The Savannah River Site is located in the Sand Hills region of South Carolina and includes an area of 800 square kilometers (about 300 square miles). The southern half of the site (building clusters with reflective white rooftops) is shown in this astronaut photograph. The nearby Savannah River and its tributary creeks provided a ready source of water for the nuclear reactors; to this end, two artificial lakes ("L" Lake and Par Pond) were constructed. The meandering channel of the river and its floodplain, characterized by grey-brown sediments, is visible on the far left of the image. Because the river is so close to the nuclear site and because the underlying geological materials (sand, clay, gravel, and carbonate rocks) are permeable, an extensive and ongoing environmental monitoring and cleanup effort is necessary to reduce potential contamination of local water sources. Final remediation of wastes posing threats to surface and groundwater is scheduled to occur by 2025.