Mud Reveals The Story Of A Cleaner Puget Sound

Pollution. Contrary to popular wisdom, pollution in the Puget Sound actually may have peaked 35 years ago. Sediment reveals the 100-year history of contaminants in the Puget Sound.

Amid the gloomy debate over disappearing Puget Sound salmon, results of an environmental "dig" are likely to puzzle the decision-makers: Puget Sound is cleaner today than at any time since before World War II.

Analysis of deep-water sediments off Seattle's shores suggests pollution peaked about 35 years ago - long before the Clean Water Act or advanced-sewage treatment, and long before anybody ever thought of Earth Day, which is Thursday.

The revelation seems to contradict popular wisdom. Two years ago, for example, a local environmental group issued a report warning that local waters "are threatened by human-caused pollution that harms the plants and animals that live in Puget Sound." In particular, the group pointed to contamination by copper, zinc, lead and mercury.

Yet the federally funded 1991 research by the Battelle Marine Sciences Laboratory concludes that, despite pollution "hot spots" such as Tacoma's Commencement Bay, the Sound's overall water quality has been improving. In particular:

-- Contamination by lead, zinc, copper, mercury and other heavy metals was at its worst in the early 1960s, and has declined dramatically to pre-war levels.

-- DDT and PCBs, man-made chemicals that tend to linger in the environment, reached their peak about 1960 and began to decline years before they were banned by the federal government.

-- Hydrocarbons, the residue from burning coal or oil, reached their maximum during World War II and have dropped to levels of the early 1900s.

In each case, the pollution began to decline well before Congress passed benchmark environmental laws. The improvement appears to have begun about the same time as publication of Rachel Carson's "Silent Spring," the book often credited with launching the environmental movement.

While costly sewage treatment can help, the study suggests the best pollution controls occur at the other end of the pipe, where people and industries decide what and what not to dump down the drain.

Yet scientists involved with the research say their findings have received almost no attention from government, environmentalists and the media.

"It disturbs me that basic research tends to be ignored," said Eric Crecelius, an oceanographer at the Battelle labs in Sequim. "It has been published and is available to anyone interested. But all I can do is present the information; I can't shove it down people's throats."

Crecelius and his colleagues base their conclusions on analysis of sediment cores taken in 1982 and 1991.

The more recent cores were taken from six sites at the bottom of central Puget Sound. Researchers concluded after the 1982 study that most contaminants gravitate toward the deepest parts of the Sound, where they mix with mud. Similar core research has been conducted around the nation, Crecelius said.

They lowered a coring device to the bottom, drove it six feet into the sediments, retrieved it and removed about 25 samples of mud, equally spaced along the core.

From there the study begins to resemble an archeological dig. By measuring the age of lead in the sediments, they were able to determine the age of each layer. Each layer was then tested for about 17 pollutants - heavy metals and a variety of organic and man-made oil compounds.

By measuring pollutants in each layer, the researchers detected patterns of pollution dating back more than 100 years. The results were published by the National Oceanic and Atmospheric Administration.

Sediments are not perfect indicators of historical pollution, Crecelius warns. Giant worms and other bottom-dwelling sea life dig through the sediments, transporting material with them. And sediments catch relatively few nutrients, the phosphorus and nitrogen that sewage-treatment plants target. Nutrients tend to remain in the water, where they are broken down by natural processes.

Still, the results provide a graphic illustration of the 100-year history of Puget Sound pollution. Sediments dating to the late 19th century show low levels of lead, copper, arsenic and other metals that occur naturally in the environment. Crecelius considers these to be "background levels."

From there, clear patterns emerge. Here are a few:

Hydrocarbons: Even before 1900, sediments show signs of "combustible hydrocarbons," a collection of complex compounds that result from burning coal or petroleum. This reflects the rapid population growth following the Klondike Gold Rush, thousands of people who used coal to heat their homes, drive their steamships and fuel new industries. Particles from chimneys and smokestacks drifted over Puget Sound, into the water and sunk to the bottom.

Between 1900 and 1940, hydrocarbon pollution increased about 20 times over. It peaked in about 1943, then declined quickly. By 1970, it had returned to the level of about 1920.

Why? The decline reflects the transition from coal to oil, which burns more efficiently, Crecelius says. It also shows the effects of clean hydroelectric power.

Lead: It began to increase in about 1890, reached its peak in the mid-1960s and then declined. The pattern is similar at all six sites, but far more dramatic at the southernmost site, near Tacoma.

