EPA's Vessel General Permit and Small Vessel General

commercial fishing boats is highly variable, ranging from a few to hundreds of gallons per day,
depending on the length of the trip and the size of the crew (USEPA 2010b). The sVGP does
not restrict graywater discharges to specified “Waters Federally Protected Wholly or in Part for
Conservation Purposes,” but effluent limits under the sVGP include:
“Minimize graywater discharges in areas that have heavy vessel traffic or heavy
recreational use and in marine sanctuaries, national wildlife refuges, national wild and
scenic rivers, and national wilderness areas. If the vessel has the capacity to store
graywater in these waters, it should be stored and later discharged in other waters or
onshore.”
The lower rate of discharge for individual vessels, taken with the sVGP requirement to minimize
discharges in sensitive areas and discharge graywater while underway greatly reduces the
likelihood of direct and undiluted exposures of elkhorn coral to human sewage pathogens.
However, since pathogen infection is described by the “one hit” model (EPA/USDA 2012),
VGP-authorized vessels in areas not restricting graywater discharges could result in an exposure.
Oil and Grease
Transportation activities are estimated to contribute 24% of the total oil input into the oceans
(Tong et al. 1999). Oil and grease are expressed in the BE in terms of hexane extractable
material (HEM) and silica gel treated hexane extractable material (SGT-HEM). HEM contains
relatively nontoxic nonvolatile hydrocarbons, oils, fats and waxes. SGT-HEM contains nonpolar
substances, including toxic partially combusted hydrocarbons and petrochemical
constituents such as polycyclic aromatic hydrocarbons, benzene, toluene, ethylbenzene and
xylene (SVOCs and VOCs).
Both petroleum and non-petroleum oils have similar physical properties that can harm wildlife
such as sticking to fur and feathers and reducing their insulative properties (USEPA, 1997).
EPA examined the physical and toxic effects of oil and grease separately because a qualitative
assessment was required for the HEM and quantitative assessments were required for the
individual toxic constituents in the SGT-HEM in the section evaluating SVOCs and VOCs.
EPA’s estuarine harbor model estimated post permit HEM concentrations to average 0.013 mg/L
and range from 0.0007 to 0.03 mg/L. These values represent an approximately 50 percent
reduction in hexane extractable material for all scenarios. For the river harbor model, EPA's
average estimated post permit hexane extractable material concentration was 0.15 mg/L and
ranged from 0.002 to 0.3 mg/L, suggesting approximately 60% reduction in discharged hexane
extractable material. While HEM averaged below the 15-mg/L U.S. Coast Guard standard
screening level benchmark in most discharges, all discharges had at least one observation that
exceeded this benchmark. Graywater was the only discharge with an average concentration
exceeding the benchmark, at 39 mg/L. Due to the highly variable graywater generation volumes
possible within vessel classes, EPA was unable to fully define graywater generation rates.
Graywater accounts for greater than 90% of the oil and grease discharged from vessels. Loads
range from as little as 4 grams per day from utility boats to as much as 600 kg per day (0.6 tons)
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