EPA's Vessel General Permit and Small Vessel General

ANS
For ballast water, EPA concludes that its proposed ballast water standards in the VGP are likely
to result in a “very small absolute risk of invasion.” Using the NEMESIS database (with the
caveats listed above), we estimated an annual average of 5.75 newly documented ANS invasions
nationwide that were attributed to ballast water discharge. The proposed VGP ballast water
numeric discharge limitations are likely to reduce the number of ANS invasions over time;
however, similar standards are not required of small vessels under the sVGP. We conclude that
there is a small likelihood that listed resources will be exposed to ANS invasions as a result of
ballast water discharges authorized by the VGPs.
EPA did not provide a qualitative or quantitative estimate of exposure of listed resources to hull
fouling ANS. We used the NEMESIS database to estimate an annual average of 13.5 newly
documented ANS invasions nationwide that were attributed to hull fouling. This number
represents a minimum number of ANS invasions annually. The VGPs require few antifouling/hull
husbandry practices or technologies that are likely to result in substantial changes to
biofouling ANS invasion rates. Therefore, there is at least a small likelihood that listed resources
would be exposed to ANS invasions as a result of hull fouling and hull husbandry as authorized
by the VGPs.
Listed resources are also likely to be exposed to ANS as a result of authorized discharges of
chain locker effluent, seawater piping effluent, and dead bait.
We conclude that EPA has not reliably estimated whether, and to what degree, listed resources
are likely to be exposed to potentially harmful impacts of discharges authorized by the permit.
We acknowledge that several, substantial uncertainties prevent or complicate the reliable
estimation of exposure to several of these stressors. These uncertainties emphasize the need for
additional monitoring and data collection, as described in the following section.
(4) Monitoring/Feedback
In this section, we ask whether EPA proposes to identify, collect, and analyze information about
its authorized discharges that may expose listed resources to harmful stressors.
The EPA requires owners/operators to self-monitor their discharges as one means to identify,
collect, and analyze information to determine whether vessel discharges into waters of the U.S.
expose listed resources to ANS or pollutants at concentrations, durations, or frequencies that are
known or suspected to produce adverse effects. Under requirements of the VGP, permittees are
required to monitor and report any unavoidable or unauthorized discharges. This places the
responsibility for oversight largely on the permittees who would have little incentive to do so,
given that such observations could result in a violation of the permit and result in enforcement
responses by the EPA. It is unlikely that the required self-monitoring and self-reporting will
allow EPA to continually identify, collect, and analyze information to evaluate exposure or
adverse effects. Therefore, EPA will review additional monitoring of discharges that have the
greatest potential to adversely affect listed resources. These include: ballast water, bilge water,
graywater, copper (from anti-fouling hull coatings and gas scrubber effluent), selenium (from gas
scrubbers effluent), and vessel-mediated ANS.
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