I’ve always wondered how much ecological good comes from removing old creosote pilings from along the shoreline, as the Washington Department of Natural Resources has been doing in its Creosote Removal Program.
I was given a new perspective on the problem Tuesday, when I visited the Doe-Keg-Wats estuary. (See my story in Wednesday’s Kitsap Sun.) Now I am better able to see the value of removing creosote logs. Still, I wish a few more quantitative field studies would be done.
We all know that creosote, generally made from coal tar, contains numerous toxic chemicals. A study completed in 2006 for the National Marine Fisheries Service, titled “Creosote-Treated Wood in Aquatic Environments: Technical Review and Use Recommendations” (PDF 1.7 mb) talks about the many toxic constituents (p. 52), routes of exposure (p. 53-54) and toxicity (p. 54-65).
The report draws this important conclusion (p. 84):
“Overall, the laboratory and field studies described above indicate that treated wood structures can leach PAHs (polycyclic aromatic hydrocarbons) and other toxic compounds into the environment. However, the degree of PAH accumulation to sediment associated with these structures appears to be relatively minor in many settings, particularly in well-circulated waters….
“Nevertheless, there are several factors that suggest that a precautionary principle might be applicable to certain treated wood uses. First, the above studies typically have evaluated responses at the community level (e.g., the benthic invertebrate studies) or to tolerant life stages (e.g., adult oysters and mussels). However, the level of environmental protectiveness applied to T&E (threatened and endangered) species (such as endangered salmonids) should occur at the individual rather than the population or community level.
“Moreover, field studies have indicated that PAHs can accumulate to potentially deleterious concentrations in poorly circulated water bodies or when the density of treated wood structures is high compared to the overall surface area of the water body. As a result, site-specific evaluations of risk should be conducted for treated wood projects that are proposed for areas containing sensitive life stages, species of special concern, or where water circulation and dilution are potentially low….”
This brings us to Doe-Keg-Wats, which appears to be one of the most pristine estuaries in the Puget Sound Region. Take a look at the aerial photo at the bottom of this page.
Because of geophysical conditions, a lot of driftwood seems to pile up in this estuary. It’s amazing the amount of driftwood you can see along the shore today, especially considering that the beach was stripped clean of floating debris during a storm with extreme tides in 2006. Chances are much of the wood was pushed far back into the estuary, which is a large and valuable salt marsh.
The amount of creosote-treated logs to be found along the beach and in the marsh is rather surprising, with estimates ranging from 10 to 20 percent of all the woody debris. Even on a cool day, one could see oil floating on the water near some treated timbers. Think of what this means for a hot day, back in the shallow marsh where waters are relatively still.
For the better part of a century, driftwood — including creosote-treated pilings, timbers and lumber — has been trapped here. This marsh would be a great spot to take some measurements of the chemicals found in water and sediments. One could repeat the sampling over time to measure the recovery after much of the treated wood has been removed.
Alas, no money was set aside for monitoring at this location.
As a result of Tuesday’s outing, I came to realize that removing creosote pilings from along the shoreline throughout Puget Sound might do more than keep creosote from leaching into high-energy waters. It might just keep these pilings from winding up in Doe-Keg-Wats and similar salt marshes throughout the region. As Dave Roberts of DNR pointed out to me, it is far easier and cheaper to remove pilings by boat or truck than by helicopter.