EPA's Vessel General Permit and Small Vessel General

skeleton that is free from fleshy or turf macroalgae cover and sediment cover (73 FR 72210). As
described above, ANS invasions are likely to reduce the availability of prey or introduce
macroalgae and thus adversely affect critical habitat for these invertebrate species.
In conclusion, there is a small likelihood that listed resources will be exposed to ANS as a result
of discharges authorized by EPA’s VGPs. If exposed, individuals are likely to experience
reductions in fitness. As a consequence, species and population viability is likely to be
diminished. In addition, exposure to ANS is likely to adversely affect designated critical habitat.
Exposure Analysis
Pollutants
The constituents of the discharges authorized by the proposed VGPs are mixtures of pollutants
capable of producing adverse effects to endangered or threatened species and their critical
habitat. This section first reviews the vessel discharges authorized by the VGPs in terms of
discharge volumes and constituent mixtures then summarizes pollutant loads and EPA’s modeled
estimates of final harbor concentrations. Pollutant load, expressed in terms of mass per day, is
the net amount of pollutant discharged based on discharge volume and pollutant concentration.
Many pollutants are found in more than one discharge source, with some sources being more
significant pollutant load contributors than others by virtue of their greater volume or constituent
concentrations.
The vessels discharge information used by EPA in its BE were taken from the Report to
Congress and other sources such as the Uniform National Discharge Standards for Vessels of the
Armed Services Technical Development document (USDOD/USEPA 1999) and several reports
generated by EPA in support of the VGPs (USEPA 2008, 2011d, b). The BE relied heavily on
discharge volume and constituents data in the Report to Congress: Study of Discharges
Incidental to Normal Operation of Commercial Fishing Vessels and Other Non--Recreational
Vessels Less than 79 Feet (EPA 2010). It is important to note this data represents opportunistic
sampling from a total of 61 vessels intended to represent a population of the greater than 90,000
non-recreational small vessels 10 tracked in the MISLE database. Not all discharge types were
sampled from each vessel. The same constituents were not analyzed for in all discharges due to
sample volume constraints or decisions made regarding whether or not the discharge would
contain a given analyte or analyte group (e.g. nonylphenols in engine exhaust). In a few cases,
target analytes differed for the same discharge type within vessel classes, for example, additional
analytes would be screened for when sample collectors observed an unexpected analyte source.
These data properties limit systematic characterization of discharges within and among vessel
service types. Given the very limited number of vessels examined, inferences made based on
these data regarding discharges from other vessels, particularly the larger vessels covered by the
VGP, are accompanied by high levels of uncertainty. After describing exposure data used in the
10 Small recreational vessels far outnumber small non-recreational vessels, but are covered under the Clean Boating
Act and are not subject to the sVGP.
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