China's rapid economic growth comes with a high price, costing the country its environmental health.

China's Environment Ministry issued the warning in its annual assessment Friday, saying the country's road to prosperity is still littered with pollution and a loss of biodiversity.

The report found about one-sixth of China's major rivers are so contaminated the water cannot even be used to irrigate crops. It also pointed to growing pollution along the coastline and said about half of the country's cities have been hit by acid rain.

Deputy Environment Minister Li Ganjie told reporters China's environment is in “very grave” condition and that the effort to clean up the damage still faces “many difficulties.”

Li did express confidence the country could make progress on pollution from heavy metals, promising new legislation to better monitor mining and construction projects.

China reported at least nine incidents of heavy metal poisoning last year, and seven through the first half of this year.

Also Friday, Li told reporters China is working to increase oversight of its nuclear power plants.

He said his ministry plans to upgrade safety requirements for the construction and operation of China's nuclear power facilities, learning lessons from the crisis at Japan's Fukushima power plant.

Japan has been battling to stop radiation from leaking at its Fukushima facility since the March 11 earthquake and tsunami that devastated parts of that country.