The endangered water shield is an aquatic plant that is used for food and medicine. After two decades of effort, Shizhu County in Southwest China's Chongqing is now the largest water shield producing region in the world, and farmers there have benefited. 

The edible part of the water shield is the tender leaf under the water, protected by thick pectin. The thicker it is, the better for sales and exports. Farmers say the best water shield in China grows in Shizhu County because of clean water, suitable temperatures and the soil.

Lei Boze is the station head of the National Chinese Medicine Technology Innovation Strategic Alliance. He has been studying water shields for many years. He says mountain spring water has only three milligrams of total dissolved solids (TDS) per liter. The TDS from a water shield field is between seven and 13 milligrams per liter. The TDS in commercially available bottled water is around 40 milligrams per liter.

Shizhu county has 13,000 mu of water shields or about 860 hectares. The annual output of each mu is one ton. According to this year's purchase price, water shield farmers can earn up to $1,500 per mu.

Cao Qunhua is a farmer in Tianwan village of Shizhu County, she told CGTN that she planted three or four mu of water shields. The government helps her replace the seedlings. She also has a subsidy of about $1,000 for water shields each year.

Apart from financial subsidies, the local government also helps local farmers develop ecological tourism by setting up hotels to boost their income. 

Because of the limited preservation time, harvested water shields are bought by the local agriculture commission and companies on the same day. Local companies are also using water shields to make products such as facial masks, noodles, and beverages to diversify usage. Farmers also have an option to be company shareholders and get dividends at the end of the year. 

For many families, this has been a ticket out of poverty, and some young adults have come back to the villages they left to help their elderly relatives sell products through e-commerce, some using techniques such as live-streaming to increase sales.