EPA's Vessel General Permit and Small Vessel General

from large cruise vessels. The sources for oil and grease in graywater are expected to be
personal care products and the oils, fats and grease used in cooking. These sources are
considered to be biodegradable and less toxic to aquatic and aquatic-dependent wildlife than oil
and grease discharges associated with engine oil (USEPA 2011a). The data support this
conclusion. The toxic SGT-HEM fraction of oil and grease representing about 17% of the total
oil and grease in graywater. Meanwhile the SGT-HEM fraction of engine associated discharges
accounts for 32-57% of total oil and grease. The SGT-HEM fraction in fish hold and deckwash
discharges is also high, at 33-51% total oil and grease. The source for the SGT-HEM is thought
to be the lubricants and other petroleum products used on the vessel. Among other vessel
sources of oil and grease, bilge water contributes an estimated 1-12 grams oil and grease per
vessel per day and deckwash (an intermittent exposure) contributes 1-14 grams per day,
depending on vessel class.
In conclusion, literature reviews conducted separately by EPA and NMFS found that the physical
effects of oil and grease are typically associated with accidents involving large amounts of oil
rather than discharges due to incidental vessel operation. Although pre-permit oil and grease
discharges exceeded the USCG limits, even these are not at the intensities encountered during oil
spill events and would not likely result in the physical effects associated with HEM.
Metals
EPA estimates that concentrations of aluminum, arsenic, cadmium, chromium, lead, nickel, and
zinc associated with vessel discharges are, and will likely remain, below levels that may cause
adverse effects to listed species. Depending on the estuarine harbor scenario modeled, overall
post-permit metals concentrations declined by an average of 5% to 13%. Overall metals
concentrations modeled for post-permit river harbor scenarios were reduced by 2% to 11%.
However, the modeling predicted a broad range of reductions for individual metals. Selenium,
nickel and arsenic concentrations were not reduced under “worst case” estuarine and river harbor
scenarios. Under the best of conditions, the permit could result in reductions of cadmium
concentrations of about 40%. Cumulative RQs for metals ranged up to 0.311 for exposures of
estuarine/marine invertebrates, with copper accounting for about 95% of the cumulative RQ.
Given the uncertainties in EPA’s exposure analysis, we believe that these concentrations may be
higher than modeled. EPA also omitted discharges from zinc sacrificial anodes in its analysis.
Our rough estimate of this metals source increases the cumulative RQ for estuarine/marine
invertebrates to 0.422. In addition, vessel discharges are likely to combine with other sources of
metals in waterways, resulting in exposure to species at concentrations greater than considered in
this analysis.
Metals are a diverse group of pollutants, many of which can be toxic to aquatic and aquaticdependent
species. As described by EPA, vessel discharges can contain a variety of metal
constituents from a variety of on-board sources. For example, EPA’s study of cruise ship
graywater found a total of 13 different metals in at least 10% of samples, with copper, nickel and
zinc detected in 100% of samples (USEPA 2008). Bilgewater has also been shown to contain
numerous metals, the exact constituents of which vary dependent upon on-board activities on the
vessel and the materials used in the construction of the vessel. Other metals, such as copper, are
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