Mountains of Mercury

The whole matter of the missing mercury might have slipped by, unnoticed. But Patty Jacobs, a permit writer for the Oregon Department of Environmental Quality, decided to check the math.



In 2005, after a federal mercury-reduction rule was passed (since vacated by the U.S. Court of Appeals), Jacobs and the nation's other regulators began paying attention to coal-fired power plants, a major source of the mercury building up in the nation's waterways. The Boardman plant, a coal-fired facility 160 miles east of Portland, reported that it had put 281 pounds of it into the air that year. That ostensibly made the plant the largest mercury source in Jacobs' territory, which covered much of central and eastern Oregon.

Even small amounts of mercury can cause harm. Once the metal is deposited in a lake or river, bacteria convert it to an organic form called methylmercury. From there, it works its way upward through aquatic microorganisms and insects, intensifying in the tissue of fish and, eventually, in the animals and people that consume them. Exposure to high levels of mercury causes reproductive declines and developmental problems in wildlife. Human babies exposed in utero suffer an increased risk of neurological disorders, including attention deficit and impaired coordination. In adults, mercury consumption has been linked to memory loss, muscle tremors and impaired vision.