We are greatly relieved to see that emergency measures have finally contained a chemical spill that might otherwise have poisoned the water supply for millions of people in the city of Harbin.

It is the second time the capital city of northeast China's Heilongjiang Province has faced such a threat of water contamination.

Memory remains fresh that a blast at a petrochemical plant in Jilin, a city in neighboring Jilin Province, released toxic benzene into the Songhua River and forced Harbin, located downstream, to cut its water supply for four days last November.

This time, preliminary investigation found that workers in a chemical plant in Jilin Province illegally discharged pollutants into the Mangniu River, a tributary of the Songhua River. The pollution is much smaller in scale and far less serious than last time. But it still caused panic among Harbin residents, who rushed to shops to stock up on bottled water in scenes reminiscent of the disorder last November.

Those responsible must be held accountable and local authorities must take meticulous measures to ensure people's health is not affected.

We appreciate the quick reaction from relevant government departments, which have coordinated to take immediate measures to prevent pollutants in the water from flowing unchecked. Tests show the water supply for Harbin has not been contaminated, according to the city's environmental protection officials.

But it is not time for us to relax. Harbin environmental officials predict that it may take about 12 days for the polluted water to reach the city, which means we have yet to see the pollution's real effect.

It is regrettable that such an incident has happened again. Last year, local officials had vowed to pay more attention to such environmental emergencies after the Songhua River pollution caught them off guard.

Drawing on last year's lessons, environmental officials in both provinces have reportedly strengthened efforts in monitoring the water flow in the Songhua River. They have devised emergency response plans, which were put to use this time.

On the other hand, the incident shows that Jilin officials have failed to effectively regulate the pollutant discharge of local enterprises.

Admittedly, it is hard for them to prevent such illegal untreated discharges entirely. But as a province lying upstream, Jilin must be aware that unrestrained industrial activities may cause serious trouble for regions downstream.

It is its obligation to closely watch the production of local enterprises.

We hope Jilin can draw lessons from the incident not so serious as it is and ensure that no one under its jurisdiction will pollute the water resource it shares with the downstream areas.

(China Daily August 25, 2006)