[1] Hagåtña, the capital of Guam, is located at the mouth of the river and associated wetlands form the eastern boundary of the city.

However, following the devastation of the U.S. bombardment during the 1944 battle, U.S. Navy Seabees rerouted the river to its current, more direct course to the sea.

This resulted in landmarks such as the Agana Spanish Bridge no longer having water flow beneath it.

The most common fish found in the river is the Eastern Pacific Bonito.

Other nearby bodies of water include, the Hagåtña Boat Channel, Hagåtña Bay, Agana Swamp and Asan Bay.