Action agencies do extensive research on safe and effective passage for juvenile fish migrating to the ocean as well as for adult fish returning to their home streams to spawn. This research helps to continually improve the effectiveness of hydrosystem operations and fish passage improvements. The agencies also conduct studies on water temperatures, water quality and the effectiveness of fish transportation.
To track fish through the hydrosystem, the agencies tag both hatchery and wild juvenile fish with various tracking devices. These tags help measure several different metrics, including the percentage survival of juvenile fish past each dam and the percentage of juvenile fish going out to the ocean that return.

Spill at Lower Granite Dam on the Snake River.