jueves, 26 de octubre de 2017

More dust or more drinking water

The area around Salt Lake City, UT, is one of the fastest-growing places in the country. It currently has about two million people—almost two-thirds of the state’s population—and that number is expected to double in the next 30 years. It’s also running short of water. The state has a possible solution, but many residents, businesses, and environmental groups say the price is far too high.

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The Bear River meanders into Utah from Idaho and Wyoming and is the single greatest tributary of the Great Salt Lake. State engineers are proposing diverting up to 20% of the river’s flow—as much as 72 billion gallons—to supply the growing need for drinking water. Although Salt Lake City’s water supply is stable for the moment, many are looking ahead to future demand and are figuring out how to pay for the project, which will cost somewhere in the neighborhood of $1.5 to $2 billion.  

There’s another cost, though; diverting that much water will cause the Great Salt Lake to shrink by about a foot. It has already been shrinking for the past 150 years as agriculture and growing cities claim more and more water, exposing hundreds of square miles of fine silt that blows away in the wind, reducing air quality. If the proposed diversion project goes ahead, some say that 30 more square miles of lakebed will be exposed and wetland habitats will be destroyed.

The area already experiences severe dust storms. During a particularly long-lasting storm in 2010, as this article describes, PM 2.5 levels in Ogden, some 40 miles north of Salt Lake City, were measured at 90.8 micrograms per cubic meter. Levels in Salt Lake City were just over 250 micrograms. EPA says anything higher than 35 micrograms is unhealthy. If the lake level drops further, the region can expect more such storms—more frequent, more intense, and possibly of longer duration.

Utah might take a lesson from another western state. California’s Owens Lake dried up in the 1920s as water was diverted to supply Los Angeles, leading to decades of dust storms, lawsuits, and mitigation efforts. As with the Great Salt Lake, the sediments left behind as the water receded are salty and don’t support much vegetation to anchor the soil. Today, a program is in place to return a bit of water to Owens Lake—just enough to create a shallow pool that reduces the dust.

If the diversion of the Bear River goes ahead, what mitigation plans might be possible to counteract dust from the newly exposed areas of lakebed? Or should the state pursue other solutions instead—limits on development? Stricter water conservation measures? Share your thoughts in the comments.

Janice Kaspersen

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