The BBC World Service Trust surveys 2,401 Cambodians from all walks of life.
About 60 million people depend on the Mekong directly or indirectly for their livelihoods.
At least eight hydroelectric dams have been proposed on the upper Mekong River.
Critics of the dam say it will hurt ecosystems in the river that provide a major source of fish for Cambodians.
Some say the connection between rural and urban areas across borders in the Mekong countries can help boost economies across the region.
Opponents say the dam could be damaging to the ecology of the river and the livelihoods of the people who rely on it.
Phnom Penh has around 5,000 families in slum areas with free access to safe water.
Vietnamese officials are criticizing the Lao government’s controversial plan to build a dam on the Mekong River.
There are 350 Cambodians registered with the Cambodian Student Association in Japan, 200 from the Tokyo area.
The Prey Lang forest spans the provinces of Kampong Thom, Steung Trang, Kratie and Preah Vihear.
Agricultural experts say the use of “pure” seeds can boost yields up to 20 percent.
Cambodia expects to have oil flowing by the end of 2012, with revenues expected to reach $1.7 billion.