Author: Leigh Taylor Johnson, Marine Advisor, Sea Grant Extension Program, San Diego County
During the next 5-10 years, recreational boaters may be required to reduce the amount of copper that leaches into the water from the hulls of their boats. The Regional Water Quality Control Board in San Diego is conducting a Total Maximum Daily Load (TMDL) analysis for copper in the Shelter Island Yacht Basin of northern San Diego Bay. They have found that the amount of dissolved copper in the yacht basin's water is well over the federal and state standard of 3.1 parts per billion (micrograms per liter). In fact, there is so much dissolved copper in the water that it kills or causes abnormal development in the larvae of mussels.
Copper also finds its way into marina sediments, where it harms creatures that live in or on the mud. When such contaminated mud is dredged, it must be disposed as hazardous waste, raising the cost of maintaining harbor depth. These costs could be passed on to marinas and boaters through leases and slip fees. Copper removed from boats during haulout and repainting raises the environmental compliance costs paid by boatyards under their National Pollutant Discharge Elimination System (NPDES) permits.
California's new Nonpoint Source Pollution Control Program (Vol. I, pp. 139-141) requires the underwater hull cleaning industry to train and certify divers in the use of best management practices. The state will step in if 75% of boat cleanings are not done by certified divers within four years. The plan also mandates a phase-out of toxic hull paints on state and local agency-owned vessels. Finally, it recommends legislation to ban toxic hull paints, if necessary, after a thorough analysis of the situation.
Depending on the results of their TMDL assessment in Shelter Island Yacht Basin, the Regional Water Quality Control Board in San Diego may require that dissolved copper levels be reduced. Whether this will be required and how it could be achieved has not been decided. However, boaters and marinas may be asked to share in the task of protecting the marine environment from excessive copper. One way to reduce copper emissions from boat hulls is for boat owners to use nontoxic antifouling strategies. However, using a nontoxic strategy successfully requires a new approach.
The traditional approach is to add a toxicant, such as cuprous oxide, to the bottom paint. The toxicant gradually leaches to the surface of the paint, where it slows fouling growth and is ultimately lost to the water. In San Diego the hull must be cleaned in the water about once a month to prevent fouling growth from becoming established. Hull cleaning accelerates copper loss and best management practices are used to keep it to a minimum. Eventually, most of the cuprous oxide has been lost, the paint is no longer effective, and the boat must be hauled and repainted.
The nontoxic approach does not slow fouling growth. Different products use different strategies and each has its pros and cons. In general, nontoxic coatings are more expensive than traditional coatings, require special hull preparation and application procedures and the hull must be cleaned in the water about twice a month. This makes them sound very unattractive to boaters. On the other hand, the life of the paint is not dependent on the life of the toxicant. So, it's possible that a durable, nontoxic hull coating could greatly extend the time between haulouts and make up the cost difference.
In order to educate boaters and to track the performance and costs of using nontoxic antifouling coatings, the University of California Sea Grant Extension Program (with state/federal funding under the 319h Nonpoint Source Pollution Program) and the San Diego Unified Port District will be conducting demonstrations of nontoxic antifouling coatings during the next two years. They will coordinate their assessments of performance and costs of using nontoxic coatings so a broader range of data can be collected. The UC-SGEP will conduct field days and workshops for boaters, develop a brochure, report results to marina, boating and other, related organizations, and post information on the Internet about the demonstration. They also anticipate a concurrent project to compare the economic costs and benefits of nontoxic and traditional antifouling coatings for recreational boats.
The University of California Sea Grant Extension Program is also writing a brochure on nontoxic antifouling strategies that will be available soon. They will also submit a review of antifouling issues and a report of the September 21-22, 2000 Alternative Antifouling Strategies Conference findings to California Sea Grant for publication and distribution. Legislators who attended the conference responded to its findings with concern and agreed that a legislative hearing would be a good first step toward determining how best to handle the problem on a statewide basis.
Copyright © 2000 University of California