BEIJING - A shortage of water quality monitoring stations is hindering China's ability to mitigate damage done by chemical spills in the nation's waterways, a senior official responsible for water resources said.

Due to the rapid expansion of heavy chemical manufacturing, a great number of chemical plants have settled along rivers, especially along the banks of the Yangtze River, China's longest waterway.

"Water safety may be at risk when environmental accidents occur because many rivers are sources of drinking water for cities along the banks," said Hu Siyi, deputy minister of water resources.

"But at this time, government authorities cannot notice every accident in a timely manner because of the limited number of water quality monitoring sites across the country. In some areas, monitoring is done only once a month," he said at a news conference organized by the State Council Information Office on Thursday.

In 2011, a total of 542 environmental accidents were handled nationwide, of which nearly 60 percent were triggered by traffic accidents and mishaps in the process of production, statistics from the Ministry of Environmental Protection showed.

In a case that happened in February, a leak of phenol from a cargo ship from South Korea potentially threatened the water supply in Zhenjiang, a city of 3 million people in East China's Jiangsu province.

Phenol, also known as carbolic acid, is an organic compound soluble in water. It can irritate the eyes and skin, and if absorbed in large amounts, can damage the liver and kidneys.

Officials said serious water shortages and pollution are "quite severe" and may threaten the country's sustainable growth.

In 2010, the total discharge of wastewater reached 75 billion tons and nearly 40 percent of river water failed to reach quality standards, according to statistics from the Ministry of Water Resources.

China's 1.3 billion people now consume more than 600 billion cubic meters of water a year, or about three-quarters of its exploitable water resources, Hu said.The average amount of water resources available per capita in China is only 2,100 cubic meters, or about 28 percent of the world's average, the ministry's figures showed.

About two-thirds of Chinese cities suffer from water shortages, while nearly 300 million rural residents lack access to safe drinking water, he added.

In January, the State Council released a document calling for a stricter water resources management system to end the country's water problems.

By 2030, China plans to contain total water consumption at less than 700 billion cubic meters a year, according to the document.

Also, the government will control the total quantity of pollutants discharged into rivers to ensure water quality of key rivers and reservoirs across the country, according to the document.

China will also spend 1.8 billion yuan ($285.6 million) to set up a nationwide information management system for water resources within the next three years.

"The country's monitoring of water resources is expected to greatly improve after the system goes into use," Hu said.

"Government authorities need to increase the frequency of water quality monitoring. Also, timely information on water quality not only needs to be open to the public at times when spills occur, but it is also necessary in daily life," said Zhang Miao, a member of Greenpeace, a non-government environmental organization.