In 2008, the Usangu Game Reserve and other important wetlands were added to the park, increasing its size to about 20,226 km2 (7,809 sq mi).

The park is a part of the 45,000 square kilometres (17,000 sq mi) Rungwa-Kizigo-Muhesi ecosystem,[2] which includes the Rungwa Game Reserve, the Kizigo and Muhesi Game Reserves, and the Mbomipa Wildlife Management Area.

[3] The park's name is derived from the Great Ruaha River, which flows along its southeastern margin and is the focus of game-viewing.

The vegetation in the park becomes dry, and rivers and water sources dwindle.

[2] In 1964, the southern portion of the reserve was excised and elevated to full park status.