Keswick Dam

Keswick Dam
Country	United States
Location	Shasta County, California
Coordinates	40°36′43″N 122°26′45″W / 40.61194°N 122.44583°W / 40.61194; -122.44583Coordinates: 40°36′43″N 122°26′45″W / 40.61194°N 122.44583°W / 40.61194; -122.44583
Construction began	1941
Opening date	1950
Owner(s)	U.S. Bureau of Reclamation
Dam and spillways
Type of dam	Concrete gravity
Impounds	Sacramento River
Height	157 ft (48 m)
Length	596 ft (182 m)
Dam volume	214,000 cu yd (164,000 m3)
Spillways	Gated overflow
Spillway capacity	250,000 cu ft/s (7,100 m3/s)
Reservoir
Creates	Keswick Reservoir
Total capacity	23,800 acre·ft (29,400,000 m3)
Catchment area	6,380 sq mi (16,500 km2)
Normal elevation	601.6 ft (183.4 m)
Power station
Turbines	3
Installed capacity	117 MW
Annual generation	383 million KWh

Keswick Dam is a concrete gravity dam on the Sacramento River about 2 miles (3.2 km) northwest of Redding, California. Part of the Bureau of Reclamation's Central Valley Project, the dam is 157 feet (48 m) high and impounds the Keswick Reservoir, which has a capacity of 23,800 acre·ft (29,400,000 m³). Its power plant has three turbines with a generating capacity of 117 megawatts (MW), uprated from the original 75 MW in 1992. The dam and reservoir serve as a forebay to regulate peaking power releases from the Shasta Dam upstream. The electrical substation at Keswick Dam distributes power from the Keswick power plant, the power plants at Trinity Dam and Lewiston Dam, the Judge Francis Carr Power plant near Whiskeytown Lake and the Spring Creek Power plant, which is located just northwest of Keswick Dam.

History

Early proposals

Keswick Dam was part of the Central Valley Project. This was started due to unequal water allocation, which left some landowners with no water supply, especially during the summer season, when water diversions for irrigation and domestic use were required in prolonged hot and dry weather.^[1] Water scarcity started in the 19th century in the gold-mining era. The discovery of gold mines in the 1840s attracted a flood of immigrants to California. After a few years, many immigrants moved into agriculture as it appeared to provide more stability than gold mining. Central Valley had fertile soils, abundant water, and a flat gentle topography suitable for farming.^[2] The California Legislature immediately enacted laws to deal with the state's water scarcity issue, and adopted riparian water rights.^[3] This law had limitations: the owners of land bordering water had a right to a reasonable amount of that water, but owners whose land did not border bodies of water had no rights to any of the water. Due to the usage restrictions arising from the riparian rights, the government directed state engineers to come up with a plan for the entire state that would accomplish a fair distribution of water for irrigation and domestic uses. An increase in demand for food caused a shift from small-scale farming to large-scale intensive farming. The low topography of the land caused flooding in the winter rainy season, but severe drought followed in summer months. Low water flow caused an increase in salinity, which resulted in the intrusion of salt in some parts of the valley, especially in the Bay. The Keswick project was primarily intended for irrigation purposes, but it became a multipurpose project for flood control, improvement in navigation of the Sacramento River, the supply of water to domestic and industrial users, the generation of electric power, the conservation of fish and wildlife, the creation of opportunities for recreation, and the enhancement of water quality.^[1]

Central Valley Project (CVP)

The CVP is a major water-conservation development extending from the Cascade mountain range in the north to the semi-arid but fertile plains along the Kern River in the south. The state legislature created the CVP in 1933, but construction did not begin until the federal government assumed control of the project. The CVP's initial features were authorized for construction by the U.S. Army Corps of Engineers. The funds for the construction of the first features of the Central Valley Project were provided by the Emergency Relief Appropriation Act of 1935. Later, the U.S. Bureau of Reclamation took over construction and operation of the CVP, and the project became subject to reclamation law under the 1937 act with three objectives: to regulate rivers and improve flood control and navigation, to provide water for irrigation and domestic use, and to generate power. As time progressed and additional canals, power plants, and dams were built, the CVP's role in the region's water structure became more complex.

