Untreated wastewater from Palestinian Arab towns has been polluting the Besor-Hebron-Be’er Sheva River for decades, thanks to international water laws. Now a 3-year project has been agreed between Israel, the PA and the Bedouin community to clean up the river.
http://arava.org/2015/03/restoration-of-the-besor-hebron-beer-sheva-river/