BEIJING/SHANGHAI (Reuters) - China will impose more curbs on agriculture and widen restrictions on industrial development in the next five years in a bid to protect scarce, already contaminated water supplies from further pollution, a government official said on Friday.

FILE PHOTO - A farmer works on a polluted river in Shanghai, China, March 21, 2016. REUTERS/Aly Song/File Photo

The government is planning to restrict farming that encroaches on major rivers, restore wetlands and ecosystems and tackle excess water consumption in its 2021-2025 five-year plan, said Zhang Bo, head of the water department at the Ministry of Ecology and Environment, speaking at a news briefing.

With per capita water resources only a quarter of the global average, China has made the restoration of contaminated supplies a priority. Zhang said the government would now take ecological value into consideration as well as economic value.

Beijing has been drawing what it calls “ecological protection red lines” that make areas off-limits to agriculture and industry. But with water demand still on the rise, it must strike a balance between bolstering economic growth, maximizing agricultural output and protecting its rivers.

“Farmland that encroaches on the river is essentially not allowed to be there anyway,” Zhang told Reuters on the sidelines of the briefing in Beijing. “The drawing of ‘ecological protection red lines’ will take food security into consideration and strike that balance.”

China is in the middle of a campaign to restore the environment of the Yangtze river, which provides water to around 40% of the country’s population. The river has been damaged by decades of land reclamation, water diversion and the dumping of toxic waste.

Local governments have already been demolishing dams, relocating chemical plants, restoring wetlands and banning farming and fishing in ecologically sensitive areas, but some regions still fail to meet state water standards.

Earlier this week, China’s top prosecution office said 7,084 people were arrested for environmental crimes on the Yangtze in 2019, up 43% on the year, with offences including illegal fishing and sand mining as well as the dumping of waste.

The environment ministry said water quality was improving overall, with 75% of surface water sampled at 1,940 sites across the country up to standard in 2019, up 3.9 percentage points compared to 2018.

China divides its water into six grades, with the first three considered safe for human use. The ministry said 3.4% remained “below grade V” - meaning it was unfit even for industrial or agricultural use - down 3.3 percentage points on the year.