A group of local officials have been punished for failing to maintain the cleanliness of Baiyangdian Lake in north China's Hebei Province, after a large amount of rotting fish were discovered in the lake in February.

They included four environmental protection officials, one county deputy magistrate and two township officials.

According to the Hebei Provincial Environmental Protection Bureau, economic loss from the pollution has reached 23.8 million yuan (US$2.93 million).

The State Environmental Protection Administration revealed on Thursday that the fish were suffocated to death because of insufficient oxygen in the water as a result of heavy pollution.

The administration made the announcement after it conducted a joint investigation with the Ministry of Agriculture and the Hebei provincial government.

The investigation found that a lack of waste treatment in nearby towns and a glut of paper mills on the upper reaches of the lake were to blame for the pollution.

According to statistics, Baoding, the largest city on the upper reaches, produces domestic and industrial wastewater of 250,000 tons per day.

However, the city has only two sewage treatment plants with a combined daily capacity of 160,000 tons, which means 90,000 tons of wastewater are directly discharged into the lake without treatment every day.

In addition, none of the 12 counties on the upper reaches of the lake have sewage treatment plants.

The investigation revealed that the paper-making industry has been running out of control in Mancheng County on the lake's upper reaches in recent years.

The county now has 156 paper mills that produce 80,000 tons of wastewater every day; however, it has only one sewage treatment plant handling 30,000 tons a day. The rest of the wastewater receives basic treatment by the plants before it's discharged.

The investigation also found that some of the plants began covertly discharging wastewater when they realized the monitoring system of local environment authorities was inadequate.

Low water levels caused by drought also contributed to the deterioration of the water. The lake needs a water level of 8.4 meters to maintain its normal ecological function; however, due to long-term drought, the lake has long been under this level.

When the rotten fish were discovered in February, the water level was only 7.07 meters.

The Baoding municipal government has so far closed or limited the wastewater discharge of 218 plants and taken action against 11 of them for illegal discharge.

In a bid to clean it up, 50 million cubic meters of water will soon be transferred from two reservoirs into the lake.

The local government has put aside more than 2 million yuan (US$247,000) to compensate fishermen for their loss.

The once-thriving Baiyangdian Lake, known as the "Pearl of North China," has an area of 366 square kilometers and is the largest freshwater lake on the North China Plain.

(China Daily April 8, 2006)