The flow of the Metolius River remains low after years of dry conditions in Central Oregon, according to recently released state data.
Officials say this isn’t out of the ordinary, but they’re still concerned about the potential impacts on native fish.
The Metolius is a Deschutes River tributary and fishery. It’s home to the bull trout, a threatened species.
According to the Oregon Water Resources Department, there is far less water traveling through the head of the river this decade than in the 2010s.
This June, the state released its latest seasonal update, finding a discharge rate of just over 58 cubic feet per second. That’s slightly higher than three years ago, but less than half of the rate recorded in June 2015.
State hydrogeologist Joe Kemper said the rate largely reflects the rainfall in the region over a multiple-year period, explaining why the flow of the Metolius has fluctuated over the decades.
“We're right at about observed minimum flows here, but still within what you could say is a historic norm,” Kemper said. “We've seen things this dry before, but it's definitely really dry.”
Beth Quillian, a spokesperson for the Oregon Department of Fish and Wildlife, said reduced flows can be hard on the fish that rely on cold, clear water.
Quillian said some fish can get stuck at waterfalls or chutes, and shallower water helps their predators. It can be particularly difficult for Chinook Salmon.
“Because of their size, they may have to navigate shallow riffles and spawn in less-than-ideal conditions with their backs out of the water,”Quillian wrote in an email to KLCC. “This can attract predators and requires fish to expend excess energy that can lead to fish dying prematurely.”
However, Quillian said the bull trout population appears to be doing well currently, and the reduced streamflow doesn’t seem to have impacted them yet.
She said the redband trout population, which the state is also monitoring, has fallen since 2021, but it’s not clear how much reduced streamflows have played a role in that. She added that the numbers are still strong and similar to earlier years.
Kemper said if precipitation in the region continues to fall short, the flows could fall outside of historical norms.
On the other hand, he said it would take several years of normal or exceptional rainfall to rise from today’s conditions back up to the historical average.
“The climate's really driving these observed lows,” he said. “We hope to have wetter-than-average years coming down in the next few years.”
