Reading passage
High in the mountains of the northern range, at an altitude of about one thousand eight hundred metres, lies Lake Song Xanh, a body of water famous for its unusual colour. On clear days the lake appears deep blue, but in the early morning it can turn a pale green that local people compare to jade. The lake is fed by underground springs and by the snow that melts on the surrounding peaks each spring, and it has no river flowing out of it.
For centuries, the lake was known mainly to the ethnic minority communities who farm the valleys below it. Their stories describe the lake as a sacred place, and certain areas of the shore were traditionally closed to visitors during important festivals. The first written description of the lake by an outsider dates from 1911, when a colonial survey officer climbed the pass and recorded the depth and temperature of the water.
Reaching the lake is still not easy. The nearest town is thirty kilometres away, and the final part of the journey must be made on foot. A marked trail climbs for about four hours through pine forest and open grassland before it reaches the shore. Most visitors hire local guides, both for safety and because the money supports the villages that maintain the path. A small entrance fee, introduced in 2010, also funds trail repairs and rubbish collection.
The best season to visit is from April to June, when wildflowers cover the meadows and the weather is relatively stable. In winter the trail can be blocked by snow for weeks at a time, and in late summer heavy rain sometimes causes landslides on the lower slopes. Tour operators advise visitors to carry warm clothing even in June, because temperatures beside the lake can fall below ten degrees at night.
Scientists are interested in the lake for different reasons. Because no river flows out of it, the water carries a record of the surrounding environment. Researchers from the national university have been measuring the lake since 2005, and their data show that the water level has dropped by nearly two metres over fifteen years. They link this fall to warmer winters, which bring less snow to the peaks, and to increasing use of spring water by farms in the valley.
The falling water level worries local communities as well. Some marshy areas around the shore, where rare frogs breed, have dried out, and the fish that visitors once caught for dinner have become scarce. Village elders say the lake has never been so low in living memory. In response, the communities and the university have agreed on a monitoring programme that measures the springs every month.
Tourism at the lake has grown, but it remains small compared with famous national parks. Around twelve thousand visitors made the climb last year, and most stayed only a day. There are no hotels by the lake; visitors who wish to stay overnight sleep in tents at a designated campsite five hundred metres from the shore, where open fires are forbidden. Rangers say these rules have kept the area remarkably clean.
Nevertheless, pressure is growing. A private company has proposed building a cable car from the valley to a viewpoint above the lake, arguing that it would allow elderly and disabled people to enjoy the scenery. Supporters say the project would double local incomes. Opponents fear it would bring tens of thousands more visitors to a fragile environment and would damage the cultural meaning of the climb itself.
For the moment, the regional government has delayed a decision, asking for further studies of the environmental impact. Whatever the outcome, the lake illustrates a wider question facing mountain tourism: how to share beautiful and remote places without changing them beyond recognition. The people who live beside the lake, who have watched its waters for generations, are determined that their voice will be part of the answer.