Can Marine Waters Withstand Shoreline Modifications and Toxic Pollutants?

Robyn du Pré served as the North Sound Baykeeper and coordinated water programs at RE Sources for eight years. She currently teaches field-based environmental studies for the Audubon Expedition Institute.Lauren Mulroy is a graduate of Huxley College and served as a RE Sources intern.

Part Six

Editor’s Note: This is the sixth in a multipart series on the health of northern Puget Sound and Georgia Strait. It was first published under the title, “State of the North Sound and Straits,” by RE Sources and the North Sound Baykeeper in October 2002.

Channel dredging and shoreline armoring through the use of riprap and bulkheads lead to changes in the bathymetry (the topography or depth) of nearshore marine environments, affecting the kinds of vegetation that can grow there. For example, dredging and armoring can create deep water near the shore. This may allow for the growth of bull kelp, but perhaps at the exclusion of eelgrass, which requires shallow, sandy substrate. This kind of change will affect the kinds of organisms that can use the area for resting, feeding, hiding or breeding. Migrating salmon are particularly challenged by the loss of shallow nearshore areas.

Bulkheads and seawalls interrupt natural shoreline processes, such as erosion, deposition, sediment transport and forage fish spawning. Instead of wave energy being dissipated as the wave rolls up the beach, it hits the bulkhead, causing the wave to turn back on itself.

Over time, this action causes a scouring of the beach, as fine sand and gravels are pulled out with the waves. The large rocks and hardpan beneath are not suitable for beach-spawning fish such as sand lance. The loss of fine substrates can also result in the loss of eelgrass beds, which are used by herring for spawning. Docks and jetties can also interrupt the flow of sediments along the shore, robbing some beaches of much-needed gravels.

Because shoreline modification is so detrimental to the marine environment, a variety of state and federal statutes regulate shoreline modification projects. However, some state statutes exempt projects associated with single-family residences, or subject them to less stringent criteria. Approximately half of all shoreline modification in Washington state is associated with single-family residences. This suggests that single-family residences are a major component of total shoreline modification, and perhaps state regulations should be extended to account for the impacts these residences may have.

Shoreline structures, such as bulkheads or riprap, have been built along approximately one-third of all shorelines in Washington state. In Whatcom County, 49 of 147 miles of shoreline have been altered. In Skagit County, 81 of 229 miles of shoreline, or 35 percent, have been modified.

There are many reasons the people of Whatcom and Skagit counties have altered the shoreline. The majority of shoreline modifications in Skagit County are in the form of dikes that drain estuarine lands for agriculture. In Whatcom County, the shoreline has been altered for agricultural, industrial and residential uses.

Perhaps the greatest single impact on the nearshore environment in Whatcom County is the railroad line by that follows Bellingham and Chuckanut Bays and continues south into Skagit County. The line is built on riprap that, in many places, completely obscures the original shoreline, creating long stretches of relatively steep banks where there were once mudflats. As well, the railroad cuts across the head of Chuckanut Bay, severely impeding the transport of sediments out of the bay. Because of the railroad riprap, this area is now known as “Mud Bay” due to the extensive mudflats that appear, even at a moderate-to-low tide.

Numerous toxic contaminants are released into the environment and reach our waterways. While some of these chemicals can result in immediate problems, such as fill kills during a sudden release of a chemical, they often act in ways that are not as fast acting. Concentrations of some toxic chemicals become magnified through the food web when predators eat contaminated prey. Over time, these contaminants accumulate in the tissues of organisms at ever higher concentrations, triggering a variety of health problems and death. This means that high-level predators, such as the resident orcas in Puget Sound, are exposed to higher concentrations of contaminants than organisms that feed lower in the food web.

Many of these toxic chemicals, such as dioxins, PCBs, chlorinated organic pesticides and some PAHs, are known to cause or promote the development of cancer in humans and other animals. Organic compounds and metals can cause neurological problems.

In recent years, scientists have found that some environmental contaminants interfere with hormone functioning and can cause reproductive problems. For example, a variety of organic compounds, including dioxins, PCBs and phthalates, have been shown to have estrogen-like effects. In addition, scientists have begun to show that environmental contamination by PCBs and other toxic chemicals can cause immune system dysfunction and increased susceptibility to disease.

Sediments are widely considered to be the major repository for toxic contaminants in the marine environment. Industrial activities, combined sewer overflows, old shoreline landfills, storm water discharges and military operations have all contributed substantial amounts of toxic chemicals to our waterways. Most of the chemicals that enter the sound attach to fine particles and eventually settle to the bottom. The species that live in or upon marine sediments, such as bottomfish, are at most risk of experiencing the effects of these contaminants.

There is one major contaminated sediment site in the waters of the North Sound and Straits: Bellingham Bay. The sediments of this urban embayment contain a host of chemicals, most notably 10 to 13 tons of mercury, deposited by the now-closed Georgia-Pacific chlorine plant.

In addition to mercury, the sediments of the bay also contain copper, lead, arsenic, zinc, tributyl tin, anthracene, dioxins and furans, pentachlorophenol, PAHs, and a host of other organic compounds according to the Washington Department of Ecology. While most of these chemicals found their way into the bay via historical processes, some, such as PAHs continue to be a major problem for water and sediment quality throughout the bay and the sound.

The Puget Sound Action Team recently included Bellingham Bay on its list of contaminated sediment sites that have impaired benthic communities as a result of the contamination. A cleanup planning process for the bay has been underway for more than five years, but as yet, there has been no final decision made as to the extent of possible dredging or the ultimate fate of dredge spoils.

There is also some sediment contamination in the Strait of Georgia. This contamination is associated with the industrial effluents in the area and appears to be relatively limited in its extent. Chemicals found in these sediment hotspots include cadmium, PCBs, furans, PAHs and other organic compounds.

In Skagit County, Padilla and Fidalgo Bays, along with Guemes Channel, also have some sediments contaminated with PCBs, although contaminant levels are not high or widespread enough to warrant cleanup action. §