Israel has considered exploiting the Litani where it "makes a 90 degree angle, turning deeper into Lebanon, only 2.5 miles from the Lebanese/Israeli border. It remains that the Litani runs within easy tunneling distance from Israel. It is less than 10 kilometers from the upper regions of the Jordan, which Israel controls, and it is only a couple of kilometers between the bend of the Litani and one of the upper tributaries of the Jordan. By using a relatively easy way to construct a tunnel through the mountains, it is believed the Litani would flow by gravity into Israel's National Water Carrier system (in part because the bed of the Litani is higher than the inlet to Lake Tiberias).
The particular point of concern is where the Litani breaks its southward course and turns west toward the Mediterranean below the Chateau de Beaufort. "This proximity is, in fact, the geopolitical link between the rivers, because Israel had hoped to connect the Litani with the Jordan, thus enabling it to pump those waters, duly blocked, into Israel proper."
Diversion of the Litani is not all that easy for the Israeli planners. In order to facilitate diversion near Beaufort, the river must be managed from central Biqa'a to Beaufort. The entire course of the Litani would need to be controlled to have the necessary water level at the inlet to the tunnel. Also, at the inlet, in order to maintain the suction pressure needed, one or more weirs would be needed to raise the water level. To further complicate things, throughout the seasons, the Litani's flow greatly varies and the result would be too much water at the flooding season and too little water during the dry season. Therefore, the River would need to be controlled from the Biqa'a Valley, which the Israelis would need to occupy in order to do so.
Additionally, much of the Litani flows through a deep gorge and is not only very difficult to manage but for Israel to conquer. Obviously, it isn't simple to use this water for irrigation. In order to use the Litani, one would have to, through civil works, control nearly the whole upper part of the river.
In order to control the needed part of southern Biqa'a, including the valley and its river, Israel would need to control the ridges on both sides of the valley. For this, money is available. Nasrallah and the Shi'ites hope to defeat Israel's plan.