XINING, June 6 (Xinhua) -- As an ecological conservator at the Sanjiangyuan National Park in northwest China, 49-year-old Wenshol has witnessed a dramatic transformation in the local environment throughout the years.

"It was windy and sandy in the past, but now there is a lot of rain, and we can see more wild animals, taller grass and a better environment," said Wenshol, who was born into a local herder's family. Both his smartphone and his camera hold catalogue of pictures of rare species of animals, such as snow leopards and white-lipped deer. These images have been captured throughout the course of his career.

Sanjiangyuan, which means the "source of three rivers," is home to the headwaters of the Yangtze, Yellow and Lancang rivers. The area provides the lower reaches of these major rivers with more than 60 billion cubic meters of water annually. Home to Sanjiangyuan, the province of Qinghai has been dubbed "the water tower of China."

According to a report on the environmental conditions of Qinghai in 2021, recently published by the provincial ecology and environment bureau, water quality of the mainstreams of the Yangtze, Yellow and Lancang rivers in Qinghai were excellent, and the overall ecological and environmental situation in the province had been stable.

Statistics show that water quality of these three rivers in the province has been evaluated as excellent for 14 consecutive years, since 2007.

The Sanjiangyuan area once witnessed large-scale ecological degradation as a result of natural changes and human activities. The headwaters of the Yellow River was once cut off and many of the grasslands that herders relied on for their livelihood became barren.

Beginning in 2005, China launched a major ecological project to protect and restore the environment in Sanjiangyuan. In 2016, China started piloting the Sanjiangyuan National Park. Thanks to the protective measures, the ecological environment in the area has steadily improved.

Eurasian otters, often used to speculate the quality of a river ecosystem, have been frequently spotted in the area in recent years.

"The presence of otters proves that the area has become a safe and healthy habitat with a well-developed river system, which indicates good water quality in the area," said Zhao Xiang, director of Shan Shui Conservation Center. The center has caught lots of images of otters with infrared cameras set up along the Batang River of Yushu Tibetan Autonomous Prefecture in Qinghai.

In 2021, Qinghai carried out water ecological restoration and water environment improvement projects in the basins of the Yangtze River, the Yellow River and the Qinghai Lake.

"Qinghai prioritizes the protection of Sanjiangyuan in its efforts to promote ecological progress," head of the provincial ecology and environment bureau Tang Wanfeng said, adding that the province is determined to ensure the continuous flow of abundant clear water from the country's "water tower."