A lake shaped by myth and geology
Rih Lake, or Rih Dil, is a natural heart-shaped lake located in the Chin State of northwestern Myanmar, only about three kilometers from the Indian border. The lake is approximately 1.6 kilometers long, 0.8 kilometers wide, and has a maximum depth of about 18 meters (60 feet). Geologically, the area is defined by a flysch sequence of Eocene age, composed of rock types like laminated siltstone, sandstone, and conglomerates. The lake itself is surrounded by mountains and sits at an elevation of around 900 meters (2,966 feet).
For the Mizo people, who live on both sides of the modern border, the lake holds deep cultural and spiritual importance. Traditional beliefs hold that the souls of the dead must pass through Rih Dil on their journey to the afterlife, known as Pialral. This belief is so ingrained that a common saying states, "The largest lake of Mizoram is Rih Dil, which is but in Burma (Myanmar)." The lake's name itself comes from folklore about a girl named Rih-i who transformed herself into water to save her younger sister.
A conservation conundrum
The unique ecosystem of Rih Lake faces a significant challenge that respects neither folklore nor geology: an international border. The lake and its watershed host fish species that have evolved in isolation. This biological reality collides with political geography. Certain endemic fish species live their adult lives in the main body of the lake in Myanmar but migrate upstream to spawn. Their spawning grounds are located in tributary streams that flow across the border into the Indian state of Mizoram.
This cross-border migration creates a complex conservation problem. Protecting the species requires coordinated efforts from both India and Myanmar. Conservation policies focused solely on the lake within Myanmar would fail to protect the critical spawning habitats in India. Likewise, actions taken in India concerning the upstream tributaries could directly affect the fish populations that form the core of the lake's ecosystem in Myanmar.
The situation is further complicated by regional instability and development pressures. A planned government housing project threatened to clear over 15 acres of forest around the lake, which could have unknown consequences for the fragile ecosystem. The India-Myanmar border has seen increased restrictions and the scrapping of the Free Movement Regime (FMR), which historically allowed local communities to travel up to 16 km across the border without a visa. These political and security issues create substantial barriers for the kind of joint scientific research and coordinated conservation management necessary to protect the lake's binational biodiversity.