As the pollution stretch on northeast China's Songhua River moves downstream, Jiamusi, the second largest city on the lower reaches, has launched a backup water source north of the river to ensure safe water supply.

The backup source, known as Jiangbei water source, is a long-term project designed to supply 200,000 tons of quality ground water per day. Its construction is almost completed and theproject will start operation before the pollution belt arrives in Jiamusi on Dec. 6, said a spokesman with the city government Friday.

The government is also having deeper wells dug across the city to ensure water safety.

Altogether 192,000 people live in 159 villages along the one-kilometer Songhua River banks in Jiamusi. The 20,000 wells they use are all shallow and susceptible to river water pollution.

Subfreezing temperature has slowed down the speed of the pollution stretch but the pollutant density is still high, the provincial environment watchdog has warned.

The water pollution was caused by a chemical plant blast on November 13 in the neighboring Jilin Province, resulting in serious leakage of poisonous substances into the Songhua River.

Harbin, capital of Heilongjiang with the Songhua as its main water supply source, enforced a four-day suspension of water supply on November 24.

Currently, the water supply in Harbin has resumed and water quality at all water supply stations have met national standards.