This BBC interview from early June is about the comments of the huge numbers going into Siem Reap, and the needs to protect the famous Wat.

http://www.bbc.co.uk/news/world-asia-18354513

I remember recently the story was the airport was built right across the river and no way for water to flow on.

Standing on the bridges, the water seems to be lifeless with no flow. Maybe this is one thing of many, to be looked at.