First in! ;')
There has been pressure on aquifers (even the desert has those) due to decreasing rainfall (it has been decreasing for at least 4000 years); also the lake is pretty shallow, and exposed to a cloudless sky and the unforgiving rays of the Sun. Other things didn't help much, such as water diversion projects, and attempts to use the water for irrigated agriculture.
Chad has good relations with Israel -- perhaps they can learn all about the trickle irrigation techniques the Israelis have developed. But first, Chad will need to get rid of the Islamofascist threat.
That, too, is something they can learn from Israel!