Part of the U.S. 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).

The Central Valley had fertile soils, abundant water, and a flat gentle topography suitable for 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, and in San Francisco 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.

[3] The Central Valley Project 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.

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 land on which the nearby city of Redding, California, was built is primarily made up of volcanic and sedimentary rocks that are metamorphosed.

In summer, outflow from Shasta Dam increases Keswick's inflow significantly, despite the prolonged dry months.

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.

The quality of surface water downstream from Keswick Dam is also influenced by other human activities along the Sacramento River, including agriculture, historical mining, and municipal and industrial inputs.

[15] From Keswick Dam south to Red Bluff, California, the Sacramento River is relatively narrow and deep with some areas of broader alluvial floodplain.

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.

Since 1993, 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 (13 °C) between Keswick Dam and compliance locations between Balls Ferry and Bend Bridge, from May 15 to September 30.

Exposure to copper and other metals physiologically affects salmonid species, especially with regard to reproduction, in the Sacramento River below Keswick Dam.

[citation needed] When the acid mine-drainage and the discharge deposits were diverted to a treatment plant, that improved the concentrations of metals by about 97%, under regular operating conditions.