Setting the course for a Colorado River with less water is an enormous challenge that’s not likely to satisfy everyone. And climate change has created a collision course with wildlife.

The river isn’t just managed to accommodate people. Governments are also responsible for the ecosystems that sustain fish, birds and other animals. The U.S. Fish and Wildlife Service (USFWS) is an important player in the battle that’s ahead. A letter submitted by USFWS to the Bureau of Reclamation has as many questions as answers.