EPA's Vessel General Permit and Small Vessel General

Table 12. Estimated Propulsion and Generator Engine Wet Exhaust Discharge Rates used
in EPAs Analysis.
Vessel Type Estimated
Propulsion Engine
Wet Exhaust
Discharge Rate
Estimated
Generator Engine
Wet Exhaust
Discharge Rate
m3/day gallons/day m3/day gallons/day
Commercial Fishinga 15.8 4,161 1.41 372
Passenger Vessels (e.g., water taxis, tour boats)b 41 10,832 6.45 1,704
Utility Boats (fire boat, tugs)c 36.3 9,590 1.80 475
EPA estimated concentrations of engine wet exhaust pollutants based on data from the Report to
Congress (Table 13). A total of 90 analytes were detected. EPA collected engine cooling water
discharge samples from a variety of vessel classes with different engine types. Two of the
sampled vessels are recreational vessels and are not study vessels. These vessels and four of the
six sampled tow/salvage vessels (those with outboard propulsion engines) were manufactured for
pleasure. EPA sampled engine effluent from these vessels because all of the sampled engines
can be installed on either recreational or nonrecreational vessels and are representative of
engines on study vessels. Contaminants of concern include copper and volatile/semivolatile
organic chemicals (sVOCs/VOCs). Table 13 includes additional information for these analytes
from the Report to Congress, which provides details on the detection frequency and distribution
of all analytes detected.
Table 13. Estimated Engine Wet Exhaust Pollutant Concentrations used in EPAs
Biological Evaluation.
Pollutant
Point
Estimate
Used in BE
Detection
frequency
Mean
(range)
50 th /75 th /90 th
Percentiles b
Copper, Dissolved (μg/L) 16 12/13 16 (nd a -53) 6.6/23/51
Benzene (μg/L) 12 9/12 12 (nd-120) 2.3/5.4/84
Benzo (a)anthracene (μg/L) 3.3 1/12 3.3 (nd-18) nc/nc/13
Benzo (a)pyrene (μg/L) 3.2 1/12 3.2 (nd-16) nc/nc/11
Benzo (b)fluoranthene (μg/L) 2.8 1/12 2.8 (nd-11) nc/nc/7.8
Benzo (k)fluoranthene (μg/L) 3.1 1/12 3.1 (nd-15) nc/nc/11
Chrysene (μg/L) 1.7 1/12 3.3 (nd-18) nc/nc/12
Indeno (1,2,3-cd) pyrene (μg/L) 3.3 1/12 2.5 (nd-8) nc/nc/5.6
a
Nondetect (censored) concentrations were replaced with ½ of the reporting limit for calculating
average concentrations.
b
Percentiles are the concentrations of each analyte below which at least that percentage of the
values fall. So the 75th percentile is the concentration below which at least 75% of the observations
were found.
c
Distribution statistics were only calculated when analytes were detected at a sufficient frequency.
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