Chinese companies are funding a multi-billion dollar project to dam the Irrawaddy river in Myanmar.
The river, the longest one left undammed in southeast Asia, is important to the Kachin people, and millions of people up and down its length would be affected by the changes, experts say.
When it is dammed, it will leave an area the size of New York City submerged.
There are now concerns over who is to benefit from the river's riches.
Our special correspondent in Myanmar, who we cannot name for security reasons, filed this report.