Chinese authorities tried to slow the spread of a toxic spill by building 51 makeshift dams along the tainted river and using fire trucks to pump out polluted water before it reaches a reservoir serving a city of 10 million people, state media said Friday.

The spill of 60 tons of coal tar into the Dasha river in north China's Shanxi province was the latest in a series of mishaps fouling the country's already polluted waterways. Officials said there have been at least 76 water pollution accidents in the last six months.

A villager who lives along the river described seeing dozens of dead fish floating in the water.

In a separate incident Thursday, a series of explosions rocked the Longxin Chemical Plant in the city of Longquan, Zhejiang province, destroying two factories and threatening to contaminate the Oujiang river, which empties into the East China Sea, the officialXinhua News Agency reported.

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A spring that feeds the Oujiang lies close to the blast site. Large amounts of sand and stones were trucked to the site in an effort to prevent any waste water from contaminating the river, Xinhua said.

One person was injured and two people were reported missing after the blast, it said.

In the Dasha river spill, a truck overloaded with 60 tons of coal tar — a substance linked to cancer — crashed Monday and dumped its contents into the river. Measurements Friday showed that levels of phenol, also known as carbolic acid, were 100 times greater than acceptable levels in some spots.

Cleanup crews scrambled Friday to absorb the toxic substance before it reaches the Wangkuai Reservoir of Baoding, a city of about 10 million people, Xinhua said.

It said a dozen fire engines were pumping polluted water downstream from the spill site and trucking it to a "closed environment" where it could be treated, without giving specifics.

The pollution was said to be traveling about nearly 1 mile per hour downstream toward Baoding, which is about 45 miles from the site of the accident.

The day after the spill, the pollution had reached Hebei's Fuping county, where some 50,000 residents rely on the river for drinking water. Fuping residents were told to take water from nearby reservoirs and seven standby wells until the river could be cleaned, Xinhua said.

Liu Qing, a villager who lives along the Dasha in Fuping, said by telephone that the water was not discolored and did not have any unusual odor but that she had this week noticed dozens of dead fish floating in the river.

Liu said her family normally drinks well water, not water from the river, so they have not been affected.

Another Fuping resident, Li Xingcui, said her family was still using the water to wash vegetables and take baths, ignoring warnings aired on local television. She said the water looked and smelled normal.

Li's family was taking water from a mountain stream for drinking.

Prolonged exposure to coal tar has been linked to increased rates of certain types of cancer but it is also used in small doses as a topical medicine to treat eczema and other skin diseases, according to the World Health Organization's International Agency for Research on Cancer.

Many of China's canals, rivers and lakes are severely tainted by industrial, agricultural and household pollution.

In November, a major chemical spill on the Songhua River halted water supplies to tens of millions in China and Russia. Local authorities were accused of reacting too slowly and delaying public disclosure of the spill.