The Keswick Dam is part of the CVP's "Shasta Division," which also includes the Shasta Dam. ^[4] Keswick Dam acts as Shasta Dam’s afterbay, stabilizing the erratic water flow released through Shasta power plant. Keswick Reservoir captures water diverted from the Trinity River through the Trinity River division.^[5] Keswick power plant further generates power using the Sacramento River.

Construction

Keswick Damm was named after Lord Keswick, the president of the Mountain Copper Company Limited. The project contract was initiated by the U.S. Bureau of Reclamation with Guy F. Atkinson Company and Kiefer Construction Company and started operation in August 1941.^[4] Operations began immediately, but a loss of labor was experienced due to problems in the Central Valley, but the U.S. Bureau of Reclamation gave it the go ahead. By the end of 1941, the foundations were completed, despite the labor challenges, by the Guy F. Atkinson Company. During the construction, weather changes were another issue. In the summer months, the workers had to spray water over the aggregates to lower the temperature during extremely hot weather. In the winter, workers heated the mixture to keep the temperatures above 50 degrees. During rainy seasons the construction was stopped due to flooding.[3] In 1944, during the end of World War II, there was a strike by workers for about a month due to the Guy F. Atkinson Company's earlier agreement to raise workers’ wages. Workers returned after a promise by the War Labor Board to consider the wage issue, and at the end of 1944, the agency increased the wages. In December 1947 exhaustion of funds had altered the building of the dam; however, the powerhouse structure was completed. Atkinson-Kier completed the Keswick spillway and repaired eroded portions of the spillway apron in July 1948. Wismer and Becker installed two of the generators at Keswick powerplant in 1949. Reclamation placed generator Units Two and Three into operation. The firm placed the fifty by fifty-foot spillway gates at Keswick early in 1950, and they started operation on February 20. Wismer and Becker installed the final generating unit at Keswick power plant on March 31, 1950 ^[4]

Hydro-meteorological aspects

Climate

The climate in Shasta County can be characterized as hot and dry in the summer, and cool and wet in winter, with the best climate occurring in the spring and fall seasons. The simplest method of analyzing the climate of a place is by using statistics to obtain the average annual rainfall and temperatures.^[6] The heavy precipitation period falls in the months of October through March, with average annual precipitation of about 69 inches. June through September receives very low rainfall, reducing the inflow. Temperatures are very high in summer in the range from ~85 to 90◦F. In winter temperatures are lower, with an average of 40◦F.^[7] In summer, there is a significant increase in discharge from the dam due to greater demands for water, especially for agricultural use. High temperatures increase the rate of evaporation, so more water is needed to sustain crops.

Hydrology

Keswick and Shasta Dams manage the stream flow of the Sacramento River below river mile 302. In summer Shasta Lake increases the inflow discharge significantly, despite the prolonged dry months that reduce the discharge. Water from the Whiskeytown Dam and Clear Creek Eeservoir is released to the Sacramento River by way of Keswick Reservoir to meet demand for water in Southern California. Under normal projected flood conditions, the floodplain width ranges from 200–500 feet below Keswick Dam. The river bed is constructed with coarse gravel at the riffle locations and fine sediments at non-riffle locations.^[8]

Water quality

Acidic sludge in Keswick Reservoir, forebay of the Shasta Dam near Redding

Iron Mountain Mine was a widely known sulfide ore deposit mine that provided valuable metals, but soon lost its fame due to extreme acid mine drainage and deposition of contaminated sediments. The contaminated metal sediments that precipitated from the mine drainage accumulated in the Spring Creek Reservoir (California) and Keswick Reservoir on the Sacramento River. The mine was located in Shasta County adjacent to Keswick Reservoir and is known to be the largest toxic metal contributor to the Sacramento River system.^[9] Copper was identified as the main pollutant of the river, but other contaminants that caused degradation of water quality include iron, zinc, cadmium, mercury, lead and acidic water.^[10] The total concentration of metals recorded in the river has been as high as 200g/L and the water acidity recorded was as low as pH 3.6.^[11] In the Sacramento River Delta, other inactive mines have contributed to the degradation of water quality at Keswick Dam. Although agencies such as the Clean Water Act and the Environmental Protection Agency are dedicated to improving the quality of drinking water by treating the contaminants, uncontrolled acid mine drainage still poses a great threat to the quality of water in the area. The quality of surface water downstream of Keswick Dam is also influenced by other human activities along the Sacramento River downstream of the dam, including agricultural, historical mining, and municipal and industrial inputs. In 2000, the water quality of the Sacramento River was reported to be relatively good. However, water temperature is a principal water quality issue in the upper Sacramento River between Keswick Dam and Red Bluff Diversion Dam (RBDD). Other unknown traces of mercury,pesticides and metals have also been recorded in the 26-mile reach from Keswick Dam to Red Bluff.^[12]

