tended season navigation has been extensively
sive computer model that can quickly and accu-
analyzed during the past 15 years. This analysis
rately forecast spill movement (Shen et al. 1986).
was undertaken even though actual spills were
The following section is a summary of the work
unknown during the demonstration program; in-
done to assess the potential of spills, the prob-
deed, spills in general are quite rare in the Great
able impacts and the response capabilities. In each
Lakes at any time of year. In addition, the gen-
case only a summary is given; the original reports
eral operational assessment is that spills in win-
contain more information and greater detail.
ter are unlikely for the following reasons:
When vessel traffic continues through an ex-
tended season, tracks are established by pre-
Spills from vessels can be divided into spills
ceding ships, so the risk of collision or
due to accidents, operational spills and spills dur-
grounding is less.
ing loading and unloading. An operational spill
Vessels moving through ice are not able to
occurs during a transfer of fuel or as a result of a
move at high rates of speed; they are not
malfunction of a fueling system. An accidental
able to move out of their tracks with ease;
spill would be the "result of collision with ice,
and when they do start to get out of the track,
other vessel or obstacle, grounding or accidental
it is relatively easy to stop them because of
spillage in transfer operations" (USCG 1973) and
is thought most likely to occur from a "vessel ill-
There are fewer vessels operating and they
equipped to navigate ice identified as the older
generally operate with an escort when they
ships in the Great Lakes fleet" (USCG 1973). Hull
are in difficult waters.
damage caused by ice crushing a drifting or
With lake waters covered or largely covered
moored and swinging ship against a large land-
by ice, the effects of wind and waves are
bound ice sheet is also a possibility (Shulze et al.
considerably reduced, and ice between ships
1982). However, due to double-hulled construc-
tends to serve as a buffer to keep vessels
tion, the presence of a forward cofferdam in the
away from danger.
bow, and the aft location of the fuel tanks, it is
Even with the excellent record of low spill oc-
thought that substantial damage to the hull must
currence and the positive operational assessment
occur before a spill would occur (Shulze et al. 1982).
given above, nearly all aspects of potential spills
A tabulation of spills from ships is available
associated with the extended season navigation
for the St. Marys River and Whitefish Bay for the
have been addressed in a series of reports. Ironi-
years 19741979 (Shulze et al. 1982) and the St.
cally the excellent record of spills has been the
Clair River, Lake St. Clair and the Detroit River
greatest hindrance to the advancement of knowl-
for the years 19741981 (Shulze and Horne 1982).
edge on tracking and forecasting spills in ice, the
There were no ship spills resulting from accidents
development of recovery techniques and the as-
in the St. Marys River or Whitefish Bay during
sessment of spill impacts. Given this, the Coast
this period. There were three spills that resulted
from collisions on the Detroit River during the
federal agencies, has a number of contingency
period covered. The average spill amount was 8
plans, with equipment and personnel in place,
gal., and 84% of the spill material was recovered.
to respond to potential spills. The ability to fore-
There were no spills on the St. Clair River or Lake
cast spill movement in the connecting channels
St. Clair due to accidents during the study pe-
during winter conditions was greatly improved
riod. A summary of all spills reported for the entire
recently, with the development of a comprehen-
period is provided in Table 1.
Table 1. Summary of oil spills on the Great Lakes connecting channels.
Number amount (gal.)
St. Clair River
and Lake St. Clair