Curecanti National Recreation Area: Personal Watercraft Use Enviornmental Assessment

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PURPOSE OF AND NEED FOR ACTION The majority of personal watercraft used today are powered by conventional two- stroke engines (NPS 1998, California Air Resources Board [CARB] 1999). Multiple studies have demonstrated that four - stroke engines are substantially cleaner than carbureted, two- stroke engines, generating approximately 90% fewer emissions (Warrington 1999; Oregon Department of Environmental Quality [ODEQ] 1999; TRPA 1999). PWIA notes that direct - injection engines have been available in personal watercraft for four years; and three PWC manufacturers introduced four - stroke engines for the 2002 model year (PWIA 2002a). The U.S. Environmental Protection Agency (EPA) assumes that the existing two- stroke engine models would not be completely replaced by newer PWC technology until 2050 (40 CFR 89, 90, 91). The average operating life of a personal watercraft is 5 to 10 years, depending upon the source. The formula for determining the operating life of personal watercraft was published in the Federal Register on October 4, 1996 (EPA 1996a). Based on this formula, the National Park Service expects that by 2012, most boat owners will already be in compliance with the 2006 EPA marine engine standards. The Personal Watercraft Industry Association believes the typical operating life of a personal watercraft rental is three years and approximately five to seven years for a privately owned vessel (PWIA 2002a). Environmental groups, PWC users and manufacturers, and land managers express differing opinions about the environmental consequences of PWC use, and about the need to manage or to limit this recreational activity. Research conducted on the effects of PWC use is summarized below for water pollution, air pollution, noise, wildlife, shoreline vegetation and erosion effects, and health and safety concerns. Water Pollution The vast majority of personal watercraft in use today are two- stroke, non - direct - injection (carbureted) engines, which discharge as much as 30% of their fuel directly into the water (NPS 1999; CARB 1999). Hydrocarbons, benzene, toluene, ethyl benzene, and xylene (BTEX) are also released, as well as methyl tertiary-butyl ether (MTBE) in states that use this additive. In 1996, the Environmental Protection Agency promulgated a rule to control exhaust emissions from new marine engines, including outboards and personal watercraft. Emission controls provide for increasingly stricter standards beginning in model year 1996 (EPA 1997). The amount of pollution directly attributed to personal watercraft compared to other motorboats, and the degree to which personal watercraft affect water quality remains debatable. As noted in a report by the Oregon Department of Environmental Quality, every water body has different conditions (e.g., water temperature, air temperature, water mixing, motorboat use, and winds) that affect the pollutants' impacts (ODEQ 1999). A recent study conducted by the California Air Resources Board consisted of a laboratory test designed to comparatively evaluate exhaust emissions from marine and PWC engines, in particular two- and four - stroke engines (CARB 2001). The results of this study showed a difference in emission (in some cases 10 times higher total hydrocarbons in two- stroke engines) between these two types of engines. An exception was air emissions of nitrogen oxides (NO,,) which was higher in four - stroke than in two- stroke engines. Concentrations of pollutants (MTBE and BTEX) in the tested water were consistently higher for two- stroke engines. In 1996, the Environmental Protection Agency estimated an overall 52% reduction in hydrocarbon emissions from marine engines from present levels by 2010, and a 75% reduction by 2030, based on conversion of polluting machines. The 1997 EPA rule delayed implementation by one year (EPA 1996a, 1997). However, changing from two- stroke carbureted engines to two- stroke direct - injection engines may result in increases of airborne particulate- associated PAH (Kado et al. 2000). Polycyclic aromatic hydrocarbons (PAH), including benzo(a)pyrene, naphthalene, and 1- methyl naphthalene, are released