Pollutants found in remote lakes, rivers
Scientists consider Sullivan Lake’s waters relatively pristine.
The 1,300-acre mountain lake in northeast Washington is home to a thriving kokanee salmon run. Along with confirmed sightings of grizzlies, wolves and bighorn sheep in the area, the lake’s off-the-beaten-path location encourages periodic reports of Bigfoot activity, said Franklin Pemberton, a spokesman for the Colville National Forest.
Remote as it is, Sullivan Lake still bears the taint of industrial activity. Fish caught from its waters during a two-year study had detectable levels of mercury, PCBs, dioxins and flame retardants.
“All water bodies and fish have been affected to some small degree by humans,” said John Roland, a senior hydrologist with the Washington Department of Ecology. The study’s results are an indication of how pervasive certain types of airborne pollutants are in the environment, he said.
Over the past two years, Ecology officials set out to measure background levels of pollutants in relatively untouched lakes and rivers in the Inland Northwest.
The study looked at 14 lakes and rivers in northeast Washington and two in Idaho: Upper Priest Lake and the headwaters of the St. Joe River were included in the sampling because of their hydrologic connection to Washington rivers.
Scientists analyzed mud from lakes and streams and tested the tissue of 160 fish. Even lakes with no immediate pollution source tested positive for toxic compounds, the study found.
Some of the metals detected in the water are the result of natural mineralization, Roland said. But the other pollutants rode winds and air currents to get into the water bodies, attaching to dust particles, snowflakes or raindrops and eventually working their way through the watershed to collect in lakes and streams.
Mercury depositions, for instance, have been linked to coal burning and other combustion of hydrocarbons. Some of the pollution in local lakes and streams originated from coal-burning plants in Asia or perhaps a coal-fired facility in Western Washington, Roland said.
Smelter operations in Trail, B.C., and a historic smelter in Northport, Wash., are other sources of mercury and heavy metals, while airborne PCBs are associated with the manufacturing of electronics. Flame retardants, which are found in many electronic and household products, are common in house dust.
“There isn’t anything surprising about the outcomes,” said Roland, noting that the global deposition of airborne pollutants is well documented.
Though most of the pollutants were found at low thresholds, they’re part of a class of toxins that Ecology officials rank as the “worst of the worst” because of the threats they pose to people, fish and wildlife.
Mercury, PCBs, dioxins and flame retardants linger in the environment for decades. As they move up the food chain, they increase in concentration. They’ve been linked to a wide range of health issues, including cancer and reproductive and developmental problems.
The Ecology Department is searching for ways to limit the spread of toxic contaminants in the environment, including a recent ban on the use of flame retardants. In the meantime, Roland said, knowing the pollutants’ background levels will help guide cleanup standards for the Spokane and Upper Columbia rivers, which are affected by direct pollution sources as well as airborne toxins.
Each water body is unique, affecting how pollutants showed up in the sampling.
Sullivan Lake, for instance, was one of the larger lakes included in the study and has a more complex food chain. Both kokanee and burbot, a freshwater cod caught in the lake, tested high for PCBs compared to other fish in the study, which is what scientists would expect of larger, older fish with a higher fat content, Roland said.
Long-lived suckers, which use habitat at the lake’s bottom and can live for up to 20 years, also had high levels of contaminants compared to other fish species analyzed in the study.