Water Conservation

In Colorado, Water Bosses Begin to Accept Climate Change Impacts

Old assumptions aren’t working to predict today’s water supplies in the Rocky Mountain state, much less the future. Many planning scenarios ‘are actually pretty scary,’ says one water official.

 

VAIL, COLORADO – The phrase “climate change” did not appear on the agenda of a recent three-day meeting of the Colorado Water Congress, but the topic was often front and center at the conference, as it increasingly is at water meetings around the state and the region.

Amy Haas, the new executive director of the Upper Colorado River Commission, told the Water Congress audience of about 300 water managers, irrigators, engineers and lawyers that “hydrology is changing more rapidly than we once thought” and that “it is primarily due to climate change.”

And, Haas said, attitudes among water managers about climate change are changing too.

“I feel that water managers are not only talking about climate change, they are talking about it frequently,” she said. “This is the new reality that we have to contend with. And I’m encouraged to hear the discussion, openly, in all sorts of water management forums.”

Haas recognized Brad Udall, who was also at Water Congress, in her remarks.

A senior climate researcher and scientist at Colorado State University, Udall continues to get the attention of water managers with studies that tie rising temperatures to declining river levels.

Udall recently published a paper, along with Mu Xiao and Dennis Lettenmaier, on the declining flows of the Colorado River.

The paper found that flows in the upper Colorado River Basin declined by 16.5percent from 1916 to 2014, while annual precipitation increased only slightly, by 1.4 percent.

By conducting experiments with a model that uses temperature and precipitation as inputs, the researchers found that “53 percent of the decreasing runoff trend is associated with unprecedented basin-wide warming, which has reduced snowpack and increased plant water use,” Udall explained. “The remaining 47 percent of the trend is associated mostly with reduced winter precipitation in four highly productive sub-basins, all located in Colorado.”

Udall is also using “aridification” at water meetings to describe what’s happening in the Colorado River Basin, and he’s offered up a succinct summary of his research on climate change, on a T-shirt that says “it’s warming, it’s us, experts agree, it’s bad, (and) we can fix it.”

Andy Mueller, the general manager of the Colorado River District, also makes no bones about climate change.

He told the Water Congress audience that the River District is “planning for a future with less water, and it being a permanent situation.”

And on September 14, at a River District seminar in Grand Junction, Mueller told an audience of over 250 water managers, users and stakeholders that science shows that “climate change is going to reduce the natural flow into Lake Powell by 20 percent by 2035 and by the end of the century, 35 percent.”

Mueller added, “We’ve got to recognize that we have a supply problem in the upper basin.”

Jim Lochhead, the CEO and manager of Denver Water, said during his remarks at the Colorado Water Congress meeting that the impact of climate change goes even beyond supply issues.

“A warming climate is something we’ve built into our scenario planning process, but it’s not just a water supply concern,” Lochhead said, also citing wildfires and the resulting runoff into reservoirs and rivers, and the increased cost for water treatment from “warmer water” and “emerging contaminants.”

He also said Denver Water no longer thinks that the past is a reliable guide to the future, citing the “over-assumptions of water supply” in interstate compacts like the 1922 Colorado River Compact, the state’s water rights system, which is based on “past hydrology,” and state and federal regulations that are based on “past water temperatures and water quality parameters.”

“Those are all geared to the past and not to the future,” Lochhead said.

Low flows on the Colorado River in Cataract Canyon. Flows on the Colorado have always risen and fallen seasonally, but water managers in the West now firmly see a future with less water overall with which to work. Photo by Brent Gardner-Smith, Aspen Journalism.

Denver Water has also “abandoned linear water-supply planning,” where, as he put it, “you look at the past hydrology, look at past population trends, and project those out into the future, look at a water supply gap, and then go out and find water to meet that gap.”

“That no longer can meet the challenges that we face today,” Lochhead said.

And Lochhead said that “firm yield,” the capacity of a given water supply system to meet demands in a dry spell, and the Holy Grail for water providers, was now an outmoded concept.

“We don’t use that term any more, actually, because we know that no yield is firm,” he said.

And if that wasn’t riveting enough for water managers to hear, Lochhead also said that “as we look at the warming climate, some of the scenarios in our scenario planning are actually pretty scary, and they will be coming at us more and more quickly.”

This article was originally published by Aspen Journalism, an independent nonprofit news organization.

The views expressed in this article belong to the authors and do not necessarily reflect the editorial policy of Water Deeply.

 

Deeply Talks: Drought on the Colorado – Can We Adapt to Changing Runoff?

Shrinking snowpack in the Colorado River watershed is not just a water supply problem, but could also lead to a variety of water quality concerns. Listen to two experts describe these changes and how we might adapt.

WRITTEN BYMatt Weiser PUBLISHED ON  READ TIMEApprox. 1 minutes
A bleached “bathtub ring” is visible on the steep rocky banks of Lake Mead near Hoover Dam in May 2015 at Lake Mead National Recreation Area, Arizona. The bleached ring has only grown larger as severe drought grips the Colorado River watershed.Justin Sullivan/Getty Images

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 National 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 Utah State University, 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.

For advance notice of upcoming Deeply Talks and exclusive access to these and other Water Deeply events, we invite you to become a contributor. Your small donation helps us to continue our uniquely insightful coverage of western water issues.

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