3 - International Joint Commission

were 21 ppb (top 1 cm) and 5 ppb for HCBD (Charlton and Oliver, 1986). The
concentrations of HCB and HCBD in Lake St. Clair are still increasing, or at
least not dropping significantly (UGLCCS, 1989). High levels of HCB (up to
140 ppb), were found in 1985 in the Detroit River adjacent to the Rouge
River, in the Trenton Channel and at the mouth of the Detroit River but no
major point sources have been identified (UGLCCS, 1989). A similar
distribution was found in 1983 for total chlorobenzenes, except for a high
concentration (3,500 ppb) west of Fighting Island (Kaiser et al., 1985).
Mirex was not detected in Lake St. Clair in 1982 (Oliver and Bourbonniere,
1985) or the Detroit River in 1980 (Hamdy and Post, 1985). Dioxins
and furans were detected in sediment samples collected in the mid-1980s
from the St. Clair River (DOE and MOE, 1985, 1986; UGLCCS, 1989). The
highest concentrations were found in the Township ditch and the 1st Street
sewer. The octa- and hepta- congeners predominated and 2,3,7,8-TCDD was
not detected.
A review of PCBs in St. Clair River sediments concluded that a
temporal trend could not be assessed because of the variations in the studies
(Pugsley et al., 1985). However, there was an increase in concentration at the
Polysar-Dow area of the St-Clair River (on the Canadian shore), (DOE and
MOE, 1986) (Figure 8). The maximum levels were considerably higher than
the dredge spoil guideline of 0.05 ppm. Other areas where there is PCB
contamination include the vicinity of Ontario Hydro's Lambton generating
station on both sides of the river and in the Belle River (UGLCCS, 1989). The
range of concentrations along the American shore was relatively low. Oliver
and Bourbonniere (1985) did not detect an increase in the concentration of
PCBs in sediments between southern Lake Huron and Lake St. Clair. In
1982, mean concentrations of PCBs in Lake St. Clair sediments were much
lower than those reported for western Lake Erie (Oliver and Bourbonniere,
1985).
The Detroit River is a major source of PCBs to Lake Erie (Oliver and
Bourbonniere, 1985). PCBs enter the river from Lake St. Clair and there are
several point sources along the river. In 1980, PCBs were found in 78% of
the bottom sediment samples (Hamdy and Post, 1985). The highest
concentrations (> 500 ppb) were found along the Michigan shore, south of
Detroit. In 1982, the highest levels were found at the head of the river (Fallon
40