Snowmelt is shrinking and runoff is coming earlier on the Upper Colorado River, the source of 90 percent of water for 40 million people in the West. This is leading to vegetation changes, water quality issues and other concerns. But it may be possible to operate reservoirs differently to ease some of these effects.
In September’s episode of Deeply Talks, we spoke with two experts about the consequences and opportunities of these changes on the river.
Bhavna Arora, a hydrological scientist at Lawrence Berkeley Laboratory, has been studying vegetation changes caused by declining snowpack on a tributary of the Gunnison River. She talked about how these changes are actually altering water quality in the Colorado River, which may eventually raise concerns for urban water treatment systems.
Jack Schmidt, a professor of watershed sciences at the University of Utah, is embarking on a comprehensive study of reservoir operations in the Colorado River watershed. By altering reservoir operations in response to changing volume and timing of snowmelt, it may be possible for existing water infrastructure to continue meeting human needs as climate change unfolds.

“These shifts in snowpack, they’re not just contributing to this water quantity change but they are also impacting the plant community and also the nitrates delivered to the rivers,” Arora said. “Historically, wildflowers and grasses dominated the ecosystem, and now it’s completely shifted to shrubs. It’s a huge impact.”
Schmidt said reservoir operation is critical, not just for water supply but also for habitat. Without changing downstream flows in accord with shrinking snowpack, aquatic habitat will become warmer throughout Grand Canyon National Park, which could change the mix of fish and other wildlife that can survive there. He emphasized that reservoir operations can be changed in many cases to adapt to shrinking snowpack, but it requires a new mindset by water project operators and politicians.
As originally published in Water Deeply by Matt Weiser on October 5, 2018
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