Lake St. Clair Coastal Habitat
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Contaminated Sediments

Sediment cleanup on the Detroit River AOC. Photo: The Rouge River Project

Lake St Clair and its tributaries lie within one of the most highly developed regions in the Great Lakes. Urban development and agriculture surrounding Lake St Clair and of its tributaries are sources of pollution to the lake's sediments. Detroit, one of the largest cities in the region, lays on the Lake and Sarnia, a large Canadian industrial center, is on the St Clair River . The United States Environmental Protection Agency estimates that of the 12 billion cubic yards of surface sediments (the first five centimeters of sediments) which lay within the United States, ten percent, or 1.2 billion cubic yards, of these sediments are contaminated to levels at which there is potential risk for aquatic organisms. They also estimate that between 3 million and 12 million cubic yards of dredged material are also contaminated.

The International Joint Commission (IJC) has identified 43 Areas of Concern (AOC) in the Great Lakes in which the levels of pollutants in the sediments contribute to impairment of beneficial uses . Many are tributaries or the connecting channel to Lake St Clair, including the Clinton River and St Clair River (including its tributaries the Belle River and Black River). The Detroit River, the outlet of Lake St Clair has also been identified as an AOC. These are areas where aquatic health has been compromised.

Polycyclic aromatic hyrdrocarbons (PAHs) are also common in the sediments of Lake St Clair and its tributaries. Trace metals are also found in abundance. Arsenic, cadmium, copper, and zinc were all found in the sediments of Lake St Clair and its tributaries. Cadmium was found at the highest levels in the Clinton River at 7.9 the Probable Effect Level (PEL). Lake St Clair has moderately elevated levels of copper, nickel, zinc, chromium, cobalt, volatile solids and phenol. Mercury and cyanide are found at especially high levels.

The elevated levels of sediment contaminants have been shown to have high potential costs. Sediment contaminants can cause disease in aquatic organisms including tumors, fin rot and the loss of species and communities. These sediments can also poison the food chain through biomagnification resulting in high concentrations of toxics in predator fish. Societal costs include the loss of recreational fisheries, revenue from polluted areas and even worse - potential long term health effects such as cancer or neurological damage and IQ impairment to children.

Remediation plans primarily include the removal of contaminated sediments and improved wastewater treatment, but are also beginning to address non-point source pollution, habitat restoration and pollution prevention among others. The cost of this remediation is estimated to be $7.4 billion dollars (USD) for the removal of toxic sediments and the improvement of wastewater infrastructure . The United States approach to raising funds for the clean up is to target the primary polluters of the AOC when possible and require these groups to pay for the costs of remediation. When this is impossible, funds must be obtained from elsewhere. Within the Lake St Clair - Lake Erie corridor, $1 billion dollars (USD) has been spent to assist in upgrading the waste water treatment infrastructure. The major hurdle which is preventing progress for many AOC's is that the high costs have not been supported .

For more information, see: Coastal Habitat Plan, Section V (PDF)