EPA's Vessel General Permit and Small Vessel General

species. (Glazebrook and Campbell 1990, PAHO 2001) While discharges containing sewage
pathogens can enhance the risk of exposures resulting in infection, a causal link has not been
established between exposure to human sewage pathogens and adverse effects in marine turtles.
While several ubiquitous pathogens are found in both humans and fish, those associated with
sewage are not known to adversely affect marine and anadromous fish.
At this time, NMFS does not have a good understanding of the potential impact of human
sewage indicator pathogens on the population health of threatened and endangered vertebrate
species. Understanding is complicated by our ability to discriminate between primary infections
and opportunistic infections in wounded or weakened animals.
VGP Measures to Mitigate Potential Exposure of Elkhorn Coral to Serratia marcescens.
Elkhorn coral critical habitat overlaps with areas restricted from graywater discharge by the
VGP. These areas, termed “Waters Federally Protected Wholly or in Part for Conservation
Purposes” include the Florida Keys National Marine Sanctuary, Virgin Islands National Park
and Virgin Islands Coral Reef National Monument of St. John and Buck Island National
Monument off the coast of St. Croix. The Florida Keys National Marine Sanctuary protects
2,900 square nautical miles of waters surrounding the Florida Keys, from south of Miami
westward to encompass the Dry Tortugas. The sanctuary excludes Dry Tortugas National Park,
but as a National Park, it is also included among the VGPs restricted waters. These protected
areas encompass the Florida Unit of the designated critical habitat for both staghorn and elkhorn
corals.
The Caribbean Unit for coral critical habitat includes Puerto Rico and the U.S. Virgin Islands.
While the Virgin Islands National Park and Virgin Islands Coral Reef National Monument of St.
John appear to encompass greater than 80% of the island’s coral reefs and Buck Island National
Monument provides some cover off of St. Croix, the remainder of the Caribbean Unit, including
St. Thomas and Puerto Rico, is not protected from graywater discharges under the VGP.
However, elkhorn coral habitat and the paths vessels authorized to discharge under the VGP do
not likely overlap. Elkhorn coral generally do not form colonies below 16.4 feet deep (Lighty et
al. 1982) and usually occur between 3.3 and 16.4 feet in depth with occasional individual corals
found at depths of up to 65 feet (Goreau and Wells 1967). This contrasts with estimates of draft
for VGP-authorized vessels (from Table 3-18 of EPA’s BE), which range from a shallowest draft
of 10 feet for barges to 15.5 feet for large ferries and medium cruise ships, 17 feet for large
commercial fishing ships and 18 feet for large cruise ships on up to 75 feet for oil and gas
tankers. VGP-authorized vessels therefore will not likely discharge over elkhorn coral habitat.
We therefor conclude that graywater discharges from VGP-authorized vessels are not likely to
result in harmful exposures of elkhorn coral to the white pox pathogen in vessel graywater.
The sVGP, on the other hand, covers smaller vessels, which have shallower draft and may travel
over and discharge untreated graywater (or graywater mixed with sewage) within elkhorn coral
habitat. These vessels also discharge graywater at much lower rates than VGP vessels.
Tugboats, with a crew of three to five persons, generate approximately 130 gallons per day of
graywater. Water taxis generate less graywater per person because the discharge is limited to
bathroom sinks, producing an estimated 75 gallons per day discharge. Graywater generation on
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