NANCHANG, March 13 -- Wang De'an, a miner at China's largest open-pit copper mine, was pleased to see that the pungent, yellow Dawu River was much clearer this year.

Wang, 58, who works at Dexing Copper Mine in east China's Jiangxi Province, has watched the water quality deteriorate over the past few decades.

"Thirty years ago, we did not treat our wastewater," said Wang, adding that, sometimes, it was dumped straight into the river.

Since the 1980s, the mine has channeled 740 million yuan (120 million U.S. dollars) to support environmental protection efforts and was among China's first batch of 37 "national-level green mine pilot enterprises" in 2011. These enterprises tested scientific exploitation, efficient use of resources, standardized management, environment-friendly production and mine environment standards.

"The key to environmental protection at the mine is the treatment of wastewater," said Guan Yongmin, head of the mine.

Drainage ditches and large acidic reservoirs were built to separate rainwater from wastewater, explained Guan.

It has also developed a process to extract thousands of tons of copper, stones and other waste materials, called tailings, from wastewater, he said.

More than 80 percent of the 492 hectares of waste land at the mine have been converted into green spaces, with plants growing on the tailings, he added.

Government supervision and public complaints about pollution have forced the mines to go green.

In this year's government work report, Premier Li Keqiangsaid the government would fight to conserve energy, reduce emissions and improve the environment.

The Ministry of Land and Resources has approved 661 mines to be national-level green mine pilot enterprises.

The experiences of pilot enterprises will be disseminated to large- and medium-sized mines so that all can achieve green mine standards by 2020. Small-sized mines will also be managed according to the green mine standards.

However, the 661 pilot enterprises are minimal compared with the 100,000 mines across the country.

The majority of China's mineral resources are extracted by small and lean mines, which produce massive pollutants and use out-of-date machinery, said Shi Jingxi, an official with the China Mining Association.

Green mines need advanced technological innovation and the upgrading of production facilities, which small mines often struggle to afford, he said.

Meanwhile, even those pioneers with the reputation of "national-level green mine pilot enterprises" are facing mounting market pressures.

"The price we pay is far more than the market cost," said Yao Shaowu, general manager of Huzhou Xinkaiyuan Crushed Stones Co. Ltd., adding that lack of policy support is a big headache.

Compared with enterprises who spend the bare minimum on environmental protection, Yao's enterprise lost out.

Yao's company has invested a lot of money in environmental protection efforts and owes 26 patents concerned with resources, energy conservation, reduction of emissions and cleaner production.

However, Yao failed to persuade the local government to list his company as a hi-tech company, which can enjoy preferential taxation policies.

Zhao Quanhou, director of the financial research office of the Research Institute for Fiscal Science at the Ministry of Finance, called for more pilot enterprises and more green mine funding.