News

SolarBee pumping project may lower mercury levels in Utah reservoir

The Salt Lake Tribune
Mon, 08/15/2011
By Mark Havnes

Newcastle • Scientists at Newcastle Reservoir are stirring things up to see if a new technique using a solar-powered pump will reduce high mercury levels in the water. If it works, the procedure may be used on other contaminated bodies of water in Utah.

Newcastle is one of 16 bodies of water in Utah that have mercury levels high enough to prompt advisories about eating fish caught in them.

Hydrologists with the U.S. Geological Survey placed the platform pump in July near the dam of the reservoir, which is about 30 miles west of Cedar City.

The theory behind the pumping technique, developed in Finland, is that bringing up water and sediment from a deep part of the reservoir — about 40 feet — would lower the amount of “sulphate-reducing bacteria” that live on the lake bottom and get nutrients from inorganic mercury. That life cycle results in a more toxic methylmercury that then infects fish and the humans who eat them.

“We hope to interrupt that cycle,” said hydrologist David Naftz.

He said the pumping action, at a rate of 7,500 gallons a minute, also oxygenates the water at deeper levels, which helps reduce methyl mercury.

Naftz said some mercury is deposited out of the atmosphere after drifting over Utah from China and India, which are burning increasing amounts of coal. Teams are also evaluating streams on the reservoir’s watershed to see if mercury is leaching into water from old iron mining operations in the area.

Methylmercury builds up in the food chain and accumulates in the flesh of some of Utah’s most popular sports fish, including largemouth bass, rainbow trout and shiners. People who eat the contaminated fish are themselves at risk.

Too much mercury can cause hair loss, heart problems and neurological problems in adults. Pregnant women, their unborn children and youngsters are at greater risk, and methylmercury in the young can cause learning disabilities and behavioral problems.

John Whitehead, assistant director with the Utah Division of Water Quality and director of Utah’s mercury work group, said Newcastle Reservoir has the highest concentrations of mercury of any lake in the state.

He recommends that people not eat fish from the lake, including rainbow trout and wipers, a type of bass hybrid.

“Anyone who consistently ate [contaminated] fish could feel some effects,” he said.

The pumping project is a cooperative effort with the USGS, and state and other federal agencies, and is costing about $500,000.

Hydrologist Ryan Jackson said the pumping process has shown success on a lake in Finland, where mercury levels were cut in half. They were reduced by 90 percent in a lake near San Jose, Calif.

Part of the project includes mapping the lake bottom and studying the water’s velocity and quality using “the yellow submarine” that also reads mercury levels.

Jackson, who traveled from Urbana, Ill., said the battery-powered piece of equipment, which looks like a yellow torpedo and is officially called an autonomous underwater vehicle, is the only one in the USGS inventory.

He programs the water craft, sprouting scientific instruments, to travel underwater while he sits on the shore.

Naftz said it will be a year before the scientists will know how effective the process is and if it is successful, similar pumps could be used on other lakes and reservoirs in the state with high levels of methylmercury.