The river rises in the Yorkey Range below Mount Romeo near, north-northwest of. The river flows generally in a north-westerly direction, joined by three minor tributaries that drain waters from the Trevethan Range before finally heading eastwards to Walker Bay. At its river mouth, the Annan River is joined by the Esk River and together the two rivers empty into the Coral Sea south of. The river descends over its course and flows through the Black Mountain National Park and the Annan River National Park. The river has a catchment area of. Being in a the river receives the majority of its approximately rainfall per year between the months of December and April, a period known as the wet season. The river is crossed by the Mulligan Highway near Rossville and again closer to its mouth.
Much of Yuku Baja hold locally indigenous names, inspire locally indigenous religious beliefs, and have been a primary source of life, sustenance, foods, and water for many thousands of generations of predecessors to the Kuku Nyungkal people, for many thousands of years. Towards the end of the 19th century non-Aboriginal peoples had started to colonize the Far NorthQueensland region, and with the shift from predominantly gold mining activity to tin, lead, silver and copper mining, they started to move into the Annan River catchment and Kuku Nyungkal country. By 1885 Charles Ross had discovered tin in the upper Annan River area. Sluicing began that year, leading to a small-scale tin mining rush into Kuku Nyungkal country during 1886. Following this rush, for a number of years, a small but vibrant tin mining industry was able to mine lucrative tin deposits directly from underground lodes, creek beds and banks. Later, the industry had to adapt to exhausted supplies by consolidating and building water channels through the Upper Annan River ranges to access higher, more difficult to reach deposits. One such -long race, known as the Annan River Company Water Race, was first built at the cost of an Adelaide based company in 1902 and is now cultural heritage listed and protected as Queensland heritage. The tin mining and other 'disturbance' history of the otherwise more pristine Annan River catchment can be briefly summarized as follows:
"This catchment has been quite extensively mined for tin since the late 19th century. Some small alluvial tin mining leases may still... contribute significant sediment loads to the river. Other disturbances in the Annan catchment include unsealed roads and fords, grazing, and a number of small residential developments."
The Department of the EnvironmentNatural Resource Atlas categorized the Annan River catchment as "Low Development", with less than 30% of its total catchment area being developed. The catchment as a whole has been described as being "...at the pristine end of the disturbance spectrum...", extensively forested as follows:
"...the southern and eastern portions predominantly rainforest and open eucalypt forest. The western and northern parts are more sparsely vegetated consisting of open eucalypt forest and woodland with pockets of rainforest along Oaky Creek. The alluvial plains are covered by tall shrubland. The estuarine portion of the river comprises large areas of ephemeral and tidal wetlands..."
