EPA's Vessel General Permit and Small Vessel General

estimate whether those discharges have occurred in concentrations, frequencies, or for durations
that violate the terms of the proposed VGPs.
ANS
In the BE, EPA identifies ANS as one of the greatest threats to biodiversity globally and one of
the largest threats to coastal and freshwater ecosystems. They describe invasive species as the
second largest threat to endangered species after habitat loss and indicate that some scientists
believe the impact of invasive species is greater than that of habitat loss. They identify
commercial shipping as the “most important means of introducing ANS to coastal environments”
and the “predominant vector for the human transport of invasive species in marine
environments.”
The EPA identifies several mechanisms by which ANS are likely to adversely affect listed
resources. These include: outcompeting native species, damaging habitat, changing food webs,
and altering the chemical and physical aquatic environment. They also identify the taxonomic
range of possible ANS, dividing the organisms by those likely to be transported via ballast water
(planktonic, but also benthic organisms) and biofouling organisms.
The EPA does not estimate the concentrations, frequencies, or durations of discharges carrying
ANS. In the BE, EPA suggests that the lack of species-specific chronic response data for ANS
precludes calculation of a risk quotient to support a quantitative effects analysis. We found
several datasets describing actual or potential responses to ANS. In our analyses, we used past
documented ANS invasions from a nationwide database to determine that listed resources are
likely to be exposed to ANS, but our analyses do not include all ANS invasions and do not
represent invasion probabilities. Instead, we agree with the conclusion of the NAS study, which
states that “the data are not sufficient in present form to characterize a biologically meaningful
relationship, much less estimate the associated uncertainty, to be able to identify with confidence
the invasion probabilities associated with particular discharge standards.” For this reason, EPA
cannot quantify ANS invasion probabilities associated with authorized ballast water discharge,
hull fouling/hull husbandry, and other vessel discharges. Instead, they use a qualitative approach
to estimate exposure (discussed below in section 3).
The EPA has identified ANS as potentially harmful stressors that are likely to be released into
the waters of the U.S. as a direct or indirect result of the vessel discharges that would be
authorized by the VGPs. To date, EPA has not reliably estimated whether those discharges have
occurred in concentrations, frequencies, or for durations that violate the terms of the proposed
VGPs; however, their monitoring and reporting plan, discussed below (section 4) will allow EPA
to reliably estimate the volumes of discharges that are likely to carry ANS and the number of
living organisms carried in ballast water.
Pollutants
In their BE, EPA used pollutant data collected for the Report to Congress to characterize the
discharges the VGPs will authorize. This required extrapolation from the sampled 61 vessels
and their discharges to the universe of vessels authorized to discharge under the VGPs. Given
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