Recreational boating, diving, sport fishing and bird watching are popular in and around coastal waters; California's boating industry contributed $11 billion to the state's economy in 1995. However, copper discharges from boat bottom (antifouling) paints have increased dissolved copper in some coastal harbors to levels that affect the early and adult life stages of many marine species that provide food for birds and sport fish. Toxic, antifouling paints are used worldwide to control fouling growth, such as algae and barnacles, on boat bottoms. This growth creates friction, slowing sailboats and increasing fuel consumption and related pollution for power boats. Badly fouled hulls are potential vectors for invasive species. Heavy metals that are added to boat bottom paints to retard fouling growth can accumulate in poorly flushed boat basins; even low levels create toxic effects in marine species. This issue is an international concern and policy developments in California are drawing international attention. Tributyl tin, a highly toxic bottom paint additive, has been banned in California for boats under 25 meters long. The International Maritime Organization (IMO) is negotiating a global phase-out of tin-based antifouling paints during 2003–2008 for vessels making international voyages. Copper-based, antifouling paints have been banned for use in parts of Europe and the European Union has asked the IMO to ban all toxic boat bottom paints. In the United States, Total Maximum Daily Load (TMDL) analyses found excessive levels of dissolved copper in parts of San Diego and Newport Bays. Dana Point Harbor and Oceanside Harbor also have elevated levels of dissolved copper. Recreational boat bottom paints have been implicated as a major source of dissolved copper in these basins. In response to the high levels of dissolved copper, policy measures in the U.S. include the U.S. EPA's Nonpoint Source Pollution "Management Measures" for Marinas and Recreational Boating and California's Plan for Nonpoint Source Pollution Control which recommend nontoxic boat bottom paints for pollution prevention. Nontoxic bottom coatings do not slow fouling growth but may be able to withstand more frequent cleaning than copper-based paints. Boatyard operators have found that epoxy- and silicone-based coatings will not adhere to residual, copper-based bottom paints, so they must first be removed. Because it does not depend on the lifespan of copper, a durable, nontoxic paint may last longer than a copper-based paint. This would allow more time between haulouts and repainting and make up for extra hull cleaning costs and the cost of removing old copper paint. Nontoxic coatings are relatively new, so their lifespan, application and maintenance, their cost profiles, and effect on dissolved copper levels in marinas will need to be evaluated during the next few years. Senate Bill 315, passed by the California Legislature in 2001, mandated California Department of Boating and Waterways to fund a study of incentives for boaters to use nontoxic alternatives to metal-based antifouling paints. The study report is due to the Legislature at the end of 2002. It is expected to include policy options that may be useful in crafting state and regional solutions to this issue. The University of California Sea Grant Extension Program (UCSGEP) and University of California at San Diego, Department of Economics are cooperating in the above study of incentives for using nontoxic alternatives. UCSGEP is also developing educational materials and conducting a State Water Resources Control Board funded field demonstration of nontoxic boat bottom paints to increase boater interest and awareness of alternative strategies for managing fouling growth. The goal of their research and educational programs is to provide information needed for developing and implementing sustainable policies and practices. Currently, few nontoxic boat bottom paints meet criteria for durability and longevity that can balance the high cost of conversion from a copper-based paint and the need for more frequent, in-water cleaning. Sustainable state and regional policies are needed that provide incentives for manufacturers to produce nontoxic bottom paints and for boaters to use them. Such policies would reduce environmental impacts of antifouling strategies, while maintaining the economic viability of recreational boating. The UCSGEP is extending the findings of their research and information programs to policy makers and stakeholders to assist them in resolving antifouling issues.