The city of Redding, California, where Keswick dam was built, is primarily made up of volcanic and sedimentary rocks that are metamorphosed.^[13]

Aesthetics

Keswick Dam is surrounded by chaparral communities, riparian vegetation and a steep terrain. Around the dam are Keswick Lake and Keswick Reservoir, which provide water to the dam and also help to stabilize releases from Shasta dam. Upstream from Keswick Reservoir, the slopes are characterized by a mix of pine and oak forests and, to varying degrees, chaparral and rock outcrops. The landscape includes topographic features of the Klamath Mountains, the southern Cascade Range, and the Central Valley. Two volcanic features – Mount Shasta and Lassen Peak – can be seen from numerous vantage points throughout the area ^[4]

Biological aspects

Wildlife and fisheries

Keswick Reservoir is among the aquatic environments associated with the Sacramento River watershed.^[14] Cold-water fish species found in Keswick Reservoir include resident rainbow trout and brown trout. Warm-water species include the same species as found at Shasta Dam. The California Department of Fish and Wildlife occasionally plants hatchery-reared fish in Keswick Reservoir. The reservoir is accessible from the shore and by boat, but it is not heavily used for fishing. Keswick Dam is the uppermost barrier to anadromous fish migrating up the Sacramento River. Because of its small size, Keswick Reservoir does not stratify. Reservoir levels fluctuate daily by one to three feet. The reservoir can fluctuate as much as eight to nine feet on an annual basis. Releases to the Sacramento River have ranged from approximately 3,300 cfs (Department Of Water Resources, 2011) during drought periods to 79,000 cfs during flood events ( Department of Water Resources,1974).^[15] From Keswick Dam to the Red Bluff, California, the river is relatively narrow and deep with some areas of broader alluvial floodplain. Most of the Chinook salmon-spawning habitat in the Sacramento River is located in this reach. The variability and magnitude of natural seasonal flows of the Sacramento River have been significantly altered for the purposes of irrigation and flood control. The dams and diversions operated by the Central Valley Project and local irrigation districts control much of the flow in the Sacramento River. To protect the holding and spawning of winter-run Chinook salmon, Reclamation has been required to manage cold-water reservoir storage and releases to maintain daily average water temperatures at or below 56°F between Keswick Dam and compliance locations between Balls Ferry and Bend Bridge from May 15 to September 30 since 1993^[16]

Ecological effects

Iron Mountain Acid Mine Drainage.The mine was in operation from 1860 s until 1963

Both Iron Mountain Mine and pyritic ore mining in Shasta County have contributed to the degradation of Sacramento River in addition to killing fish and other aquatic organisms downstream of Sacramento River to Keswick Dam.^[17] This is as a result of acidity of the water and other metal deposits contaminating the sediments in the river. Exposure to copper and other metals alters the physiological and reproductive alterations in salmonid species in Sacramento River below Keswick Dam. Winter-run Chinook salmon spawn in the river are one of the major salmonid species that are threatened. Endangered Species Act. Spring Creek Reservoir was built to control the drainage prior to discharge into Keswick Reservoir. The acid level, which was previously recorded in the pH range between 1.5 and -3.6, improved to a pH of about 3. All the acid mine drainage and the discharge deposits had to be diverted into the treatment plant. This also improved the concentrations of metals by about 97% under regular operating conditions. Currently, the water-quality characteristics at Spring Creek Debris Dam outlet to Keswick Reservoir meet the water standards for the Sacramento River as set and regulated by the Water Control Board.

See also

• List of dams and reservoirs in California
• List of power stations in California

References