Deficiency in rainfall is reflected in an absence of permanent rivers or streams, and the approximately twenty perennial lakes are brackish or salty. The allocation of limited water is considered of sufficient importance to warrant the existence of the Secretariat of Dams and Water Resources, and damaging a source of water can be penalized by a heavy fine or imprisonment.

The government has constructed a network of dams in wadis, dry watercourses that become torrents after heavy rains. These dams are used both as water reservoirs and for flood and erosion control. The wadis are heavily settled because soil in their bottoms is often suitable for agriculture, and the high water table in their vicinity makes them logical locations for digging wells. In many wadis, however, the water table is declining at an alarming rate, particularly in areas of intensive agriculture and near urban centers. The government has expressed concern over this problem and because of it has diverted water development projects, particularly around Tripoli, to localities where the demand on underground water resources is less intense. It has also undertaken extensive reforestation projects.

There are also numerous springs, those best suited for future development occurring along the scarp faces of the Jabal Nafusah and the Jabal al Akhdar. The most talked-about of the water resources, however, are the great subterranean aquifers of the desert. The best known of these lies beneath Al Kufrah Oasis in southeastern Cyrenaica, but an aquifer with even greater reputed capacity is located near the oasis community of Sabha in the southwestern desert. In the late 1970s, wells were drilled at Al Kufrah and at Sabha as part of a major agricultural development effort. An even larger undertaking is the so-called Great Man-Made River, initiated in 1984. It is intended to tap the tremendous aquifers of the Al Kufrah, Sarir, and Sabha oases and to carry the resulting water to the Mediterranean coast for use in irrigation and industrial projects.