Villagers say their livelihoods there are being threatened by continuous government concessions to private rubber and other companies.
Flooding along the Mekong River in three provinces has claimed six lives and left hundreds of families homeless.
Hardest hit are the provinces of Stung Treng and Kratie, where families have been evacuated and where roads and towns are flooded.
But an analyst says the U.S. engagement in Asia is motivated in large part by concern about China's growing influence.
Bird flu has claimed the life of a 4-year-old girl from Banteay Meanchey province, health officials confirmed Friday.
China has four hydrodams in operation on the Mekong and has plans for four more. Cambodia and Laos plan to build 12 more more dams.
Since the late 1980s, Mekong countries, especially China, have been looking at hydrodams as key energy sources to power economic growth.
Experts say as little as 30 percent of the country’s forest cover remains, while logging continues to be a problem.
Organizers look to collect 1,000 signatures before sending the petition to US President Barack Obama.
Tun Channareth said at least 156 other countries have signed the international treaty to ban landmines.
Representatives of both companies have been tight-lipped so far on the proposed dam’s construction.
In their letter, SRP lawmakers said more than 29,000 people from four different provinces had signed a petition.