Anajás River

The Anajás River (Portuguese: Rio Anajás) is a river of Marajó, which itself is an island in the Amazon Delta. It is located in the state Pará in northern Brazil.

Its source is in Ponta de Pedras municipality, in the swamp areas called mondongos that are normally flooded during the wet season. It mainly flows in a westerly direction. Its main tributary is the Moções River on its right bank. It joins the Anajás opposite the main town along the river, which is also called Anajás. To the south of the river is an area of flooded igapó forests.

The Anajás is a tidal river. During high tides, it receives an influx of waters from the Amazon River. Its headwaters and those of its tributaries become brackish due to the influence of the Atlantic Ocean, or they even dry up during summer.

Excavations attest to the expansion of the Marajoara culture along the Anajás River between 700 and 1100 AD. The inhabitants occupied river headwaters, lakes and seasonally flooded areas and reproduced hydraulic control systems to optimise the capture of water, in a system of dams and reservoirs. Platforms were constructed of beaten earth for housing, ceremonies and festivals.

Since the 1980s, there have been plans for canals to connect the Anajás to the Atuá River or its tributary the Anabiju to facilitate transport between Belém and Macapá, but these haven't materialised.