@Northern_Water Fall Symposium recap #ClimateChange #ColoradoRiver #COriver #drought

From The Sterling Journal Advocate (Jeff Rice):

Climate change will require municipal water planners to do a lot of planning in the 21st century.

Jeff Lukas via the Western Water Assessment.

Jeff Lukas, a water researcher at the University of Colorado, and Meagan Smith, water resource engineer for the city of Fort Collins, told the Northern Water Fall Symposium in Loveland Wednesday that water planners will have to think outside the box to keep up with risks to Colorado’s water supply.

Lukas told the more than 300 people attending the symposium, hosted by the Northern Colorado Water Conservancy District, that traditional methods of water planning won’t serve as well going forward.

“Traditional water planning assumes history will repeat itself,” Lukas said. “It’s the ‘assumption of the stationary,’ and it looks at a single target for meeting water demand.”

The drought of 2000-2002 called all of those assumptions into doubt, Lukas said, when the Colorado River showed the lowest annual flows on record.

Meanwhile, northern Colorado experienced an increase in average temperatures of 2 degrees Fahrenheit. Projections are that Colorado will warm up by another 2 to 6 degrees by 2050. That means Colorado will become drier and the swings between wet and dry years will become greater.

“We can expect more variability from year to year,” Lukas said. “That means the future is inherently uncertain, but we have to keep planning.”

Concentric rings of various widths mark the annual growth of trees. Photo by Peter Brown, Rocky Mountain Tree-Ring Research. Photo credit: NOAA

He said tree ring studies have yielded some information going back several hundred years and, if the conclusions are correct, Colorado may have endured much worse droughts than anything humans have recorded.

Smith said Fort Collins had embraced that uncertainty and has conducted a supply and demand study that yielded as many as 2,000 different scenarios the city could face. Smith said the study tracked 100 different river flows and 20 climate probabilities to try to find the variabilities her office might have to plan for. Looking at the Poudre River flows at the mouth of Poudre Canyon, Smith said the current average of 273,000 acre feet per year could shrink to as little as 190,000 acre feet, or about 30 percent less. But that’s not the number people should be focused on, she said…

While much of the concern about future water supplies tends to focus on the Colorado River, Lukas said, the headwaters of the Colorado and the headwaters of the South Platte Basin share the same climate.

Colorado Rivers. Credit: Geology.com

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