) tunnel with a capacity of 810 cubic feet per second (23 m3/s), running northwest to the Log Cabin Diversion Dam on Oregon Creek. From here the combined waters of the Middle Yuba and Oregon Creek are sent west into a shorter 1.3-mile (2.1 km) tunnel with a capacity of 1,100 cubic feet per second (31 m3/s) into the eastern (Willow Creek) arm of New Bullards Bar Reservoir.[4] The diversions add about 173.9 square miles (450 km2) to the effective catchment area of New Bullards Bar Reservoir.

The dam furnishes water to the New Colgate Powerhouse, which is located 5.2 miles (8.4 km) downstream. The added distance increases the head (i.e. elevation change). Its two Pelton wheels have a combined capacity of 340 megawatts and are the largest of their kind in the world.[5] At maximum generation, the powerhouse utilizes a flow of 3,430 cubic feet per second (97 m3/s), and is an important source of peaking power for the region.[3] The small Fish Release powerhouse was constructed in 1986 at the base of the dam. It has a capacity of 150 kilowatts and generates power from water releases for fish on the Yuba River. Total annual generation at New Colgate Powerhouse is about 1,314,000 megawatt hours (MWh), while the Fish Release powerhouse produces 1,300 MWh.[6]

A 14-foot (4.3 m)-diameter penstock drains water from the New Bullards Bar Reservoir several miles through a mountain and down a large hill to deliver water to the Colgate Powerhouse. In 2006 a 168 inch (4.3 m) butterfly valve was designed and manufactured in Europe for installation in the penstock at the top of the hill to protect the powerhouse from flooding in the event that an earthquake or other event caused the penstock to rupture. This valve uses a design similar to that of the dam's base release works.

Images[edit]

A view of Bullards Bar dam and reservoir from Marysville Rd

See also[edit]

References[edit]

External links[edit]

Coordinates: 39°23′36″N 121°08′35″W / 39.39333°N 121.14306°W / 39.39333; -121.14306