Baoding, China ? The toxic coal spill down the Dasha River has slowed, Chinese authorities said.

Officials were scrambling to clean up the sludge – which had earlier been reported to amount to 60 tons – before it reached the Wangkuai reservoir in Baoding, a city of 10 million in Hebei province, the official Xinhua News Agency reported. The sludge was 32 miles from the reservoir Sunday.

The reservoir is also meant to be a standby source for the Olympic Games, Xinhua said.

The spill occurred when a truck overloaded with 80 tons of toxic coal tar fell into the Dasha River last Monday, leaking some of its contents into the river.

Dams, pumps and cotton quilts helped slow the sludge’s flow so that it traveled just one mile down the Dasha River over the past two days, the official Xinhua News Agency reported. Cleanup work was stepped up as government leaders urged local residents and officials to deal aggressively with the latest mishap to damage the country’s heavily polluted waterways.