Many Wood River Valley residents will recall the proposal by San Diego-based Sempra Energy to construct a 600-megawatt coal-fired power plant at a site in the Magic Valley region nine miles northeast of Jerome.
Ultimately abandoned by the company in 2006, the $1 billion idea nonetheless galvanized Idahoans of all backgrounds and political affiliations to come out and fight the proposal. Not long after Sempra's pullout from the area, the Idaho Legislature approved a two-year moratorium on such power plants.
In doing so, the legislators cited the mercury emissions these plants send aloft as just one of the reasons to proceed cautiously when considering such proposals in the future.
Now imagine the equivalent of 160 of these coal-fired power plants spewing similar mercury-laden emissions into the air over populated southern Idaho.
Sound far-fetched? Not according to Justin Hayes, program director for the Idaho Conservation League.
During a lecture at the Hailey Public Library Thursday, Dec. 13, Hayes told a small crowd of local residents that such a scenario is in fact a reality.
Arriving like a storm cloud into the state is a large plume of mercury—a toxic element considered to be especially harmful to pregnant women and children—Hayes said.
"This is a human health issue," he said.
Hayes said the main source of the large mercury plume is 25 gold mines located in a relatively small area of northern Nevada.
"The scale of mining in Nevada is really something to beheld," he said.
Hayes said that up until a few years ago, state and federal officials in charge of enforcing environmental regulations in northern Nevada relied upon a voluntary testing program to monitor emissions from the mines. He said the results of the program indicated very little mercury emissions.
But that picture began to change after Hayes and other ICL staffers used portable mercury monitoring equipment to test the air near the Nevada mines. He said the results were staggering and contradicted the results provided by the voluntary monitoring program.
Hayes said the results also indicated a need for a mandatory monitoring program overseen by Region 9 of the federal Environmental Protection Agency, which covers northern Nevada. He said the agency is now in the process of implementing such a program.
"They'd never actually taken a measurement," he said. "They had no idea how big the problem was." Unlike gold mines elsewhere, mines in northern Nevada use ore roasters to superheat the gold-bearing ore to several thousand degrees. Hayes said that in doing so, the mercury that occurs naturally in the rock is converted from its normal liquid state into vapor. Once vaporized, the mercury becomes airborne.
Aloft in the atmosphere, Hayes said, winds carry the mercury to downwind sites far removed from the element's original source. And because winds in northern Nevada generally trend northeast, he said, southern Idaho is the most common recipient of those mercury emissions.
He said Idaho's waterways and fish populations are most impacted. Through a complex process, elemental mercury is converted into organic methyl mercury, a more toxic form of the element.
Throughout Idaho, numerous bodies of water have been tested and shown to contain fish with high levels of mercury in their flesh. In southern Idaho, those include Salmon Falls Creek Reservoir, where test results have shown fish to have the highest known levels of mercury in the state. The scenic reservoir is located in the high, sagebrush steppe region of southern Idaho just northeast of the 25 mines Hayes and others have cited as the source of the mercury contamination.
But the mercury problem isn't just limited to the southernmost portions of the state, as a November announcement by the Idaho chapter of The Nature Conservancy indicated.
To the intense dismay of Wood River Valley anglers, outdoorspeople and elected officials, the conservation group announced that testing conducted earlier this year in June indicates Silver Creek—whose waters and large trout draw tourists from throughout the world—is also contaminated by unhealthy levels of mercury.
Throughout his lecture, Hayes repeatedly pointed out that humans do not become unhealthy by breathing mercury-laden air. Rather, he said the most common way is to consume fish that live in mercury contaminated waters.
He said the Idaho Department of Health and Welfare will likely release a fish advisory soon that will tell people the amount of fish from Silver Creek considered safe to eat.
"That said, my children won't be eating these fish," he said.
Silver Creek, in southern Blaine County, has been identified as one of several Idaho waterways contaminated with mercury. Photo by Mountain Express
