EPA's Vessel General Permit and Small Vessel General

EPA’s copper monitoring plan will identify areas of high concentrations of ships with copperhull
coatings. Where these areas overlap with sensitive listed species, additional actions will be
taken to reduce exposure. Because copper toxicity can manifest quickly (minutes to hours) at
very low concentrations, we expect adverse effects such as disrupted chemoreception to occur
even with this monitoring in place. However, we expect that EPA’s monitoring plan will prevent
these effects from rising to the level of jeopardy.
Selenium
EPA reported that selenium was detected in several vessel discharges authorized by the VGPs
(EPA BE and Report to Congress). Among those, discharges from Exhaust Gas Scrubbers have
the potential to generate substantial selenium loadings. As described above, exhaust gas
scrubbers are used to clean the exhaust gas system on marine diesel engines. These discharges
can be highly acidic, and can contain traces of oil, polycyclic aromatic hydrocarbons (PAHs),
nitrogen, selenium and other metals. Relatively few vessels currently use seawater scrubber
technology, however, more restrictive air emissions standards, adopted in 2008, will become
enforceable in 2012 (USEPA 2011b). To comply with these new standards, which require lower
emissions of SOx, vessels can either burn low sulfur fuel oil or clean the exhaust gas. Cleaning,
or scrubbing, the exhaust gas is generally accepted to be more economical (USEPA 2011b).
Therefore, EPA anticipates that the number of vessels using exhaust gas scrubbers may increase
significantly (EPA BE Table 3-3).
In their Biological Evaluation, EPA estimated selenium loadings to Reference Action Area
(RAA) harbors from vessel discharges authorized under the VGPs, resulting concentrations of
selenium in harbor waters, and risk to listed species from selenium exposure. EPA modeled
several RAA harbor scenarios using different values for selected parameters, i.e. flushing time,
percentage of vessels equipped with wet exhaust gas scrubbers, and concentration of selenium in
scrubber effluent. Scenarios expected to produce the highest selenium concentrations in water
also predicted the highest selenium loading. For some harbors, loads exceeded 30 lb Se/day and
would represent a significant new source of selenium. For example, recent studies of the San
Francisco Bay-Delta report selenium loading from oil refineries, which along with agricultural
drainage comprise the two major sources of selenium to the system, of 1287 lb Se/year in 2009
or about 3.5 lb Se/day (Presser and Luoma 2010a). EPA predicted selenium loading to San
Francisco Bay, from vessel discharges, of 30.3 lb Se/day (Post-permit: EPA BE Table G-9),
which is nearly 9 times greater than loading from refineries and more than twice the combined
load from refineries and agriculture.
Following discussions with the Services, EPA re-assessed their original loading estimates for
selenium. They acknowledged that their initial predictions of the number of vessels that would
be using exhaust gas scrubbers (10% of vessels in specific classes) were unrealistically high.
They also re-examined the analytical data for selenium in exhaust gas scrubber washwater
effluent and concluded that concentrations may be unexpectedly high because of matrix
interferences found in seawater. EPA revised their loading estimates for selenium using two
approaches to account for potential interferences (USEPA 2012a). The revised selenium
loadings and predicted concentrations of selenium in RAA harbors and substantially lower than
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