The Kishon River drains the Jezreel Valley into the Mediterranean Sea, and it was the location of the slaughter of the prophets of Baal during the time of Elijah (1 Kgs 18:40).   From Arutz-7:

The Kishon River, considered the most polluted river in Israel, will soon be the object of a major cleaning and purification project. The initiative is a joint project of the Ministry of the Environment, the Kishon River Authority, and factories and chemical plants on the river’s banks. At the same time, the Shefa Yamim company continues to seek diamonds under the Kishon riverbed, based on advice from the late Lubavitcher Rebbe. The company, which has already found diamonds and associated minerals in the vicinity, plans a stock issue of $100 million in the coming months. The Kishon River’s pollution stems in part from daily contamination for over 40 years by runoff of mercury and other metals from nearby chemical plants. It has been claimed that there are more chemicals than water in the Kishon. The river runs 70 kilometers from Jenin in Samaria, via the Jezreel Valley and Zevulun Valley, and into the Mediterranean Sea near Haifa.

The full story is here.