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Weathering Change: Adapting to Earlier Snowmelt

11 March 2013
Published in Science and Society
Written by  Maura Hahnenberger and Julie Kiefer

In the fourth part of our series, Weathering Change,we look at how a predicted early snowmelt will impact water supply along the Wasatch Front, and how Salt Lake City plans to adapt.

 

The iconic winter image of white peaks towering over the Wasatch Front metropolis may one day become a rare sight. The prediction comes from dozens of global climate models, which project a warming of two to four degrees Celsius by the century’s end.

Somewhat surprisingly, it is expected the amount of precipitation that will fall along the Wasatch Front will remain about the same. But Courtenay Strong, assistant professor of atmospheric sciences at the University of Utah, cautions that not all precipitation is equal.

“Those warmer conditions would be conducive to more of our precipitation coming as rain, and a little bit less as snow,” explains Strong. “Once the snow is on the ground, warmer temperatures would be consistent with it melting earlier, and a little bit faster.”

The findings trigger alarm bells because municipalities across the Intermountain West use snowpack as a way to store water. As weather warms, snow melts into mountain streams, bringing water directly to treatment plants and onto consumers. For Salt Lake City, nature’s faucet provides over half of its drinking water. The remainder comes from water stored in local reservoirs which help meet water demand during the late summer irrigation season.

Salt Lake City is collaborating with scientists to determine how the change may affect water users in the future. “If the snowmelt that feeds those streams comes earlier, then we start to see this gap emerge between the peak of the [mountain stream water] supply and the peak of the [consumer] demand,” says Salt Lake City water resources manager Laura Briefer. “We’ll have to figure out how to make up for that demand.”

An expected population increase will only compound the problem. The Governor’s Office of Planning and Budget indicates that Salt Lake City’s population is expected to grow by 19% by 2050, and Salt Lake County’s by nearly 60%, further draining the region’s water supply.

Conserving for the Future

Utah has a reputation as a water guzzler. It is second only to Nevada in water usage as measured by gallons per person per day, according to the U.S. Geological Survey in 2005. According to the Utah Division of Water Resources, Utah's heavy water use is due in part to a cultural preference for thirsty Kentucky Bluegrass lawns, despite living in the second most arid state in the nation. Such facts may cast doubt on whether locals will be able to make cutbacks that will significantly lower peak demand.

However recent statistics suggest residents in Salt Lake City are cutting down on water use. “Salt Lake City’s total gallon per capita in 2000 was 285, compared with 184 for 2011 [a reduction of 35%],” says Stephanie Duer, water conservation program coordinator for Salt Lake City. “This, despite a growing population, increasing industrial base, the expansion of our airport, and growth at our universities and in our workforce.”

She attributes the decline to a multi-faceted approach including public education, a tiered water rate structure, and changing an ordinance mandating that yards have grass.

Yet unlike other western cities, Salt Lake City does not have ordinances against wasting water (water squandering), watering restrictions, nor does it have a rebates program for water saving appliances.

Further, some surveys indicate that Salt Lake City uses more gallons per person per day than western cities such as Denver, Albuquerque, and Phoenix. Duer points out that such survey comparisons can be inaccurate because measurements may “not account for climate and evapotranspiration, length of season, industry, commuter population, and visitors.”

Art Raymond, spokesperson for Salt Lake City Mayor Ralph Becker, writes that conservation is a priority and efforts are ongoing. He states that in the near future Salt Lake City will be enhancing water conservation by releasing a new manual and interactive website for water wise landscaping, and may soon be developing policy for a landscape ordinance. He adds that, “Salt Lake City does have a water shortage contingency plan that allows us to mandate water use restrictions if necessary.”

Preparing for Constant Change

Though water conservation will be instrumental, it will be one of many approaches the city will use to address impending water problems, says Briefer. “I’m not positive that water conservation alone will be able to solve that gap [between water supply and demand] over time.”

Given that there is no room to build additional reservoirs locally, the city is considering altenative approaches. One candidate is treating wastewater for reuse in large irrigation projects (ie. golf courses) or for industrial use. Another is aquifer storage recovery (ASR), injecting the early snowmelt runoff, that otherwise would go largely unused by consumers, into the groundwater aquifer as a form of storage.

Both methods are costly, and are not needed now, but are under consideration for the future. “The costs and benefits of that same alternative may become more equal as these challenges become more significant in the future,” Briefer says. “It may be that in a 30 year time frame, that becomes a better alternative.”

Briefer adds that this attitude reflects a shift over the last decade in the business of water resource management. These days, she meets at least monthly with scientists to reassess climate models and gauge impacts on the region’s water. “It’s this constant iterative process that we’re now having to plug into our water management decisions.”

She adds that water managers like her stay away from the word “predict” because with the changing climate, it is difficult to know exactly what will happen in any given year. Instead she says they monitor, develop scenarios, and adapt as needed.

Watch the video to see Salt Lake water manager Laura Briefer and scientists Courtenay Strong and Tim Bardsley discuss the future of Wasatch Front water.

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