Guyana Supreme Court has ordered that a $2B class action lawsuit filed against Omai Gold Mines in connection with a 1995 tailings dam accident be dismissed and costs awarded to the defendants.

The defendants to the suit were Omai Gold Mines, a subsidiary of Quebec’s Cambior, consultants Golder Associates, Home Insurance, environmental consultants Knight Piesold, Golden Star Resources, and several international banks.

A tailings dam at the mine was breached on 19 August 1995. Company officials said the spill was caused by the failure of the dam’s compressed saprolite core. The structural integrity of this highly weathered bedrock material had been attested to by two Canadian engineering firms. Over a period of 100 hours, 120M gallons of gold mine tailings spilled into the Omai and Essequibo rivers.

The Essequibo river serves as the primary source of water for drinking, cooking, bathing, livestock and agriculture for local residents. After the spill, a ban was placed on the sale and consumption of all fish from the river, along with a ban on bathing, drinking, cooking and other domestic uses. A preliminary report by the Pan American Health Organization, however, estimated that only between 100 and 200 people actually suffered exposure to environmental health risks from the spill. Although environmental NGOs originally claimed more than 11,000 fish and a number of hogs were poisoned in the spill, it was actually determined that only 351 dead fish were found in the Omai river. No dead fish were found in the Essequibo river into which the Omai flows.

A number of national and international agencies were called in to monitor and remediate the spill’s effects, including the United Nations, the OAS, the World Health Organization and the Pan American Health Organization. Meanwhile, a Guyana Commission of Inquiry found no criminal liability for the spill.

The spill generated international headlines, and is still cited by environmentalists as an example of an alleged environmental disaster resulting from the use of cyanide in mining processes, and the disposal of heavy metals in mine tailings. The Omai mine was shut down in the third quarter of 2005 after 13 years of operation due to the depletion of mineral reserves.