More than 200 state and federal workers will poison the Chicago Sanitary and Ship Canal early next month in an attempt to keep destructive Asian carp from reaching Lake Michigan.

They will use rotenone, the potent, plant-based chemical recently used to poison unwanted goldfish threatening endangered native species in two Dundas Valley ponds.

Ecologist Shari Faulkenham says the Hamilton Conservation Authority used about 25 litres, while the United States effort will require almost 200,000.

Before the poison is applied, crews will use electrodes to shock fish to the surface and identify sport fish that can be safely relocated.

U.S. officials say the electric fish barrier blocking the canal needs maintenance, but before it can be shut down they need to make sure the carp won’t get past it when the power is cut.

John Rogner, of the Illinois Department of Natural Resources, says they’ll do that with a two-day, $1.5-million US project to poison nearly 10 kilometres of canal just southwest of Chicago. It’s scheduled to start Dec. 2.

The invasive Asian carp have been detected within 1.5 kilometres of the barrier, which is about 30 kilometres downstream from the Lake Michigan shoreline.The canal is a manmade waterway that connects the Great Lakes and the Mississippi River basin.

Asian carp have moved up the Mississippi and Illinois rivers during the past 15 years, and are now threatening to enter the Great Lakes, where they are considered a serious threat.