Río Arque is one of the headwaters of Río Grande and Mamoré River in Bolivia. Río Arque has its source in the Cordillera Tres Cruces on the western slope of Cerro Huaylluma at , 50 km northeast of the mining city Oruro and 65 km southwest of Cochabamba.
The river flows 50 km in a southeasterly direction before it turns northeast. At kilometer 58 there is the provincial capital Arque on the northern bank of the river, at kilometer 72 Estancia Umani on the southern bank, and at kilometer 85 the town of Capinota on the northern bank.
The watershed of Río Arque comprises 2.224 km². At Capinota, the base flow of the river is 2 to 2.5 m³/s. However, when the river rises during the rainy season (November-April), the flow can be up to 900 m³/s. The sediments which Río Arque carries in the rainy season can be up to 120 g/l.
After a total of 88 km Río Arque joins Río Rocha at at an elevation of 2,350 m to form Río Caine. Río Caine after another 162 km merges into Rìo Grande which after a total of 1,438 km from the source of Río Rocha joins Río Ichilo.