http://english.al-akhbar.com/content...E2%80%99-water
So with this we may see the first full blown water war, the longer this goes on the more likely for this to happen and it completely shut down the flow 2 weeks ago. The fact that we aren't hearing about this until now may mean that all 3 nations are looking for a war. Syria of course has been having issues with Syria but can't do much due to the Civil war, Iraq and Turkey have also had issues in the past. Another thing of note is that the areas in both countries that will be most effected by this are areas that are controlled mostly by ISIS, that is terrorist controlled areas. Such areas are more likely to attack the Dam and Turkey which would likely lead Turkey to claim that it was attacked by either Syria or Iraq and "defensively" declare war. NATO nations would be required to defend them, however, other nations would likely see this as an offensive war due to Turkey shutting the water down in the first place.
This could lead to issues, however, Syria and Russia are still good allies and if Russia went to help out Syria NATO could legally go to war on Turkey's side to defend it from Russia.
TLDR; Most Pre-WW1 like scenario we have seen in awhile. On the other hand this could be nothing seeing as there has been little news on it.
So discuss i suppose.