evidence: The Orange River is the largest river in South Africa, flowing through three countries – Lesotho, South Africa, and Namibia. It is about 2,200 km long and is an important source of drinking water, as well as being used to irrigate agricultural land. The river begins in Lesotho, then flows through South Africa and Namibia where it empties into the Atlantic Ocean. [...] The Orange River, also known as the Gariep, Groot and Senqu, is the longest river in South Africa. [...] The Orange River is home to Gariep, the largest dam and reservoir of the same name in South Africa, and Vanderkloof, the second largest dam. Below these two structures, the current becomes calmer, the river flows through the plain and is mostly disassembled for irrigation.