New study refines Puget Sound pollution issuesMay 18th, 2011 by cdunagan
A third-generation study of toxic pollution in Puget Sound claims to be the best estimate so far of total amounts of toxics entering Puget Sound each year.
As Craig Welch of the Seattle Times points out in a story today, it’s a big exaggeration to think that Puget Sound is suffering through enough drips and drabs of oil — largely from vehicles — to equal an Exxon Valdez spill every two years.
Craig is right to point out how previous studies overestimated the amount of several toxics. After all, politicians having been tossing around the dramatic Exxon Valdez analogy when it serves their purposes. Still, the total amount of oil or any other pollutant in Puget Sound is not really a good measure of the problems we face.
If you want to understand pollution in a waterway, it’s better to measure the concentration of the pollutant, see where that level falls on a toxicity scale, then consider how fish and other organisms are exposed to the pollution.
The new study for the Department of Ecology, titled “Toxics in Surface Runoff to Puget Sound,” analyzed 21 chemicals or groups of chemicals in 16 streams in the Puyallup and Snohomish river watersheds. The watersheds contain all different land types — commercial-industrial, residential, agricultural, forest, fields and other undeveloped lands. The idea is that researchers could extrapolate from these land types to represent all of Puget Sound. But such an extrapolation still requires a number of assumptions, which can throw off the estimates by wide margins.
At least we can say the latest study involved actual water-quality sampling. Previous estimates — including those that produced the Exxon Valdez analogy — were based on measurements of stormwater in other parts of the country.
For example, the first-generation study estimated that between 21 million and 120 million pounds of oil and grease were spilled into Puget Sound each year. The second Puget Sound study reduced the estimate to between 13 million and 92 million pounds each year. The latest estimate: between 18 and 23 million pounds of oil and grease each year.
One problem is that the early estimates for oil and grease — which include soaps, cooking oil and other nonpetroleum oils — was assumed to be entirely petroleum in developing the Exxon Valdez analogy. I guess people forgot about that little glitch.
The latest estimate for petroleum compounds is between 710,000 and 800,000 pounds per year. This is a third less than the first estimate for oil and grease, when looking at the bottom of the range. It’s 1/150 times smaller at the top of the range.
Here are some other revisions, taking the bottom of the range:
- Zinc dropped from 380,000 pounds per year to 250,000
- Copper dropped from 110,000 to 61,000
- And polycyclic aromatic hydrocarbons dropped from 7,800 to 300
Rob Duff, who manages Ecology’s Environmental Assessment Program, told me that the earlier estimates were mainly designed to analyze the contributions of stormwater with respect to other pollution sources, such as wastewater, industrial discharges and atmospheric deposition. Somehow, people got carried away with the idea of rolling up all the numbers, he said.
Calculating total pollution loads for Puget Sound is not meaningless, however, Rob noted, because it can suggest ubiquitous problems, such as copper from brake pads. Widespread problems may suggest the need for statewide legislation, such as a brake-pad bill approved last year.
But the true problems are seen when measuring concentrations of copper in freshwater streams and understanding how salmon become disoriented when they are exposed to levels actually found there.
“This is a question of regional versus local strategies,” Duff said. “Sometimes it is smart to focus on the local sources of pollution. Other times, it is best to act regionally. In developing future strategies, both of those things must be considered.”
Kitsap County Health District’s Pollution Identification and Correction Program is an example of a local effort, because investigators track down sources of bacterial pollution when they find elevated levels in a stream.
One of the key findings in the new report is that commercial and industrial lands release toxic chemicals at a higher rate than other land covers. But commercial and industrial lands occupy less than 1 percent of the total Puget Sound watershed. Because of that smaller area, the total loading from commercial and industrial lands is actually lower than other land uses.
Still, if you want to find high concentrations, look in streams and stormwater flows coming out of developed areas, including residential.
While toxic chemicals were rarely found in forested areas, such areas make up 83 percent of the land surface draining to Puget Sound. While chemical concentrations are generally low, the total loading is significant. The source of some pollutants is atmospheric deposition.
Policy implications regarding this new report — and scientific studies in general — can lead to endless debates.
Brandon Houskeeper, a policy analyst for the Washington Policy Center, said he would expect to see some changes in the Puget Sound Partnership’s policies, considering that the Puget Sound Action Agenda was based on a much larger estimate of petroleum pollution.
“Aren’t you able to dial in a little more where you should be going?” he asked. “If the ’08 Action Agenda was based on the first couple of phases of this report, then we need to revisit those policies.” Check out the news release issued today.
But Bruce Wishart, policy director for People for Puget Sound, said the study only refines the numbers; it does not result in any dramatically new conclusions.
“I don’t think anyone debates that the concentration of petroleum in stormwater is a serious problem or that stormwater is the number-one source of pollution to Puget Sound,” he said.
“We can continue to discuss the relative concentration of each pollutant,” he added, “but the real issue is not to study this endlessly. The real concern is that we are not doing enough to solve the stormwater problem.”