Crecelius points to two factors. First, the decline shows the introduction of unleaded gasoline in the late 1960s; much of the lead came from car exhausts.

The other cause was shipbuilding and other heavy industry, especially the enormous Asarco smelter in Tacoma. At one point, the smelter emitted a plume that was 40 percent lead, he says. By the late 1960s, such mills were under increasing pressure to reduce their emissions. Arsarco closed its Tacoma smelter in 1985.

Arsenic: Concentrations increased rapidly in the 1890s - precisely the time the Tacoma smelter started spewing the stuff. As with lead, arsenic pollution was greatest at the Tacoma study site, and seemingly insignificant at the northernmost site, near Edmonds.

Once again, the contamination was greatest in the early 1960s, and has declined significantly.

Silver: It increased steadily until the 1960s and then began to decline.

Why? Credit photo-processing labs, which used to dump their chemicals down the drain - including trace amounts of silver from film. At its height, a ton of silver per year was going into Puget Sound, Crecelius says. Beginning in the 1960s, labs figured out it made economic sense to recycle their silver.

DDT: The dreaded insecticide, which helped inspire "Silent Spring," showed up first in the 1930s, increasing rapidly until about 1960 - two years before the book was published. From there it dropped just as fast to levels of one or two parts per billion.

Apparently people had begun to switch to other compounds even before the chemical was banned in 1972.

PCBs: This harmful chemical began to appear in about 1910, peaked in the early 1960s and declined to pre-war levels. PCBs were banned in 1976.

Detergents: The scientific term is linear alkyl benzens, or LABs. They were introduced in the 1960s and appeared to have peaked about a decade later, but the timeline is too short to draw conclusions.

So what does it all mean?

"Obviously, pollution was a lot worse 20 to 30 years ago, and it's getting better," Crecelius says. "In most cases, the improvement predates the laws. I don't know why, but maybe it means that industry was more aware of these issues than we gave them credit for."

Alyn Duxbury, a retired oceanography professor, explains that few people paid attention to what they dumped into the Sound until the 1960s. "We had raw sewage at Magnolia. If you had a barrel of chemicals, you dumped it into the Sound."

But that mentality changed: "Society has become less wasteful," he says. "We still have toxic hot spots, but they're confined to a few small areas. We've learned to control pollution at its source."

Nobody suggests this research justifies complacency. The ecosystem is stressed by other factors such as shoreline development and lost fish habitat. Excessive nutrients from leaky septic tanks or untreated sewage can foul the water, especially in confined bays. And Crecelius admits there are pollutants - such as dioxins - for which he could not test.

"We have better treatment, more recycling, but we also have these huge increases in population," says John Armstrong of the federal Environmental Protection Agency. "In some things, you're doing well if you stay even."

Ross Anderson's phone message number is 206-464-2061.

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DIGGING THROUGH THE CORE OF POLLUTION.

Scientists at Battelle Marine Laboratory, Sequim, have used core samples from central Puget Sound sediments to analyze the history of local water pollution. Findings from a sample taken just outside Elliott Bay are summarized here, but the patterns were similar for five cores taken from other sites in the deepest parts of the sound.

1995: Secondary treatment goes on line at West Point.

1990s: DDT, PCBs back to pre-WWII levels.

1985: Asarco smelter in Tacoma closes down after 100 years of pollution.

Mid-1980s: Hydrocarbons fall to level of about 1915.

Early 1980s: Seattle debates whether to add secondary treatment at West Point plant.

1976: Congress bans PCBs.

1973: Congress passes Clean Water Act.

1972: Congress bans DDT.

1970: Congress passes Clean Air Act.

1970s: Rapidly declining amounts of arsenic, silver, lead, tin and zinc.

1965: Primary treatment plant at West Point.

1965: Maximum arsenic, silver, lead, tin and zinc.

1960s: Sharp decline in DDT, PCBs.

1962: Rachel Carson's book, "Silent Spring," helps launch the environmental movement.

1960: Maximum DDT, PCBs levels peak.

1950s: Hydrocarbons decline, probably due to hydroelectric power replacing coal and burning wood.

1949: Maximum mercury, probably from shipyards.

1943: Hydrocarbons peak, reflecting wartime shipbuilding and other industries.

1930s: Continuing increase in most pollutants, expecially hydrocarbons.

1920s: First signs of DDT, PCBs

1900-1910: Increasing amounts of hydrocarbons, arsenic, silver, copper, mercury, zinc. Rapid population growth. Beginnings of industrialization.