The eco-system around the lake is also under threat from over-grazing.

"The wetland is the habitat for wildlife and is also closely linked with the life of human beings. It is affected by human activities such as grazing," said Tsewang Tengyal.

The eco-system of the pasture in the wetland worsened as a result of over-grazing, he said.

To protect the eco-system and biodiversity of the wetland, in 2015, the Lake Manasarova Wetland was listed as a pilot area for an eco-compensation mechanism funded by the Ministry of Finance.

Under the pilot program, impoverished local herdsmen are employed by Purang forest bureau as rangers to patrol the wetland, which has put the wetland under protection and also offered job opportunities to impoverished families. Pema and other rangers receive a monthly salary of around 2,000 yuan ($316).

In addition to the hiring of rangers, subsidies are provided to herdsmen to compensate their economic losses incurred from limitations on grazing.

In 2017, a total of 25 million yuan was used to finance the wetland eco-compensation program in Tibet.

The efforts have paid off as residents have more impetus to protect the natural environment in the wetland.

"We no longer litter the pasture with garbage when grazing livestock and drive away wild animals," said Ukin, a villager in Shongpa. "More and more water birds rest at the lake," he said.

"As every piece of grass and tree is protected, the natural environment in the wetland area has improved, drawing an increasing number of visitors and bringing more incomes to villagers," said Pema Gyalpo, former head of the Party branch of Shongpa.

In July 2017, Lake Manasarova Wetland was upgraded to a national-level wetland preserve, and more efforts are expected to maintain the pristine environment of the "holy lake".

"We will enhance the self-sustaining ability of the preserve and build a scientific and efficient management system with the view to building the Lake Manasarova Wetland into a beautiful international wetland park," said Tsewang Tengyal.