After rising steeply for many years, emissions of three important pollutants began to decline last year, the Chinese Ministry of Environmental Protection announced Thursday as part of an annual report.

But total levels of pollution in China's lakes, rivers and coastal waters continued to rise, the ministry said, as more pollutants continued to flow into them than their ecologies could absorb. In addition, the air in many Chinese cities remains severely polluted.

The ministry said that emissions of sulfur dioxide, mainly emitted by coal-fired power plants and the primary cause of acid rain, declined 4.66 percent last year.

The government has been pursuing a stringent program of requiring power plants to cleanse most of the sulfur dioxide from their flue gases before they are emitted, and environmentalists had been expecting this program to show success eventually.

Emissions of organic pollutants into waterways, as measured by tests of chemical oxygen demand, also declined by 3.14 percent last year, the ministry said. And industries reduced their discharges of solid waste into the air and water by 8.1 percent last year.

Ma Jun, an environmentalist in Beijing, said that while the calculations might be accurate, they did not mean that the air and water in China were becoming cleaner.

That was because the overall levels of pollutants are still far higher than the environment can tolerate, he said, adding that pollutants are particularly accumulating in China's waters.

''We need to have the understanding this is just the turning point in pollution discharges, this isn't the turning point in the environment,'' he said.

The ministry said that the percentage of China's coastal waters rated at the worst possible level of pollution rose to 25.4 percent last year, from 24.3 percent a year earlier.

The proportion of coastal waters in good condition dropped to 62.8 percent from 67.7 percent.

The proportion of Chinese cities with fairly good air quality was practically unchanged last year, while the number of extremely polluted cities declined.

Air quality tends to improve faster than water quality in China when pollution is reduced.

Fresh air typically flows in from Siberia and Central Asia while China's polluted air is wafted east across the Korean peninsula, Taiwan and Japan, with some pollution reaching the United States.

The pollutants identified by the environmental ministry as showing improvement, particularly sulfur dioxide, tended to be those emitted by relatively few factories and power plants, many of them state-owned or state-controlled. That makes it easier to limit pollution.

Air quality experts calculate that up to 90 percent of deaths from air pollution are caused by tiny particles of soot. The biggest contributors inside cities, released close to where people breath, are trucks, which China has struggled to clean up.

The ministry provided no figures on Thursday for emissions of particles.