Runoff into Sound a key toxin source
Expert says reform is urgently needed
SEATTLE – Samples of the muddy layers beneath Puget Sound give a mixed prognosis for the waterway’s environmental condition, scientists say.
Researchers at the Pacific Northwest National Laboratory who are studying sediment observed a steady decline in contaminants after environmental laws were passed decades ago.
But increased urban growth and the associated storm water runoff more recently has slowed the decline of arsenic, lead, copper and other contaminants observed in the well-preserved sediment.
That means a setback for ongoing efforts to clean up Puget Sound, the scientists say.
“It demonstrates the positive impact these environmental regulations had on the overall water quality of Puget Sound,” said Jill Brandenberger, a marine chemist at the Sequim lab.
But “if we continue what we’re doing now, it is likely Puget Sound will never recover.”
While pollution from specific sources may be decreasing, the data suggests that contamination from everyday sources such as cars and homes is becoming more significant, Brandenberger said.
Since 1982, scientists have taken 10-foot long sediment cores from various seafloor sites throughout the sound, including near Seattle and Tacoma.
The sediment cores taken in 1982, 1991 and 2005 provide “a historical rap sheet of toxins” going back more than a century, Brandenberger said. Higher concentrations of lead and arsenic found in the muddy layers reflect past human activities.
The study found the first accumulations of hazardous metals around 1890, when metal smelting began near Tacoma.
Concentrations rose during the first and second world wars and decreased during the Great Depression when smelting production stopped, said Eric Crecelius, a marine scientist at the lab.
Contaminants declined further when clean-water regulations were passed in the late 1960s and when major sources of pollution such as the Asarco Smelter in Tacoma closed.
Progress slowed after the late 1980s, when regulation of point sources of pollution became less effective and it became apparent that storm water runoff was the main source of water pollution.
The scientists say their findings suggest new approaches are needed to regulate runoff.