Big Gaps in New EPA Report
by Bill Rudolph
The regional EPA office has released a new report on toxic contaminants that is part of a larger plan to clean up some of the dirtiest waters left in the Columbia Basin.
According to the executive summary, the report focuses on four contaminants--mercury, DDT, PCBs, and PDBEs (flame retardants), "because they are found throughout the Basin at levels that could adversely impact people, fish and wildlife." Some of these compounds have been banned for more than 30 years, but are still found throughout the basin.
The report also identifies major information gaps that need to be filled before impacts to the ecosystem are analyzed and a plan is developed to prioritize actions to reduce toxic levels.
Some of these toxics are from regional sources, but most heavy metals found in the basin's fish and bird populations, such as mercury, enter the region via the atmosphere from global sources. The EPA report estimates that 11,500 pounds of mercury enters the basin by air every year, with only about 15 percent coming from local sources.
DDT was banned in 1972, but agricultural runoff is still its primary source in the river, though DDT concentrations in fish, wildlife and most tributary sediments have shown declines over the past 20 years.
Major changes in irrigation practices in the Yakima Basin have helped reduce DDT levels, but other places, such as the reservoir above Bonneville Dam, are still hot spots where white sturgeon have shown relatively high levels of the long-banned but persistent pesticide.
But other animals have shown significant improvement in their numbers. Eagle populations in the lower Columbia have rebounded as DDT levels declined, growing from 22 nesting pairs in 1980 to 133 pairs in 2006.
PCBs were in wide use by the electric utility industry for their cooling properties, until they were banned in the 1970s, but were also found in hydraulic fluids and other petrochemical products, fire retardants, plastics and paints. They proved so popular that 700 million tons of PCBs were produced in the U.S. before the ban took effect.
PCBs concentrate in the fatty tissue of animals and can be passed from mother to young. They have been linked to cancer, liver damage, neurological impairment and reproductive problems,
According to the report, PCBs enter the basin's ecosystem from disposal sites along the lower river, at dams, or via the atmosphere from other parts of the world. Stormwater runoff and discharge are other sources that scientists are increasingly concerned about.
But PCB levels in Columbia Basin fish are declining, though some still show amounts of health concern, such as sturgeon behind Bonneville Dam. Recent studies have shown that juvenile fall chinook in the lower Columbia near the mouth of the Willamette show higher levels of PCBs than fish upriver from there.
Other studies have shown much higher PCB levels in water below the dam, with the Portland/Vancouver urban areas likely the principal source.
"There are currently no data to indicate whether PCB levels in the mainstem of the Columbia River are increasing or decreasing," said the report.
But at some sites, the report noted, PCB levels in some juvenile salmon were just as high as those found in young salmon near a Superfund site in Seattle's Duwamish waterway.
Another area of increasing concern is how much compounds, known as PBDEs, are showing up in the environment. Used as flame retardants in plastics and fabrics, the report says they are released slowly in the environment and show up everywhere, including in fish. Though the exact mechanism by which they reach the river is not known, municipal wastewater is high on the list of suspects.
PBDEs have shown to cause adverse health effects in animals, but no studies have been conducted on humans. Nor is their use currently regulated.
But like the other toxins under review, there is little trend data available to determine whether PDBE levels are going up or down in the basin's juvenile salmon, sturgeon, mink, otters and Asian clams. But resident fish, bald eagles and osprey are showing increases.
PCB levels in resident fish, eagles and osprey, mink and otter populations are showing declines, but no trend data is available for salmon, sturgeon, or resident fish.
Mercury levels in resident fish, eagles and osprey are rising, but no trend data is available for the other animal populations under review.
DDT and its breakdown products are declining in resident fish, birds, and fish-eating mammals, but no trend data has been collected for salmon, sturgeon, or clams.
Many sites in the basin have been in various stages of a clean-up process for years, and EPA has worked with states in the Coeur d'Alene Basin in Idaho, the Upper Columbia above Grand Coulee, the Clark Fork and Flathead basins in Montana.
The agency has also worked with the states to help clean up contaminated sediments in the Portland harbor, near Bonneville Dam, and at the Alcoa plant in Vancouver, Wash. -B. R.
, January, 2009
Big Gaps in New EPA Report on Columbia Basin Toxics
NW Fishletter, February 9, 2009
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