上游 (shàng yóu): upper reaches (of a river); upper level; upper echelon; upstream

There was especially heavy rain this summer, and the water level in the upper reaches kept rising, so villagers living by the river were all told to evacuate in advance.

There is a chemical plant in the upper reaches of this river; worried that the polluted water would flow downstream, government departments have already sent people to inspect it.

We took a boat upstream along the Yangtze River for three days; the mountains on both banks grew higher and higher, and the scenery became more and more spectacular.

In order to find the cleanest water source, the survey team walked all the way to the upper reaches of the river, where almost no one lives.