A nonprofit has released its annual report on endangered rivers in the U.S., and Arizona’s largest waterway has made the list for the second year in a row.

For years, researchers have simulated historic high flows on the Colorado River by releasing large amounts of water.

But climate change has reduced flows and dropped reservoirs to all-time lows, so the releases have stopped.

Smallmouth bass have also found their way into the stream, which could affect endangered native fish such as the humpback chub.

"Since 2000, the volume of water in the Colorado River has declined by about 20%," said Sinjin Eberle, Southwest communications director with American Rivers. "And projections are that the river will be about 30 percent smaller than its historic flows, by 2050."

This is the 38th year the nonprofit has compiled the list.

Six of the rivers in the top 10 were in the West.