Preventing invasive species through
better ballast water management

But ships carrying ballast water can also carry a host of viruses, bacteria, and marine and estuarine plants and animals in various life stages from one port to another.

For example, in the northern part of San Francisco Bay, a small Asian clam (Potamocorbula amurensis) has virtually taken over the mudflats and disrupted the entire ecosystem. Scientists believe this invasive clam got its start in the bay as a larval stowaway in ballast water.

• How ballasting works
• Challenges to managing ballast water
• What’s being done in Washington State

How ballasting works
Ship operators take on water at port or soon after leaving port by pumping water into the vessel’s ballast tanks. When the ship enters protected waters or is at port loading cargo, the operator discharges—or de-ballasts—the contents of the ship’s ballast tanks. Everything in the tanks—water, sediments, non-native organisms and pathogens—empties into a whole new ecosystem. 

Each year, ship operators discharge an average of more than 2.5 billion gallons (9.5 million cubic meters)—or nine times the volume of the Tacoma Dome--of ballast water into Puget Sound. Of this total, about 90 percent has undergone some form of prior treatment or offshore exchange.

The good news: the number of vessels effectively managing their ballast water prior to entering our waters has increased in the past couple of years.

But each year, an average of 12 million gallons (44,000 cubic meters) of untreated, high-risk ballast water still gets dumped into the Puget Sound waters.  Almost all of this volume is from vessels originating from California ports.

Challenges to managing ballast water

Vessels arrive daily in Puget Sound from ports around the globe and from up and down the West Coast. Managing ballast water along the coast involves a complex combination of international, national and state entities with authority over boundaries that often overlap.

The U.S. Coast Guard regulates ballast water discharges from vessels that arrive at Washington ports from outside of the Economic Exclusion Zone (EEZ), which is 200 nautical miles offshore. The Coast Guard does not regulate ballast water from vessels engaged in commerce inside the EEZ.

To fill this critical gap, Washington, Oregon and California have state programs for managing ballast water. Although these programs are not identical, each state has tried to align its program as much as possible with neighboring states.

At the national level, the Coast Guard has not adopted treatment standards for ballast water, whereas the states of Washington and California have standards—and neither standard is alike. The lack of uniform national or even regional standards makes it difficult for the shipping industry to comply and invest in treatment technologies to meet different standards.

What’s being done to manage ballast water in Washington State

The Puget Sound Partnership chairs and provides staff to the work group, which includes representatives from the shipping industry, public ports, shellfish growers, tribal governments, the environmental community and the Washington Department of Fish and Wildlife.

The Ballast Water Management Act (2000) declares that introduced non-native marine plants and animals will damage the state’s economy and environment, and that current efforts to stop the introduction of exotic species from ships are not adequate. The act supports and complements the International Maritime Organization and Coast Guard efforts to manage ballast water.

The Ballast Water Work Group  studies all issues relating to managing ballast water, including exchange and treatment methods, management plans and costs. In early 2007, the work group presented the results of its study and recommended steps to improve the state’s efforts.

>> For more information about ballast water management and the Puget Sound Partnership's Aquatic Nuisance Species Program, contact Kevin Anderson, 360.725.5452.