tributary

It is estimated that 11% of the rubbish which enters the River Clyde - which flows through the city - and its tributaries is eventually washed up at Arrochar.

Biologists from the California Department of Fish and Wildlife have spotted fall-run Chinook salmon in tributaries miles upstream from where Iron Gate Dam was removed.

Water is the eternal conundrum in this state, especially as climate change has diminished the summer monsoons and the Rio Grande and its tributaries slowly dry up.

One section of the river is lined with concrete, and the remnants of tributary creeks sit in straight ditches.

This undammed river, a tributary of the Klamath River near the California-Oregon border, is one of the last remaining strongholds of a type of salmon that is increasingly at risk of extinction: spring-run chinook.